Allopurinol
Allopurinol. Xanthine oxidase inhibitor — converts to active oxipurinol; both compete with hypoxanthine + xanthine for XO active site. Lowers… Oral half-life 0.8 h.
Xanthine oxidase inhibitor — converts to active oxipurinol; both compete with hypoxanthine + xanthine for XO active site. Lowers serum uric acid in gout + tumor lysis syndrome. SCAR (severe cutaneous adverse reactions) risk in HLA-B*5801 carriers (Asian / African ancestry).
PK: THE HALF-LIFE WAS OFF BY A FACTOR OF 2.5 AND TWO PRIMARIES SAY SO. "Serum half-lives of allopurinol and oxipurinol were 39 +/- 11 min and 13.6 +/- 2.8 hr" and "an elimination half-life of 47.8 +/- 10.6 min" — ALLOPURINOL HALF-LIFE IS FORTY TO FORTY-EIGHT MINUTES, not the 2 h stored, which is the textbook range endpoint. The whole block moves to one study that dosed BOTH intravenously and orally, giving a verbatim half-life, a verbatim clearance of 11.37 ml/min/kg and a verbatim "The bioavailability of oral allopurinol computed from plasma data was 90.4 +/- 8.7%"; the volume and absorption rate are derived from those inside that single fit and the derived peak lands at 0.98 h, INSIDE that paper own "reached within 30 to 120 min". The previously stored bioavailability was itself verbatim and correctly sourced, from four subjects, and is superseded only to keep one coherent set. V 65 L WAS PROBABLY A CLEARANCE READ AS A VOLUME: the cited abstract gives a volume only for the METABOLITE, and neither of its two figures is 65, but it does state "Total clearance of allopurinol ... (15.7+/-3.8 ml min-1 kg-1)", which at the reference weight is 65.94 L/h. Offered as a hypothesis. The record pharmacology belongs to oxipurinol, but it carries no occupancy row, so nothing currently makes a false effect claim.
Pharmacokinetics
- Oral — t½ 48 min · F 90% · ka 1.18 h⁻¹ · Vd 54.9 L
Sources: PMID:7094977, PMID:10583019, PMID:639435