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药剂学代写-PHRM2021
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Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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This exam paper must not be removed from the venue
School of Pharmacy
EXAMINATION
Semester One Final Examinations, 2019
PHRM2021 Dosage Form Design A1
This paper is for St Lucia Campus students.
Examination Duration: 120 minutes
Reading Time: 10 minutes
Exam Conditions:
This is a Central Examination
This is a Closed Book Examination - specified materials permitted
During reading time - write only on the rough paper provided
This examination paper will be released to the Library
Materials Permitted In The Exam Venue:
(No electronic aids are permitted e.g. laptops, phones)
Calculators - Casio FX82 series or UQ approved (labelled)
Materials To Be Supplied To Students:
1 x Multiple Choice Answer Sheet
Instructions To Students:
Additional exam materials (eg. answer booklets, rough paper) will be
provided upon request.
MCQ Questions to be answered in pencil NOT pen on the computer answer
sheet provided. Each question carries the number of marks indicated and there
is only ONE correct answer
Venue ____________________
Seat Number ________
Student Number |__|__|__|__|__|__|__|__|
Family Name _____________________
First Name _____________________
For Examiner Use Only
Question Mark
Total ________
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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DATA SHEET
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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SECTION A — MULTIPLE CHOICE QUESTIONS — 120 MARKS
Answer this section on the multiple choice answer sheet provided.
Fill in the answer sheet using pencil, NOT pen. Mistakes must be completely
erased (avoid smudging). Answer by filling in, not circling or crossing the spaces.
Do not write on the multiple choice answer sheet except where indicated.
EACH QUESTION IS WORTH 2 MARKS,
EXCEPT QUESTIONS 39,40,41,47 WHICH ARE WORTH 3 MARKS.
THERE IS ONLY ONE CORRECT ANSWER TO EACH QUESTION.
1. Which one of the following is a synthetic suspending agent?
(a) Bentonite
(b) Acacia
(c) Alginate
(d) Tragacanth
(e) Carbomer (Carbopol)
(2 Marks)
2. What is the pH of 0.05 M sodium acetate (CH3COONa) given that the pKa of
acetic acid is 4.66?
(a) 7.4
(b) 5.01
(c) 4.66
(d) 18.02
(e) 8.68
(2 Marks)
3. Complete the following statement. Good Laboratory Practice (GLP) in the
pharmaceutical industry involves:
(a) laboratory equipment & instrumentation
(b) records, documenting & archiving
(c) sampling procedures
(d) stability programs
(e) All of (a), (b), (c) and (d)
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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4. Which ONE of the following statements about formulating suspensions is
INCORRECT?
(a) A suspension is an appropriate dosage form when an insoluble active
pharmaceutical ingredient (API) needs to be given in liquid form
(b) Suspension is preferred over solution when an API needs to be given in
liquid form, but hydrolyses in water
(c) Suspension is preferred over solution when a suspended insoluble salt
may be more stable compared to the parent compound
(d) Suspension is preferred over solution when an API is unpalatable and
therefore compliance will be greater
(e) Suspension is preferred over solution because suspended drug particles
absorb faster than drug molecules in solution
(2 Marks)
5. Which option correctly completes the following statement: according to the British
Pharmacopoeia descriptive code for solubility, if sulfadiazine is sparingly soluble
in water, sulfadiazine sodium is MOST LIKELY to be ____________ in water.
(a) practically insoluble
(b) slightly soluble
(c) freely soluble
(d) sparingly soluble
(e) none of (a), (b), (c) or (d)
(2 Marks)
6. What is the pH of 1% w/v solution of ethanolamine (Mw = 61.08, pKa = 9.4)?
(a) 4.6
(b) 9.4
(c) 11.3
(d) 1.2
(e) 7.4
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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Questions 7-9 relate to homatropine. Homatropine (MW 275; solubility 1 g/500 ml) is
formulated as an eye drop by preparing a 2% aqueous solution of homatropine
hydrobromide (MW 356) because the salt of homatropine is much more soluble
(solubility 1 g/6 ml).
Homatropine
7. Homatropine is:
(a) Acidic in aqueous solution with a pKa of 9.7
(b) A zwitterion in solution with two pKa values of 3.3 and 9.7
(c) Acidic in aqueous solution with a pKa of 3.3
(d) Basic in aqueous solution with a pKa of 9.7
(e) Basic in aqueous solution with a pKa of 3.3
(2 Marks)
8. The molar solubility of homatropine is:
(a) 0.0036 M
(b) 0.0056 M
(c) 0.0028 M
(d) 0.0073 M
(e) 0.468 M
(2 Marks)
9. What pH below is the closest to the pH at which precipitation of homatropine
starts to occur?
(a) pH 8.9
(b) pH 7.9
(c) pH 4.1
(d) pH 10.5
(e) pH 7.3
(2 Marks)
O
OH
O
N
CH3
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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10. Fluoxetine has the following structure and a pKa of 8.4. What percentage of
fluoxetine would be ionised at pH 6?
(a) < 1 %
(b) 10 %
(c) 50 %
(d) 90 %
(e) > 99 %
(2 Marks)
For questions 11-14 consider the compound below:
This is the structure of the antibiotic flucloxacillin (mw 454, solubility at 25°C = 4.4 x
10-4 M).
11. Flucloxacillin has one ionisable group and consequently one pKa value. Based
on the structure above, select the CORRECT statement:
(a) Flucloxacillin is acidic in aqueous solution with a pKa of 7.7
(b) Flucloxacillin is a zwitterion in solution with pKa values of 2.7 and 7.7
(c) Flucloxacillin is basic in aqueous solution with a pKa of 7.7
(d) Flucloxacillin is acidic in aqueous solution with a pKa of 2.7
(e) Flucloxacillin is basic in aqueous solution with a pKa of 2.7
(2 Marks)
O
N
NH
N
CH3
S
CH3CH3
OH
O
O O
Cl
F
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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12. What is the % ionization of flucloxacillin in plasma at pH 7.4?
(a) 0.002%
(b) 33.4%
(c) 50.1%
(d) 66.6%
(e) 99.998%
(2 Marks)
13. You are required to formulate an aqueous solution of flucloxacillin to obtain a
concentration of 50 mg per 5 ml at 25°C. What is the molarity of this solution?
(a) 0.022 M
(b) 0.22 M
(c) 0.044 M
(d) 0.44 M
(e) 0.055 M
(2 Marks)
14. What would be the minimum pH to which you could formulate your aqueous
solution of flucloxacillin with a concentration of 50 mg per 5 ml at 25°C?
