Drugmaker Lupin Ltd said
The decline was, however, offset by higher sales in India, its second biggest market, and the Asia-Pacific and EMEA (Europe, Middle East and Africa) regions, which helped profit beat the consensus estimate.
India's pharmaceutical firms, which supply a third of the drugs sold in the United States, have been grappling with weaker sales amid sanctions imposed by international regulatory bodies and warnings over quality control at production sites.
Margins too have been hit by increased scrutiny over drug pricing.
Lupin said sales in the United States fell about 32 per cent to Rs 13.61 billion ($210 million), dragging down overall sales, which slipped 8 per cent to Rs 38.74 billion.
Sales in India were up 16.4 per cent at Rs 11.59 billion, while that from the Asia-Pacific and EMEA regions rose 15 per cent and 17 per cent, respectively.
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Net profit fell to Rs 4.55 billion in the quarter ended Sept. 30, slightly above the average analysts' forecast of Rs 4.33 billion, Thomson Reuters data showed.
Shares of the company jumped as much as 8.9 per cent in early trade but pared gains to close up 2.4 per cent. The broader BSE Sensex ended 0.4 per cent higher.