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Influence of two newly synthesized bile acids derivates, namely sodium salt of monoketocholic acid MKH-Na and methyl ester of monoketocholic acid MKH-Me on tramadol (12.5 mg/kg oral and intramuscular) analgesic effect was examined in this research. Analgesic effect was measured by antinociceptive hot plate method. Interaction was estimated by detection of changes in analgesic effect of tramadol combined with bile acids (subcutaneous administration of 4 mg/kg 20 min before tramadol) compared to analgesic effect of the same dose of tramadol given alone. Hydrosoluble sodium salt of monoketocholic acid did not show interaction with tramadol, regardless of the route of administration of tramadol. However, methyl ester of monoketocholic acid increased the analgesic effect of tramadol when it was given intramuscularly. After oral administration of tramadol, methyl ester of monoketocholic acid decreased the analgesic effect of tramadol. According to the time point when interaction reached statistically significant difference, it can be presumed that after intramuscular administration of tramadol, methyl ester of monoketocholic acid increases tramadol absorption and transport to brain and in that way increases its analgesic effect. The analgesic effect of tramadol after oral administration was decreased, which could be explained by the induction of tramadol metabolism in the liver, but should be examined in more details.

The aim of ths study was to investigate the pharmacokinetics of cefotaxime sodium (CEF) pharmacokinetics after oral application in the form of sodium 3alpha,7alpha-dihydroxy-12-keto-5beta-cholanate (MKC) microvesicles (MV) in rat. Thirty Male Wister rats were divided into six groups (n=5 per group). Groups were treated orally with: (i) CEF (15 mg/kg) saline solution (15 mg/kg); (ii) CEF (15 mg/kg) saline solution with MKC (2 mg/kg); (iii) CEF saline solution mixed with blank microvesicles; (iv) CEF (15 mg/kg) encapsulated in microvesicles with saline solution; (v) CEF saline solution (15 mg/kg) mixed with blank MKC microvesicules; (vi) CEF (15 mg/kg) encapsulated in MKC microvesicules with saline solution. Data were analyzed using noncompartmental model. CEF oral bioavailability was increased twofold when coadministered with MKC and when encapsulated in microvesicles and ninefold when encapsulated in MKC microvesicles compared to the same CEF dose administered orally as saline solution. The increased bioavailability of CEF resulting from CEF encapsulation in microvesicules with MKC suggests that this formulation can extend the application of CEF from parenteral only to oral application.