The effect of PEG4000 solution on the in vitro release of nifedipine, a calcium entry blocker and a poorly water soluble drug was evaluated. Nifedipine tablets containing 10 mg of nifedipine, 20% of one four polymers–Eudragit L-100 and Rs, ethylcellulose and carbopol 941, 2% lubritab and an adequate quantity of Encompress to yield 300 mg weight tablets–were formulated using the direct compression method. Tablets were compressed to a hardness of 5N, and an in vitro dissolution profile was performed on the tablets in 70% ethanol and in ethanolic PEG4000 solutions. The results obtained indicated enhancement of nifedipine release from two of the polymer matrices (Eudragit L-100 and ethylcellulose) in the presence of PEG4000 and a retardant effect from carbopol 941 matrix. It is suggested that carbopols may not be suitable for use in the formulation of nifedipine tablets since there are some physiological surfactants present in the gastrointestinal tract (GIT).
Biological & Pharmaceutical Bulletin 06/1997; 20(5):574-6. DOI:10.1248/bpb.20.574