Pharmacokinetics, efficacy and adverse effects of sublingual salbutamol in patients with asthma

Abstract

Administration of drugs by the sublingual route provides rapid systemic absorption and avoids first-pass metabolism. The purpose of the present study was to assess the pharmacokinetics, efficacy and adverse effects of standard salbutamol tablets given by this route to patients with asthma. Seven asthmatic patients were given either sublingual salbutamol tablet 2 mg (SL), swallowed tablet 2 mg (O), metered dose inhaler 200 micrograms (MDI) or placebo (PL), in a randomized single-blind cross-over design. Airways responses (FEV1, FVC, PEFR), finger tremor (Tr), heart rate (HR), plasma potassium (K) and plasma salbutamol were measured over a 6 h period following drug administration. There were highly significant changes in FEV1 with MDI, O and SL routes compared with PL, although the response to MDI was greater and more rapid than with O or SL. There were similar findings for FVC and PEFR responses. There were no adverse effects with MDI, whereas both 0 and SL produced significant tremor responses. There were no differences between O and SL for any of the pharmacodynamic parameters. In addition, pharmacokinetic profiles for O and SL were also similar apart from an initial delay in absorption with SL. There were however, no significant differences in any of the pharmacokinetic parameters, between O and SL. This suggest that buccal absorption of salbutamol was negligible, and that systemic absorption occurred after swallowing of the dissolved sublingual tablet. These results show that sublingual administration of salbutamol tablet has no clinical benefit over the oral route.