Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Mechanisms of action
| Question | Answer |
|---|---|
| What is the mechanism of action of amiodarone? | Amiodarone blocks potassium channels, prolonging phase 3 repolarization and increasing action-potential duration and refractory period. It also has sodium-channel, calcium-channel, and noncompetitive β-blocking effects, |
| What is the mechanism of action of epinephrine? | Epinephrine is a potent α- and β-adrenergic agonist that causes peripheral vasoconstriction via α1, increases heart rate and contractility via β1, and produces bronchodilation via β2 activation. |
| How does ephedrine work? | Ephedrine indirectly increases norepinephrine release from sympathetic nerve terminals and also weakly stimulates α and β receptors directly, increasing heart rate, blood pressure, and bronchodilation. |
| What is the mechanism of action of atropine? | Atropine is a competitive muscarinic acetylcholine receptor antagonist that blocks parasympathetic activity. In the heart, it increases SA node firing and AV conduction by inhibiting vagal tone. |
| How does albuterol cause bronchodilation? | Albuterol selectively stimulates β2-adrenergic receptors in bronchial smooth muscle, increasing cAMP via adenylate cyclase activation and causing smooth-muscle relaxation. |
| What is the mechanism of action of aspirin? | Aspirin irreversibly inhibits COX-1 and COX-2, blocking prostaglandin and thromboxane synthesis. Platelet inhibition lasts for the platelet’s entire lifespan because platelets cannot regenerate COX-1. |
| Why is esmolol useful in acute cardiac settings? | Esmolol is an ultra-short-acting, cardioselective β1-blocker that reduces heart rate, contractility, and AV nodal conduction. It is rapidly metabolized by red-blood-cell esterases, allowing tight titration. |
| What receptors does labetalol block? | Labetalol blocks β1, β2, and α1 receptors, decreasing heart rate and systemic vascular resistance. α1 blockade lowers blood pressure with minimal reflex tachycardia. |
| How does lidocaine act as an antiarrhythmic? | Lidocaine is a class Ib antiarrhythmic that blocks fast sodium channels, shortening action-potential duration in ventricular myocardium and preferentially suppressing ischemic or depolarized tissue. |
| What are the key pharmacologic effects of diphenhydramine? | Diphenhydramine is a first-generation H1 antagonist that blocks histamine-mediated allergic responses and has anticholinergic effects, causing sedation and drying of secretions. |
| What is the mechanism of action of dexamethasone? | Dexamethasone is a potent glucocorticoid that binds intracellular receptors to alter gene transcription, reducing inflammatory cytokines, capillary permeability, and tissue edema. |
| How does naloxone reverse opioid overdose? | Naloxone is a competitive μ-opioid receptor antagonist that rapidly reverses opioid-induced respiratory depression and CNS effects; repeat dosing may be needed due to its short duration. |
| What is the mechanism of action of flumazenil? | Flumazenil competitively inhibits benzodiazepine binding at the GABA-A receptor, reversing sedation and respiratory depression; its short half-life may require redosing. |
| How does adenosine terminate supraventricular tachycardia? | Adenosine activates A1 receptors in the AV node, opening potassium channels and hyperpolarizing tissue, transiently blocking AV conduction and interrupting re-entrant SVTs. |
Created by:
user-2015162