(a) 10.0
(b) 9.4
(c) 6.0
(d) 4.7
(e) 4.4
(2 Marks)
15. Which of these factors affect solubility?
(a) Temperature
(b) Polarity
(c) Co-Solvent
(d) Solute presence
(e) All of (a), (b), (c) and (d)
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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16. Identify the polar functional group from options (a) to (e) below:
(a) -CH3
(b) -CH3Cl
(c) -F
(d) -R-OH
(e) –OCH2CH3
(2 Marks)
17. Select the CORRECT statement:
(a) Amino acids that have a net charge of zero are neutral
(b) Amino acids always carry a net negative charge at low pH
(c) Amino acids do not have pKa values, they have a pI to describe ionization
(d) If the pH is more than the pI then the amino acid will have a net negative
charge
(e) When amino acids are unionized they are not very soluble in water
(2 Marks)
18. The structures of sulphanilamide (pKa 10.4) and sulfacetamide (pKa 5.4) are
shown. Which one of the following statements is CORRECT?
(a) Both drugs are acidic in solution, and sulfacetamide is a stronger acid than
sulfanilamide
(b) Sulfacetamide acts as a base in solution, while sulfanilamide is an acid
(c) Sulfanilamide is neutral in solution but sulfacetamide acts as a base
(d) Both drugs are basic in solution, and sulfanilamide is a stronger base than
sulfacetamide
(e) Sulfanilamide is basic in solution while sulfacetamide is acidic
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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Questions 19-20 relate to fluoxetine: The structure below is fluoxetine, which has a
pKa of 8.4.
F
F F
O NH
CH3
Fluoxetine
19. In which of the following solvents would you expect fluoxetine to have the highest
solubility:
(a) Pure water
(b) 0.1 M buffer at pH 9.4
(c) 0.1 M hydrochloric acid
(d) 0.1 M buffer at pH 8.4
(e) Human plasma at pH 7.4
(2 Marks)
20. Which of the following statements is CORRECT regarding fluoxetine in aqueous
solution?
(a) It is a weak acid because it has a proton that will be donated at the correct
pH
(b) It is a weak base because the lone pair of electrons are available
(c) Is non-ionisable because it has a lone pair of electrons that are
delocalised into the benzene rings
(d) It is a weak acid because it has an oxygen atom that is available to accept
a proton
(e) It is a weak base because it has an amide group at the end of the carbon
chain
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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21. Which of the following statements are CORRECT regarding micelle formation?
I Micelles form when the interface is saturated with the surface active agent
II Increasing the length of the hydrophobic chain causes CMC to decrease
III Adding electrolyte to a solution containing ionic surfactants causes CMC to
decrease
IV Increasing the hydrophilicity of the head group causes CMC to increase
V Increasing the temperature causes CMC to decrease
(a) I, II, and IV only
(b) I and V only correct
(c) II, III and V only
(d) I, III and V only
(e) All I, II, III, IV and V
(2 Marks)
22. Identify the species acting as a base in the following reaction at equilibrium:
HCO3- + H3O+ ↔ H2CO3 + H2O
(a) H2CO3 only
(b) H3O+ only
(c) HCO3- only
(d) HCO3- and H2O
(e) H2CO3 and H3O+
(2 Marks)
23. If you acidify water by adding HCl and find that the pH=5 what is the
concentration of H+ present?
(a) -0.699 M
(b) zero – it is all present as HCl
(c) 1 x 10-5 M
(d) 0.699 M
(e) 5 M
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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24. Select the CORRECT completed statement:
The structure above:
(a) Is a cationic surface active agent because it has a positively charged head
group
(b) Is a non-ionic surface active agent because it has an overall neutral
charge
(c) Is a non-ionic surface active agent because of the non-polar tail
(d) Is an anionic surface active agent because of the polar head group
(e) Is an ampholytic surface active agent because it has positive and negative
charges
(2 Marks)
25. Select the INCORRECT statement:
(a) Creaming can be retarded by increasing the density difference between
the oil and water phases
(b) Surfactants with HLB values above 8 are suitable for stabilising oil in water
(o/w) emulsions
(c) Cracking of emulsions refers to coalescence of droplets of the disperse
phase
(d) Cetrimide is an example of a cationic surfactant
(e) Tween surfactants are normally used to stabilise oil in water (o/w)
emulsions
(2 Marks)
26. Thixotropy is a desirable property for oral suspensions such that the suspension
thins on shaking and rethickens on standing. Which of the following formulation
approaches would you use to achieve this?
(a) Formulate a suspension with a high concentration of deflocculated
particles
(b) Keep the viscosity of your formulation low
(c) Use a high viscosity vehicle such as syrup that exhibits Newtonian flow to
suspend your drug
(d) Add an electrolyte to act as a flocculating agent
(e) Incorporate a long chain polymer such as methylcellulose with
pseudoplastic flow that forms a 3-D network
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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Use the diagram below to answer question 27:
27. Which of the following statements is CORRECT for fluids demonstrating time-
dependent rheology:
(a) Fluids with pseudoplastic flow may exhibit rheopexy
(b) Thixotropic flow is not a desirable characteristic for pharmaceutical
suspensions
(c) Thixotropic flow may cause problems with mixers and overheating during
production
(d) Hysteresis is seen when the up- and down- curves are superimposable
(e) A Newtonian liquid will not exhibit thixotropy
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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Use the diagram below to answer question 28:
28. The diagram shows a viscosity modifying polymer in its neutral coiled state.
Which of the following formulation approaches would you consider MOST
LIKELY to increase the viscosity of products that could use this polymer?
(a) Investigate the effect of adding increasing amounts of triethanolamine on
viscosity and pH
(b) Add citric acid to lower the pH to 2 units below the natural pH of your
formulation
(c) Add a buffer to keep the pH stable at the natural pH of your formulation
(d) Increase the concentration of the polymer
(e) Add 0.1 M sodium hydroxide solution and measure the viscosity and pH
(2 Marks)
29. What flow properties would you expect for a simple linctus using syrup as the
primary thickening agent?
(a) Dilatant flow
(b) Newtonian flow
(c) Pseudoplastic flow
(d) Plastic flow
(e) Thixotropic flow
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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30. How would you characterise the flow properties of a suspension to determine if it
exhibited thixotropic pseudoplastic flow?
(a) Using a capillary viscometer with the sample subjected to non-turbulent
streamlined laminar flow
(b) Using a falling sphere viscometer to measure the viscosity compared with
a known thixotropic system
(c) Using a rotational viscometer measuring the viscosity at increasing and
then decreasing shear rates (rpm)
(d) Using a Brookfield viscometer measuring the viscosity at increasing shear
rates (rpm)
(e) Using a Brookfield viscometer and measuring the viscosity at two different
spindle speeds
(2 Marks)
Use the diagram below to answer question 31:
31. You have to scale-up production of a paste containing 70% w/w of an insoluble
drug in a non-aqueous ointment base using a high shear mixer. Given that the
product shows the above flow diagram, what part of the manufacturing process
would you consider to have the MOST risk associated with it and why?
