Penile Injections Treatment

Most people fear needles, and the idea of a penile injection is even less appealing for most men.  But penile injections are a good erectile dysfunction treatment option for some men who cannot use oral forms of erection treatment, like drugs or herbal supplements.

In particular penile injections may offer effective ED treatment alternatives for:

  • diabetic men
  • those suffering ED as a result of radical prostatectomy (RP) for prostate cancer
  • men with serious underlying cardiac disease

Penile injections claim to work faster than drugs – sometimes within a few minutes - and about 80 per cent of the men tested during clinical trials got an erection with the injection treatment.
Penile injections are:

  • The only ED treatment which initiates erection
  • Were the first ED treatment approved by the FDA
  • Work for men with a broad range of medical conditions

Who is Most Suited for Penile Injections?

If you are experiencing erection problems because of diabetes or prostate cancer surgery, the injection may be your best option to restore your sex life. (About 50 per cent of diabetic men will experience impotence.)
 
And although injection therapy tends to have a high dropout rate, men who learn how to use injections successfully can enjoy a long and happy sex life.
 
A Chinese study of 416 ED patients treated with injections of Prostaglandin E1 (PGE1 – or commercially available as alprostadil) – the drug in Caverject and Edex commercial injections – showed

  • Nearly 63 per cent were satisfied and kept using it
  • 6.5 per cent returned to normal sexual function after five injections
  • 51.2 per cent kept using it for over a year
  • 6.2 per cent continued using it for over 5 years
  • 2.9 per cent continued using it over 8 years
  • 1.7 per cent continued using it over 10 years

And a Finnish study with Prostaglandin E1 found an even higher rate of men who experienced improvement in the rate of spontaneous erections – to nearly 35 per cent.

How Do Penile Injections Work?

The erectile dysfunction solution in the penile injection syringe or plunger device contains a vasodilator (an agent that relaxes blood vessels and increases blood flow) which is injected directly into the side of the penis. This dilates the arteries and causes an erection anywhere from 5 to 15 minutes after injection. It lasts from 30 minutes to an hour.
 
The pain of the needle is described by most men as very slight – like the sensation like 'pulling a hair out of the back of their hand'.
 
You should not use the penile injection treatment more than ten to 12 times a month, or three times a week, and not on consecutive days. And you should ideally vary the needle site on the right and left side of the penis to reduce the risk of developing scar tissue.
 
Your erection will last after you climax, until the medication stops working in your system.

What Do Penile Injections Contain?

There are over 40 different medications specialist urologists can use in penile injections, and individual doses made by a compounding pharmacy can also be prescribed, but the three most common ingredients in penile injections are:

  • Prostaglandin E – a naturally occurring hormone in the body.  The most commonly used. Commercially available as the drug Alprostadil, a synthetic version of Prostaglandin E-1 found in brand name erection injections like Caverject, and Caverject Impulse (Pharmacia Upjohn) or Edex (Schwarz Pharma).
  • Papaverine hydrochloride – like Prostaglandin this relaxes the muscle in the lining of the penis and increases blood flow. When a doctor prescribes an injection with more than one ingredient, papaverine is a likely addition.
  • Phentolamine (commercially available as Regitine) has a similar action to papaverine and is often prescribed with it. The Swedish injection Invicorp, (Evolan), contains phentolamine and  the drug avaptadil  (also known as a vasoactive intestinal polypeptide (VIP) )

Reasons Why Men Stop Using Penile Injections

There is a high drop-out rate amongst men using penile injections, even though they are effective and the risk of negative side effects is quite low.

