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8th Annual Conference Of The British HIV Association [BHIVA]19 – 21 April 2002, University of York, York |
[AUTHOR(S):] SE Gibbons, HE Reynolds, J Lloyd, JF Tjia, SH Khoo, DJ Back
Department of Pharmacology and Therapeutics, University of Liverpool
BHIVA Conf 2002 Apr 19-21;8:O17
INTRODUCTION: Recent studies have put forward putative target concentrations for the nonnucleoside reverse transcriptase inhibitors (NNRTIs) efavirenz (EFV) and nevirapine (NVP), attempting to correlate plasma concentrations with virological response or the development of toxicity. However, the case for TDM of NNRTIs is currently not as strong as for protease inhibitors.
METHODS: EFV and NVP requests received by the Liverpool TDM service since 1999 were categorized according to virological status at the time of TDM or (in the case of EFV) reported toxicity. Only adult patients receiving EFV at 600 mg once daily or NVP at 200 mg twice daily were included in the analysis. Target concentrations for viral suppression were 1200 ng/mL for EFV and 3000 ng/mL for NVP. EFV concentrations >4000 ng/mL have been reported to be associated with increased toxicity.
RESULTS: For EFV, viral load (VL) data were available from 113 patients, with 50 being virally suppressed (VL <50 copies/mL). There was no apparent difference in EFV trough concentrations between the two groups: 25% of patients with VL >50 copies/mL had concentrations <1200 ng/mL compared with 20% of virally suppressed patients. Only 31% of patients with suspected EFV toxicity had trough concentrations >4000 ng/mL. For NVP, VL data were available from 102 patients, with 33 being virally suppressed. 41% of patients with VL >50 copies/mL had NVP trough concentrations <3000 ng/mL, compared with 24% of virally suppressed patients.
CONCLUSIONS: The results from our selective TDM data set suggest that for NVP and EFV, plasma concentrations alone are insufficient to account for viral response or the development of toxicity. Full clinical and virological data are essential to interpret TDM results.
PRESENTING AUTHOR: SE Gibbons
020419
O17
Copyright © 2002 - 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