Evergreening viagra, revisited

Back in April, I wrote:

Of course, if it turns out that Viagra (or sildenafil) is an effective treatment for babies suffering from stunted growth, then that is a great thing. And not just for the babies. Pfizer (the patent-holder for Viagra) would have protection from generic versions of sildenafil for another twenty years, meaning another twenty years of market power - not just for Viagra used for treating babies, but Viagra used for all treatments (including the highly profitable market for treating erectile dysfunction). A really cynical person would probably recognise that the sudden interest in new uses of Viagra now (the four trials mentioned in the article are not the only trials trying to find new uses for Viagra - see here for another example) is because Viagra comes off patent in April 2020. The clock is ticking for Pfizer, if they want to keep milking their Viagra cash cow.

The context was a drug trial for the use of Viagra to treat babies at risk of stunting. If Pfizer can find a new use for Viagra before it comes off patent in 2020, they can re-start the patent clock and retain their market power and high profits from the drug.

In today's news though:

Overseas deaths of babies involved in a clinical trial has prompted a review from researchers who have been running an aligned study here in New Zealand.

The international research STRIDER consortium has involved four trials - one of them carried out here and in Australia - investigating a possible use for the drug sildenafil in treating fetal growth restriction.

Sildenafil is better known as the drug behind Viagra, which is used to treat male erectile dysfunction by dilating blood vessels in the pelvis.

The researchers drew on a generic version of sildenafil, not manufactured by Viagra's makers Pfizer, to investigate whether it might work the same way in pregnant women by increasing blood supply to the placenta.

But last week, one of the trials, which was being carried out in the Netherlands, was terminated early due to safety concerns.

Results from a planned interim analysis showed more babies in the sildenafil group suffered a serious lung condition, called persistent pulmonary hypertension, which may have led to 11 more liveborn babies dying before hospital discharge.

Are we now seeing the real cost of attempts to evergreen the patent for Viagra? It's hard to say. As Thomas Lumley noted on StatsChat this morning:

It looks as though something might have been different about the Amsterdam study — although it’s also possible they were extremely unlucky.

In other words, it's too early to say, and the other drug trials (in the UK, Canada, and New Zealand/Australia) haven't shown such negative effects (but apart from the New Zealand/Australia study, they also haven't shown positive effects). However, eleven additional deaths as a result of a drug trial is far too many, and it's appropriate that the Dutch researchers have called it off. As Lumley notes, a trial that shows a negative effect is still a positive outcome, if it prevents future deaths from inappropriate treatment.

However, would this trial have gone ahead if Pfizer weren't intent on evergreening their Viagra patent? If I extend my cynicism from my April post on evergreening Viagra though, this episode demonstrates that the ability to evergreen patents might not only have costs in terms of lost economic welfare (due to the ongoing market power of the patent-holder), but might have real human costs.