The goal of the current study was to develop an intranasal (IN) formulation of the acetylcholinesterase inhibitor galantamine, an important therapeutic for treating Alzheimer's disease. To allow for delivering a therapeutically relevant dose, it was necessary to greatly enhance drug solubility. Various approaches were examined to this end, including adding co-solvents, cyclodextrins, and counterion exchange. Of these, the latter, for example, replacement of bromide ion with lactate or gluconate, resulted in a dramatic drug solubility increase, more than 12-fold. NMR confirmed the molecular structure of new drug salt forms. An in vitro epithelial tissue model was used to assess drug permeability and cellular toxicity. In vitro, galantamine lactate formulations performed as well as or better than their hydrobromide (HBr) counterparts with respect to drug permeation across the epithelial membrane with minimal toxicity. In vivo studies in rats compared pharmacokinetic (PK) profiles of different formulations. The in vivo studies confirmed that IN galantamine achieves systemic blood levels comparable to those of conventional oral administration. Both the in vitro and in vivo data support the feasibility of IN administration of this important drug.
(c) 2005 Wiley-Liss, Inc. and the American Pharmacists Association