(a) Preparation of the non-aqueous ointment base because the product
exhibits dilatant flow
(b) Incorporating the drug into the ointment base using the mixer because the
product exhibits dilatant flow
(c) Incorporating the drug into the ointment base using the mixer because the
product exhibits pseudoplastic flow
(d) Filling the paste into the pack because the product exhibits plastic flow
(e) Sampling the finished product because of inadequate mixing due to
Newtonian flow
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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32. Which of the following statements is CORRECT?
(a) Pastes have a lower percentage of solids than ointments
(b) Pastes are ideally suited for application to hairy parts of the body
(c) Pastes contain preservative to prevent microbial growth
(d) Pastes are effective at absorbing secretions
(e) Pastes are easy to wash off with water
(2 Marks)
33. Which of the following statements is CORRECT?
(a) Creams prepared using cetrimide emulsifying ointment should not be used
as a base for cationic drugs
(b) Creams prepared using cetomacrogol emulsifying ointment should not be
used as a base for cationic drugs
(c) Creams prepared using cetomacrogol emulsifying ointment should not be
used as a base for anionic drugs
(d) Creams prepared using cetrimide emulsifying ointment should not be used
as a base for anionic drugs
(e) None of (a), (b), (c) or (d)
(2 Marks)
34. Select the option that correctly completes the statement. A liquid applied to the
skin with friction as a rubefacient is:
(a) a lotion
(b) a paint
(c) a liniment
(d) a cream
(e) an instillation
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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Use the formula below to answer questions 35-38:
Zinc oxide 25 g
Starch 21 g
Salicylic acid 2 g
Liquid paraffin 2 g
White soft paraffin 50 g
35. Which term BEST describes the dosage form in the above formulation?
(a) Cream
(b) Paste
(c) Ointment with water-miscible base
(d) Ointment with absorption base
(e) Gel
(2 Marks)
36. This formulation appears to be missing a preservative. Which of the following
options is most appropriate for the formulation above?
(a) Chlorbutol should be added to this formulation as a preservative at 0.5 – 1
% w/w
(b) No preservative is required in this formulation because after checking the
source of the formula there was no preservative included
(c) Phenoxyethanol 1% should be added as it is used in other creams
(d) No preservative is required as there is no aqueous component to support
bacterial growth
(e) Adding the preservative listed in option (a) or option (c) is correct
(2 Marks)
37. What is the concentration of salicylic acid in this formulation?
(a) 0.2 %
(b) 0.4 %
(c) 2 %
(d) 4 %
(e) None of (a), (b), (c) or (d) is correct
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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38. If the formulation above is prepared as written, but then further diluted by the
addition of another 25 g of white soft paraffin, what is the concentration of
salicylic acid in the diluted product?
(a) 0.8 %
(b) 1.6 %
(c) 2.7 %
(d) 3.2 %
(e) None of (a), (b), (c) or (d) is correct
(2 Marks)
39. What is the approximate molar ratio of sodium acetate (salt) to acetic acid (acid)
required to produce a pH 4.1 acetate buffer at 25°C? (The pKa of acetic acid at
25°C is 4.70).
(a) 1:2
(b) 3:1
(c) 4:1
(d) 1:1
(e) 1:4
(3 marks)
40. If the molar ratio of disodium hydrogen phosphate (conjugate base) to sodium
dihydrogen phosphate (weak acid) required to prepare a pH 8.0 phosphate buffer
is 15.8:1 (conjugate base : weak acid), what approximate mass of each
compound would be required to prepare 1 L of this buffer having a concentration
of 0.3 M?
[The molecular weight of disodium hydrogen phosphate (conjugate base) is 176
g/mole and the molecular weight of sodium dihydrogen phosphate (weak acid) is
156 g/mole.]
(a) 2.8 g disodium hydrogen phosphate, and 49.7 g sodium dihydrogen
phosphate
(b) 49.7 g disodium hydrogen phosphate, and 2.8 g sodium dihydrogen
phosphate
(c) 52.8 g disodium hydrogen phosphate, and 3.0 g sodium dihydrogen
phosphate
(d) 3.0 g disodium hydrogen phosphate, and 52.8 g sodium dihydrogen
phosphate
(e) 24.8 g disodium hydrogen phosphate, and 1.4 g sodium dihydrogen
phosphate
(3 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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Question 41 is related to the figure below, which shows the rate of degradation of the
drug pilocarpine in buffer solutions of various pH values.
41. Which of the following mole fractions of weak acid (pKa 4.70) and its conjugate
base would give a buffer solution in which the stability of the drug is maximal?
Mole fraction of conjugate base Mole fraction of weak acid
(a) 0.61 0.39
(b) 0.39 0.61
(c) 0.07 0.93
(d) 0.50 0.50
(e) 0.93 0.07
(3 Marks)
42. Which of the following statements is/are CORRECT?
Tissue irritation due to differences between the pH of a buffered formulation and
tissue pH can be minimised by:
I. Lowering the buffer capacity of the buffer solution
II. Increasing the buffer capacity of the buffer solution
III. Administering a larger volume of buffer solution
(a) I only
(b) II only
(c) III only
(d) I and III only
(e) II and III only
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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43. Which of the following combinations of compounds INCREASES the oral
absorption of the drug due to complex formation?
I. Tetracycline (drug) and iron tablets
II. Gentamicin (drug) and anionic liposaccharide
III. Ergotamine (drug) and caffeine
(a) II only
(b) III only
(c) I and II only
(d) II and III only
(e) I, II, and III
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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44. The following graph shows the log D – pH profile of a drug.
By reference to the log D – pH profile above, which of the following statements are
CORRECT?
I. The log P of the drug is 2.0
II. The log P of the drug is 4.0
III. The drug is a weak acid
IV. The drug is a weak base
V. The drug will be absorbed by passive diffusion mostly from the jejunum
and ileum
VI. The drug will be absorbed by passive diffusion mostly from the duodenum
with minor absorption from the stomach
(a) I, III, and VI only
(b) I, IV, and V only
(c) II, III, and VI only
(d) II, IV, and V only
(e) II, IV, and VI only
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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45. Classify each of the structures below according to the type of complex.
