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Chapter: Pharmaceutical Drugs and Dosage: Tablets

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


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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