The pharmacokinetics of the beta 2-adrenoceptor agonist, tulobuterol, given transdermally and by inhalation.

We have studied the pharmacokinetics of tulobuterol given transdermally or by aerosol inhalation in healthy male volunteers. Tulobuterol was rapidly absorbed after inhalation, with a tmax of 0.8-1.5 h. The Cmax and the AUC increased linearly with dose. Tulobuterol was well absorbed after transdermal administration, with an absorption lag-time of about 4 h. The Cmax and AUC increased linearly with dose and the tmax was about 9-12 h. The mean percentage of drug absorbed during the application of a patch for 24 h was 82-90% after a single dose and 82-85% during repeated dosing. The mean urinary recoveries as unchanged drug after a single inhalation and patch application were 3-4% and 5-6% respectively. Tulobuterol did not accumulate during repeated inhalation or transdermal application. It was well tolerated, except for an increase in heart rate of 10-20 beats.min-1 after five repeated applications of a 4 mg patch.