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Table 3 Final model parameters describing joint fixed plasma and hair pharmacokinetics of atazanavir

From: A population pharmacokinetic model is beneficial in quantifying hair concentrations of ritonavir-boosted atazanavir: a study of HIV-infected Zimbabwean adolescents

Parameter Population mean (SE as %) 1000 samples bootstrap medians (90% CI) Variability (SE as %) 1000 samples bootstrap medians (90% CI)
k12 (litres hour− 1) 0.44 fixed 0.44 fixed 0.45 fixed 0.44 fixed
CL/F (litres hour−1) 10 fixed 10 fixed 1.04 (99) 0.97 (0.50–1.98)
Vc (litres) 63.4 fixed 63.4 fixed 0.50 fixed 0.50 fixed
Frac 0.16 (16) 0.15 (0.06 to 0.26)   
Vh (litres) 1 fixed 1 fixed   
Occasion (Follow-up)_ Frac * *   
Occasion (Enrolment)_ Frac −0.30 (23) −0.27 (−0.50 to −0.07)   
Adherence score_ Frac 0.02 (18) 0.015 (0.004 to 0.017)   
Body Mass Index-for-age (Normal)_ Frac * *   
Body Mass Index-for-age (Thin)_ Frac 0.54 (22) 0.49 (0.06 to 0.74)   
Body Mass Index-for-age (Overweight)_ Frac −0.21 (121) − 0.15 (− 0.26 to − 0.05)   
Guardian (Grandparent)_ Frac * *   
Guardian (Parent)_ Frac 0.53 (56) 0.55 (0.03 to 2.58)   
Guardian (Uncle/Aunt)_ Frac 0.12 (177) 0.17 (0.05 to 1.60)   
Guardian (Sibling)_ Frac −0.54 (35) −0.60 (− 0.92 to − 0.27)   
ɛADD 0.30 (1) 0.29 (0.14 to 0.44)   
ɛPROP 0.50 (2) 0.50 (0.39 to 0.61)   
σ 1 1   
  1. k12: Absorption rate constant; CL/F: apparent drug clearance; Vc and Vh: apparent volume of distribution in the central and hair compartments, respectively; Frac amount of drug cleared into the hair as a proportion of the amount of drug in plasma at steady-state troughs; FACTOR_ Frac: effect of covariate on Frac; ɛADD and ɛPROP: additive and proportional error terms, respectively; σ: residual error; SE: standard error. *: reference group