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. 2015 Nov 1;212(9):1402-6.
doi: 10.1093/infdis/jiv239. Epub 2015 Apr 20.

Strong Correlation Between Concentrations of Tenofovir (TFV) Emtricitabine (FTC) in Hair and TFV Diphosphate and FTC Triphosphate in Dried Blood Spots in the iPrEx Open Label Extension: Implications for Pre-exposure Prophylaxis Adherence Monitoring

Monica Gandhi  1 , David V Glidden  2 , Albert Liu  3 , Peter L Anderson  4 , Howard Horng  5 , Patricia Defechereux  6 , Juan V Guanira  7 , Beatriz Grinsztejn  8 , Suwat Chariyalertsak  9 , Linda-Gail Bekker  10 , Robert M Grant  11 ; iPrEx Study Team
Collaborators, Affiliations

Strong Correlation Between Concentrations of Tenofovir (TFV) Emtricitabine (FTC) in Hair and TFV Diphosphate and FTC Triphosphate in Dried Blood Spots in the iPrEx Open Label Extension: Implications for Pre-exposure Prophylaxis Adherence Monitoring

Monica Gandhi et al. J Infect Dis. .

Abstract

Self-reported adherence to pre-exposure prophylaxis (PrEP) has limitations, raising interest in pharmacologic monitoring. Drug concentrations in hair and dried blood spots (DBS) are used to assess long-term-exposure; hair shipment/storage occurs at room temperature. The iPrEx Open Label Extension collected DBS routinely, with opt-in hair collection; concentrations were measured with liquid chromatography/tandem mass spectrometry. In 806 hair-DBS pairs, tenofovir (TFV) hair levels and TFV diphosphate (DP) in DBS were strongly correlated (Spearman coefficient r = 0.734; P < .001), as were hair TFV/DBS emtricitabine (FTC) triphosphate (TP) (r = 0.781; P < .001); hair FTC/DBS TFV-DP (r = 0.74; P < .001); hair FTC/DBS FTC-TP (r = 0.587; P < .001). Drug detectability was generally concordant by matrix. Hair TFV/FTC concentrations correlate strongly with DBS levels, which are predictive of PrEP outcomes.

Keywords: HIV prevention; PrEP; adherence; dried blood spot (DBS) concentrations; hair concentrations; iPrEx Open Label Extension (OLE); pharmacologic monitoring; pre-exposure prophylaxis; tenofovir/emtricitabine.

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Figures

Figure 1.
Figure 1.
Scatterplots showing correlations between hair tenofovir (TFV) and dried blood spot (DBS) TFV-diphosphate (DP) levels (A); hair TFV and DBS emtricitabine (FTC)-triphosphate (TP) levels (B); hair FTC and DBS FTC-TP levels (C); and hair FTC and DBS TFV-DP levels (D). Abbreviation: BLQ, below limit of quantification.
See this image and copyright information in PMC

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