Mumbai, April 26: Sun Pharmaceutical shares plunged today after the Indian maker of generic drugs received a double blow in US courts that threatened to halt the sale of two money-making pills in that country.

A jury at a New Jersey district court upheld the validity of Pfizer Inc’s patent for heartburn drug Protonix, while another court barred Sun Pharma from selling a generic version of Sanofi Aventis’ drug Eloxatin from June. The Sun Pharma stock sank 4.77 per cent, or Rs 80.35, to Rs 1,604.25 on the BSE today.

The original patent of Protonix (pantoprazole) is held by Swiss drug maker Nycomed which was licensed to Wyeth. The latter was subsequently acquired by Pfizer. Both Teva Pharmaceutical Industries Ltd of Israel and Sun Pharma (January 2008) had launched generic versions of the drug at their own risk.

An at-risk launch happens when litigation pertaining to a drug is still on. The big risk is that in the event of the generic company losing the case, it may have to pay for damages incurred by the innovator. Nycomed and Wyeth had filed their patent infringement lawsuit against Teva and Sun Pharma in May 2004.

Sources said though the jury had given out its ruling, an order from the district court judge Jose L. Linares was yet to come. “A decision by the district court judge independent of today’s verdict will be sufficient to invalidate the patent,” Teva said in a statement.

Analysts who are awaiting the order from the district court judge say it is too early to make an estimate of the financial impact on Sun Pharma.

They, however, point out that while the final decision of the court is likely to be appealed at a federal court, Pfizer can also claim loss of profit later.

In a separate development, a US court barred Sun Pharma from selling a copycat version of the Sanofi Aventis anti-cancer drug Eloxatin from late June. This means that Sun Pharma can start selling the drug from 2012.