Transdermal drug delivery formulation containing 5 mg/patch of salbutamol sulfate (SS), providing an input rate of 100 microg/h of SS was formulated and subjected for pharmacokinetic and pharmacodynamic evaluation in moderately asthmatic patients (n=6). A linear correlation was observed between cumulative amount of drug diffused in vitro and cumulative AUC0-t of serum concentration-time curve (R2=0.99). A steady-state serum concentration of 2.87+/-0.1 ng/ml (per milligram dose) was attained after an initial lag period of 4.67+/-1.03 h. The elimination half-life, clearance rate and elimination rate constant was 3.35+/-1.07 h, 256.12+/-3.55 ml/min and 0.24+/-0.09 h(-1), respectively. The mean forced expiratory volume in one minute (FEV1) of the patients was 2.2+/-0.14l during steady state. The pharmacokinetic results correlated well with the FEV1 response of patients.