A recent review demonstrated that

  • 15% of men who are offered the penile injection therapy do not even try it
  • 40% will discontinue treatment within 3 months
  • only 20% to 30% of men will continue with penile injection therapy for more than 3 years

Reasons given for not continuing with penile injections included:

  • “Needle fear” and difficulty administering the injection
  • Loss of spontaneity
  • Side effects like the possibility of developing an erection that lasts longer than you want (priapism) – particularly with the two older drugs, papaverin and phentolamine.
  • Developing scar tissue from repeated injections – once again more likely with papaverin and phentolamine
  • A dull aching pain in the penis and testicles – particularly associated with Prostaglandin E.
  • Partner discontent or relationship ended
  • Return of spontaneous erections (a Finnish study showed 34 per cent of men experienced the return of spontaneous erections after being  on penile injection therapy)

What Penile Injections Doctors Are Likely to Prescribe

Most doctors will begin by recommending one of the commercially prepared penile injections like Caverject or Edex, containing Prostaglandin E (and the only penile injections currently approved by the FDA).
These may not satisfy for a number of reasons including:

  • The size of the needle may be larger and uncomfortable to administer
  • Prostaglandin causes an aching pain in the testicles and penis in nearly 40 per cent of men who use it.


In these cases, the doctor may prescribe the Invicorp penile injection, which has a very fine needle which is virtually painless to administer, and also it does not cause the aching groin pain.

Or he(or she) may prescribe a combination penile injection product which is made by a compounding pharmacist to the urologist’s instructions.  These are generally less expensive than the commercially produced injections, and minimise the aching pain of prostaglandin.
 
Because no specific pharmaceutical company has the licensing rights to the penile injection combinations, FDA studies have never been conducted, and likely never will, to determine their exact safety and reliability. These combination agents, however, have been used for more than a decade longer than Caverject and Edex and are just as safe and probably more effective in most men.

The most common of these penile injections are:

  • Bimix – is a blend of papaverine and phentolamine, not commercially available, must be made up by a compounding pharmacist to urologist’s prescription.
  • Trimix – also known as Triple P - a blend of prostaglandin, papaverine and phentolamine, also made by a compounding pharmacist under the doctor’s individually-designed formula.

Popular Penile Injections in Australia

The most popular penile injections in Australia are:

  • Caverject Impulse, according to Dr Michael Lowy a sexual health physician at the Sydney Mens Health Centre. The Caverject Impulse has a double chamber injection mechanism which mixes the powder and sterile water during delivery. The needle is finer than in the Caverject and pain minimal. However the possible risk of the needle breaking while inserted in the penis is slightly increased.
  • Caverject - uses the same drug Alprostadil from the same manufacturer, but uses a regular syringe injector with a bigger needle. Many men complain the needle is too large.
  • Invicorp injection – with a fine needle and no painful after effects, it  reported to be essentially pain free and has a negligible risk of producing an erection for too long. (Invicorp is approved for use in Europe and is working on getting FDA approval.)

Side Effects of Penile Injections

1)      Groin Pain: The most common side effect with penile injections – particularly those containing alprostadil alone, is a mild to moderate dull ache which usually strikes from 5 to 20 minutes after the injection. The ache is increased by standing, and subsides when the erection is complete.
 
The alternative is to use a specially compounded mixture of papaverine, phentolamine and alprostadil (synthetic Prostaglandin E) which is effective and painless.
 
2)      Scarring: A small bruise usually will develop at the injection site, and if the same site is injected repeatedly, scarring or fibrosis on the inner side of the penis may occur.

3)      An erection that won’t go down: Sometimes the penile injection medication may produce a painful, sustained erection called priapism. If an erection lasts more than three to four hours you should seek immediate medical treatment, but it is reversed easily if treated early.

Tips For Administering Penile Injections

According to the ED Guidance website:

  • Always inject at the base of the penis. The needle should be at a 90 degree angle
  • Roll the penis between the palms gently after injection to spread the medication.
  • Alternate injection on right and left sides to minimise risk of scarring
  • Apply pressure to the injection site for a minute or two. If there is any bleeding, hold the pressure for about 5 minutes. Men taking blood thinners should apply pressure to the injection site for about 5 minutes.
  • Never re-inject once you have injected, even if you fear that you have not injected properly.
  • Do not inject more frequently than every 48 to 72 hours.
  • Remember that with Edex and Caverject, once the medication has been reconstituted (i.e., once the powder is dissolved in the sterile water), it must be refrigerated. The solutions in penile injections tend to lose their efficacy after 7 days.