Page 229 - SAHCS HIVMed Journal Vol 20 No 1 2019
P. 229
Page 4 of 6 Original Research
35 r = 0.741, p < 0.0001 a 35 r = 0.672, p < 0.0001 b
30
30
Plasma FEV concentra on (ug/mL) 25 Plasma EFV concentra on (ug/mL) 25
20
20
15
15
10
5 10 5
0 0
0 5 10 15 20 25 30 35 40 45 50 0 5 10 15 20 25 30 35 40 45 50
Hair EFV concentra on (ng/mg) Hair EFV concentra on (ng/mg)
35 r = 0.701, p < 0.0001 c 35 r = 0.710, p < 0.0001 d
30
30
Plasma EFV concentra on (ug/mL) 25 Plasma EFV concentra on (ug/mL) 25
20
20
15
15
10
5 10 5
0 0
0 5 10 15 20 25 30 35 40 45 50 0 5 10 15 20 25 30 35 40 45 50
Hair EFV concentra on (ng/mg) Hair EFV concentra on (ng/mg)
FIGURE 2: Scatterplots showing the correlation between plasma and hair efavirenz (EFV) concentrations at weeks 16 (a), 32 (b), 48 (c) and for all weeks combined (d).
Spearman’s correlation coefficients used to assess the relationship between EFV concentrations in hair and plasma are shown.
significant impact on EFV hair concentration in this cohort measure (compared with pharmacy refills, pill counts, self-
was metaboliser status (data not shown). Age, sex and report and plasma EFV concentrations) for predicting
adherence did not significantly alter EFV hair concentration. virological failure and resistance development. However,
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lack of correlation between adherence measures does not
Very few individuals in the study cohort experienced imply that the measures do not predict outcomes as there is
virological failure; and, in a similar regression model, no no gold standard adherence measure.
variables, including hair EFV concentrations, had an impact
on virological failure (data not shown). Hair EFV concentrations are significantly influenced by
participants’ CYP2B6 metaboliser status. A similar result was
Discussion reported when the corresponding plasma samples, collected
for the related sub-study, were analysed according to
In this adherent study cohort, hair and plasma EFV metaboliser status. Participants with the slow metaboliser
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concentrations were highly correlated. Hair samples were genotype displayed significantly higher median EFV
provided by participants who were both retained in care and
willing to donate a head hair sample. Data from the parent concentrations in both short- and long-term EFV exposure.
study showed that a high percentage of the participants in This observation is consistent with the results reported in an
this cohort who provided pharmacokinetic samples were earlier study where individuals with the slow metaboliser
virally suppressed. We were unable to show an association genotype were shown to have greater than threefold increases
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between hair EFV concentrations and virological failure, in EFV concentrations in both plasma and hair samples.
likely because of the low occurrence of virological failure in Besides this study, one other study has also investigated
the study cohort. There was no relationship between hair the influence of CYP2B6 polymorphisms on hair EFV
EFV concentrations and adherence measured by EAMD, concentrations. Hair samples were collected from
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which we have previously shown was the best adherence HIV-infected women in South Africa, and results from the
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