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Table 5 Final model parameters describing joint fixed plasma and hair pharmacokinetics of ritonavir

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) 2.31 fixed 2.31 fixed 0.45 fixed 0.45 fixed
CL/F (litres hour−1) 12.8 fixed 12.8 fixed 0.28 (31) 0.28 (0.01 to 0.68)
Vc (litres) 105 fixed 105 fixed 0.50 fixed 0.50 fixed
Frac 0.18 (16) 0.18 (0.14 to 0.21)   
Vh (litres) 1 fixed 1 fixed   
Occasion (Follow-up)_ Frac * *   
Occasion (Enrolment)_ Frac −0.42 (22) −0.39 (−0.56 to −0.21)   
Adherence score_ Frac 0.02 (47) 0.014 (0.008 to 0.017)   
ɛADD 0.34 (95) 0.36 (0.04 to 0.63)   
ɛPROP 0.26 (26) 0.24 (0.13 to 0.31)   
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; FACTOR_ Frac: effect of covariate on Frac; ɛADD and ɛPROP: additive and proportional error terms, respectively; σ: residual error; SE: standard error. *: reference category