Table 2.

Final parameter estimates by NONMEM, together with bootstrap estimates presented as medians

ParameteraNONMEM value/bootstrap valueb
Estimate% relative SEc
ka (h−1)0.474/0.49824/19
IIV on ka (% CV)39d/4380/61
MTT (h)0.789/0.77017/18
IIV on MTT (% CV)93e/9020/22
Effect of presence of HIV on F (fractional change)−0.154/−0.16240/39
CL/F (liter/h)39.9/39.73.1/5.9
IIV on CL/F (% CV)20f/2157/86
IOV on CL/F (% CV)36/3445/87
V1/F (liters)82.4/90.042/29
V2/F (liters)623/642g22/30g
Q (liters/h)34.3/33.810/7.9
Additive residual error (mg/liter)0.107/0.10420/29
Proportional residual error (% CV)31.8/31.64.4/4.6
  • a ka, absorption rate constant; MTT, mean transit time; V1/F, central volume of distribution; V2/F, peripheral volume of distribution; Q, intercompartmental clearance; CV, coefficient of variation. Typical value of F = 1 · (1 − 0.154 × HIV), with HIV being 0 and 1 for negative and positive HIV status, respectively; typical value of CL/F = 39.7 · (body weight/50)3/4; typical value of central volume of distribution = 82.4 · (body weight/50); typical value of peripheral volume of distribution = 623 · (body weight/50); typical value of intercompartmental clearance = 34.3 · (body weight/50)3/4.

  • b The relative standard errors for bootstrap estimates reported as standard error/median.

  • c For interindividual and interoccasion variability terms, the relative standard errors are given for the corresponding variance term.

  • d Eta shrinkage, 40%.

  • e Eta shrinkage, 22%.

  • f Eta shrinkage, 49%.

  • g One extreme bootstrap estimate (85,500) was excluded; inclusion of this value produces a bootstrap median of 642 (relative standard error, 540%).