What is Peyronie's disease? Share your Peyronie's disease experience Andropeyronie penis extender Visit my Peyronie's shop

Xiaflex Is FDA Approved Peyronie's Treatment

FDA logo

FDA approved Xiaflex for Peyronie's disease on 6th December 2013.

Xiaflex is the first (and currently only) FDA approved treatment proven effective for Peyronie's disease in men with a palpable plaque and a curvature deformity of 30 degrees or greater at the start of the treatment.

This was a big day for men with Peyronie's disease. Xiaflex does not cure Peyronie's but this means it has been shown to be effective treatment for some men with Peyronie's disease. And the more treatment options available the better.

Or as Audrey Gassman, M.D., deputy director of the Division of Bone, Reproductive and Urologic Products in the FDA's Center for Drug Evaluation and Research, puts it:

"Today's approval expands the available treatment options for men experiencing Peyronie's disease, and enables them, in consultation with their doctor, to choose the most appropriate treatment option" (Los Angeles Times - fDA News Release 06/12/13Opens in new window symbol)

What Is Xiaflex?

Xiaflex is the US brand name but the generic name is collagenase clostridium histolyticum. It has been known as Xiapex in Europe. For simplification, I use Xiaflex as the common term.

Xiaflex injections needle

Xiaflex is an enzyme produced by the bacterium Clostridium histolyticum, which dismantles collagen. FDA approved Xiaflex in 2010 for treating Dupuytren's contracture, a disorder where abnormal build up of collagen in the fingers causes permanently clenched fingers.

As you may recall, in the case of Peyronie's disease, abnormal build up of collagen in the penis forms the penis plaque. The collagenase breaks down the collagen that makes up the Peyronie’s plaque.

Will Sargent, Auxilium (manufacturer of Xiaflex) VP of corporate communications, illustration of how Xiaflex for Peyronie's works is simple but explanatory:

“Picture, he said, the kind of long balloon that a clown blows up. Now imagine that you put inflexible tape on one side of the balloon before you blow it up. When inflated, the balloon will deviate in one direction. That's Peyronie's Disease.

With Xiaflex, he said, you inject the drug — which is an enzyme that breaks down collagen — just under the skin into the plaque at the maximal point of curvature. The drug acts like an enzymatic scalpel, he said, and the goal is to just eat away enough of that tape so that the tape breaks in two pieces and the balloon becomes straighter” (Common Health, June 2012 Opens in new window symbol)

How Does Xiaflex Peyronie's Treatment Work?

Xiaflex for Peyronie's is available by prescription only. It is injected directly into the penis by qualified health professional.

Each treatment cycle includes two Xiaflex injections. Up to four treatment cycles (eight injections) may be administered in the course of treatment.

Penile modeling (gentle stretching in the opposite direction of the deformity) is recommended after every treatment cycle in an effort to further disrupt the plaque.

If there are multiple plaques present, then the Xiaflex is injected into the plaque causing the penile curvature.

What Are Benefits Of Xiaflex Injection?

Xiaflex injections deliver the medication directly to the plaque, hence less affect on the rest of your body.

The Downsides Of Xiaflex For Peyronie's?

Some men have problem with the intimate nature of penile injection treatments. However, the biggest downside of Xiaflex for Peyronie's is likely to be the treatment cost.

How much Xiaflex Peyronie's treatment will cost is not known at this stage, but figures like $3,300 per injection have been mentioned (Xiaflex Peyronie's treatment would include up to 8 injections).

This would mean that Xiaflex treatment is not an option for the masses unless national health care providers or insurance companies will cover the cost (fully, or at least partly).

What Are The Xiaflex Side Effects?

Based on clinical studies (see more later) Xiaflex injections are generally well tolerated but the most common side effects were hematoma, pain and swelling at the treatment site. Most resolved within 14 days.

Is There Any Health Risk Involved In Xiaflex For Peyronie's?

If things go wrong, it can have serious consequences for the men in question. In the clinical studies 3 men (of 551, or 0.54%) experienced penile fracture or rupture that had to be surgically repaired. There were also some cases of serious hematoma.

Auxilium has worked with FDA to develop a risk evaluation and mitigation strategy (REMS) to certify that the appropriate physicians and practice sites are aware and trained in targeting serious adverse events.

The Results Of Using Xiaflex Injection For Peyronie's

Xiaflex has just recently been approved for treating Peyronie's patients (6th December 2013). The best information about the results of Xiaflex Peyronie's treatments is therefore from the clinical trials.

BioSpecifics in collaboration with Auxilium Pharmaceuticals conducted the clinical trials. Two clinical trials (IMPRESS I and IMPRESS II) have already been concluded (June 2012) and their result is promising.

The two randomized, double blind, placebo-controlled Phase 3 studies enrolled over 800 patients at 64 sites in the US and Australia with a 2:1 ratio of Xiaflex to placebo.

The Xiaflex was injected twice a week every sixth week for up to four treatment cycles and each treatment cycle was followed by penile modeling procedure.

