Resumen de Blood and Urinary Concentrations of Salbutamol in Asthmatic Subjects

Jimmi Elers, Lars Pedersen, John Henninge, Thomas K. Lund, Peter Hemmersbach

• Purpose: Data on blood and urinary concentrations of salbutamol after inhalation and oral administration in healthy subjects are scarce. Accordingly, we examined the pharmacokinetics of inhaled and oral salbutamol in asthmatic subjects.

  Methods: We enrolled 10 men aged 18-45 yr in an open-label study in which 0.8 mg of inhaled or 8 mg of systemic salbutamol was administered in a crossover design. All subjects had doctor-diagnosed asthma, used [beta]2 agonist when needed, and abstained from any medicine, [beta]2 agonist inclusive, for 14 d before visit. Urine was collected from all subjects (0-4, 4-8, and 8-12 h), and blood samples were taken at 0, 0.5, 1, 2, 3, 4, and 6 h after salbutamol administration.

  Results: Maximum urine concentration was reached during the first 4 h after administration of both inhaled and oral salbutamol. We found differences in median urinary concentrations (Cmax) of 260.9 and 2422.2 ng[middle dot]mL-1, respectively (P < 0.005). Urinary concentrations show high individual variability irrespective of the route of administration. Blood analyses showed a systemic exposure of salbutamol after both inhaled and oral salbutamol with peak concentration after inhalation before the oral intake (P < 0.05). A difference in median Cmax after inhalation and oral treatment was found: 1.75 and 18.77 ng[middle dot]mL-1, respectively (P < 0.05).

  Conclusions: Median urinary concentrations after oral administration of 8 mg of salbutamol were significantly higher than those after inhalation of 0.8 mg of salbutamol