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Pharmacodynamics and Mechanism of Action Flashcards

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

Read the first 7 Pharmacodynamics and Mechanism of Action flashcards as text

  1. Which type of drug-receptor interaction is characterized by the formation of a covalent bond, making the interaction essentially permanent?

    Answer: Irreversible binding

    Covalent bond formation between a drug and receptor results in irreversible binding, as seen with aspirin's acetylation of cyclooxygenase.

  2. Which pharmacodynamic concept explains why a drug that occupies only 1% of receptors can still produce a maximal response?

    Answer: Spare receptors (receptor reserve)

    Spare receptors exist when maximal tissue response can be achieved with only a fraction of receptors occupied, due to amplification in the signaling cascade.

  3. A Gq-coupled receptor activation leads to which downstream cascade?

    Answer: Phospholipase C activation → IP3 + DAG

    Gq activates phospholipase C-beta, which cleaves PIP2 into IP3 (releases Ca2+ from ER) and DAG (activates protein kinase C).

  4. Which receptor type directly phosphorylates tyrosine residues on target proteins upon ligand binding?

    Answer: Receptor tyrosine kinase (RTK)

    Receptor tyrosine kinases (e.g., insulin receptor, EGF receptor) autophosphorylate tyrosine residues upon ligand binding, triggering downstream signaling cascades.

  5. A drug with a therapeutic index (TI) of 2 compared to one with TI of 20: which is safer and why?

    Answer: TI=20, because higher TI means greater margin between effective and toxic doses

    The therapeutic index (TD50/ED50) measures safety margin; a higher TI indicates a larger separation between the effective and toxic dose ranges.

  6. Which pharmacodynamic interaction occurs when two drugs produce an effect greater than the sum of their individual effects?

    Answer: Potentiation (synergism)

    Synergism (potentiation) describes an interaction where the combined effect exceeds the arithmetic sum of each drug's individual effects.

  7. Nuclear receptors differ from membrane receptors primarily in that they:

    Answer: Mediate effects by directly regulating gene transcription

    Nuclear receptors (e.g., glucocorticoid receptor) act as transcription factors, binding DNA to alter gene expression after ligand binding.