Type of complex
Answer Cyclodextrin inclusion complex Chelate
Ionic complex
between organic
molecules
(a) Z X Y
(b) X Z Y
(c) X Y Z
(d) Y Z X
(e) Z Y X
(2 marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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46. Which ONE of the following statements is INCORRECT?
(a) Cyclodextrins are composed of a ring of amino acids linked by amide
bonds
(b) A driving force for drug-cyclodextrin complex formation is the substitution
of the energetically unfavoured polar-nonpolar interactions with favoured
interactions
(c) Cyclodextrins have an outer surface that is polar and hydrophilic while the
internal cavity is nonpolar and hydrophobic
(d) Drug-cyclodextrin complexes increase drug absorption because more
drug is solubilised and available for membrane permeation
(e) Inclusion complexes of drugs with cyclodextrins dissociate before
absorption of a drug can occur
(2 marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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47. The following graph illustrates the solubility of three drugs (A, B, C) in water-
cosolvent mixtures.
0 0.5 1
So
lub
ilit
y
Volume fraction cosolvent
Drug A
Drug B
Drug C
Compound log P
Water (solvent) 4.0
Isopropanol (cosolvent) 0.5
Alprazolam (drug) 1.72
Theophylline (drug) 0.07
Triglycine (drug) 5.0
Refer to the table below and choose the answer that CORRECTLY identifies
drugs A, B and C:
Answer Drug A Drug B Drug C
(a) Triglycine Alprazolam Theophylline
(b) Triglycine Theophylline Alprazolam
(c) Alprazolam Theophylline Triglycine
(d) Theophylline Alprazolam Triglycine
(e) Alprazolam Triglycine Theophylline
(3 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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48. Which of the following statements is/are CORRECT?
A co-solvent solubilised parenteral drug is LIKELY to precipitate when injected if:
I. It is formulated so that the dilution line is always above the solubility curve
II. It is formulated so that the dilution line is always below the solubility curve
III. It is injected slowly
IV. It is injected rapidly
(a) I only
(b) III only
(c) IV only
(d) I and IV only
(e) II and III only
(2 marks)
49. Select the CORRECT completed statement. There is surface tension at the
interface between water and oil BECAUSE…
(a) thermal motion of molecules increases at warmer temperatures
(b) oil is less dense than water
(c) the forces in the bulk solution of water are equal
(d) water forms a sphere in zero gravity
(e) the forces at the interface are unequal
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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50. Which ONE of the following statements about wetting and spreading behaviour is
INCORRECT?
(a) A contact angle of zero indicates complete wetting of a solid surface by a
liquid
(b) A liquid will remain as a droplet on a surface if cohesive forces > adhesive
forces
(c) The properties of the pharmaceutical powder are important in defining the
contact angle with a liquid droplet
(d) A contact angle of 90° indicates that no wetting occurs
(e) Wetting agents are added to reduce the contact angle between the
surface and the liquid phase
(2 Marks)
51. Which ONE of the following statements about colloids is INCORRECT?
(a) Association colloids are formed spontaneously on addition of solvent
loving particles to water as long as the concentration is greater than the
critical micelle concentration (CMC)
(b) Association colloids are not particles because the amphipathic component
molecules are in dynamic equilibrium with free molecules in solution
(c) Non-polar drugs can be transported in the hydrocarbon core of an
association colloid
(d) Liposomes are a type of association colloid
(e) Above the CMC, the amount of drug that can be solubilised is directly
proportional to the number of association colloids present
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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52. The image below depicts surfactant molecules at an interface between two
liquids, A and B. Select the statement that CORRECTLY describes the image:
(a) The surfactant is oriented so that the ionic head group is in the oil phase
(b) Liquid A is more dense than liquid B
(c) A is a hydrophobic liquid, and B is a hydrophilic liquid
(d) The surfactant has absorbed to the surface of liquid B
(e) Micelles, which form at the critical micelle concentration, will contain liquid
A on the inside
(2 Marks)
53. Select the CORRECT statement:
(a) Water and octanol are immiscible because the adhesion forces between
octanol and water are much less than the cohesion forces between the
molecules in each bulk liquid phase
(b) Interfacial tension between two liquids is high for miscible liquids because of
the high adhesion forces between liquids that are miscible.
(c) Surface tension is a result of strong adhesion forces pulling surface
molecules apart
(d) Interfacial tension only exists when one of the bulk phases is water because
interfacial tension is expressed relative to water
(e) At the surface, molecules are pulled towards the bulk solution because
molecules at the surface are chemically different to molecules in the bulk
solution
(2 Marks)
Liquid A
Liquid B
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 27 of 29
The distribution of charge at the surface of a colloidal particle suspended in an
electrolyte solution is shown in the figure below. Questions 54-55 relate to this
diagram:
54. At which plane is the Nearnst potential measured?
(a) A
(b) B
(c) C
(d) D
(e) E
(2 Marks)
55. Increasing the electrolyte concentration would be expected to:
(a) Move plane D further away from the particle surface
(b) Merge plane D and plane E
(c) Move plane D closer to the particle surface
(d) Increase the Debye-Huckel length
(e) Have no effect on the location of plane D
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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The potential energy of interaction (VT) vs inter-particle distance for charged colloidal
particles in an electrolyte solution is shown in the diagram below.
56. Select the CORRECT answer. At inter-particle distances for which VT is positive:
(a) particles will be attracted towards each other
(b) particles will be repelling each other
(c) particles will be flocculated
(d) particles will be de-flocculated
(e) particles will be caked
(2 Marks)
H
Distance
between
particles
Total
potential
energy
(VT)
(+)
A
B
C
D
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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Questions 57-58 relate to the following information about a dispersion of solid
particles in a liquid.
Solid particles of 0.2 mm diameter and a density of 1300 kg.m-3 are dispersed in
polymer solution having a density of 1100 kg.m-3 and viscosity of 0.109 Pas.
Acceleration due to gravity is 9.81 m s-2
57. At what rate will the particles sediment?
a) 4 x 10-4 m s-1
b) 4 x 10-5 m s-1
c) 4 x 10-6 m s-1
d) 4 x 10-7 m s-1
e) 4 x 10-8 m s-1
(2 Marks)
58. If the dispensing bottle is 10 cm tall, how long after shaking would you expect the
sediment to have formed?
a) Less than 1 second
b) between 1 second and 1 minute
c) between 1 minute and 10 minutes
d) between 10 minutes and 1 hour
e) between 1 hour and 1 day
(2 Marks)
END OF EXAMINATION
Page 1 of 29
This exam paper must not be removed from the venue
School of Pharmacy
EXAMINATION
Semester One Final Examinations, 2019
PHRM2021 Dosage Form Design A1
This paper is for St Lucia Campus students.
