Enhancing effects of cyclodextrins on nasal absorption of insulin in rats

Medicinal applications of cyclodextrins

Some cyclodextrins are produced industrially, and available in pharmaceutical quality, at reasonable prices. Their medicinal use means mainly--but not exclusively--the complexation of problematic drugs (poorly soluble, unstable, irritating, difficult to formulate substances). The CD complexation generally results in improved wettability, dissolution, and solubility; improved stability; reduced side effects; or in mildering of other undesired properties (e.g., bitter tastes, bad smells). CDs can be used advantageously practically in any drug forms: oral, rectal, pulmonary, external, ocular, etc. formulations. In oral solid and liquid formulations the chemical and physical stability and bioavailability, but particularly the role of absorption is improved. With appropriate highly soluble chemically modified CDs aqueous parenteral formulations can be prepared from poorly soluble drugs. Using CDs the transdermal penetration or nasal absorption of such drugs becomes possible, which earlier could not be administered through these ways. The direct therapeutic effects of CDs (or their derivatives) are demonstrated in several examples as well as the use of beta CD as vehicle in tabletting.

Nasal administration of an ACTH(4-9) peptide analogue with dimethyl-beta-cyclodextrin as an absorption enhancer: pharmacokinetics and dynamics

1. The systemic absorption and the neurotrophic effect of the metabolically stabilized ACTH (4-9) analogue, Org2766, were investigated following intranasal (i.n.) administration. 2. Without additives the nasal bioavailability of the peptide was in the order of 15 and 10% in rats and rabbits, respectively. The absorption could be improved by addition of a variety of absorption enhancers to the nasal preparation. The beta-cyclodextrin derivative, dimethyl-beta-cyclodextrin (DM beta CD) at a concentration of 5% (w/v) improved the absorption in rats about 5 fold from 13 +/- 4% (mean +/- s.d.) for administration of the peptide alone to 65 +/- 21%, and in rabbits 1 to 2 fold, from 10 +/- 6% to 17 +/- 8%. 3. The increased permeability of the rat nasal mucosa for Org2766 caused by DM beta CD in rats reversed substantially within 1 h. However, the nasal absorption had not yet completely returned to the level without enhancer. 4. S.c. administered Org2766 accelerated the functional recovery from peripheral nerve damage in rats. However, the peptide did not facilitate nerve repair following i.n. administration with DM beta CD, in spite of the fact that Org2766 was well absorbed. I.v. injection of Org2766 was also ineffective.