Pharmacokinetics and metabolism of indoprofen in the hamster.

2-[p-(1-Oxo-2-isoindolinyl)phenyl]propionic acid (indoprofen) is rapidly absorbed after oral administration (2 mg/kg) to male and female hamsters. Peak plasma levels of about 12-13 microgram/ml are reached within 1 h of dosing. Plasma concentrations in males and females are similar until 4 h but different at subsequent observation times. The half-life of indoprofen in plasma is approximately 7 h for males and 16 h for females. In experiments with 14C-labelled compound, radioactivity is mainly excreted in the urine: 94% of the dose in 6 days for males and 73% in 5 days for females. The females also excrete a significant amount of the drug (22%) in the faeces, probably via the bile. Residual radioactivity in female carcasses on the 5th day represents 1% of the dose. The main excretory product is the unchanged drug as such (about 35% and 21%, respectively, in 0-24 hour urine for males and females) and as glucuronic acid conjugate (29% and 12%). Small amounts of 5- and 6-hydroxy-isoindolinyl derivatives, and of two metabolites whose structures have not been identified, are also found in the urine of the animals of both sexes.

Tissue distribution of 14C-indoprofen in the rat.

The tissue distribution of 14C-labelled 2-[p-(1-oxo-2-isoindolinyl)phenyl)propionic acid (indoprofen) after i.v. injection was studied in male and pregnant rats by whole-body autoradiography. Distribution was characterized by a rapid localization in the liver, kidneys and lungs. A significant amount of radioactivity found in the intestinal contents suggested biliary excretion. There was no indication of retention of the drug in the brain. In pregnant rats, radioactivity crossed the blood-placenta barrier to a moderate extent and low concentrations were found in foetuses.

Gastro-intestinal blood loss during administration of indoprofen, aspirin and ibuprofen.

The acute effect of three non-steroidal anti-inflammatory drugs, ibuprofen, acetylsalicylic acid (ASA) and indoprofen, on faecal blood loss was investigated in 15 subjects by means of 51Cr-labelled erythrocytes. Ibuprofen (900 mg/day for 5 days) and indoprofen capsules and tablets (300 mg and 600 mg/day for 5 days, respectively) slightly increased the amount of blood eliminated in faeces. The increase was of the same order of magnitude for both doses of indoprofen. ASA (1,500 mg/day for 5 days) caused about a 6-fold increase in blood loss. Four days after withdrawal of ASA, faecal blood was still about twice as high as in faeces of subjects given ibuprofen and indoprofen. The method appears sensitive and reliable for comparison of the immediate effect of anti-inflammatory drugs on gastro-intestinal mucosa.