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Example Drugs - Updated - E xample D r ugs ASA(= non-prop...

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Example Drugs ASA (= “non-proprietary name” = “official name”)(note: in US the non-proprietary name is “aspirin”). Note The only o.t.c. drug on this list. Galenical Source Willow bark Brand Names (= “proprietary names”): Many (learn Ancasal, Arthrinol, Asprin , Astrin). (Note: Trade names are capitalized. Non-proprietary names are not.) It’s an old drug (long “off patent”) and still a good seller. It’s sold as a “generic” under many trade names. Drug Class analgesic, NSAID (?) (means it’s anti-inflammatory), antithrombolitic (means it’s “anti-platelets”), antipyretic (lowers fever) Related Drugs Salicylic acid (active metabolite), sodium salicylate. Actions Blocks COX (irreversibly) and therefore prostaglandin synthesis (COX 1 and 2) pKa: 3.5 . It’s an acid. Mean Vd 0.15 L/kg (As SA? Smallest Vd of the example drugs.) Reasons? It’s 80% protein bound, and charged at pH 7.) (Size?) Plasma Protein Binding 80% (SA) Oral Bioavailability Really 100% (70% as ASA, 30% as SA). Half-Life 15-20 minutes as ASA (broken down in blood, etc.). SA (after a moderate dose), 2.5-3 hours. (Note: higher doses extend half life of SA.) The actual therapeutic effects of the drug can be even longer, since it irreversibly inhibits an enzyme. Absorption Passive diffusion from stomach (less) and small intestine (more). (Small molecule. Can pass through aquaporins.) Antacids (affect pH) may decrease absorption from the stomach. Enteric coating may impair or prevent absorption. Distribution Throughout the body (despite the small mean Vd), but unevenly distributed. (High in blood, low in brain.) Crosses the placenta. Found in breast milk.
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Elimination ASA to SA in gut, blood and other tissues. SA is eliminated unchanged and also biotransformed by the liver (four pathways, two saturable). In overdose, some of the pathways go to “pseudo-zero order” metabolism) and the SA builds up. Alkaline pH in the renal tubules (sodium lactate, pH 5 goes to pH 8) can increase the elimination of SA by “ion trapping” it in the urine. (Over 20 fold increase. Used after overdose.) Note: Elimination of SA is slower in the elderly and in patients with kidney disease. ADR’s G.i. problems (nausa, vomiting, heartburn, cramps, indigestion - bleeding and ulcers with chronic use), tinnitus, vertigo (dizziness) temporary deafness, elevated prothrombin times (bruising and bleeding). There is a rare “hypersensitivity” syndrome (Non-dose related?) seen in less than 1 in 200 people. Interactions Displacement of other acids from plasma proteins (e.g., bilirubin). Causes more bleeding if combined with anticoagulants (e.g., warfarin.) Diazepam (= “non-proprietary” name = “official” name) Brand Names (= “proprietary names”): Many: Apodiazepam, Diazemuls, E-Pam, Valium ) (Valium was the original trade name.) It’s an old drug (long “off patent”) and still a good seller. It’s sold as a “generic” under many trade names.
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