The stock pared gains after surging as much as 4.71%, to an intra-day high of Rs 840.

As many as 1,78,094 shares changed hands in the counter on BSE.

Dr. Reddy's Laboratories said, it had received final approval from the US Food and Drug Administration for ondansetron hydrochloride tablets, the generic equivalent of GlaxoSmithKline’s Zofran, an antiemetic that prevents nausea and vomiting caused by chemotherapy and anaesthesia.

Dr Reddy's has 180 days of marketing exclusivity from the date of expiry of the patent.

In November, the company launched an offering of American Depositary Shares (ADSs) of up to 13.5 million shares, excluding the underwriter's over- allotment option.

Dr Reddy’s Laboratories is present across the pharmaceutical value chain: basic research, finished dosages, generics, bulk actives, biotechnology and diagnostics.

DRL’s quarterly net profit more than tripled in Q2 September 2006, helped by strong growth in the key US market and gains from drugs exclusivity.

Net profit, according to US accounting standards, rose to Rs 280 crore from Rs 89 crore. Total revenue jumped to Rs 2,000 crore from Rs 580 crore, while revenue from its core businesses, excluding the contribution from authorised generics and acquisitions, grew 42%, to Rs 820 crore.