Pharmaceutical Sciences Flashcards

What is the purpose of a preservative in a multi-dose ophthalmic solution?

Answer: To prevent microbial contamination between uses

Preservatives such as benzalkonium chloride in multi-dose eye drops prevent bacterial and fungal contamination after the container is opened and used repeatedly.

Which dosage form provides the most rapid onset of systemic drug action after oral administration?

Answer: Sublingual tablet

Sublingual tablets dissolve under the tongue, where drugs are rapidly absorbed directly into systemic circulation through the oral mucosa, bypassing hepatic first-pass metabolism.

What does 'hygroscopic' mean in pharmaceutical storage?

Answer: The substance readily absorbs moisture from the surrounding air

Hygroscopic substances absorb water vapour from the environment, which can alter drug stability, potency, and physical form, requiring storage in airtight containers.

What is the significance of a drug's pKa value in pharmacokinetics?

Answer: It determines the pH at which the drug is 50% ionised and 50% un-ionised, affecting membrane permeability

At a pH equal to the pKa, a drug exists in equal proportions of ionised and un-ionised forms; this ratio governs how easily the drug crosses lipid membranes for absorption and distribution.

Which excipient category is used to increase tablet hardness and provide bulk in solid dosage forms?

Answer: Diluents/fillers (e.g., lactose, microcrystalline cellulose)

Diluents or fillers like lactose and microcrystalline cellulose add bulk and improve compressibility to achieve the required tablet weight and hardness.

What is meant by the term 'therapeutic equivalence' between two drug products?

Answer: Both products are pharmaceutically equivalent and produce the same clinical effect when administered to patients under specified conditions

Therapeutic equivalents are pharmaceutically equivalent products demonstrated to produce the same clinical outcomes, meaning they can be substituted for each other safely in clinical practice.