title: Injection therapy for the treatment of erectile dysfunction: a comparison between alprostadil and a combination of vasoactive intestinal polypeptide and phentolamine mesilate.
abstract: OBJECTIVE
  To compare two injectable treatments, alprostadil 5-20 microg powder for injection and a combination of vasoactive intestinal polypeptide (VIP) and phentolamine in patients with erectile dysfunction (ED).
  
  
  METHODS
  This was an open multicentre, randomised crossover study comprising two phases. The first phase established the dose of each drug required to produce an erection suitable for sexual intercourse (grade 3 erection). In phase 2, responders to both drugs received, in random order, four doses of VIP/phentolamine, presented as ampoules, and four doses of alprostadil, presented as powder for injection. This was followed by four doses of VIP/phentolamine, presented in an autoinjector. In both phases, patient preference was assessed for each preparation.
  
  
  RESULTS
  187 patients were recruited. In the first phase, both treatments were effective, (83% alprostadil vs. 73% VIP/phentolamine, p = 0.002) but more patients preferred VIP/phentolamine (69 vs. 31%, p = 0.011). In phase 2 (n = 107), the proportion of injections that produced a grade 3 erection was similar for all three treatments (83-85%), but both presentations of VIP/phentolamine (ampoule and auto-injector) were preferred by significantly more patients (p < 0.001). Compared with both presentations of VIP/phentolamine, alprostadil produced a higher frequency of pain (28% of injections vs. 3% for each VIP/phentolamine presentation; p < 0.001) and a lower frequency of facial flushing (3 vs. 16-17%; p < 0.001).
  
  
  CONCLUSIONS
  VIP/phentolamine and alprostadil were effective treatments for ED, however the VIP/phentolamine combination was preferred by more patients, which may be because it was much less likely to cause pain.
authors: Institute of Urology and Nephrology, London, UK.
authors: P J R
authors: PJ
authors: Shah
authors: W
authors: W
authors: Dinsmore
authors: R A
authors: RA
authors: Oakes
authors: Geoff
authors: G
authors: Hackett
mesh_terms: D000328:Adult; D000368:Aged; D000527:Alprostadil / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D018592:Cross-Over Studies; D004359:Drug Therapy, Combination; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D007267:Injections; D008297:Male; D008875:Middle Aged; D010646:Phentolamine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D016896:Treatment Outcome; D014660:Vasoactive Intestinal Peptide / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D014660:Vasoactive Intestinal Peptide; D000527:Alprostadil; D010646:Phentolamine