15 Aug 2013

Viagra in hand with ringJune 2013 marked end of Pfizer's monopoly on little blue pill

Since it came on the market in 1998, Viagra (sildenafil) has transformed treatment of erectile dysfunction (ED), and brought in huge revenues for its patent holder, Pfizer - perhaps not surprising at about £6 per tablet.  But the high price has made it too costly to freely prescribe.  For many men, this means that their NHS prescription is limited to one tablet a week.  With the recent end to the drug company's patent, might this be about to change?

We look at what Viagra is, how it works, and whether a change in price will mean a boost to men who need it.

What is Viagra, and how does it work?

Viagra, sold as blue, diamond-shaped pills, is used to treat erectile dysfunction - not being able to get or keep enough of an erection for sex. 

In a recent survey, around 65% men treated for prostate cancer experienced erectile dysfunction.  For many men, being unable to get an erection can cause anxiety, loss of self-esteem and increased tension in relationships with partners. 

Viagra can help overcome the physical problems involved in getting an erection.

When a man is sexually stimulated, a substance called nitric oxide (NO) gets released in the penis.  This increases levels of another substance called cyclic guanosine monophosphate (cGMP).  In turn, increased cGMP causes the arteries in the penis to open wider, so that blood can rush in and the penis becomes erect.  

In most cases, erectile dysfunction happens when the arteries in the penis aren't widening enough to allow enough blood to get in.

Viagra, and other tablets like Cialis (tadalafil) and Levitra (vardenafil), work by blocking phosphodiesterase type 5 (PDE5), which is the enzyme that makes an erection subside by breaking down cGMP. This allows more cGMP to build up, widening the arteries and increasing blood flow into the penis, making it erect. 

These drugs only work when a man is sexually stimulated and levels of cGMP rise.  So, while tablets like Viagra are effective treatments for men with purely physical problems getting an erection, they may not be recommended if, for example hormone therapy or anxiety has reduced a man's desire for sex.  Read about other ways to treat erectile dysfunction.

What does Viagra coming off patent mean for men with prostate cancer?

GPs can prescribe Viagra to any man who needs it, and can use it safely, but it's only available for free on the NHS for men with certain conditions, including those with prostate cancer, or who have had their prostate removed.  Even in these cases NHS prescriptions may be limited to one tablet per week.  Although GPs can use their clinical judgment to prescribe more than this, it's not clear how many GPs are aware of the prescription guidelines. 

In 2012 Viagra cost the NHS £40 million, even though prescriptions are restricted.  Now that the UK patent on Viagra has expired, drug companies, including Pfizer itself, are bringing much cheaper versions of the drug (known by its generic name, sildenafil) to market - pushing up competition, and driving down prices.  It's thought that this will mean a price drop from about £6 per tablet to as little as £1 or less.  We don't know whether this will result in the NHS lifting prescription limits, but it will be cheaper if you have to pay for a Sildenafil prescription yourself.

So, lower prices will make sildenafil far more accessible for men with erectile dysfunction, but is this too good to be true?

Not necessarily, but as with all things, there is a 'but'.  Firstly, Viagra alone may not be the best treatment immediately after surgery for prostate cancer (prostatectomy).  Many men may benefit from a combination of Viagra, Cialis and/or a vacuum pump to fully rehabilitate their penis after surgery; and this isn't covered by current prescription guidelines.

Men will still need a prescription to get sildenafil tablets, and should still be careful, especially if buying from online pharmacies.  The arrival of generic version s of Viagra will make it harder to distinguish between genuine and fake medications. 

There might also be small differences between the genuine versions of sildenafil. Legal manufacturers of generic drugs conform to strict quality control standards and produce generic products that are 'bioequivalent' to the original drug. But this does not mean exactly the same. There may be small differences in the manufacturing process or non-active ingredients that could affect how well generic versions of the tablet work for you. Talk to your GP if you have any concerns about changing to a generic version of the drug.

We're now collecting evidence for our new campaign to make sure that every man who experiences erectile dysfunction as a result of prostate cancer treatment can access the best information, services, support and products to help deal with it.  If you are a man, or the partner of a man, who has been treated for prostate cancer, we'd like to hear from you.

More from Prostate Cancer UK

From heart disease to jet-lag: the Viagra story

Prostate cancer and sex - its time we all talked about it

Prostate cancer and my sex life - men talk about their experiences

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