Pharmacokinetics of intravenous and oral salbutamol and its sulphate conjugate.
The pharmacokinetics of salbutamol and its sulphate conjugate metabolite were investigated after intravenous and steady-state oral administration of salbutamol to 10 healthy volunteers. With intravenous administration, total plasma clearance was 480 +/- 123 ml min-1, elimination half-life was 3.86 +/- 0.83 h and apparent volume of distribution was 156 +/- 381. Urinary excretion of unchanged drug and sulphate conjugate were 64.2 +/- 7.1% and 12.0 +/- 3.1% of the dose, respectively. With oral administration, systemic availability was 0.50 +/- 0.04, and urinary excretion of unchanged drug and sulphate conjugate were 31.8 +/- 1.9% and 48.2 +/- 7.3% of the dose, respectively. The drug eliminated on the first-pass could be accounted for entirely as sulphate conjugate formed, presumably, in the intestinal wall. Renal clearance of salbutamol was 291 +/- 70 ml min-1 after intravenous and 272 +/- 38 ml min-1 after oral administration, while the renal clearance of the sulphate conjugate was 98.5 +/- 23.5 ml min-1 after oral administration. Heart rate increased with increasing plasma salbutamol concentration, although a lag was evident. The effect on heart rate was lower after 24 h continuous oral salbutamol administration.
D000284:Administration, Oral; D000328:Adult; D000420:Albuterol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D001798:Blood Proteins / Q000378:metabolism; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D007668:Kidney / Q000378:metabolism; D007700:Kinetics; D008297:Male; D011485:Protein Binding
D001798:Blood Proteins; D000420:Albuterol