Single-dose bioavailability of oral and intramuscular thiocolchicoside in healthy volunteers

A single dose of 8 mg of thiocolchicoside was administered to 12 healthy volunteers according to a Latin square design, either as tablets (reference), oral solution, or intramuscular injection. Serum thiocolchicoside concentrations showed an absorption phase followed by a biexponential decay with a terminal half-life (t1/2 beta) of approximately 5 h, similar for the three formulations. The relative bioavailability of both oral formulations was approximately 25%, compared to the intramuscular formulation. There was a trend for the oral solution to have a slightly larger AUC and Cmax, as well as a slightly shorter Tmax, than the tablet formulation. However, the comparison of the two oral forms did not show statistically significant differences in the pharmacokinetic parameters Cmax, Tmax, and AUC, suggesting that the Coltramyl tablets have an adequate in vivo dissolution profile.