The Wockhardt share has fallen as much as 12.8 per cent to its lowest level since September 23, 2015.
The shares posted their biggest single-day percentage fall since August 24, 2015.
Wockhardt has received a notice from the US Food and Drug Administration highlighting concerns with its Shendra drug manufacturing plant in Maharashtra, according to reports.
Wockhardt plans to respond to the FDA's observations in the so-called 'Form 483' with its corrective actions plan in 15 days, the report says.
A Wockhhardt spokesman did not immediately respond to a Reuters request for comments.
Multiple Wockhardt plants are barred from exporting to its largest market, the US.
A notice posted on the US FDA website on Wednesday said about 62,555 bottles of the antibiotic azithromycin manufactured by Wockhardt were being recalled because the company had failed to adequately investigate consumer complaints about them.
At 2.10 pm the share was down 10 per cent at Rs 1,368.80 on the BSE on Friday.