The anti-depressant drug market in the US is primarily ruled by Effexor XR (Venlafaxine) of Wyeth (now owned by Pfizer).
The firms -- Aurobindo Pharma, Lupin, Wockhardt, Orchid Pharma and Dr Reddy's Labs -- have received the US Food & Drug Administration nod to launch the generic version of the $2.5-billion Effexor, used to treat depression and anxiety disorders, from June 1. The patent for Effexor expired last year.
However, the major concern for the Indian firms is the lower margin for the copycat version due to high competition.
Teva, the largest generic player in the world, has already launched Effexor generic in July last year, with six-month exclusivity.
According to analysts, about $15-20 million sales revenue can be achieved by each firm through the generic sale once other copycats are launched.
The consumers' reluctance to shift over to generics in such space will be another hit for the firms, said experts.
Two weeks earlier, Wockhardt received US FDA approval to sell the generic version of Effexor's extended release capsules in dosages of 37.5mg, 75mg and 150mg from June 1. Aurobindo Pharma Limited received the final nod from the US FDA for Effexor generic in April.
Muralidharan Nair, partner, health sciences advisory practice, at consultancy Ernst and Young, said: "For anti-anxiety drugs, the US is a significant market and one of the top selling ten drugs in US always will be in that category.
"However, there could be a lesser rate of adoption to the generic space by the consumer. Affluent patients may not immediately shift to cheaper copycat versions of these categories. Also, margins will not be attractive for generic players."
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