Pharmaceutical Sciences & Calculations Flashcards

What is the molecular basis of drug tolerance?

Answer: Receptor downregulation

Tolerance often develops due to receptor downregulation — the number or sensitivity of receptors decreases with repeated drug exposure, reducing effect.

Which type of emulsion is most suitable for intravenous administration?

Answer: Oil-in-water (O/W)

O/W emulsions are miscible with blood (which is aqueous-based), making them suitable for IV use. W/O emulsions are not compatible with blood.

A drug with a narrow therapeutic index requires:

Answer: Therapeutic drug monitoring

Narrow therapeutic index drugs have a small margin between therapeutic and toxic doses, necessitating regular therapeutic drug monitoring (TDM) to ensure safety.

Which process describes drug movement from blood into tissues?

Answer: Distribution

Distribution refers to the reversible transfer of a drug from the systemic circulation into tissues and organs throughout the body.

What is the significance of a drug's pKa?

Answer: It determines the degree of ionisation at a given pH

pKa is the pH at which 50% of the drug is ionised. It helps predict ionisation state at physiological pH, influencing absorption and distribution.

Parenteral preparations must be:

Answer: Sterile and pyrogen-free

Parenteral (injectable) preparations must be sterile and free from pyrogens (bacterial endotoxins) as these can cause fever and serious reactions when injected.