title: Therapeutic drug monitoring of lopinavir/ritonavir given alone or with a non-nucleoside reverse transcriptase inhibitor.
abstract: OBJECTIVE
  To evaluate the interindividual variability in the plasma concentrations of lopinavir in the context of routine monitoring with or without treatment with a non-nucleoside reverse transcriptase inhibitor and to assess the interaction between the coformulation of lopinavir/ritonavir and efavirenz or nevirapine.
  
  
  METHODS
  Plasma trough and peak concentrations (C(trough), C(max)) of lopinavir from 182 HIV-1-infected patients were analysed by high-performace liquid chromatography. Three lopinavir/ritonavir regimens were assessed, namely (A) 400 mg lopinavir/100 mg ritonavir twice daily given alone (n = 125), (B) 400/100 mg twice daily together with a non-nucleoside reverse transcriptase inhibitor (n = 25), and (C) 533/133 mg twice daily together with a non-nucleoside reverse transcriptase inhibitor (n = 32).
  
  
  RESULTS
  Median (ng ml(-1)) C(trough) and C(max) lopinavir (interquartile range, CV) were: (A) 4852 (3198-6891, 56%) and 8501 (6333-11 584, 41%), (B) 2979 (1704-5186, 74%) and 5612 (3362-11 704, 76%) and (C) 5082 (2696-7226, 74%) and 9757 (4883-12 963, 60%). Median C(trough) of lopinavir was lower in patients taking both efavirenz [P = 0.01, 95% confidence interval (CI) for difference between medians 343, 2713] and nevirapine (P = 0.019, 95% CI for difference between medians 354, 3681) compared with those taking lopinavir/ritonavir alone. A higher interindividual variability was observed when lopinavir/ritonavir was given with a non-nucleoside reverse transcriptase inhibitor. The risk of achieving a 'suboptimal'C(trough) of lopinavir (below a threshold of 3000 ng ml(-1)) was statistically higher in patients treated with a non-nucleoside reverse transcriptase inhibitor (P < 0.001, 95% CI for difference between percentages 8.8, 43.1%) compared with those receiving lopinavir/ritonavir alone.
  
  
  CONCLUSIONS
  Our results confirmed the interaction between lopinavir and efavirenz, and also demonstrated a significant interaction between the former drug and nevirapine, resulting in lower C(trough) of lopinavir. The wide interpatient variability in this interaction suggests that therapeutic drug monitoring may be useful in optimizing the dose of lopinavir.
authors.affiliation: Department of Pharmacokinetics, AP-HM Timone, Marseille, France. caro_solas@yahoo.fr
authors.forename: Caroline
authors.initials: C
authors.lastname: Solas
authors.forename: Isabelle
authors.initials: I
authors.lastname: Poizot-Martin
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Drogoul
authors.forename: Isabelle
authors.initials: I
authors.lastname: Ravaux
authors.forename: Catherine
authors.initials: C
authors.lastname: Dhiver
authors.forename: Alain
authors.initials: A
authors.lastname: Lafeuillade
authors.forename: Thierry
authors.initials: T
authors.lastname: Allegre
authors.forename: Malika
authors.initials: M
authors.lastname: Mokhtari
authors.forename: Jacques
authors.initials: J
authors.lastname: Moreau
authors.forename: Gérard
authors.initials: G
authors.lastname: Lepeu
authors.forename: Nathalie
authors.initials: N
authors.lastname: Petit
authors.forename: Alain
authors.initials: A
authors.lastname: Durand
authors.forename: Bruno
authors.initials: B
authors.lastname: Lacarelle
mesh_terms: D000293:Adolescent; D000328:Adult; D004341:Drug Evaluation; D004359:Drug Therapy, Combination; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D017320:HIV Protease Inhibitors / Q000627:therapeutic use*; D006801:Humans; D061466:Lopinavir; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011744:Pyrimidinones / Q000627:therapeutic use*; D012189:Retrospective Studies; D018894:Reverse Transcriptase Inhibitors / Q000627:therapeutic use*; D019438:Ritonavir / Q000627:therapeutic use*
chemical_list: D017320:HIV Protease Inhibitors; D011744:Pyrimidinones; D018894:Reverse Transcriptase Inhibitors; D061466:Lopinavir; D019438:Ritonavir