Ranbaxy, controlled by Japan's Daiichi Sankyo Co, recorded a loss of 5.99 billion rupees on foreign currency derivatives in fiscal second quarter ended June, compared to a gain of 1.12 billion rupees a year earlier, it said.
Net sales rose 54.5 percent to 31.74 billion rupees, Ranbaxy said.
Analysts had forecast net profit at 3.21 billion rupees on net sales of 29.06 billion rupees, according to Thomson Reuters I/B/E/S.
The depreciation of the Indian rupee against the dollar, though favourable to Ranbaxy's export business, had an adverse impact on the company, said Ranbaxy.
"Sales and profitability grew in the quarter with overall improvement across major regions, aided further by exclusivity sales in some of the key markets," Arun Sawhney, chief executive, said in a statement.
Sales in North America, Ranbaxy's biggest market, grew 140 percent to 14.71 billion rupees in April-June, primarily due to the generic version of Lipitor, Pfizer's
Ranbaxy settled a compliance-related dispute with the U.S. drug regulator early this year and can now ship products from its Indian factories to the world's largest drug market.
Indian drugmakers including Ranbaxy, Dr Reddy's Laboratories
But they face intense competition, rising lawsuits from rival drugmakers and a stricter U.S. health regulator in their race for the lucrative off-patent market.
Valued at $3.9 billion, shares in Ranbaxy closed down 2.7 percent at 501.80 rupees on Thursday. The stock is up about 24 percent this year, in line with the benchmark healthcare index's 24.4 percent rise.