title: 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.
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.
authors.affiliation: Department of Medicine, University of California.
authors.forename: Monica
authors.initials: M
authors.lastname: Gandhi
authors.affiliation: Department of Epidemiology and Biostatistics, University of California.
authors.forename: David V
authors.initials: DV
authors.lastname: Glidden
authors.affiliation: Department of Medicine, University of California Bridge HIV, San Francisco Department of Public Health.
authors.forename: Albert
authors.initials: A
authors.lastname: Liu
authors.affiliation: Department of Pharmaceutical Sciences, University of Colorado, Denver.
authors.forename: Peter L
authors.initials: PL
authors.lastname: Anderson
authors.affiliation: Department of Bioengineering and Therapeutic Sciences, University of California.
authors.forename: Howard
authors.initials: H
authors.lastname: Horng
authors.affiliation: Gladstone Institutes, San Francisco.
authors.forename: Patricia
authors.initials: P
authors.lastname: Defechereux
authors.affiliation: Investigaciones Medicas en Salud, Lima, Peru.
authors.forename: Juan V
authors.initials: JV
authors.lastname: Guanira
authors.affiliation: STD/AIDS Clinical Research Laboratory, Evandro Chagas National Institute of Infectious Diseases-Fiocruz, Rio de Janeiro, Brazil.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Grinsztejn
authors.affiliation: Research Institute for Health Sciences, Chiang Mai University, Thailand.
authors.forename: Suwat
authors.initials: S
authors.lastname: Chariyalertsak
authors.affiliation: The Desmond Tutu HIV Centre, University of Cape Town, South Africa.
authors.forename: Linda-Gail
authors.initials: LG
authors.lastname: Bekker
authors.affiliation: Department of Medicine, University of California Gladstone Institutes, San Francisco.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Grant
mesh_terms: D002853:Chromatography, Liquid; D059788:Dried Blood Spot Testing; D000068679:Emtricitabine / Q000032:analysis*; D005260:Female; D006197:Hair / Q000737:chemistry*; D006801:Humans; D008297:Male; D055118:Medication Adherence; D065129:Pre-Exposure Prophylaxis; D053719:Tandem Mass Spectrometry; D000068698:Tenofovir / Q000032:analysis*; D063106:Transgender Persons
chemical_list: D000068698:Tenofovir; D000068679:Emtricitabine
keywords: HIV prevention; PrEP; adherence; dried blood spot (DBS) concentrations; hair concentrations; iPrEx Open Label Extension (OLE); pharmacologic monitoring; pre-exposure prophylaxis; tenofovir/emtricitabine