The invention relates to an improved topical pharmaceutical composition for burn treatment and microbial infections on human beings or animals. The pharmaceutical composition comprises 0.1% w/w to 1% w/w of an antimicrobial drug, i.e., silver sulfadiazine and 0.2% w/w antiseptic, i.e., chlorhexidine gluconate; wherein silver sulfadiazine is in nanonized form.