Bioavailability of morphine after oral administration as retard tablets

The oral bioavailability of morphine following administration of a single dose of 30 mg morphine hydrochloride as Vendal retard film tablets (Lannacher Heilmittel) was investigated and compared with the bioavailability of morphine following administration of 30 mg morphine sulphate as Mundidol retard film tablets (Mundipharma). A randomized crossover study was conducted in 24 male, healthy volunteers. In 6 of them a pilot study with formulations containing 60 mg was conducted. Morphine and its metabolites were quantitated with an immunofluorimetric solid-phase assay (DELFIA). With regard to the following parameters the novel controlled-release formulation was statistically different from the reference formulation: area under the concentration-time curve, time to maximum and half value duration. After a single dose of the test formulation analgesic serum levels were maintained over a longer lasting period of time than after administration of the reference formulation. The maximal levels in serum and the elimination half life were not different. From the improved pharmacokinetic parameters of the novel controlled-release formulation an improved clinical efficacy can be expected.