title: Low dose lopinavir/ritonavir tablet achieves adequate pharmacokinetic parameters in HIV-infected Thai adolescents.
abstract: BACKGROUND
  Lopinavir/ritonavir (LPV/r) is an effective and commonly used protease inhibitor in HIV-infected adolescents. Previous data showed high plasma concentrations of LPV in Thai patients. This study determined the pharmacokinetic (PK) parameters of a low-dose LPV/r tablet (70% of standard dose) in HIV-infected Thai adolescents.
  
  
  METHODS
  A total of 24 adolescents on LPV/r-containing HAART regimens with HIV RNA<50 copies/ml were included. Standard and low doses for two different weight bands using LPV/r 100/25 mg tablet formulation twice daily were prescribed as follows: 3 and 2 tablets for adolescents weighing 25-35 kg, and 4 and 3 tablets for those weighing >35 kg, respectively. On the fourth week of treatment, PK was performed for all doses at 0 (pre-dose), 2, 4, 6, 8, 10 and 12 h. LPV and ritonavir concentrations were measured using the HPLC method.
  
  
  RESULTS
  The median (IQR) age was 13.5 (12-15) years. The median LPV doses of standard and low doses were 290 and 208 mg/m(2). The mean (sd) area under the concentration-time curve at 0-12 h, maximum concentration and plasma concentration at 12 h for the standard dose were 97.6 (25.7) mg•h/l, 11.1 (2.6) mg/l and 4.1 (2.0) mg/l, and for the low dose were 87.4 (29.0) mg•h/l, 11.0 (3.1) mg/l and 3.2 (1.9) mg/l, respectively. No significant differences were detected between the groups. One child had plasma concentration at 12 h <1.0 mg/l while on low-dose LPV/r but HIV RNA was undetectable.
  
  
  CONCLUSIONS
  The low-dose LPV/r tablet provides adequate PK parameters in HIV-infected Thai adolescents. A randomized study to assess the efficacy of low and standard doses of LPV/r among Thai HIV-infected adolescents should be explored.
authors.affiliation: Division of Infectious Diseases, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Arunee
authors.initials: A
authors.lastname: Klinklom
authors.forename: Thanyawee
authors.initials: T
authors.lastname: Puthanakit
authors.forename: Meena
authors.initials: M
authors.lastname: Gorowara
authors.forename: Chayapa
authors.initials: C
authors.lastname: Phasomsap
authors.forename: Stephen
authors.initials: S
authors.lastname: Kerr
authors.forename: Chulalak
authors.initials: C
authors.lastname: Sriheara
authors.forename: Jintanat
authors.initials: J
authors.lastname: Ananworanich
authors.forename: David
authors.initials: D
authors.lastname: Burger
authors.forename: Kiat
authors.initials: K
authors.lastname: Ruxrungtham
authors.forename: Chitsanu
authors.initials: C
authors.lastname: Pancharoen
mesh_terms: D000293:Adolescent; D023241:Antiretroviral Therapy, Highly Active; D002648:Child; D018592:Cross-Over Studies; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D017320:HIV Protease Inhibitors / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D006801:Humans; D061466:Lopinavir / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D008297:Male; D011446:Prospective Studies; D019438:Ritonavir / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D013785:Thailand
chemical_list: D017320:HIV Protease Inhibitors; D061466:Lopinavir; D019438:Ritonavir