Physical Properties of Solid Dispersions of Poorly Water-Soluble Drugs with Enteric Coating Agents

Enteric coating agents, such as hydroxypropylmethylcellulose phthalate, methacrylic acidmethacrylic acid methyl ester copolymer, cellulose acetate phthalate, carboxymethylethylcellulose, were investigated as possible carriers for poorly water-soluble drugs in solid dispersions. In most cases, the drugs were present in amorphous form in the solid dispersions of 1 : 3 weight ratio of drug to polymer, though griseofulvin and phenytoin were not. Dissolution behavior was investigated using nifedipine, griseofulvin or spironolactone as a drug. The amorphous solid dispersions showed supersaturation phenomena in JPX 2nd fluid (pH 6.8), but the dissolution rate was suppressed in JPX 1st fluid (pH 1.2). It was confirmed that the physicochemical state of solid dispersions plays a predominant role in the dissolution of the drug from the solid dispersions.