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

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Abstract
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.