Possible mechanism for drug retardation from glyceryl monostearate matrix system

Lipophilicity was evaluated as a possible mechanism for drug retardation fr om a glyceryl monostearate matrix system. Lipophilicity of the glyceryl mon ostearate matrix system was studied using contact angle measurement of wate r droplets on the surface of compressed disks, extrudate ascension of water , and movement of water through a powder mixture packed in a high-performan ce liquid chromatographic (HPLC) column. Increase in glyceryl monostearate content resulted in an increase in water droplet contact angle, decrease in the rate of water ascending the extrudate, and increase in the pressure va lues as a function of flow rare of water moving through the powder mixture. These could be clue to the increase in lipophilicity of the matrix, render ing the matrix less wettable. As a result, the rate of water penetration in to the matrix decreased, and the drug release could be sustained.