Anastrozole Mechanism of Action Anastrozole is a reversible, non‑steroidal aromatase inhibitor that competitively binds the heme moiety of the aromatase enzyme (CYP19A1). It irreversibly blocks the conversion of androstenedione and testosterone to estrone and estradiol, thereby suppressing peripheral estrogen synthesis in post‑menopausal women. Inhibition is biphasic: an initial rapid binding followed by a slower, more … Read more
Ampicillin Ampicillin is a semi‑synthetic penicillin V derivative with a broad spectrum of activity against many Gram‑positive and Gram‑negative organisms. It is widely used for community‑acquired infections, prophylaxis in certain surgical settings, and as a first‑line agent in pediatric therapy. Mechanism of Action Inhibits bacterial cell‑wall synthesis by binding to and inactivating penicillin‑binding proteins (PBPs) that … Read more
Amoxicillin Amoxicillin is a semi‑synthetic, broad‑spectrum β‑lactam antibiotic widely used to treat bacterial infections caused by gram‑positive and gram‑negative organisms. It is typically available as an oral formulation (capsule, chewable tablet, liquid) and as an intravenous formulation for severe infections. Mechanism of Action Inhibition of bacterial cell‑wall synthesis: Amoxicillin binds to penicillin‑binding proteins (PBPs) on … Read more
Amlodipine Mechanism of Action Amlodipine is a dihydropyridine calcium‑channel blocker (CCB) that selectively inhibits L‑type voltage‑dependent Ca²⁺ channels in vascular smooth muscle. It reduces intracellular Ca²⁺ influx, causing vasodilation of arteriolar beds ➜ ↓ systemic vascular resistance and arterial pressure. Minimal effect on cardiac conduction; at therapeutic doses it produces little change in heart rate … Read more
Amitriptyline Amitriptyline is a tricyclic antidepressant (TCA) with a broad spectrum of therapeutic uses beyond depression, including neuropathic pain, migraine prophylaxis, and sleep disorders. It acts primarily by inhibiting the reuptake of serotonin and norepinephrine, producing both antidepressant and analgesic effects. Mechanism of Action Amitriptyline exerts its pharmacologic effects through multiple pathways: Serotonin‑Norepinephrine Reuptake Inhibition … Read more
Amiodarone Amiodarone is a long‑acting, multi‑class antiarrhythmic agent commonly used to treat serious ventricular arrhythmias and supraventricular tachyarrhythmias. Mechanism of Action Class III activity: Potassium channel (IKr, IKs) blockade prolongs repolarization and the QT interval. Class I(a) and III effects: Sodium channel blockade slows conduction, especially in diseased myocardium. Class IV-like β‑blockade: Reduces automaticity and Ca²⁺ … Read more
Amantadine Amantadine is a low‑molecular‑weight, first‑generation antiviral that also serves as a dopaminergic agent used in movement disorders. Below is a concise, clinically‑oriented drug card ready for medical‑students and practitioners. — Mechanism of Action Amantadine acts through two primary mechanisms: Mechanism Clinical Relevance Inhibition of viral RNA uncoating Blocks the M2 proton channel of influenza … Read more
Alprazolam Mechanism of Action Alprazolam is a benzodiazepine that potentiates inhibitory neurotransmission. Enhances the activity of the γ‑aminobutyric acid (GABA)‑A receptor complex. Increases chloride ion influx, hyperpolarizing neuronal membranes. Produces anxiolytic, sedative‑hypnotic, anticonvulsant, and muscle‑relaxant effects. Pharmacokinetics Absorption – Rapid, peak plasma levels within 1–2 h; bioavailability ≈ 96 %. Distribution – Highly protein‑bound (~ 94 %); crosses blood–brain barrier … Read more
Allopurinol Allopurinol is the cornerstone xanthine oxidase inhibitor used to manage chronic gout and hyperuricemia, prevent nephrolithiasis, and control uric acid production in tumor lysis syndrome. — Mechanism of Action Blockade of xanthine oxidase (XO) → ↓ conversion of hypoxanthine → xanthine → uric acid. Results in ↓ serum urate and ↓ urinary urate excretion. … Read more
Alfuzosin — Mechanism of Action Alfuzosin is a selective α1-adrenergic receptor antagonist. It preferentially blocks α1A‑ and α1B‑receptors in the smooth muscle of the prostate, bladder neck, and lower urinary tract. By inhibiting adrenergic stimulation, it reduces urethral and prostatic smooth‑muscle tone, thereby improving urine flow and decreasing bladder outlet obstruction. Its high receptor selectivity … Read more