Cipla, India's fourth-largest drugmaker by sales, fell as much as 3 per cent to Rs 660 in early trade before recovering to Rs 670.70, still down 1.12 per cent or Rs 7.60.
Traders cited a letter, a so-called 'form 483', that the US Food and Drug Administration sent to US firm InvaGen Pharmaceuticals Inc in May highlighting quality control issues one of its manufacturing plants
Cipla said last month it was buying InvaGen as part of a deal worth $550 million, following rivals with a push to enhance its presence in the world's largest generics market.
The letter, posted on the FDA website, was sent after FDA officials inspected InvaGen's Hauppauge, New York plant for two weeks in May
"The 483 was known when Cipla bought the plant. It's only now that a copy is available for purchase from private websites," an analyst tracking the sector said