title: Gender differences in the relationship between the risperidone metabolism and the plasma prolactin levels in psychiatric patients.
abstract: BACKGROUND
  Risperidone (RIS) has the highest propensity to elevate plasma prolactin (PRL) levels. While the active metabolite 9-hydroxy-risperidone (9-OH-RIS) plays a predominant role in the efficacy and side effects of RIS, the mechanistic details are still poorly understood. The present study evaluated the gender differences in the relationship between plasma levels of RIS or 9-OH-RIS and PRL.
  
  
  METHODS
  Twenty-one male and 19 female subjects treated with RIS were enrolled in the present series. All patients had been receiving RIS for at least 4 weeks at an average dosage of 4.7 mg/day. Plasma RIS, 9-OH-RIS and PRL levels were measured.
  
  
  RESULTS
  In the male patients, there was no correlation between the RIS dosage and plasma PRL levels, between plasma RIS levels and PRL levels, or between the plasma 9-OH-RIS levels and PRL levels. In the female patients, there was a significant positive correlation between the plasma 9-OH-RIS levels and PRL levels (rs=0.456, p=0.049). There was a trend toward a significant positive correlation between the RIS dosage and plasma PRL levels. There was no correlation between the plasma RIS levels and PRL levels.
  
  
  CONCLUSIONS
  9-OH-RIS is considered to play a more important role in PRL elevation than RIS, and a gender difference exists in the effect of 9-OH-RIS on PRL level.
authors.affiliation: Department of Psychiatry, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: Yutaro
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Naoki
authors.initials: N
authors.lastname: Fukui
authors.forename: Junzo
authors.initials: J
authors.lastname: Watanabe
authors.forename: Shin
authors.initials: S
authors.lastname: Ono
authors.forename: Takuro
authors.initials: T
authors.lastname: Sugai
authors.forename: Nobuto
authors.initials: N
authors.lastname: Tsuneyama
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Inoue
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Someya
mesh_terms: D000328:Adult; D000368:Aged; D002853:Chromatography, Liquid / Q000379:methods; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D007555:Isoxazoles / Q000097:blood*; D008297:Male; D001523:Mental Disorders / Q000188:drug therapy / Q000378:metabolism*; D008875:Middle Aged; D000068882:Paliperidone Palmitate; D011388:Prolactin / Q000097:blood; D011743:Pyrimidines / Q000097:blood*; D018967:Risperidone / Q000378:metabolism* / Q000627:therapeutic use*; D012727:Sex Characteristics; D053719:Tandem Mass Spectrometry / Q000379:methods; D055815:Young Adult
chemical_list: D007555:Isoxazoles; D011743:Pyrimidines; D011388:Prolactin; D018967:Risperidone; D000068882:Paliperidone Palmitate