Pharmacokinetic properties of tramadol sustained release capsules. 2nd communication: investigation of relative bioavailability and food interaction.

In an open, randomized four-period crossover study in 24 healthy male volunteers a newly developed tramadol (CAS 27203-92-5) sustained release capsule with and without concomitant food intake and an instant release formulation were administered. Additionally, a sustained release tablet was applied as further reference substance. Statistical analysis of AUC(0-infinity) and Cmax after logarithmic transformation yielded bioequivalence of tramadol sustained release capsules with and without concomitant food intake. Therefore, lack of food interaction could be concluded. The investigation also showed an only slightly diminished bioavailability of the tramadol sustained release capsules compared to the instant release formulation. Furthermore, the sustained release capsules investigated showed enhanced retardation at almost identical bioavailability compared with the sustained release competitor drug.