title: Nimodipine plasma concentration and retinal blood flow in healthy subjects.
abstract: OBJECTIVE
  Calcium antagonists are strong vasodilators, and nimodipine is known to improve cerebral blood flow. The purpose of this study was to measure retinal blood flow and nimodipine plasma concentrations during repeated oral dosing.
  
  
  METHODS
  In a double-blind, two-way, crossover study, 20 healthy subjects (mean age, 22.8 +/- 3.7 years) underwent examination of retinal perfusion and nimodipine plasma concentrations. In a placebo-controlled fashion, nimodipine was orally administered at a dosage of 30 mg three times a day for two periods of 5 days including a 9-day washout interval. At days 1, 5, 15, and 19, plasma concentrations of nimodipine and retinal perfusion were measured 11 times within 3 hours. Stereoselective analysis of nimodipine plasma concentrations was performed with the use of liquid chromatography-tandem mass spectrometry. Scanning laser Doppler flowmetry was used to measure the microcirculation of the juxtapapillary retina. Perfusion images were evaluated with the automatic full-field evaluation procedure (AFFPIA).
  
  
  RESULTS
  Areas under the plasma concentration versus time curves were similar at day 1 and day 5 of nimodipine administration (t test: P = 0.64). Values of C(max) displayed a large interindividual variance and ranged from 0 ng/mL to 57.5 ng/mL. On average, maximum nimodipine plasma concentrations (C(max)) were 16.6 +/- 14.9 ng/mL and 12.0 +/- 10.3 ng/mL at day 1 and day 5, respectively (P = 0.068). They were observed at 81 +/- 50 and at 93 +/- 40 minutes (t(max)) after the administration of nimodipine at day 1 and day 5, respectively (P = 0.43). Retinal microcirculation was greater after nimodipine than after placebo, as reflected in significantly larger areas under the curves of percentage change in blood flow from baseline versus time (P < 0.01). The maximum increase of retinal blood flow from baseline was significantly more pronounced after nimodipine (28.5% +/- 14.4% and 39.6% +/- 21.4% at day 1 and day 5, respectively) than after placebo (20.5% +/- 16.8% and 31.9% +/- 14.6% at day 1 and day 5, respectively; P = 0.032).
  
  
  CONCLUSIONS
  Oral nimodipine significantly increases retinal perfusion in healthy subjects.
authors.affiliation: Department of Ophthalmology, University Erlangen-Nürnberg, Germany. georg.michelson@rzmail.uni-erlangen.de
authors.forename: Georg
authors.initials: G
authors.lastname: Michelson
authors.forename: Simone
authors.initials: S
authors.lastname: Wärntges
authors.forename: Steffen
authors.initials: S
authors.lastname: Leidig
authors.forename: Jörn
authors.initials: J
authors.lastname: Lötsch
authors.forename: Gerd
authors.initials: G
authors.lastname: Geisslinger
mesh_terms: D000284:Administration, Oral; D000328:Adult; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002121:Calcium Channel Blockers / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006339:Heart Rate; D006801:Humans; D007429:Intraocular Pressure; D017078:Laser-Doppler Flowmetry; D008297:Male; D008833:Microcirculation; D009553:Nimodipine / Q000493:pharmacokinetics*; D012171:Retinal Vessels / Q000502:physiology*; D014665:Vasodilator Agents / Q000493:pharmacokinetics*
chemical_list: D002121:Calcium Channel Blockers; D014665:Vasodilator Agents; D009553:Nimodipine