Blood and urinary concentrations of salbutamol in asthmatic subjects.
OBJECTIVE
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 beta2 agonist when needed, and abstained from any medicine, beta2 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 x 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 x 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.
Elers
Jimmi
J
Respiratory and Allergy Research Unit, Bispebjerg Hospital, Copenhagen, Denmark. jele0004@bbh.regionh.dk
Pedersen
Lars
L
Henninge
John
J
Lund
Thomas K
TK
Hemmersbach
Peter
P
Dalhoff
Kim
K
Backer
Vibeke
V
D000280:Administration, Inhalation; D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000420:Albuterol / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics / Q000652:urine*; D001249:Asthma / Q000188:drug therapy*; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000097:blood* / Q000652:urine*; D018592:Cross-Over Studies; D003718:Denmark; D004300:Doping in Sports; D006801:Humans; D008297:Male; D008875:Middle Aged; D012129:Respiratory Function Tests; D011795:Surveys and Questionnaires; D055815:Young Adult
D001993:Bronchodilator Agents; D000420:Albuterol