title: Co-administration of low doses of intranasal PT-141, a melanocortin receptor agonist, and sildenafil to men with erectile dysfunction results in an enhanced erectile response.
abstract: OBJECTIVE
  To evaluate the safety and pharmacodynamic effect of co-administration of subtherapeutic doses of PT-141, a cyclic heptapeptide melanocortin analogue, and sildenafil to patients with erectile dysfunction.
  
  
  METHODS
  Nineteen patients with erectile dysfunction who were responders to either Viagra or Levitra by self-report were given 25 mg sildenafil and 7.5 mg intranasal PT-141, 25 mg sildenafil and an intranasal placebo spray, and a placebo tablet and an intranasal placebo spray in a randomized cross-over design. Erectile activity in response to two 30-minute episodes of visual sexual stimulation was assessed by RigiScan during a 6-hour postdose period.
  
  
  RESULTS
  The erectile response induced by co-administration of PT-141 and sildenafil was significantly greater than the response elicited by administration of sildenafil alone. Co-administration of PT-141 and sildenafil was safe and well-tolerated and did not result in new adverse events or adverse events that were increased in frequency or severity compared with monotherapy.
  
  
  CONCLUSIONS
  Co-administration of intranasal PT-141 and a phosphodiesterase type 5 inhibitor may constitute a treatment alternative for patients in whom higher doses of a single therapy are not effective or well tolerated.
authors.affiliation: Palatin Technologies, Inc., Cranbury, New Jersey 08512, USA. ldiamond@palatin.com
authors.forename: L E
authors.initials: LE
authors.lastname: Diamond
authors.forename: D C
authors.initials: DC
authors.lastname: Earle
authors.forename: W D
authors.initials: WD
authors.lastname: Garcia
authors.forename: C
authors.initials: C
authors.lastname: Spana
mesh_terms: D000281:Administration, Intranasal; D000328:Adult; D000368:Aged; D004359:Drug Therapy, Combination; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000008:administration & dosage*; D010865:Pilot Projects; D010879:Piperazines / Q000627:therapeutic use*; D011687:Purines; D012074:Remission Induction; D000068677:Sildenafil Citrate; D013450:Sulfones; D000521:alpha-MSH
chemical_list: D010456:Peptides, Cyclic; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000521:alpha-MSH; C476721:bremelanotide; D000068677:Sildenafil Citrate