Positron emission tomography evaluation of sedative properties of antihistamines

Kazuhiko Yanai, Dongying Zhang, Manabu Tashiro, Takeo Yoshikawa, Fumito Naganuma, Ryuichi Harada, Tadaho Nakamura, Katsuhiko Shibuya, Nobuyuki Okamura

Research output: Contribution to journalArticlepeer-review

51 Citations (Scopus)


Introduction: H1 antihistamines are often used in the medication for allergic diseases, coughs and colds, and insomnia, with or without prescription, even though their sedative properties are a potentially dangerous unwanted side effect that is not properly recognized. These sedative properties have been evaluated using the incidence of subjective sleepiness, objective cognitive and psychomotor functions, and positron emission tomography (PET) measurement of H1 receptor occupancy. Areas covered: This article reviews the current updated literature on the sedative properties of antihistamines examined by PET measurement of H1 receptor occupancy. Expert opinion: The use of PET to examine antihistamine penetration in the human brain in relation to psychometric and other functional measures of CNS effects is a major breakthrough and provides a new standard by which the functional CNS effects of antihistamines can be related directly to H1 receptor occupancy. Therapy with antihistamines can be better guided by considering histamine H1 receptor occupancy from the view of their sedative properties.

Original languageEnglish
Pages (from-to)613-622
Number of pages10
JournalExpert Opinion on Drug Safety
Issue number4
Publication statusPublished - 2011 Jul


  • H antihistamines
  • PET
  • brain
  • histamine H receptors
  • histamine neurons
  • receptor occupancy
  • sedation
  • tissue pharmacokinetics

ASJC Scopus subject areas

  • Pharmacology (medical)


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