Practice Test Geeks(PSA) Prescribing Safety Assessment Practice Test
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Pharmacology Principles Flashcards

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

Read the first 7 Pharmacology Principles flashcards as text

  1. An inverse agonist at a receptor will produce which effect?

    Answer: A response opposite in direction to the endogenous agonist

    An inverse agonist binds the receptor and produces an effect opposite to the endogenous agonist, stabilising the inactive receptor conformation below baseline constitutive activity.

  2. The EC50 of a drug is defined as:

    Answer: The concentration producing 50% of the drug's maximal effect

    EC50 (effective concentration 50) represents the drug concentration at which 50% of maximum effect (Emax) is achieved, and reflects drug potency.

  3. Competitive antagonism at a receptor produces which characteristic change in the dose-response curve?

    Answer: Rightward shift with no change in maximum effect (Emax)

    Competitive antagonists reversibly compete with agonists at the same binding site; increasing agonist concentration can overcome this, so Emax is preserved but more agonist is needed (rightward shift).

  4. The therapeutic index (TI) of a drug is calculated as:

    Answer: TD50 / ED50

    Therapeutic index = TD50 / ED50; a higher TI means a greater margin between therapeutic and toxic doses, indicating a safer drug.

  5. Tolerance to opioids develops primarily through which pharmacological mechanism?

    Answer: Mu-opioid receptor downregulation and desensitisation

    Chronic opioid exposure leads to downregulation and desensitisation of mu-opioid receptors via internalisation and uncoupling from G-proteins, requiring higher doses for the same effect.

  6. Beta-2 adrenoceptors are G-protein coupled receptors (GPCRs) that activate adenylate cyclase. Which second messenger is produced by this activation?

    Answer: Cyclic AMP (cAMP)

    Gs-coupled receptors like beta-2 adrenoceptors activate adenylate cyclase, increasing intracellular cAMP, which activates protein kinase A to mediate bronchodilation.

  7. Non-competitive antagonism differs from competitive antagonism because:

    Answer: It reduces Emax and cannot be overcome by increasing agonist concentration

    Non-competitive antagonists bind irreversibly or at an allosteric site, reducing the maximum achievable response (Emax) regardless of agonist concentration.