11th Annual Conference Of The British HIV Association [BHIVA] 20–23 April 2005, Burlington Hotel·Dublin·Ireland

[AUTHOR(S):] D Maitland¹, M Boffito¹, S Mandalia¹, S Gibbons², D Back², M Nelson¹, B Gazzard¹, G Moyle^1
1Chelsea and Westminster Hospital, London, ²University of Liverpool, UK

BHIVA Conf 2005 Apr 20-23;11:O24

AIM: To investigate the usefulness of TDM of EFV in ARV-naïve patients starting an OD regimen containing ddI/EFV and tenofovir (TDF) or 3TC.

METHODS: EFV TDM was performed prospectively following ARV initiation with blood samples collected at weeks 4 and 12. Concentrations of EFV were determined by HPLC in plasma, samples collected 10–15h post-evening-EFV dose. For samples >15h, concentrations were back extrapolated to 12h by linear regression.

RESULTS: Samples from 66 patients (9 females, median age 37 years, baseline median CD4+ and mean viral load 174 cells/mm³ and 5.01 log¹⁰-copies/ml) were analysed (n=132). Median EFV-[C] were 1569 (range 354-11611) and 1705 (466-13351) ng/ml week 4 and 12. Among responders, 17 had at least one EFV-[C] lower than the suggested effective-[C] (MEC) of 1000 ng/ml. Of the 5 non-responders, 3 had EFV-[C]<1000ng/ml (despite 100% adherence assessed by MEMSCAPS). Coefficient of variation in EFV-[C] was 90% at week 4 and 12. Subjects with higher (>1100ng/ml) EFV-[C] at week 4 and 12 were more likely to show virologic response (<50 copies/ml) at week 12 (p<0.001, ROC method).

CONCLUSIONS: Our prospective analysis confirms the association between EFV-[C] and virologic response but with wide variability in EFV-[C], suggesting a role for EFV TDM in naïve patients.

PRESENTING AUTHOR: D Maitland

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2005-04-20
O24

Copyright © 2005 - British HIV Association (BHIVA) Reproduction of this abstract (other than one copy for personal reference) must be cleared through the BHIVA Organising Secretariat 1 Mountview Court, 310 Friern Barnet Lane, London N20 0LD