Examination Duration: 120 minutes
Reading Time: 10 minutes
Exam Conditions:
This is a Central Examination
This is a Closed Book Examination - specified materials permitted
During reading time - write only on the rough paper provided
This examination paper will be released to the Library
Materials Permitted In The Exam Venue:
(No electronic aids are permitted e.g. laptops, phones)
Calculators - Casio FX82 series or UQ approved (labelled)
Materials To Be Supplied To Students:
1 x Multiple Choice Answer Sheet
Instructions To Students:
Additional exam materials (eg. answer booklets, rough paper) will be
provided upon request.
MCQ Questions to be answered in pencil NOT pen on the computer answer
sheet provided. Each question carries the number of marks indicated and there
is only ONE correct answer
Venue ____________________
Seat Number ________
Student Number |__|__|__|__|__|__|__|__|
Family Name _____________________
First Name _____________________
For Examiner Use Only
Question Mark
Total ________
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 2 of 29
DATA SHEET
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 3 of 29
SECTION A — MULTIPLE CHOICE QUESTIONS — 120 MARKS
Answer this section on the multiple choice answer sheet provided.
Fill in the answer sheet using pencil, NOT pen. Mistakes must be completely
erased (avoid smudging). Answer by filling in, not circling or crossing the spaces.
Do not write on the multiple choice answer sheet except where indicated.
EACH QUESTION IS WORTH 2 MARKS,
EXCEPT QUESTIONS 39,40,41,47 WHICH ARE WORTH 3 MARKS.
THERE IS ONLY ONE CORRECT ANSWER TO EACH QUESTION.
1. Which one of the following is a synthetic suspending agent?
(a) Bentonite
(b) Acacia
(c) Alginate
(d) Tragacanth
(e) Carbomer (Carbopol)
(2 Marks)
2. What is the pH of 0.05 M sodium acetate (CH3COONa) given that the pKa of
acetic acid is 4.66?
(a) 7.4
(b) 5.01
(c) 4.66
(d) 18.02
(e) 8.68
(2 Marks)
3. Complete the following statement. Good Laboratory Practice (GLP) in the
pharmaceutical industry involves:
(a) laboratory equipment & instrumentation
(b) records, documenting & archiving
(c) sampling procedures
(d) stability programs
(e) All of (a), (b), (c) and (d)
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 4 of 29
4. Which ONE of the following statements about formulating suspensions is
INCORRECT?
(a) A suspension is an appropriate dosage form when an insoluble active
pharmaceutical ingredient (API) needs to be given in liquid form
(b) Suspension is preferred over solution when an API needs to be given in
liquid form, but hydrolyses in water
(c) Suspension is preferred over solution when a suspended insoluble salt
may be more stable compared to the parent compound
(d) Suspension is preferred over solution when an API is unpalatable and
therefore compliance will be greater
(e) Suspension is preferred over solution because suspended drug particles
absorb faster than drug molecules in solution
(2 Marks)
5. Which option correctly completes the following statement: according to the British
Pharmacopoeia descriptive code for solubility, if sulfadiazine is sparingly soluble
in water, sulfadiazine sodium is MOST LIKELY to be ____________ in water.
(a) practically insoluble
(b) slightly soluble
(c) freely soluble
(d) sparingly soluble
(e) none of (a), (b), (c) or (d)
(2 Marks)
6. What is the pH of 1% w/v solution of ethanolamine (Mw = 61.08, pKa = 9.4)?
(a) 4.6
(b) 9.4
(c) 11.3
(d) 1.2
(e) 7.4
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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Questions 7-9 relate to homatropine. Homatropine (MW 275; solubility 1 g/500 ml) is
formulated as an eye drop by preparing a 2% aqueous solution of homatropine
hydrobromide (MW 356) because the salt of homatropine is much more soluble
(solubility 1 g/6 ml).
Homatropine
7. Homatropine is:
(a) Acidic in aqueous solution with a pKa of 9.7
(b) A zwitterion in solution with two pKa values of 3.3 and 9.7
(c) Acidic in aqueous solution with a pKa of 3.3
(d) Basic in aqueous solution with a pKa of 9.7
(e) Basic in aqueous solution with a pKa of 3.3
(2 Marks)
8. The molar solubility of homatropine is:
(a) 0.0036 M
(b) 0.0056 M
(c) 0.0028 M
(d) 0.0073 M
(e) 0.468 M
(2 Marks)
9. What pH below is the closest to the pH at which precipitation of homatropine
starts to occur?
(a) pH 8.9
(b) pH 7.9
(c) pH 4.1
(d) pH 10.5
(e) pH 7.3
(2 Marks)
O
OH
O
N
CH3
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 6 of 29
10. Fluoxetine has the following structure and a pKa of 8.4. What percentage of
fluoxetine would be ionised at pH 6?
(a) < 1 %
(b) 10 %
(c) 50 %
(d) 90 %
(e) > 99 %
(2 Marks)
For questions 11-14 consider the compound below:
This is the structure of the antibiotic flucloxacillin (mw 454, solubility at 25°C = 4.4 x
10-4 M).
11. Flucloxacillin has one ionisable group and consequently one pKa value. Based
on the structure above, select the CORRECT statement:
(a) Flucloxacillin is acidic in aqueous solution with a pKa of 7.7
(b) Flucloxacillin is a zwitterion in solution with pKa values of 2.7 and 7.7
(c) Flucloxacillin is basic in aqueous solution with a pKa of 7.7
(d) Flucloxacillin is acidic in aqueous solution with a pKa of 2.7
(e) Flucloxacillin is basic in aqueous solution with a pKa of 2.7
(2 Marks)
O
N
NH
N
CH3
S
CH3CH3
OH
O
O O
Cl
F
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 7 of 29
12. What is the % ionization of flucloxacillin in plasma at pH 7.4?
(a) 0.002%
(b) 33.4%
(c) 50.1%
(d) 66.6%
(e) 99.998%
(2 Marks)
13. You are required to formulate an aqueous solution of flucloxacillin to obtain a
concentration of 50 mg per 5 ml at 25°C. What is the molarity of this solution?
(a) 0.022 M
(b) 0.22 M
(c) 0.044 M
(d) 0.44 M
(e) 0.055 M
(2 Marks)
14. What would be the minimum pH to which you could formulate your aqueous
solution of flucloxacillin with a concentration of 50 mg per 5 ml at 25°C?
