PSI Pharmaceutical Sciences 4

Question 1

Which process converts a prodrug to its active form?

Accepted Answer

Bioactivation

Answer

Bioactivation is metabolic conversion of an inactive prodrug to its pharmacologically active metabolite. Example: enalapril → enalaprilat; codeine → morphine (via CYP2D6).

Question 2

Which preservative is commonly used in multi-dose eye drop formulations?

Accepted Answer

Benzalkonium chloride

Answer

Benzalkonium chloride (BAK) is the most widely used preservative in ophthalmic preparations. It disrupts bacterial cell membranes but can cause ocular surface toxicity with prolonged use.

Question 3

Zero-order release from a drug delivery system means drug is released at:

Accepted Answer

A constant rate independent of concentration

Answer

Zero-order release provides a constant amount of drug per unit time, maintaining steady plasma levels. This is ideal for potent drugs with narrow therapeutic windows.

Question 4

Which test ensures that a parenteral product is free of fever-causing bacterial products?

Accepted Answer

Pyrogen/endotoxin test

Answer

The pyrogen/endotoxin test (LAL test — Limulus Amebocyte Lysate) detects bacterial endotoxins that cause fever when injected. It is a critical quality test for parenteral products.

Question 5

Lyophilisation (freeze-drying) is used primarily to improve the stability of:

Accepted Answer

Thermolabile or moisture-sensitive drugs

Answer

Freeze-drying removes water by sublimation under vacuum, preserving the drug structure without heat. It is used for biologicals, vaccines and unstable drugs.

PSI Pharmacy Practice Test

PSI Pharmacy Practice Test

PSI Pharmaceutical Sciences 4