title: Effects of size and frequency of oral doses of charcoal on theophylline clearance.
abstract: The effect of size and frequency of oral doses of activated charcoal on theophylline kinetics was studied. Six fasting, healthy men received intravenous infusions of aminophylline (6 mg/kg) over 1 hr, followed by either no activated charcoal as a control, 5 gm activated charcoal every 2 hr for 6 doses, 10 gm every 2 hr for 6 doses, 10 gm every hr for 12 doses, 20 gm every 2 hr for 6 doses, or 40 gm every 4 hr for 3 doses. Five grams every 2 hr decreased serum theophylline t 1/2 from the control of 9.1 +/- 0.7 to 5.6 +/- 0.4 (SE) hr and decreased the AUC from the control of 123 +/- 11 to 79 +/- 6 mg X hr/l. The regimen of 20 gm every 2 hr further decreased theophylline t 1/2 to 4.3 +/- 0.4 hr and decreased AUC to 62 +/- 6 mg X hr/l. When a 120-gm dose of activated charcoal was given as a regimen of 40 gm every 4 hr or as a regimen of 10 gm every hr, there were small differences in serum theophylline t 1/2 (5.4 +/- 0.3 and 4.3 +/- 0.2 hr) and in AUC (73 +/- 5 and 60 +/- 4 mg X hr/l). Repeated small doses of oral activated charcoal enhanced the total body clearance of theophylline, and larger doses induced a relatively small further increase. There was little difference between the effects of the same total dose every 4 hr vs every hour.
mesh_terms: D000328:Adult; D002606:Charcoal / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006207:Half-Life; D006801:Humans; D007700:Kinetics; D008297:Male; D013806:Theophylline / Q000378:metabolism*
chemical_list: D002606:Charcoal; D013806:Theophylline