Jonathan C. Evans

Development and Characterization of a Scalable Controlled Precipitation Process to Enhance the Dissolution of Poorly Water-Soluble Drugs

AbstractPurpose. Poorly water-soluble compounds are being found with increasing frequency among pharmacologically active new chemical entities, which is a major concern to the pharmaceutical industry. Some particle engineering technologies have been shown to enhance the dissolution of many promising new compounds that perform poorly in formulation and clinical studies (Rogers et. al., Drug Dev Ind Pharm 27:1003-1015). One novel technology, controlled precipitation, shows significant potential for enhancing the dissolution of poorly soluble compounds. In this study, controlled precipitation is introduced; and process variables, such as mixing zone temperature, are investigated. Finally, scale-up of controlled precipitation from milligram or gram to kilogram quantities is demonstrated. Methods. Dissolution enhancement capabilities were established using two poorly water-soluble model drugs, danazol and naproxen. Stabilized drug particles from controlled precipitation were compared to milled, physical blend, and bulk drug controls using particle size analysis (Coulter), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), dissolution testing (USP Apparatus 2), and residual solvent analysis. Results. Stabilized nano- and microparticles were produced from controlled precipitation. XRD and SEM analyses confirmed that the drug particles were crystalline. Furthermore, the stabilized particles from controlled precipitation exhibited significantly enhanced dissolution properties. Residual solvent levels were below FDA limits. Conclusions. Controlled precipitation is a viable and scalable technology that can be used to enhance the dissolution of poorly water-soluble pharmaceutical compounds.

THE PREPARATION OF OPTICALLY ACTIVE 2-CYCLOPENTEN-1,4-DIOL DERIVATIVES FROM FURFURYL ALCOHOL

Abstract The preparation and enzymatic resolution of several cis-mono-4-O-protected-2-cyclopenten-1,4-diols are described. The process starts with inexpensive furfuryl alcohol and lends itself to the preparation of multigram quantities of various protected, optically active 2-cyclopenten-1,4-diol derivatives. Stereoselective reduction of 4-O-protected-2-cyclopentenone to the cis-mono-O-protected-2-cyclopenten-1,4-diol using LiAlH 4 LiI or Red-Al • NaI is described. Subsequent pancreatin-promoted, stereoselective acylation was conducted on these cis-(+/−)-mono-O-protected-cyclopenten-1,4-diols to afford the corresponding alcohols and acetates in moderate to excellent enantioselectivities.

Preparation, Characterization, and Scale-up of Ketoconazole with Enhanced Dissolution and Bioavailability

ABSTRACT Many new molecular entities targeted for pharmaceutical applications face serious development challenges because of poor water solubility. Although particle engineering technologies such as controlled precipitation have been shown to enhance aqueous dissolution and bioavailability of poorly water soluble active pharmaceutical ingredients, the data available are the results of laboratory-scale experiments. These technologies must be evaluated at larger scale to ensure that the property enhancement is scalable and that the modified drugs can be processed on conventional equipment. In experiments using ketoconazole as the model drug, the controlled precipitation process was shown to produce kg-scale modified drug powder with enhanced dissolution comparable to that of lab-scale powder. Ketoconazole was demonstrated to be stable throughout the controlled precipitation process, with a residual methanol level below the ICH limit. The modified crystalline powder can be formulated, and then compressed using conventional high-speed tableting equipment, and the resulting tablets showed bioavailability more than double that of commercial tablets. When appropriately protected from moisture, both the modified powder and tablets prepared from the modified powder showed no change in dissolution performance for at least 6 months following storage at accelerated conditions and for at least 18 months following storage at room temperature.