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Pharmaceutical Sciences Flashcards

6 cards from real PSI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Which process converts a prodrug to its active form?

    Answer: Bioactivation

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

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

    Answer: Benzalkonium chloride

    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.

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

    Answer: A constant rate independent of concentration

    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.

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

    Answer: Pyrogen/endotoxin test

    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.

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

    Answer: Thermolabile or moisture-sensitive drugs

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

  6. Which term describes the fraction of administered drug that reaches systemic circulation unchanged?

    Answer: Bioavailability

    Bioavailability (F) is the proportion of dose reaching systemic circulation in active form. IV = 100%; oral bioavailability is reduced by incomplete absorption and first-pass metabolism.