A comparative study of controlled release matrix tablets of diclofenac sodium, ciprofloxacin hydrochloride, and theophylline.

The need for controlled release formulations for diclofenac sodium, ciprofloxacin, and theophylline is well recognized. In our study, controlled release tablets of the three drugs were formulated by the matrix-embedding technique using ethyl cellulose as retardant. Tablets of all the drugs were of good physical quality with respect to appearance, drug content uniformity, hardness, weight variation, and friability. In vitro release rate studies showed that ethyl cellulose extended the release of the three drugs to 12 hr or more. Release patterns from formulations of the three drugs followed Higuchi's square root kinetics. At pH 6.8, the release rate was higher in all three drugs, probably due to increased solubility of the drugs and/or increased swelling of ethyl cellulose at the higher pH. The formulations were highly stable and possessed reproducible release kinetics across batches.