Don't worry, Pfizer isn't planning to market Viagra to kids.
The additional exclusivity arises because Viagra shares an active ingredient, sildenafil, with another Pfizer drug, Revatio, which is marketed to treat pulmonary arterial hypertension, or high blood pressure in the lung's arteries.
The U.S. Food and Drug Administration previously asked Pfizer to test Revatio in children with pulmonary hypertension. Pfizer conducted the studies and has applied for FDA approval to market Revatio for use in children; an FDA decision is expected in May.
Federal law provides for such extensions of exclusivity as an incentive for drug makers to test products that may be helpful to children. During exclusivity periods, competing generic copies are generally prohibited from entering the market. The FDA granted the six-month pediatric extension for sildenafil on Feb. 9, according to the FDA website.
The patent extension applies to any drug containing sildenafil, even Viagra, which is only approved for use by men with erectile dysfunction and not for use by children.
As a result, the U.S. period of exclusivity for Viagra would extend by six months until April 2020, said Pfizer spokeswoman Victoria Davis. That is based on a patent due to expire in 2019, which covers sildenafil's use to treat ED. This patent was upheld by a federal judge last year, though Teva Pharmaceutical Industries Ltd. (TEVA), which challenged the patent's validity, has appealed that decision.
The basic patent for sildenafil was due to expire in March 2012. The pediatric exclusivity period now extends to September.