Vitamin B12 Mechanism of Action Vitamin B12 (cobalamin) is an essential cofactor for two critical enzymatic reactions in humans: Methionine synthase (MTR): Transfers a methyl group from 5‑methyltetrahydrofolate to homocysteine, generating methionine and tetrahydrofolate. Methylmalonyl‑CoA mutase: Converts methylmalonyl‑CoA to succinyl‑CoA in the mitochondrial matrix, a key step in odd‑chain fatty‑acid and choline catabolism. By maintaining … Read more
Vistaril — Mechanism of Action Hydroxyzine, the active ingredient in Vistaril, is a first‑generation H1‑histamine receptor antagonist with significant anticholinergic properties. H1 Blockade: Prevents histamine binding → ↓ CNS arousal, ↓ peripheral vasodilation, ↓ smooth‑muscle contraction. Contributes to its anti‑pruritic, anxiolytic, and sedative effects. Anticholinergic Activity: Blocks muscarinic M1–M5 receptors → ↓ secretions, ↓ GI … Read more
Vimpat Vimpat (lacosamide) is an antiepileptic drug (AED) that selectively stabilizes inactivated voltage‑gated sodium channels, providing targeted seizure control with a favorable safety profile. Mechanism of Action Selective Stabilization of Inactivated Na⁺ Channels – slows recovery from inactivation, limiting hyperexcitable neuronal firing without affecting peak channel activation. Reduced Interneuronal Excitability – decreases repetitive firing in … Read more
Vilazodone Vilazodone (brand name Viibryd™) is a selective serotonin reuptake inhibitor (SSRI) with added partial agonist activity at the serotonin‑1A (5‑HT₁A) receptor, approved for the treatment of major depressive disorder (MDD) in adults. Mechanism of Action Serotonin reuptake inhibition: Blocks the serotonin transporter (SERT), increasing extracellular serotonin. 5‑HT₁A partial agonism: Acts as a partial agonist … Read more
Viibryd Viibryd (vilazodone) is a novel, serotonin‑selective reuptake inhibitor and partial agonist of the 5‑HT1A receptor, approved for the treatment of major depressive disorder (MDD) in adults. — Mechanism of Action Serotonin Reuptake Inhibition Vilazodone blocks the serotonin transporter (SERT), raising extracellular 5‑HT levels in the synaptic cleft, similar to conventional SSRIs. 5‑HT1A Partial Agonism … Read more
Victoza Victoza (liraglutide) is a once‑daily glucagon‑like peptide‑1 (GLP‑1) receptor agonist approved for type 2 diabetes mellitus (T2DM). It improves glycemic control, promotes weight loss, and carries modest cardiovascular benefits. Mechanism of Action GLP‑1 receptor agonist: Binds to GLP‑1 receptors on pancreatic β‑cells, enhancing glucose‑dependent insulin secretion and suppressing glucagon release. Delay gastric emptying: Slows intestinal … Read more
Vicodin Vicodin is a fixed‑dose combination analgesic containing 5 mg of hydrocodone (an opioid μ‑agonist) and 300 mg of acetaminophen (a non‑opioid analgesic). It is widely used for moderate‑to‑severe acute pain management, especially post‑operative or after traumatic injury. Mechanism of Action Acetaminophen: Inhibits central prostaglandin synthesis (COX‑1/COX‑2) with limited peripheral activity, providing antipyretic and analgesic effects without … Read more
Vibramycin Vibramycin (generic: tetracycline) is a broad‑spectrum tetracycline antibiotic used to treat a variety of bacterial infections. Mechanism of Action Binds 30S ribosomal subunit of susceptible bacteria, blocking attachment of aminoacyl‑tRNA. Inhibits peptide bond formation → ↓ bacterial protein synthesis. Activity depends on the presence of divalent cations; chelation (e.g., calcium) reduces absorption. Pharmacokinetics Parameter … Read more
Vibegron Vibegron (brand names: GEMBIL in the U.S. and VIBEGRON elsewhere) is a selective, oral β3-adrenergic receptor agonist approved for the management of overactive bladder (OAB) with urgency, urge urinary incontinence (UUI), and frequency. Mechanism of Action Selective β3-adrenergic receptor agonist activates urothelial β3 receptors. Promotes relaxation of the detrusor muscle during the storage phase, … Read more
Viagra Viagra (generic name sildenafil citrate) is the first‑approved phosphodiesterase‑5 (PDE5) inhibitor indicated for men with erectile dysfunction (ED). Its pharmacology is fundamental to understanding its therapeutic use, safety profile, and clinical nuances. Mechanism of Action Selectively inhibits PDE5 → prevents degradation of cyclic guanosine monophosphate (cGMP) in corpus cavernosum smooth muscle. Enhances nitric‑oxide (NO)–mediated … Read more