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 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.