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VIP for erectile dysfunction

Clinical bottom line

There is no evidence that intracavernosal VIP is effective. Intracavernosal VIP combined with phentolamine appears to have promise based on the results from one trial.

Searching

Searching was done using PubMed, Medline and the Cochrane Library, up to September 2005. Randomised trials in which VIP was compared with placebo were sought. Details of the trials were abstracted and quality scoring done with a 5 point scale. For crossover or partial crossover designs, details of the first phase were used (as a parallel group trial) where possible, and where this was not possible the full crossover data was used.

The outcome sought was patient/partner judgement of satisfactory erections suitable for intercourse, or actual intercourse, at home. Ideally this was on a patient basis, rather than on event basis, which was a secondary outcome. Relative risk and NNT were calculated using standard methods.

Results

Intracavernosal VIP

In one study of 24 men with non vasculogenic erectile dysfunction, none of them achieved penile rigidity sufficient for intercourse with a series of intracavernosal injections of 200 or 400 pmol of VIP (Table 1).

Intracavernosal VIP plus phentolamine

Use of 25 µg VIP plus 1 mg or 2 mg phentolamine in a single intracavernosal injection achieved satisfactory erections suitable for intercourse in 74% of uses, compared with 13% with placebo in 1200 attempts in 105 men who entered a randomised trial and used the treatment. The relative benefit was 5.9 (4.1 to 8.4) and the NNT was 1.6 (1.5 to 1.8).

Details are in Table 1, and references for all treatments at the end of the article. Note that the intracavernosal VIP plus phentolamine data were published twice.

Table 1: Randomised studies of intracavernosal VIP with phentolamine

Study

Design

Quality score

Patients

Treatment

Outcome

Result

Adverse events

Dinsmore et al, 1999 Randomised, double blind crossover with 5:1 active:placebo

3

 236 men with nonpsychogenic erectile dysfunction 25 ug VIP plus 1.0 / 2.0 mg phentolamine for 12 injections or six months Sexual intercourse in home environment 747/1017 with VIP-phentolamine, 26/207 placebo Flushing noted with 50% of injections. Other local AEs common, including bruising. 1 case of priapism
Roy et al, 1990 Randomised, double-blind, crossover

4

 24 men with nonvascular aetiology 200/400 pmol intracavernosal VIP Penile length, girth and rigidity No penile rigidity adequate for intromission No data

Comment

A treatment for which there is relatively little information, most particularly concerning adverse events. There is too little information on which to judge efficacy, and while an NNT has been calculated, it is not a robust estimate with this trial design, and is based on successful attempts, not on men achieving success with the treatment. It should not be used as a basis making therapy choices.

Phentolamine has also been used in combination with papaverine.

References

Reference

Notes

Dinsmore WW, Gingell C, Hackett G et al. Treating men with predominantly nonpsychogenic erectile dysfunction with intracavernosal vasoactive intestinal polypeptide and phentolamine mesylate in a novel auto-injector system: a multicentre double-blind placebo-controlled study. BJU Int 1999; 83(3):274-9.
RCT
Sandhu D, Curless E, Dean J et al. A double blind, placebo controlled study of intracavernosal vasoactive intestinal polypeptide and phentolamine mesylate in a novel auto-injector for the treatment of non-psychogenic erectile dysfunction. Int J Impot Res 1999; 11(2):91-7.
Duplicate publication of Dinsmore
Roy JB, Petrone RL, Said SI. A clinical trial of intracavernous vasoactive intestinal peptide to induce penile erection. J Urol 1990; 143(2):302-4.
RCT
Del Popolo G, Natali A, Lombardi G et al. The treatment of erectile failure in spinal cord injury: Intracavernosal VIP alone and in combination with PGE1. Preliminary results. ACTA-UROL-ITAL Acta-Urologica-Italica. 1993; 7(SUPPL. 2):187-8.
Not an RCT
Dinsmore WW, Alderdice DK. Vasoactive intestinal polypeptide and phentolamine mesylate administered by autoinjector in the treatment of patients with erectile dysfunction resistant to other intracavernosal agents. Br J Urol 1998; 81(3):437-40.
Not an RCT