Beta-cyclodextrin derivatives are a useful tool for improving the stability and solubility problems of hydrophobic molecules. With steroid hormones, for example, as much as a 50-fold increase in solubility and bioavailability can be achieved through the use of beta-cyclodextrin derivatives (beta-CDs) as carrier molecules.1 Given the space limitations inherent in an implantable drug delivery system, beta-CDs are a viable option for use in ALZET ® Osmotic Pumps.
Cyclodextrins are conjoined glucose molecules forming a “donut” structure, or torus. The non-polar interior of the torus encapsulates hydrophobic molecules to increase solubility in aqueous solutions. The morphology of cyclodextrins encourages complexation, yet aqueous dilution elicits complete dissociation.2 beta-cyclodextrins occur naturally, but derivatives formed by substitution with hydroxyalkyl groups have reduced toxicity and optimized solvent action. One popular derivative is 2-hydroxypropyl-beta-cyclodextrin, which is sold as Trappsol ® by CTD, Inc., in either a powder or a pre-mixed solution.1,3