title: Pharmacokinetics of cetirizine in tear fluid after a single oral dose.
abstract: BACKGROUND
  Antihistamines (histamine H(1) receptor antagonists) are effective and convenient drugs for the treatment of allergic conjunctivitis. Because of the short duration of action generally observed for drugs administered topically to the eye, the oral route is often preferred. However, the presence of a selective barrier between blood and ocular tissues, the so-called blood-ocular barrier, does not allow a priori assessment of the most suitable dosage for ocular therapy.
  
  
  OBJECTIVE
  To investigate the tear concentrations of cetirizine, a second-generation antihistamine, over time following oral administration, and to study the relationship between plasma and tear fluid concentrations.
  
  
  METHODS
  Pharmacokinetic study of a single oral dose of cetirizine 10mg in 40 patients treated for allergic conjunctivitis.
  
  
  METHODS
  Patients received a single oral dose of cetirizine. Samples of blood and tear fluid were taken according to predefined sampling schedules and the concentrations of cetirizine were determined by a new high performance liquid chromatography method.
  
  
  RESULTS
  Concentration-time profiles for cetirizine in serum and tear fluid were similar, although the mean maximum concentration in tear fluid was reached later than in serum (90 and 30 min, respectively). However, at 60 and 120 min the cetirizine concentration in tear fluid was 98 and 92% of the mean maximum concentration, respectively, showing a plateau region and indicating that the disposition rate for the tear fluid compartment was very similar to that for the blood compartment.
  
  
  CONCLUSIONS
  Oral administration of cetirizine yields therapeutically effective concentrations of the drug at the anterior surface of the eye.
authors.affiliation: Department of Pharmaceutical and Toxicological Chemistry, University Federico II, Via D. Montesano 49, I-80131 Naples, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Grumetto
authors.forename: Gilda
authors.initials: G
authors.lastname: Cennamo
authors.forename: Antonio
authors.initials: A
authors.lastname: Del Prete
authors.forename: Maria I
authors.initials: MI
authors.lastname: La Rotonda
authors.forename: Francesco
authors.initials: F
authors.lastname: Barbato
mesh_terms: D000284:Administration, Oral; D000328:Adult; D017332:Cetirizine / Q000097:blood* / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid; D003233:Conjunctivitis, Allergic / Q000378:metabolism*; D005260:Female; D006634:Histamine H1 Antagonists / Q000097:blood* / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D013666:Tears / Q000737:chemistry*
chemical_list: D006634:Histamine H1 Antagonists; D017332:Cetirizine