Prediction of drug release from HPMC matrices: effect of physicochemical properties of drug and polymer concentration

A working equation to predict drug release from hydroxypropyl methylcellulose (HPMC) matrices was derived using a training set of HPMC matrices having different HPMC concentration (w/w, 16.5-55%) and different drugs (solubilities of 1.126-125.5 g/100 ml in water and molecular volumes of 0.1569-0.4996 nm(3)). The equation was log(M-t/ M-infinity)=-0.6747+ 1.027 log t -0.1759 (log C-S) log t +0.4027 (log V) log t - 1.041C(H) +0.3213 (log C-S) C-H -0.4101 (log V) C-H - 0.3521 (log V) log C-S (n=263, r=0.9831), where M-t is the amount of drug released at time M-t/M-infinity the amount of drug released over a very long time, which corresponds in principle to the initial loading, t the release time (h), C-S the drug solubility in water (g/100 ml), V the volume of drug molecule (nm(3)), and C-H is HPMC concentration (w/w). The benefit of the novel model is to predict M-t/M-infinity values of a drug from formulation and its physicochemical properties, so applicable to the HPMC matrices of different polymer levels and different drugs including soluble drugs and slightly soluble drugs. (C) 2004 Elsevier B.V. All rights reserved.