title: Effects of pentoxifylline and alprostadil on ocular hemodynamics in healthy humans.
abstract: OBJECTIVE
  Alprostadil, a prostaglandin (PG)E(1) analogue and pentoxifylline, an alkylxanthine derivate, have been shown to exert vasodilatory effects in several vascular beds. The purpose of the present study was to investigate the effect of PGE(1) and pentoxifylline on the ocular circulation.
  
  
  METHODS
  A placebo-controlled, double-masked, three-way, crossover study was performed in 15 healthy male subjects. Subjects received pentoxifylline (300 mg), PGE(1) (alprostadil 60 mug), or placebo intravenously over 2 hours on three trial days. Choroidal red blood cell flow was assessed with laser Doppler flowmetry and pulsatile choroidal blood flow with laser interferometric measurement of fundus pulsation amplitude (FPA). Retinal blood cell flow was calculated based on the measurements of maximum erythrocyte velocity in a retinal vein assessed with bidirectional laser Doppler velocimetry, and diameter measurements of retinal vessels were obtained with a retinal vessel analyzer.
  
  
  RESULTS
  Pentoxifylline increased FPA by 15.4% +/- 1.1% (P < 0.001 versus placebo and baseline). Alprostadil tended to increase FPA, but this effect did not reach the level of significance (P = 0.07 versus placebo). Choroidal blood flow as measured with laser Doppler flowmetry tended to increase during pentoxifylline and PGE(1) infusion by 8.9% +/- 2.9% (P = 0.062) and 4.5% +/- 6.2% (P = 0.29), respectively, but none of these effects was significant. The drugs under study had no effect on mean red blood cell velocity in retinal veins, on retinal vessel diameters, intraocular pressure, blood pressure, or pulse rate.
  
  
  CONCLUSIONS
  PGE(1) did not alter the parameters of retinal or choroidal circulation in healthy subjects. Pentoxifylline increased FPA, but did not change choroidal blood flow as measured with laser Doppler flowmetry and did not affect retinal blood flow parameters. Accordingly, neither pentoxifylline nor PGE(1) appears to be suitable to improve ocular blood flow in healthy subjects. Whether long-term treatment with alprostadil would improve choroidal blood flow in patients with vascular disease remains to be established.
authors.affiliation: Departments of Clinical Pharmacology, Medical University of Vienna Allgemeines Krankenhaus Wien, Waehringer Guertel 18-20, A-1090, Vienna, Austria.
authors.forename: Guido T
authors.initials: GT
authors.lastname: Dorner
authors.forename: Claudia
authors.initials: C
authors.lastname: Zawinka
authors.forename: Hemma
authors.initials: H
authors.lastname: Resch
authors.forename: Michael
authors.initials: M
authors.lastname: Wolzt
authors.forename: Leopold
authors.initials: L
authors.lastname: Schmetterer
authors.forename: Gerhard
authors.initials: G
authors.lastname: Garhofer
mesh_terms: D000328:Adult; D000527:Alprostadil / Q000494:pharmacology*; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure; D002829:Choroid / Q000098:blood supply*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004912:Erythrocytes / Q000502:physiology; D006801:Humans; D007429:Intraocular Pressure; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D010431:Pentoxifylline / Q000494:pharmacology*; D012039:Regional Blood Flow / Q000187:drug effects; D012171:Retinal Vessels / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D014665:Vasodilator Agents; D000527:Alprostadil; D010431:Pentoxifylline