title: Betahistine metabolites, aminoethylpyridine, and hydroxyethylpyridine increase cochlear blood flow in guinea pigs in vivo.
abstract: OBJECTIVE
  Betahistine is a histamine-like drug that is used in the treatment of Ménière's disease. It is commonly believed that betahistine increases cochlear blood flow and thus decreases the endolymphatic hydrops that is the cause of Ménière's. Despite common clinical use, there is little understanding of the kinetics or effects of its metabolites. This study investigated the effect of the betahistine metabolites aminoethylpyridine, hydroxyethylpyridine, and pyridylacetic acid on cochlear microcirculation.
  
  
  METHODS
  Guinea pigs were randomly assigned to one of the groups: placebo, betahistine, or equimolar amounts of aminoethylpyridine, hydroxyethylpyridine, or pyridylacetic acid. Cochlear blood flow and mean arterial pressure were recorded for three minutes before and 15 minutes after treatment.
  
  
  METHODS
  Thirty Dunkin-Hartley guinea pigs assigned to one of five groups with six guinea pigs per group.
  
  
  RESULTS
  Betahistine, aminoethylpyridine, and hydroxyethylpyridine caused a significant increase in cochlear blood flow in comparison to placebo. The effect seen under aminoethylpyridin was greatest. The group treated with pyridylacetic acid showed no significant effect on cochlear blood flow.
  
  
  CONCLUSIONS
  Aminoethylpyridine and hydroxyethylpyridine are, like betahistine, able to increase cochlear blood flow significantly. The effect of aminoethylpyridine was greatest. Pyridylacetic acid had no effect on cochlear microcirculation.
authors.affiliation: * Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center Göttingen , Germany.
authors.forename: Mattis
authors.initials: M
authors.lastname: Bertlich
authors.forename: Fritz
authors.initials: F
authors.lastname: Ihler
authors.forename: Kariem
authors.initials: K
authors.lastname: Sharaf
authors.forename: Bernhard G
authors.initials: BG
authors.lastname: Weiss
authors.forename: Michael
authors.initials: M
authors.lastname: Strupp
authors.forename: Martin
authors.initials: M
authors.lastname: Canis
mesh_terms: D000085:Acetates / Q000494:pharmacology; D000818:Animals; D001621:Betahistine / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects; D003051:Cochlea / Q000098:blood supply / Q000187:drug effects*; D006168:Guinea Pigs; D017442:Histamine Agonists / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use*; D008575:Meniere Disease / Q000188:drug therapy*; D008833:Microcirculation / Q000187:drug effects*; D011725:Pyridines / Q000494:pharmacology; D011897:Random Allocation
chemical_list: D000085:Acetates; D017442:Histamine Agonists; D011725:Pyridines; C492873:2-pyridylacetic acid; C000598601:2-(2-hydroxyethyl)pyridine; C006183:2-(2-aminoethyl)pyridine; D001621:Betahistine
keywords: Betahistine; Ménière's disease; aminoethylpyridine; cochlear blood flow; histamine; hydroxyethylpyridine; pyridylacetic acid