title: Bioavailability of intramuscularly administered tenoxicam.
abstract: Bioavailability of intramuscularly administered tenoxicam relative to single oral and relative to intravenous doses was determined in two separate randomized crossover studies. Twelve healthy volunteers (12 males, age 20-30 years) received a rapid intravenous injection and a single intramuscular dose and 12 other subjects (11 males, 1 female, age 21-25 years) a single oral and a single intramuscular dose of 20 mg of tenoxicam on two different occasions. The wash-out period between the two consecutive treatments was 4 weeks. Plasma concentrations after dosing were determined by a specific HPLC method. Differences in tenoxicam concentration-time profiles after the different routes of administration were limited to the first 2 h after dosing. Later, plasma concentrations were almost superimposable within and across the two studies. The extent of absorption of intramuscularly administered tenoxicam was complete (mean +/- CV per cent: F(abs) 0.99 +/- 20 per cent) with no difference between the two extravascular administrations (F(rel) 0.95 +/- 10 per cent, intramuscular vs oral). After intramuscular administration tenoxicam was more rapidly absorbed compared to the oral dose (Tmax 0.71 h +/- 80 per cent vs 1.4 h +/- 62 per cent; p > 0.05). Peak concentrations after oral and intramuscular administration (Cmax 2.5 mg l-1 +/- 19 per cent vs 2.7 mg l-1 +/- 14 per cent; p < 0.05) were very similar.
authors.affiliation: F. Hoffmann-La Roche Ltd, Basel, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Stebler
authors.forename: T W
authors.initials: TW
authors.lastname: Guentert
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D001682:Biological Availability; D006801:Humans; D007273:Injections, Intramuscular; D007275:Injections, Intravenous; D008297:Male; D010894:Piroxicam / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D010894:Piroxicam; C032801:tenoxicam