Nasal drug delivery is an attractive approach for the systemic delivery of
high potency drugs with a low oral bioavailability due to extensive gastroi
ntestinal breakdown and high hepatic first-pass effect. For lipophilic drug
s nasal delivery is possible if they can be dissolved in the dosage form. P
eptide and protein drugs often have a low nasal bioavailability because of
their large size and hydrophilicity, resulting in poor transport properties
across the nasal mucosa. Cyclodextrins are used to improve the nasal absor
ption of these drugs by increasing their aqueous solubility and/or by enhan
cing their nasal absorption. With several cyclodextrins very efficient nasa
l drug absorption has been reported, but also large interspecies difference
s have been found. Studies concerning the safety of cyclodextrins in nasal
drug formulations demonstrate the non-toxicity of the cyclodextrins and als
o clinical data show no adverse effects. Therefore, some cyclodextrins can
be expected to become effective and safe excipients in nasal drug delivery.
(C) 1999 Elsevier Science B.V. All rights reserved.