(a) 10.0
(b) 9.4
(c) 6.0
(d) 4.7
(e) 4.4
(2 Marks)
15. Which of these factors affect solubility?
(a) Temperature
(b) Polarity
(c) Co-Solvent
(d) Solute presence
(e) All of (a), (b), (c) and (d)
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 8 of 29
16. Identify the polar functional group from options (a) to (e) below:
(a) -CH3
(b) -CH3Cl
(c) -F
(d) -R-OH
(e) –OCH2CH3
(2 Marks)
17. Select the CORRECT statement:
(a) Amino acids that have a net charge of zero are neutral
(b) Amino acids always carry a net negative charge at low pH
(c) Amino acids do not have pKa values, they have a pI to describe ionization
(d) If the pH is more than the pI then the amino acid will have a net negative
charge
(e) When amino acids are unionized they are not very soluble in water
(2 Marks)
18. The structures of sulphanilamide (pKa 10.4) and sulfacetamide (pKa 5.4) are
shown. Which one of the following statements is CORRECT?
(a) Both drugs are acidic in solution, and sulfacetamide is a stronger acid than
sulfanilamide
(b) Sulfacetamide acts as a base in solution, while sulfanilamide is an acid
(c) Sulfanilamide is neutral in solution but sulfacetamide acts as a base
(d) Both drugs are basic in solution, and sulfanilamide is a stronger base than
sulfacetamide
(e) Sulfanilamide is basic in solution while sulfacetamide is acidic
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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Questions 19-20 relate to fluoxetine: The structure below is fluoxetine, which has a
pKa of 8.4.
F
F F
O NH
CH3
Fluoxetine
19. In which of the following solvents would you expect fluoxetine to have the highest
solubility:
(a) Pure water
(b) 0.1 M buffer at pH 9.4
(c) 0.1 M hydrochloric acid
(d) 0.1 M buffer at pH 8.4
(e) Human plasma at pH 7.4
(2 Marks)
20. Which of the following statements is CORRECT regarding fluoxetine in aqueous
solution?
(a) It is a weak acid because it has a proton that will be donated at the correct
pH
(b) It is a weak base because the lone pair of electrons are available
(c) Is non-ionisable because it has a lone pair of electrons that are
delocalised into the benzene rings
(d) It is a weak acid because it has an oxygen atom that is available to accept
a proton
(e) It is a weak base because it has an amide group at the end of the carbon
chain
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 10 of 29
21. Which of the following statements are CORRECT regarding micelle formation?
I Micelles form when the interface is saturated with the surface active agent
II Increasing the length of the hydrophobic chain causes CMC to decrease
III Adding electrolyte to a solution containing ionic surfactants causes CMC to
decrease
IV Increasing the hydrophilicity of the head group causes CMC to increase
V Increasing the temperature causes CMC to decrease
(a) I, II, and IV only
(b) I and V only correct
(c) II, III and V only
(d) I, III and V only
(e) All I, II, III, IV and V
(2 Marks)
22. Identify the species acting as a base in the following reaction at equilibrium:
HCO3- + H3O+ ↔ H2CO3 + H2O
(a) H2CO3 only
(b) H3O+ only
(c) HCO3- only
(d) HCO3- and H2O
(e) H2CO3 and H3O+
(2 Marks)
23. If you acidify water by adding HCl and find that the pH=5 what is the
concentration of H+ present?
(a) -0.699 M
(b) zero – it is all present as HCl
(c) 1 x 10-5 M
(d) 0.699 M
(e) 5 M
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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24. Select the CORRECT completed statement:
The structure above:
(a) Is a cationic surface active agent because it has a positively charged head
group
(b) Is a non-ionic surface active agent because it has an overall neutral
charge
(c) Is a non-ionic surface active agent because of the non-polar tail
(d) Is an anionic surface active agent because of the polar head group
(e) Is an ampholytic surface active agent because it has positive and negative
charges
(2 Marks)
25. Select the INCORRECT statement:
(a) Creaming can be retarded by increasing the density difference between
the oil and water phases
(b) Surfactants with HLB values above 8 are suitable for stabilising oil in water
(o/w) emulsions
(c) Cracking of emulsions refers to coalescence of droplets of the disperse
phase
(d) Cetrimide is an example of a cationic surfactant
(e) Tween surfactants are normally used to stabilise oil in water (o/w)
emulsions
(2 Marks)
26. Thixotropy is a desirable property for oral suspensions such that the suspension
thins on shaking and rethickens on standing. Which of the following formulation
approaches would you use to achieve this?
(a) Formulate a suspension with a high concentration of deflocculated
particles
(b) Keep the viscosity of your formulation low
(c) Use a high viscosity vehicle such as syrup that exhibits Newtonian flow to
suspend your drug
(d) Add an electrolyte to act as a flocculating agent
(e) Incorporate a long chain polymer such as methylcellulose with
pseudoplastic flow that forms a 3-D network
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 12 of 29
Use the diagram below to answer question 27:
27. Which of the following statements is CORRECT for fluids demonstrating time-
dependent rheology:
(a) Fluids with pseudoplastic flow may exhibit rheopexy
(b) Thixotropic flow is not a desirable characteristic for pharmaceutical
suspensions
(c) Thixotropic flow may cause problems with mixers and overheating during
production
(d) Hysteresis is seen when the up- and down- curves are superimposable
(e) A Newtonian liquid will not exhibit thixotropy
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 13 of 29
Use the diagram below to answer question 28:
28. The diagram shows a viscosity modifying polymer in its neutral coiled state.
Which of the following formulation approaches would you consider MOST
LIKELY to increase the viscosity of products that could use this polymer?
(a) Investigate the effect of adding increasing amounts of triethanolamine on
viscosity and pH
(b) Add citric acid to lower the pH to 2 units below the natural pH of your
formulation
(c) Add a buffer to keep the pH stable at the natural pH of your formulation
(d) Increase the concentration of the polymer
(e) Add 0.1 M sodium hydroxide solution and measure the viscosity and pH
(2 Marks)
29. What flow properties would you expect for a simple linctus using syrup as the
primary thickening agent?
(a) Dilatant flow
(b) Newtonian flow
(c) Pseudoplastic flow
(d) Plastic flow
(e) Thixotropic flow
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 14 of 29
30. How would you characterise the flow properties of a suspension to determine if it
exhibited thixotropic pseudoplastic flow?
(a) Using a capillary viscometer with the sample subjected to non-turbulent
streamlined laminar flow
(b) Using a falling sphere viscometer to measure the viscosity compared with
a known thixotropic system
(c) Using a rotational viscometer measuring the viscosity at increasing and
then decreasing shear rates (rpm)
(d) Using a Brookfield viscometer measuring the viscosity at increasing shear
rates (rpm)
(e) Using a Brookfield viscometer and measuring the viscosity at two different
spindle speeds
(2 Marks)
Use the diagram below to answer question 31:
31. You have to scale-up production of a paste containing 70% w/w of an insoluble
drug in a non-aqueous ointment base using a high shear mixer. Given that the
product shows the above flow diagram, what part of the manufacturing process
would you consider to have the MOST risk associated with it and why?
