I was just going through a batch of press releases and came across one entitled "Viagra to be used for children" - I am not sure whether to congratulate the authors for headline grabing or go after them with a long stick for incompetent reporting.

The story underlying the headline is quite interesting and also a bit of a master stroke froim Pfizer and so I just wanted to take a few moment to explain.

Pretty much everyone knows what Viagra is by now...a bit of a revolution in its time for the treatment of male erectile dysfunction. Viagra has also been highly profitable for Pfizer. In the Q1 2011 figures released last week Pfizer announced that Viagra generated $470 million worldwideand so it remains a blockbluster and Pfizer's 6th highest earner.

In 2005 the EMA and the FDA approved a product known as Revatio. This drug contains the same molecule as Viagra, sildenafil but is used for the treatment of pulmonary hypertension. This is a serious condition that affects the pulmonary valculature of all age groups. Revatio revenue is respectable, $123 million last quarter, but a fraction of that generated by Viagra.

However, the problem for Pfizer is that the patent on sildenafil is soon due to expire. One common approach to increasing revenue of a drug is to get a 6 month paediatric extension. This is obviously not possible for Viagra however pulmonary hypertension does affect children and gaining approval for Revatio in this indication extend the life of both brands. An extra 6 months of sales represents approximatley $200 million in EU sales, and it is the EMA that has recently extended the exclusivity of sildenafil. This figure will increased dramatically if the FDA follows suit although this is not certain at the moment. The reason for this is complicated and I won't go into now.

There is still something irritating about the headlines coming through the wire - Viagra for children? Facgtually incorrect if you want to be picky...the headline should read Revatio for children but who has heard of Revatio? I guess that it is the point.

If anyone is interested in reading more about pulmonary hypertension drug development we recommend: