Merck lost its monopoly on the antibiotic Tienam (imipenem-cilastatin) in Italy after the country’s antitrust regulator forced it to grant a license to local firm ACS Dobfar, even though its patent on the drug is not due to expire in February 2006.

ACS Dobfar, a specialist in the manufacture of bulk antibiotics, asked Merck in February for a license to make imipenem-cilastatin so it could export the drug to other European countries where the patents on the active ingredients have already expired. Merck refused, but has now been forced to issue a license by Italy’s Autorita Garante della Concorrenza e del Mercato.

The antitrust ruling means that ACS Dobfar and any other company that wishes to do so can manufacture imipenem-cilastatin – for export – at facilities in Italy.

Tienam, also sold under the Primaxin tradename, remains an important product for Merck despite the loss of patent protection in a number of markets around the globe. Last year the product brought in revenues of $641 million dollars, with sales slipping 10% in the US but rising 2% overall compared to 2003.