Hepatic and renal disposition of pancuronium and gallamine in patients with extrahepatic cholestasis

Biliary secretion of rosuvastatin and bile acids in humans during the absorption phase

AIM

The aim of this study was to investigate the biliary secretion of rosuvastatin in healthy volunteers using an intestinal perfusion method after administration of 10mg rosuvastatin dispersion in the intestine.

METHODS

The Loc-I-Gut tube was positioned in the distal duodenum/proximal jejunum and a semi-open segment was created by inflating the proximal balloon in ten volunteers. A dispersion of 10mg rosuvastatin was administered below the inflated balloon and bile was collected proximally of the inflated balloon. Bile and plasma samples were withdrawn every 20 min during a 4h period (absorption phase) and additional plasma samples were collected 24 and 48 h post-dose.

RESULTS

The study showed that there is a substantial and immediate transport of rosuvastatin into the human bile, with the maximum concentration appearing 42 min after dosing, 39,000+/-31,000 ng/ml. Approximately 11% of the administered intestinal dose was recovered in the bile after 240 min. At all time points the biliary concentration exceeded the plasma concentration, and the average bile to plasma ratio was 5200+/-9200 (range 89-33,900, median 2000). We were unable to identify any bile-specific metabolites of rosuvastatin in the present study.

CONCLUSION

Rosuvastatin is excreted via the biliary route in humans, and the transport and accumulation of rosuvastatin in bile compared to that in plasma is rapid and extensive. This intestinal perfusion technique offers a successful way to estimate the biliary secretion for drugs, metabolites and endogenous substances during the absorption phase in healthy volunteers.

Influence of renal and hepatic function on pharmacodynamics and pharmacokinetics of non-depolarizing muscle relaxants

Liver and kidney function disturbances influence the pharmacodynamic and pharmacokinetic behaviour of drugs. Because of the differences in metabolism and excretion between the various muscle relaxants, liver and kidney disturbances do influence their pharmacodynamics and pharmacokinetics to a different extent. A description of the changes is given for the most frequently used non-depolarizing muscle relaxants. It is related to the practical clinical implications of the difference in the pharmacokinetics.

Relationship between gallamine plasma concentration and neuromuscular paralysis in surgical patients

The pharmacodynamics of the neuromuscular blocking drug gallamine were investigated in 10 surgical patients using a constant-rate infusion regimen, and results are compared to those for d-tubocurarine (dTc). Gallamine effect (paralysis)-time data gathered during and following the infusion were fitted to a pharmacodynamic effect model, while paralysis-plasma concentration data gathered during (onset) and following (offset) the infusion were fitted separately to a nonlinear form of the Hill equation. The effect model was most appropriate in characterizing the combined (on and off infusion) effect data. While there was also an excellent characterization of onset and offset data with the Hill equation, the two effect-concentration curves were not superimposable. The mean (+/- S.D.) plasma concentration of gallamine at 50 per cent paralysis during onset of action (Cp50(onset) 8.0 +/- 1.8 micrograms/ml) or that predicted to exist at steady state using the effect model (Cp50(ss) 5.4 +/- 1.4 micrograms/ml). Cp50(offset) and Cp50(ss) did not differ significantly, and there was no significant difference in the power factor (lambda) estimates for the various model fits. Comparison of the pharmacodynamic parameters for gallamine and dTc using the effect model revealed no significant differences in keo, t1/2(keo), and lambda estimates. However, Cp50(ss) for gallamine (5.4 +/- 1.4 micrograms/ml) was nine times higher than that for dTc (0.61 +/- 0.15 micrograms/ml) in absolute terms and seven times higher when compared on a molar basis.