INGECTION TREATMENTS FOR ED
Dr Virag's 1982 discovery of the benefits of papaverine for erectile dysfunction has had a huge influence on the treatment of this condition. Since this event, injection therapy has become the cornerstone of medical treatment for erectile dysfunction.
Papaverine was used on its own for some time. It required the injection of fairly large doses and the results were quite variable among patients. It also carried certain risks, such as producing a priapism. With priapism, the high-pressure inflow of blood is maintained and the low-pressure outflow continues to be obstructed. This may result in an erection that can remain for more than six hours. Secondly, the large volumes of papaverine that are required to be injected cause significant displacement of tissue within the penis. This has the potential to cause the formation of scar tissue. In the early days of this treatment, papaverine was dispensed to patients almost exclusively by urologists.
Over the years, other vasodilators and muscle relaxants were tried with good results. The combination of two or more of these drugs enhanced the effect and required a smaller total volume of medication. Those used alone include:
• Papaverine
• Prostaglandin Ei
• Moxisylate
• Lisidomine
• Nitroprusside.
The combinations of injectable treatments that have been used include:
• Papaverine with phentolamine (regitine
• Phentolamine with Prostaglandin Ei
• Papaverine, Phentolamine and Prostaglandin Ei
• Papaverine, Phentolamine, Prostaglandin Ei and Atropine
• Papaverine, Chlorpromazine, Prostaglandin Ei and Atropine.
Other drugs that have been added to these regimens, but are not commonly used, include:
• Forscolin
• Vasoactive Intestinal Peptide
• Lisidomine
• Ketanserin.
My own experience has been with the use of the following injectable treatments:
1. Prostaglandin Ei alone (PGE)
2. Papaverine, Phentolamine, Atropine and Prostaglandin Ei (PRAPg)
3. Papaverine, Chlorpromazine, Atropine and Prostaglandin Ei (PCAPg)
4. Papaverine, Phentolamine and Prostaglandin Ei (PRPg)
5. Papaverine, Phentolamine and Atropine (PRA).
I have found PCAPg to be the strongest mixture, with PRAPg a close second. PGE alone is the weakest mixture,with pain being a possible side effect. PRA can
be given to patients who cannot refrigerate their medication. This medication can be very strong, and it may not give consistent results. PGE and PRAPg are the two injectable medications most often available today. Injection therapy has a response rate of over 90 per cent.
Initially, most men receie PGE. However, due to the pain factor or inadequate results, they will usually switch to PRAPg. The rationale for the use of drug combinations is based on the different mechanisms of action and the synergistic effect they have together.
Prostaglandin Ei was used to treat new-born babies with congenital heart defects. It was discovered that injection of this drug in a dilute form into the penis would result in an erection. It has become the most studied injectable substance for erectile dysfunction. Copious amounts of information about its efficacy, safety profile and long-term patient satisfaction have been made available through the many trials that have been undertaken.
Prostaglandin is an officially approved drug in many countries for the treatment of erectile dysfunction. However, because of its cost, it is more commonly combined with other drugs such as papaverine, atropine and regitine. The 'tri-mix' and 'quad-mix', as they are known, have become the most widely used combination of drugs for the treatment of erectile dysfunction throughout the world. The 'tri-mix' and 'quad-mix' will produce an equivalent effect to that of papavarine on it's own, using only one tenth of the volume. The combinations are far more powerful, safer, and appear to have a more predictable outcome than papavarine.
In 1996, the American Urological Association proclaimed Prostaglandin Ei as the 'First Choice drug' for the treatment of impotence. The drug, Caverject, has received FDA (Food and Drug Administration) approval in the US as a commercial product of PGEi and soon after was approved by the TGA in Australia.
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