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| LETTER TO EDITOR |
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| Year : 2012 | Volume
: 4
| Issue : 1 | Page : 52-53 |
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Measuring the efficacy of antiretroviral therapy
Dilip Gude
Department of Internal Medicine, AMC, Medwin Hospital, Hyderabad, Andhra Pradesh, India
| Date of Web Publication | 12-May-2012 |
Correspondence Address:
Dilip Gude
Registrar, Internal Medicine, AMC, 3rd Floor, Medwin Hospital, Chirag Ali Lane, Nampally, Hyderabad - 500 001, Andhra Pradesh
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0974-7753.96103
How to cite this article:
Gude D. Measuring the efficacy of antiretroviral therapy. Int J Trichol 2012;4:52-3 |
Sir,
Hair levels of antiretroviral therapy (ART) are inexpensive, easy-to-collect biomarkers of pre-exposure prophylaxis (PrEP) as well as treatment reflecting average levels over extended periods of time. They can also integrate adherence and pharmacokinetics into a single assay. The regimen durability can be prolonged based on hair antiretroviral concentrations. Interventions can be planned based on low antiretroviral exposure in hair prior to virologic failure in settings where measurement of viral loads is unavailable.
Tenofovir (TFV) levels in scalp hair demonstrate a clear and consistent correlation with dose. Hair is a promising biomarker of TFV dosing/PrEP and has feasibility advantages over other methods. In a study, 15 Human immune deficiency virus (HIV)-uninfected, dark-haired men and women at low risk for HIV infection received modified directly observed dosing of TFV 300 mg for 2, 4, and 7 doses/week in random order. A log-linear relationship was seen between doses per week and TFV hair level, with a 65% increase in hair level per 2-fold dose increase. [1]
A study on hair samples of participants in the Women's Interagency HIV Study (WIHS) analyzed atazanavir (ATV) hair concentrations longitudinally for women receiving ATV-based therapy. After adjusting for age, race, treatment experience, pretreatment viral load, cluster of differentiation 4 count and AIDS status, and self-reported adherence, hair levels were the strongest predictor of suppression. Categorized hair ATV levels revealed a monotonic relationship to suppression. Hair ATV concentrations were even more strongly associated than serum levels with re-suppression of viral loads in subgroups in which there had been previous lapses in adherence, low hair levels, or detectable viremia. [2] WIHS also studied the association between hair protease inhibitor (PI) levels (lopinavir (LPV) and ATV) and initial virologic responses to therapy. They showed that LPV and ATV concentrations in hair were strongly and independently associated with treatment response in those starting a new PI-based regimen. [3]
A cross-sectional survey studied LPV hair and plasma levels to investigate the etiology of virologic failure in two public health antiretroviral clinics that documented the prevalence of virologic failure and genotypic antiretroviral resistance. A threshold hair concentration indicating longer term LPV exposure was instrumental in determining the etiology of virologic failure and identifying patients in need of adherence counseling or resistance testing. [4] In another study on 43 HIV-infected patients, significant association was found between HIV - ribonucleic acid below 50 copies/ml and indinavir concentrations in hair but not in plasma. [5]
A specific, sensitive, and reproducible liquid chromatography-tandem mass spectrometry method for measuring nevirapine (NVP) levels in human hair (as small as a single short strand of hair) was developed and successfully applied to analyze more than 1000 hair samples. Great extraction efficiencies (>95%) were noted when repeated extractions were done. Deuterated NVP-d5 was used as an internal standard. The accuracies for spiked NVP hair control samples were 98% to 106% with coefficients of variation less than 10%. [6]
The noninvasive nature and the ease of collecting and storing samples make hair analysis an ideal way to determine ART exposure, especially in the epidemic of HIV in resource-poor settings.
 References | |  |
| 1. | Liu A, Gandhi M, Bacchetti P, Huang Y, Anderson P, Goggin K, et al. Validating hair as a biological marker of tenofovir drug exposure in HIV pre-exposure prophylaxis (PrEP). 18th Conference on Retroviruses and Opportunistic Infections. Boston, MA, 2011. 
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| 2. | Gandhi M, Ameli N, Bacchetti P, Anastos K, Gange SJ, Minkoff H, et al. Atazanavir concentration in hair is the strongest predictor of outcomes on antiretroviral therapy. Clin Infect Dis 2011;52:1267-75.
[PUBMED] [FULLTEXT] |
| 3. | Gandhi M, Ameli N, Bacchetti P, Gange SJ, Anastos K, Levine A, et al. Protease inhibitor levels in hair strongly predict virologic response to treatment. AIDS 2009;23:471-8.
[PUBMED] [FULLTEXT] |
| 4. | van Zyl GU, van Mens TE, McIlleron H, Zeier M, Nachega JB, Decloedt E, et al. Low lopinavir plasma or hair concentrations explain second-line protease inhibitor failures in a resource-limited setting. J Acquir Immune Defic Syndr 2011;56:333-9.
[PUBMED] [FULLTEXT] |
| 5. | Duval X, Peytavin G, Breton G, Ecobichon JL, Descamps D, Thabut G, et al. Hair versus plasma concentrations as indicator of indinavir exposure in HIV-1-infected patients treated with indinavir/ritonavir combination. AIDS 2007;21:106-8.
[PUBMED] |
| 6. | Huang Y, Yang Q, Yoon K, Lei Y, Shi R, Gee W, et al. Microanalysis of the antiretroviral nevirapine in human hair from HIV-infected patients by liquid chromatography-tandem mass spectrometry. Anal Bioanal Chem 2011;401:1923-33.
[PUBMED] [FULLTEXT] |
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