(a) Preparation of the non-aqueous ointment base because the product
exhibits dilatant flow
(b) Incorporating the drug into the ointment base using the mixer because the
product exhibits dilatant flow
(c) Incorporating the drug into the ointment base using the mixer because the
product exhibits pseudoplastic flow
(d) Filling the paste into the pack because the product exhibits plastic flow
(e) Sampling the finished product because of inadequate mixing due to
Newtonian flow
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 15 of 29
32. Which of the following statements is CORRECT?
(a) Pastes have a lower percentage of solids than ointments
(b) Pastes are ideally suited for application to hairy parts of the body
(c) Pastes contain preservative to prevent microbial growth
(d) Pastes are effective at absorbing secretions
(e) Pastes are easy to wash off with water
(2 Marks)
33. Which of the following statements is CORRECT?
(a) Creams prepared using cetrimide emulsifying ointment should not be used
as a base for cationic drugs
(b) Creams prepared using cetomacrogol emulsifying ointment should not be
used as a base for cationic drugs
(c) Creams prepared using cetomacrogol emulsifying ointment should not be
used as a base for anionic drugs
(d) Creams prepared using cetrimide emulsifying ointment should not be used
as a base for anionic drugs
(e) None of (a), (b), (c) or (d)
(2 Marks)
34. Select the option that correctly completes the statement. A liquid applied to the
skin with friction as a rubefacient is:
(a) a lotion
(b) a paint
(c) a liniment
(d) a cream
(e) an instillation
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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Use the formula below to answer questions 35-38:
Zinc oxide 25 g
Starch 21 g
Salicylic acid 2 g
Liquid paraffin 2 g
White soft paraffin 50 g
35. Which term BEST describes the dosage form in the above formulation?
(a) Cream
(b) Paste
(c) Ointment with water-miscible base
(d) Ointment with absorption base
(e) Gel
(2 Marks)
36. This formulation appears to be missing a preservative. Which of the following
options is most appropriate for the formulation above?
(a) Chlorbutol should be added to this formulation as a preservative at 0.5 – 1
% w/w
(b) No preservative is required in this formulation because after checking the
source of the formula there was no preservative included
(c) Phenoxyethanol 1% should be added as it is used in other creams
(d) No preservative is required as there is no aqueous component to support
bacterial growth
(e) Adding the preservative listed in option (a) or option (c) is correct
(2 Marks)
37. What is the concentration of salicylic acid in this formulation?
(a) 0.2 %
(b) 0.4 %
(c) 2 %
(d) 4 %
(e) None of (a), (b), (c) or (d) is correct
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 17 of 29
38. If the formulation above is prepared as written, but then further diluted by the
addition of another 25 g of white soft paraffin, what is the concentration of
salicylic acid in the diluted product?
(a) 0.8 %
(b) 1.6 %
(c) 2.7 %
(d) 3.2 %
(e) None of (a), (b), (c) or (d) is correct
(2 Marks)
39. What is the approximate molar ratio of sodium acetate (salt) to acetic acid (acid)
required to produce a pH 4.1 acetate buffer at 25°C? (The pKa of acetic acid at
25°C is 4.70).
(a) 1:2
(b) 3:1
(c) 4:1
(d) 1:1
(e) 1:4
(3 marks)
40. If the molar ratio of disodium hydrogen phosphate (conjugate base) to sodium
dihydrogen phosphate (weak acid) required to prepare a pH 8.0 phosphate buffer
is 15.8:1 (conjugate base : weak acid), what approximate mass of each
compound would be required to prepare 1 L of this buffer having a concentration
of 0.3 M?
[The molecular weight of disodium hydrogen phosphate (conjugate base) is 176
g/mole and the molecular weight of sodium dihydrogen phosphate (weak acid) is
156 g/mole.]
(a) 2.8 g disodium hydrogen phosphate, and 49.7 g sodium dihydrogen
phosphate
(b) 49.7 g disodium hydrogen phosphate, and 2.8 g sodium dihydrogen
phosphate
(c) 52.8 g disodium hydrogen phosphate, and 3.0 g sodium dihydrogen
phosphate
(d) 3.0 g disodium hydrogen phosphate, and 52.8 g sodium dihydrogen
phosphate
(e) 24.8 g disodium hydrogen phosphate, and 1.4 g sodium dihydrogen
phosphate
(3 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 18 of 29
Question 41 is related to the figure below, which shows the rate of degradation of the
drug pilocarpine in buffer solutions of various pH values.
41. Which of the following mole fractions of weak acid (pKa 4.70) and its conjugate
base would give a buffer solution in which the stability of the drug is maximal?
Mole fraction of conjugate base Mole fraction of weak acid
(a) 0.61 0.39
(b) 0.39 0.61
(c) 0.07 0.93
(d) 0.50 0.50
(e) 0.93 0.07
(3 Marks)
42. Which of the following statements is/are CORRECT?
Tissue irritation due to differences between the pH of a buffered formulation and
tissue pH can be minimised by:
I. Lowering the buffer capacity of the buffer solution
II. Increasing the buffer capacity of the buffer solution
III. Administering a larger volume of buffer solution
(a) I only
(b) II only
(c) III only
(d) I and III only
(e) II and III only
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
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43. Which of the following combinations of compounds INCREASES the oral
absorption of the drug due to complex formation?
I. Tetracycline (drug) and iron tablets
II. Gentamicin (drug) and anionic liposaccharide
III. Ergotamine (drug) and caffeine
(a) II only
(b) III only
(c) I and II only
(d) II and III only
(e) I, II, and III
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 20 of 29
44. The following graph shows the log D – pH profile of a drug.
By reference to the log D – pH profile above, which of the following statements are
CORRECT?
