Page 226 - SAHCS HIVMed Journal Vol 20 No 1 2019

Southern African Journal of HIV Medicine
ISSN: (Online) 2078-6751, (Print) 1608-9693
Page 1 of 6 Original Research

Correlation of hair and plasma efavirenz concentrations

in HIV-positive South Africans

Authors: Background: Antiretroviral concentrations in hair provide a longer window of drug detection
Jenna Johnston 1 and are useful for measuring longer-term drug exposure. Efavirenz is an important component
Lubbe Wiesner 1
Peter Smith 1 of first-line treatment in resource-limited settings, but its concentrations in hair have not been
Gary Maartens 1 well studied.
Catherine Orrell
2,3
Methods: This study is a supplementary to a randomised controlled trial of an adherence
Affiliations: intervention using an electronic adherence measuring device. Hair and plasma samples were
1 Division of Clinical
Pharmacology, Department of collected from human immunodeficiency virus-positive patients in Cape Town, South Africa.
Medicine, University of Cape Previously validated liquid chromatography tandem mass spectrometry methods were used
Town, Cape Town, South Africa to measure efavirenz concentrations in the collected hair and plasma samples. CYP2B6
genotyping of participants was also performed. Data analysis was performed using descriptive
2 Desmond Tutu HIV Centre,
Institute of Infectious Disease and comparative statistics as well as regression modelling.
and Molecular Medicine, Results: Hair samples were collected from 59% of patients enrolled in the parent study. Results
Cape Town, South Africa
indicated that hair efavirenz concentrations were significantly influenced by participants’
3 Department of Medicine, CYP2B6 metaboliser status. Median efavirenz concentrations for extensive, intermediate and
University of Cape Town, slow metaboliser genotypes were 3.54 ng/mg, 5.11 ng/mg and 10.66 ng/mg, respectively. A
Cape Town, South Africa strong correlation was observed between the efavirenz concentrations measured in hair and
plasma samples (Spearman’s correlation coefficients, 0.672–0.741, p < 0.0001). No relationship
Corresponding author:
Jenna Johnston, between hair efavirenz concentrations and virological failure or adherence measured using an
[email protected] electronic adherence was shown.

Dates: Conclusion: The results from this study provide further insight into the potential of using hair
Received: 04 July 2018 as a matrix for measuring antiretroviral concentrations. However, challenges experienced in
Accepted: 21 Feb. 2019
Published: 29 Apr. 2019 collecting hair samples suggest that this adherence measure may have limited utility in an
African population.
How to cite this article:
Johnston J, Wiesner L, Keywords: Adherence; Antiretroviral therapy; Hair; Plasma; Drug concentrations.
Smith P, Maartens G, Orrell C.
Correlation of hair and plasma
efavirenz concentrations in Introduction
HIV-positive South Africans.
S Afr J HIV Med. 2019;20(1), For antiretroviral therapy (ART) to be successful in preventing disease progression, high levels of
a881. https://doi.org/ adherence are required. Methods for measuring adherence include patient self-report, pill counts,
1,2
10.4102/sajhivmed.v20i1.881
pharmacy refill records, electronic drug monitoring and therapeutic drug monitoring (TDM). TDM
Copyright: involves the determination of drug or drug metabolite concentrations in plasma and, more recently,
© 2019. The Authors. hair. Each of these methods has both advantages and disadvantages which have been discussed in
3
Licensee: AOSIS. This work detail in the literature. 1,2,4,5,6 There remains no gold standard for determining adherence. 7
is licensed under the
Creative Commons
Attribution License. TDM is a direct method of monitoring adherence by measuring drug exposure. Drug concentrations
in plasma provide a short-term (up to a few days) assessment of drug exposure, whereas drug
concentrations in hair provide a longer window of drug detection (weeks to months). There are
3
benefits in analysing both plasma and hair samples because, while a low plasma concentration
indicates recent poor drug exposure, a low hair concentration indicates average poor drug
exposure for the previous month, as suggested by Van Zyl et al. Additionally, a high plasma
8
concentration in combination with a low hair concentration could provide insight into the
adherence patterns of patients and identify cases where medication is being taken just prior to
clinic visits. Little data have been published comparing the relationship between antiretroviral
Read online: (ARV) drug concentrations in these two matrices. 8,9
Read online:
Scan this QR
Scan this QR
code with your
code with your
smart phone or
smart phone or Currently, the most preferred ART for first-line treatment in resource-limited settings includes
mobile device
mobile device efavirenz (EFV) in combination with tenofovir and either emtricitabine or lamivudine. There is
10
to read online.
to read online.
only one other study that has reported data comparing EFV concentrations in hair and plasma, in
http://www.sajhivmed.org.za 219 Open Access