Pharmaceutical Drugs and Dosage: Tablets - Review questions answers
Review questions
20.1 Which
condition usually increases the rate of drug dissolution from a tablet?
A. Increase in the
particle size of the drug
B. Decrease in the
surface area of the drug
C. Use of the ionized
or salt form of the drug
D. Use of sugarcoating
around the tablet
20.2 Which of
the following is NOT true for tablet formulations?
A. A disintegrating
agent promotes granule flow
B. Lubricants prevent
adherence of granules to the punch faces of the tableting machine
C. Glidants promote
flow of the granules
D. Binding agents are
used for adhesion of powder into granules
E. All of the above
F. None of the above
20.3 Agents
that may be used in the enteric coating of tablets include
A. Hydroxypropyl
methylcellulose
B. Carboxymethylcellulose
C. Cellulose acetate
phthalate
D. All of the above
E. None of the above
20.4 Patients
who cannot swallow enteric-coated tables should
A. Dissolve the tablet
before taking
B. Crush before taking
it
C. Swallow tablet
without water
D. Consult a pharmacist
for an alternative
20.5 Adequate
powder flow ensures that after tableting
A. Tablets of constant
weight are produced
B. Rapid drug release
C. Drug molecules are
crushed
D. Smooth tablets are
produced
20.6 To
provide enough bulk for compression, which of the following excipients is often
added to tablet formulation?
A. Glidants
B. Diluents
C. Lubricants
D. Disintegrants
20.7 Mixing of magnesium
stearate with tablet granules will
A. Decrease the
crushing strength of tablets
B. Increase tablet
dissolution
C. Increase tablet
hardness
D. Increase tablet
disintegration
20.8 Which of the
following excipients can be used as a binder in granulation?
A. Magnesium stearate
B. Starch mucilage
C. Fumed silica
D. Isopropanol
20.9 Your lab is
designing a tablet dosage form of a highly insoluble com-pound, Lisinopril. You
have recently faced the problem of tablet sticking to the punches during the
tablet compression operation.
A. Explain what
modification in the formulation would be the easiest way to solve the problem
B. What problem do you
anticipate this step to result in and why? How do you correlate this with
Fick’s law?
20.10 Explain
how the role of a glidant in a tablet formulation is different from the role of a
lubricant, during the process of tablet compression.
A. Define briefly
disintegration, dissolution, and absorption.
B. You desire to
formulate a highly insoluble compound into an oral pharmaceutical formulation.
The formulation you prepared has excellent disintegration characteristics but
the dissolution profile in water or acid media is very low (less than 10%
dissolved in 60 minutes). You desire to redesign the dissolution conditions so
as to achieve higher dissolution rates. Suggest what all experi-ments would you
conduct for this purpose.
20.11 What are
the two main properties of drugs that are used to categorize drugs in the
biopharmaceutics classification system (BCS)?
A. Solubility
B. Stability
C. Permeability
D. Bioavailability
E. Manufacturability
Answers:
20.1 C. The
ionized, or salt, form of a drug is generally more water soluble and therefore dissolves
more rapidly than the nonionized (free acid or free base) form of the drug.
According to the Noyes–Whitney equation, the dissolution rate is directly
proportional to the sur-face area and inversely proportional to the particle
size. Therefore, an increase in the particle size or a decrease in the surface
area slows the dissolution rate. Use of sugarcoating around the tablet will
also decrease the dissolution rate.
20.2 A.
Disintegrating agents are added to the tablets to promote breakup of the tablets when
placed in the aqueous environment. Lubricants are required to prevent adherence
of the granules to the punch faces and dies. Binding agents are added to bind
powders together in the granulation process. Glidants are added to tablet
formula-tions to improve the flow properties of the granulations.
20.3 C.
Enteric-coating materials include cellulose acetate trimellitate, poly(vinyl
acetate)phthalate, hydroxypropyl methylcellulose phthalate, and cellulose
acetate phthalate.
20.4 D. An
enteric-coated tablet has a coating that remains intact in the stomach but dissolves in
the intestine when the pH exceeds 6.
20.5 A.
20.6 B.
20.7 A.
20.8 B.
20.9 A.
Increase in lubricant concentration.
B.
Decrease in dissolution rate. The diffusion coefficient across the membrane
increases because lubricants are hydrophobic.
20.10 Glidant
is used for improving the flow properties of the solids/gran-ules, whereas
lubricant serves to prevent adhesion of the tablet to dies and punches.
20.11 A.
Disintegration is the process of breaking up of a tablet/capsule dosage form into the
constituent granules. Dissolution is the pro-cess whereby the solid drug in a
dosage form turns into a solution in the surrounding liquid media. Absorption
is the process of the dissolved drug crossing the cellular membrane barrier to
enter the systemic circulation.
B.
Increase the volume of the media, (ii) add a surfactant to the media, (iii) use
a cosolvent such as alcohol, (iv) use biphasic solu-tion such as water and
chloroform, (v) increase paddle rpm, and (vi) change from basket to paddle
apparatus.
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