Monday, February 16, 2009

Dapoxetine: The Final Blockbuster?


Janssen-Cilag (a Johnson & Johnson company) announced on Feb 10 that it had received regulatory approval in Finland and Sweden for its dapoxetine drug Priligy™. These approvals follow the December 2008 decentralised marketing authorisation procedure adopted by seven European Union countries: Sweden, Austria, Finland, Germany, Spain, Italy and Portugal. The two Scandinavian countries can now boast another claim to fame: being the first nations to offer their men an approved treatment for Premature Ejaculation (PE).

Dapoxetine hydrochloride is a novel, selective serotonin reuptake inhibitor (SSRI) compound that last made headlines in 2005 when the US FDA declined to approve the drug for PE. The reasons cited back then were lack of sufficient evidence and side effect issues. Dapoxetine has now been extensively evaluated in five randomised, placebo-controlled Phase III clinical trials involving more than 6,000 men with PE and their partners. More details about that here. J&J hopes that their comprehensive trial programme pays dividends, and has applied for market authorization in the other 5 European nations with a decentralized system as well as 10 other countries, including Canada, Australia, Mexico and Turkey. Successful approval in these markets may well mean that it is only a matter of time before the FDA is faced with a second review of dapoxetine.

So why the big fuss you ask? Well, according to a well publicized 2005 study in the Journal of Sexual Medicine, PE is the most common male sexual dysfunction affecting between 20-30% of males (It just so happens that the study was funded in part by J&J and its subsidiary Alza). Nonetheless, it is a legitimate condition that millions suffer from, and at a time when pipelines can no longer cater to blockbuster categories, J&J finds itself sitting on a golden cash cow. The US erectile dysfunction (ED) market (Viagra, Cialis and Levitra) was $3.4 billion in 2007 and continues to grow; according to industry analysts, the market for PE drugs is estimated to be as large as the erectile dysfunction market. In contrast to ED, which is more prevalent in men over 50, PE is a problem encountered by sexually active men of all ages. Importantly, there is no major competition being faced as both Pfizer & GSK abandoned their candidate drugs after the FDA rejection in 2005. A Massachusetts company – NeuroHealing Pharmaceuticals- has a d-modafinil (of Provigil fame) isomer in development for PE, but they don’t expect to commence clinicals until early 2010.

Even more astonishing (and a testament to J&J’s superior deal-making capacity) is that the rights to dapoxetine were bought for a meager $65 million. Dapoxetine (originally known as LY 210448) was one of David Wong’s creations (others include Prozac, Cymbalta, Stattera) in the late 80’s when Eli Lilly actively began pursuing the depression market. However, after several failures, Lilly sold the patent to J&J in 2003 subsequent to their purchase of Alza. Although it is known that high serotonin levels do play a major factor in lengthening ejaculatory response, off label use of currently approved SSRI’s in treating PE have been largely discouraged due to the side effects such as ED, loss of libido, nausea, serotonin syndrome, and increased suicide risk. The beauty of dapoxetine however, is its very short half life of 1.2 hours, meaning men can take the medication on demand with low risk of accumulation.

Whether dapoxetine is effective or if it will be a successful product are no longer valid questions. In a post Viagra world, it is almost certain that it will achieve near-cult status. The real question is whether dapoxetine’s success will be its eventual downfall. Not unlike the COX drugs, the potential for flagrant prescribing of dapoxetine is high. Combined with what will certainly be a high rate of abuse, it will be interesting to see what medical precautions & dispensing limitations are placed. One thing is for sure, a dapoxetine tragedy can not be blamed solely on the manufacturer. This time around, the entire medical community will have to shoulder the responsibility.

1 comments:

Anonymous,  February 17, 2009 at 8:22 AM  

some good articles on it here: http://www.pehomepage.com/Treating-PE/Medications/Treatment_for_premature_ejaculation_Interview_with_Lead_Investigator_for_Dapoxetine_77.html

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