The in vitro metabolic inversion of R(-) to S(+) indoprofen

The paper reports a study on the metabolic inversion of indoprofen (2-[4-(2-isoindolinyl-1-one)-phenyl]-propionic acid) following incubation of the drug with liver microsomes from non-induced and phenobarbital-induced rats. The enantiomeric composition of the drug was determined after different incubation times of the racemate and the individual isomers. The S(+)/R(-) ratio was evaluated by densitometry following HPTLC separation of the R(+)-1-phenylethylamides. After incubation of the racemate and the individual isomers, no detectable amounts of indoprofen catabolites were extracted from the acidified incubation mixture. An appreciable enrichment in the S(+) enantiomer was observed after incubation of both racemate and R(-)-indoprofen; the S(+)/R(-) ratio reached a maximum after 1 h. Values were higher in the case of induction. After incubation of S(+)-indoprofen, a small but statistically significant decrease of the S(+)/R(-) ratio was observed. The increase of the S(+)-isomer concentration observed following incubation of R(-)-indoprofen can be ascribed to metabolic inversion by phenobarbital-inducible liver enzymes.

Pharmacokinetic profile of indoprofen in elderly subjects

Multiple dosing four times daily for 7 days of indoprofen 200 mg, a non-steroidal anti-inflammatory drug with a short half-life (t1/2), revealed drug accumulation in eight elderly subjects. This indicates a substantially longer t1/2 (11 h) than that reported in young persons (3 h). A reduction in dose compared to younger subjects is recommended in elderly patients with osteoarthritis.

Some novel observations of a drug (indoprofen)--albumin interaction

Indoprofen, a new-steroidal anti-inflammatory agent, binds to human serum albumin in an endothermic reaction at low degrees of saturation and with an exothermic reaction at higher drug to protein ratios. Although indoprofen appears to bind to the same primary site as diazepam, dialysis studies show an increased binding of both drugs in the presence of the other. This novel observation is probably due to the effect of the drugs on the N leads to B conformational change of human serum albumin.

Intra-articular drug therapy in rheumatoid arthritis. A study with indoprofen

Six patients (4 men, 2 women) with moderate/large knee effusions due to rheumatoid arthritis (RA) were studied after receiving indoprofen, 25 mg intra-articularly and then 200 mg orally 1 week later. There was significant improvement in pain (t = 3.74, P less than 0.05), morning stiffness (t = 2.91, P less than 0.05) and range of movement (t = 2.52, P less than 0.05) for at least 1 week following the intra-articular injection. The terminal phase plasma half-life after the 200 mg oral dose was 6.4 +/- 0.7 h (mean +/- SEM) and was significantly longer than the often quoted plasma half-life of 2-3 h from previous studies, but much less than the pharmacodynamic half-life. Synovial fluid concentration were not significantly different from those in plasma in the post-distribution phase. Intra-articular indoprofen may be a useful addition to the treatment of RA.

How frequently should anti-inflammatory drugs be given? A study with indoprofen

Indoprofen, despite its relatively short plasma half-life, was just as effective given twice daily as when the same daily total was given in four divided doses. There was a trend in favour of the twice daily regime for changes in morning pain and the duration of morning stiffness. Preferences were equally divided between the two regimes and efficacy was the usual reason for patients preferring one or other. Side-effects were no more frequent with the twice daily regime. Pharmacokinetics are no substitute for clinical experiment in planning the dosage regime of a non-steroidal anti-inflammatory drug.

Plasma and synovial fluid pharmacokinetics and prostaglandin inhibitory effect of indoprofen in patients with rheumatoid arthritis

Indoprofen was given intravenously (bolus followed by infusion) and orally to 7 patients suffering from active rheumatoid arthritis with knee joint effusion. Indoprofen readily penetrated into synovial fluid in amounts which were directly correlated with areas under curves of plasma drug levels. Synovial fluid acted as a compartment distinct from the central (plasma) compartment. Indoprofen caused a substantial decrease in E2 and F2 alpha prostaglandin concentration in synovial fluid.

Kinetics of analgesic response in man; an example with two non-steroidal anti-inflammatory analgesic drugs

A double-blind, controlled trial is described in which a total of forty hospital in-patients suffering from severe post-operative pain were randomly allocated to treatment with one of two non-steroidal anti-inflammatory drugs, namely, either indoprofen which has a short half-life (two-hours) or naproxen which has a long half-life (thirteen hours). The drugs were administered orally on a single-dose basis. The doses used in this way were 300 mg of indoprofen or 250 mg of naproxen. Patients scored the severity of their pain on a five-point scale and these scores were recorded prior to and at fixed time intervals up to eight hours following administration of medication. No significant differences emerged between the two test drugs and the duration of the response was also found to be similar for the two compounds despite their very different plasma half-life values.