Nasal absorption of alprenolol and metoprolol

Abstract

In order to determine the importance of hydrophobicity in nasal drug absorption, we studied the bioavailability of the β-adrenoceptor blocking drugs, alprenolol and metoprolol, in volunteers, after nasal administration. The results were related to the oral and sublingual administration. The intranasal bioavailability, T max-, MRT- and MAT corr-values of the hydrophilic metoprolol after intranasal administration did not differ significantly from the oral and sublingual administration ( n = 4). Metoprolol is probably swallowed after intranasal and sublingual administration and absorbed in the gastrointestinal tract. In contrast, great differences were found in the intranasal bioavailability, T max-, MRT-, and MAT corr-values of the hydrophobic alprenolol, related to the oral dose ( n = 5). Nasal absorption of alprenolol was fast and showed a high bioavailability (T max = 0.45 ± 0.11 h). MRT-values after intranasal administration were significantly different from the other two administrations (MRT in = 3.0 ± 0.5 h, MRT sl = 3.9 ± 0.9 h, MRT or = 3.5 ± 0.6, P = 0.047 and P = 0.022, respectively). The results of this study indicate that hydrophobicity may be an important factor in nasal membrane passage.