MOA: exact mechanism of analgesia still unknown. Weak COX 1 and 2 inhibitor in pheriphery and COX 3 in brain (stops PGE synthesis)
Use: Analgesis, Antipyretic, no anti-inflammatory activity. Used by 23% of US adults in any given week
Metabolism: Major pathway --> conjugation to metabolites excreted in urine. Minor pathway --> P450 oxidation producing toxic intermediate which is detoxified by conjugation with glutathione
Dose: Capsules, tablets, suppositories, solution 80-500 mg (extra strength), 650 mg (Tylenol Arthritis Strength). Pediatric liquid (160 mg/5 ml). Combined with opioids such as oxycodone (Percocet), hydrocodone (Vicoden), and codeine (Tylenol #3). Adults: not to exceed 4 gm/day (give every 4-8 hrs)
. Do not exceed 3 gm/day in elderly, in kids 10-15 mg/kg every 4-6 hrs.
Adverse effects: generally safe at therapeutic doses, no effect on bleeding time or GI tract, potential for renal tubular necrosis with chronic dosing.