I. The log P of the drug is 2.0
II. The log P of the drug is 4.0
III. The drug is a weak acid
IV. The drug is a weak base
V. The drug will be absorbed by passive diffusion mostly from the jejunum
and ileum
VI. The drug will be absorbed by passive diffusion mostly from the duodenum
with minor absorption from the stomach
(a) I, III, and VI only
(b) I, IV, and V only
(c) II, III, and VI only
(d) II, IV, and V only
(e) II, IV, and VI only
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 21 of 29
45. Classify each of the structures below according to the type of complex.
Type of complex
Answer Cyclodextrin inclusion complex Chelate
Ionic complex
between organic
molecules
(a) Z X Y
(b) X Z Y
(c) X Y Z
(d) Y Z X
(e) Z Y X
(2 marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 22 of 29
46. Which ONE of the following statements is INCORRECT?
(a) Cyclodextrins are composed of a ring of amino acids linked by amide
bonds
(b) A driving force for drug-cyclodextrin complex formation is the substitution
of the energetically unfavoured polar-nonpolar interactions with favoured
interactions
(c) Cyclodextrins have an outer surface that is polar and hydrophilic while the
internal cavity is nonpolar and hydrophobic
(d) Drug-cyclodextrin complexes increase drug absorption because more
drug is solubilised and available for membrane permeation
(e) Inclusion complexes of drugs with cyclodextrins dissociate before
absorption of a drug can occur
(2 marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 23 of 29
47. The following graph illustrates the solubility of three drugs (A, B, C) in water-
cosolvent mixtures.
0 0.5 1
So
lub
ilit
y
Volume fraction cosolvent
Drug A
Drug B
Drug C
Compound log P
Water (solvent) 4.0
Isopropanol (cosolvent) 0.5
Alprazolam (drug) 1.72
Theophylline (drug) 0.07
Triglycine (drug) 5.0
Refer to the table below and choose the answer that CORRECTLY identifies
drugs A, B and C:
Answer Drug A Drug B Drug C
(a) Triglycine Alprazolam Theophylline
(b) Triglycine Theophylline Alprazolam
(c) Alprazolam Theophylline Triglycine
(d) Theophylline Alprazolam Triglycine
(e) Alprazolam Triglycine Theophylline
(3 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 24 of 29
48. Which of the following statements is/are CORRECT?
A co-solvent solubilised parenteral drug is LIKELY to precipitate when injected if:
I. It is formulated so that the dilution line is always above the solubility curve
II. It is formulated so that the dilution line is always below the solubility curve
III. It is injected slowly
IV. It is injected rapidly
(a) I only
(b) III only
(c) IV only
(d) I and IV only
(e) II and III only
(2 marks)
49. Select the CORRECT completed statement. There is surface tension at the
interface between water and oil BECAUSE…
(a) thermal motion of molecules increases at warmer temperatures
(b) oil is less dense than water
(c) the forces in the bulk solution of water are equal
(d) water forms a sphere in zero gravity
(e) the forces at the interface are unequal
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 25 of 29
50. Which ONE of the following statements about wetting and spreading behaviour is
INCORRECT?
(a) A contact angle of zero indicates complete wetting of a solid surface by a
liquid
(b) A liquid will remain as a droplet on a surface if cohesive forces > adhesive
forces
(c) The properties of the pharmaceutical powder are important in defining the
contact angle with a liquid droplet
(d) A contact angle of 90° indicates that no wetting occurs
(e) Wetting agents are added to reduce the contact angle between the
surface and the liquid phase
(2 Marks)
51. Which ONE of the following statements about colloids is INCORRECT?
(a) Association colloids are formed spontaneously on addition of solvent
loving particles to water as long as the concentration is greater than the
critical micelle concentration (CMC)
(b) Association colloids are not particles because the amphipathic component
molecules are in dynamic equilibrium with free molecules in solution
(c) Non-polar drugs can be transported in the hydrocarbon core of an
association colloid
(d) Liposomes are a type of association colloid
(e) Above the CMC, the amount of drug that can be solubilised is directly
proportional to the number of association colloids present
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 26 of 29
52. The image below depicts surfactant molecules at an interface between two
liquids, A and B. Select the statement that CORRECTLY describes the image:
(a) The surfactant is oriented so that the ionic head group is in the oil phase
(b) Liquid A is more dense than liquid B
(c) A is a hydrophobic liquid, and B is a hydrophilic liquid
(d) The surfactant has absorbed to the surface of liquid B
(e) Micelles, which form at the critical micelle concentration, will contain liquid
A on the inside
(2 Marks)
53. Select the CORRECT statement:
(a) Water and octanol are immiscible because the adhesion forces between
octanol and water are much less than the cohesion forces between the
molecules in each bulk liquid phase
(b) Interfacial tension between two liquids is high for miscible liquids because of
the high adhesion forces between liquids that are miscible.
(c) Surface tension is a result of strong adhesion forces pulling surface
molecules apart
(d) Interfacial tension only exists when one of the bulk phases is water because
interfacial tension is expressed relative to water
(e) At the surface, molecules are pulled towards the bulk solution because
molecules at the surface are chemically different to molecules in the bulk
solution
(2 Marks)
Liquid A
Liquid B
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 27 of 29
The distribution of charge at the surface of a colloidal particle suspended in an
electrolyte solution is shown in the figure below. Questions 54-55 relate to this
diagram:
54. At which plane is the Nearnst potential measured?
(a) A
(b) B
(c) C
(d) D
(e) E
(2 Marks)
55. Increasing the electrolyte concentration would be expected to:
(a) Move plane D further away from the particle surface
(b) Merge plane D and plane E
(c) Move plane D closer to the particle surface
(d) Increase the Debye-Huckel length
(e) Have no effect on the location of plane D
(2 Marks)
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 28 of 29
The potential energy of interaction (VT) vs inter-particle distance for charged colloidal
particles in an electrolyte solution is shown in the diagram below.
56. Select the CORRECT answer. At inter-particle distances for which VT is positive:
(a) particles will be attracted towards each other
(b) particles will be repelling each other
(c) particles will be flocculated
(d) particles will be de-flocculated
(e) particles will be caked
(2 Marks)
H
Distance
between
particles
Total
potential
energy
(VT)
(+)
A
B
C
D
Semester One Final Examinations, 2019 PHRM2021 Dosage Form Design A1
Page 29 of 29
Questions 57-58 relate to the following information about a dispersion of solid
particles in a liquid.
Solid particles of 0.2 mm diameter and a density of 1300 kg.m-3 are dispersed in
polymer solution having a density of 1100 kg.m-3 and viscosity of 0.109 Pas.
Acceleration due to gravity is 9.81 m s-2
57. At what rate will the particles sediment?
a) 4 x 10-4 m s-1
b) 4 x 10-5 m s-1
c) 4 x 10-6 m s-1
d) 4 x 10-7 m s-1
e) 4 x 10-8 m s-1
(2 Marks)
58. If the dispensing bottle is 10 cm tall, how long after shaking would you expect the
sediment to have formed?
a) Less than 1 second
b) between 1 second and 1 minute
c) between 1 minute and 10 minutes
d) between 10 minutes and 1 hour
e) between 1 hour and 1 day
(2 Marks)
END OF EXAMINATION
