Pharmacokinetic properties of tramadol sustained release capsules. 3rd communication: investigation of relative bioavailability under steady state conditions.

In an open, randomized two-period crossover study in 24 healthy male volunteers multiple doses of tramadol (CAS 27203-92-5) test and reference medication were administered as follows: Test: sustained release capsules containing 100 mg tramadol hydrochloride, a total of 6 capsules at intervals of 12 h; Reference: instant release capsules containing 50 mg tramadol hydrochloride, a total of 12 capsules at intervals of 6 h. As a result of the statistical analysis of AUCss(48-72 h) after logarithmic transformation a bioavailability of 100% for the sustained release capsules compared with the instant release capsules was obtained. As expected statistical analysis of the peak trough fluctuation at steady state PTFss(48-72 h) yielded a distinct diminution of the fluctuation.