title: Therapeutic drug monitoring of nevirapine in saliva in Uganda using high performance liquid chromatography and a low cost thin-layer chromatography technique.
abstract: BACKGROUND
  In resource limited settings access to laboratory monitoring of HIV treatment is limited and therapeutic drug monitoring is generally unavailable. This study aimed to evaluate nevirapine concentrations in saliva using low-cost thin-layer chromatography (TLC) and nevirapine concentrations in plasma and saliva using high performance liquid chromatography (HPLC) methods; and to correlate nevirapine plasma concentrations to HIV treatment outcomes in Ugandan patients.
  
  
  METHODS
  Paired plasma and stimulated saliva samples were obtained from Ugandan, HIV-infected adults on nevirapine-based ART. Nevirapine concentrations were measured using a validated HPLC method and a novel TLC method. Plasma nevirapine concentrations <3.0 mg/L using HPLC were considered subtherapeutic. Negative/positive predictive values of different thresholds for subtherapeutic nevirapine concentrations in saliva were determined. Virologic testing and, if applicable, HIV drug resistance testing was performed.
  
  
  RESULTS
  Median (interquartile range, IQR) age of 297 patients was 39.1 (32.8-45.2) years. Three hundred saliva and 287 plasma samples were available for analysis. Attempts failed to determine nevirapine saliva concentrations by TLC. Using HPLC, median (IQR) nevirapine concentrations in saliva and plasma were 3.40 (2.59-4.47) mg/L and 6.17 (4.79-7.96) mg/L, respectively. The mean (coefficient of variation,%) nevirapine saliva/plasma ratio was 0.58 (62%). A cut-off value of 1.60 mg/L nevirapine in saliva was associated with a negative/positive predictive value of 0.99/0.72 and a sensitivity/specificity of 87%/98% for predicting subtherapeutic nevirapine plasma concentrations, respectively. Only 5% (15/287) of patients had subtherapeutic nevirapine plasma concentrations, of which 3 patients had viral load results > 400 copies/mL. Patients with nevirapine concentrations in plasma <3.0 mg/L had an Odds Ratio of 3.29 (95% CI: 1.00 - 10.74) for virological failure (viral load >400 copies/mL).
  
  
  CONCLUSIONS
  The low-cost TLC technique for monitoring nevirapine in saliva was unsuccessful but monitoring nevirapine saliva and plasma concentrations using HPLC was shown to be feasible in the research/specialist context in Uganda. Further optimization and validation is required for the low-cost TLC technique.
authors.affiliation: Infectious Diseases Institute, Makerere University College of Health Sciences, Kampala, Uganda. mlamorde@idi.co.ug.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Lamorde
authors.forename: Quirine
authors.initials: Q
authors.lastname: Fillekes
authors.forename: Kim
authors.initials: K
authors.lastname: Sigaloff
authors.forename: Cissy
authors.initials: C
authors.lastname: Kityo
authors.forename: Allan
authors.initials: A
authors.lastname: Buzibye
authors.forename: Joshua
authors.initials: J
authors.lastname: Kayiwa
authors.forename: Concepta
authors.initials: C
authors.lastname: Merry
authors.forename: Lillian
authors.initials: L
authors.lastname: Nakatudde-Katumba
authors.forename: David
authors.initials: D
authors.lastname: Burger
authors.forename: Tobias F Rinke
authors.initials: TF
authors.lastname: de Wit
mesh_terms: D000328:Adult; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019829:Nevirapine / Q000627:therapeutic use*; D010949:Plasma / Q000737:chemistry; D011237:Predictive Value of Tests; D012463:Saliva / Q000821:virology; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014454:Uganda; D019562:Viral Load
chemical_list: D019829:Nevirapine