COMPATIBILITY STUDY BETWEEN CEPHALEXIN MONOHYDRATE AND SOME EXCIPIENTS

The interaction between cephalexin monohydrate with tablet and capsule excipients was investigated using differential scanning calorimetry I nfrared studies were also carried out on the drug with some excipients . The effect of these excipients on the dissolution rate of cephalexin monohydrate powder was studied as well. From the results of the disso lution test, it was observed that most of the insoluble excipients (Av icel PH 101 and PH 102, Emcocel, dicalcium phosphate, titanium dioxide and magnesium stearate) decrease the dissolution rate of the drug, wh ile the starch has little effect on the dissolution rate of the antibi otic. On the other hand, most of the soluble excipients such as sorbit ol, mannitol, Explotab and Aerosil 200 had no significant effect on th e dissolution rate of the drug, while polyethylene glycol 6000 and sod ium carboxymethyl cellulose decrease the dissolution rate to different extents. Differential scanning calorimetry revealed cephalexin to be compatible with Avicel PH 101 and PH 102, Emcocel, dicalcium phosphate , titanium dioxide, magnesium stearate, starch, Explotab and sodium ca rboxymethyl cellulose. The interaction of cephalexin was observed with polyethylene glycol 6000, sorbitol and mannitol. The infrared studies indicated that there was no modification ill the strong characteristi c bands for the pure drug, while there was some modification in the we ak bands (less than 600 cm(-1)), indicating the possible interaction b etween the drug and some excipients.