The average deformity of the penis at the beginning of IMPRESS I was 48.8 degrees but 31.0 degrees at the end of the 52 weeks, or 37.6% mean reduction in penile curvature. The mean reduction in the placebo group was 21.3% (from 49.0 degrees to 39.0 degrees).

The average deformity of the penis at the beginning of IMPRESS II was 51.3 degrees but 35.1 degrees at the end of the 52 weeks, or 30.5% mean reduction in penile curvature. The mean reduction in the placebo group was 15.2% (from 49.6 degrees to 41.1 degrees).

At first between 30.5% – 37.6% mean reduction in penis curvature looks quite impressive. However if compared to the reduction in the placebo group, it's less so.

Note, it is important to distinguish between the percentage improvement and the actual improvement in the penis curvature (measured in curvature degrees).

The difference in the actual penis curvature is less than 8 degrees when you compare the degrees improvement between using Xiaflex versus using placebo (substance or procedure that has no therapeutic effect, used as a control in testing new drugs).

  Impress I Placebo Impress II Placebo
Degrees Beginning 48.8 49 51.3 49.6
Degrees End 31.0 39 35.1 41.1
Degrees Improvement 17.8 10.0 16.2 8.5
Degrees Difference   7.8 7.7

So can you only expect 8 degrees better result from using Xiaflex than doing nothing? Is it enough to justify the effort, risk, time, and cost involved?

First, the good improvement in the placebo group seems to have come somewhat as a surprise. It is normally estimated that only 5 - 15% of Peyronie's cases resolve without any treatment (during the acute stage) but the result from the placebo injections were better than that.

It raises the interesting question if just injecting needle in the penis may have any positive effect on the Peyronie's plaque?

Still, most men would be pleased with 16.2 – 17.8 degrees improvement in their penis curvature, right?


Auxilium used Peyronie's Disease Questionnaire (PDQ) to evaluate the overall impact on the Peyronie's patient quality of life.

The results are somewhat surprising. The improvement in the PDQ Bother Score between the two groups (Xiaflex vs. placebo) was just about statistically significant.

Sure men felt better after having the Xiaflex treatment but not as much as you might have expected, especially if compared with the placebo group that also felt better after their pretense treatment.

You can find more information about IMPRESS I and II on Xiaflex websiteOpens in new window symbol.

Dr. Irwin Goldstein is one of the leading experts in the use of Xiaflex injections to treat men with Peyronie's disease. He participated in the Xiaflex clinical trial and was one of the leading recruiters for the double blind placebo-controlled clinical research trial.

Dr. Goldstein has performed several thousand intralesion Xiaflex injections and according to him the results have been excellent. I recommend reading My Peyronie's Interview With Dr. Irwin Goldstein.

Scientific Support For Xiaflex Peyronie's Treatment

The above clinical studies are among the information that FDA based their approval on. The FDA approval confirms that Xiaflex Peyronie's treatment is effective for some Peyronie's patients.

While this study (IJIR 2018) shows limited success with clostridium collagenase histolyticum following FDA approval for the treatment of Peyronie’s disease.

My Personal Experience And Opinion Of Using Peyronie's Xiaflex Injections

I do not have personal experience of Xiaflex Peyronie's treatment. Actually, few have as Xiaflex injections have only recently become available to the general Peyronie's patients. It is therefore not easy to find someone that has tried Xiaflex for Peyronie's.

The founder of the website curepeyronies.net participated in the phase IIb study but he received placebo treatment. However, after the trial finished he participated in the open source clinical trial that ran concurrently with the last phase III Xiaflex trial.

He has kindly agreed to share his Experience Of Xiaflex with My Peyronie's readers. It is a must read for anyone interested in using Xiaflex for Peyronie's disease.

Unfortunately, he was one of the few that experienced serious side effects, i.e. severe case of hematoma. Reading about his ordeal will make your friend cringe but it clearly emphasizes the importance of qualified health professionals and using the correct injection technique.

We owe the founder of curepeyronies.net thanks for his honest and open account of his experience and for all the valuable information on his website.

Xiaflex risk reward ratio

John was unlucky to develop serious side effects but most side effects resolve within 14 days. There is still a risk involved, as with all invasive treatments and medication. At the moment I'm kind of more concerned about the high cost involved than the potential risk.

Everyone has to weigh the pros and cons for themselves, i.e. do the potential benefits outweigh the potential risk. Are Xiaflex injections worth the risk, effort, time, and money?

Many men will without a doubt think so. Let's face it, the options are limited and most include some level of risk, effort, time and money. It is however important that any decision about Peyronie's treatment is an educated decision, i.e. that you research all your options carefully prior to starting your treatment.

There is no magic drug for Peyronie's and Xiaflex does not change that. Xiaflex is however a valuable alternative for many Peyronie's patients.

For more information about Xiaflex, visit the official Xiaflex Website Opens in new window symbol.

For the latest information about Xiaflex for UK Peyronie's patients, see my article about Xiapex.

Hello, I'm Birgir

This website is based on my experience of Peyronie's disease