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‘Tail’ regimen for PMTCT the way to go

Written by Health-e News

A single dose of two antiretrovirals given to mothers shortly after giving birth has shown to reduce the chances of the women developing later resistance, a new study from Zambia has shown.

Single dose nevirapine given to the mother and infant are an essential part of HIV prevention in many poorer countries, including South Africa, but research has shown that a high percentage of women develop HIV resistance to the non-nucleoside reverse transcriptase inhibitor class of drugs, a component of first-line antiretroviral regimens throughout the world.

The Zambia study added a single dose of two ‘€œtail’€ drugs to an AZT and nevirapine combination. AZT will soon be added to the current single dose nevirapine regimen as part of South Africa’€™s revised Prevention of Mother to Child Transmission (PMTCT) protocol.

The revision of South Africa’€™s current protocol was mainly driven by the search for a new, efficacious regimen and the urgent need to address the resistance in mothers, who received nevirapine, once they are put onto triple therapy, something the Zambia study addresses pertinently.

Resistance has shown to be present even when nevirapine was used in conjunction with AZT. The resistance issue is expected to continue dogging PMTCT programmes despite the addition of AZT, as countless women will continue to receive the single dose of nevirapine only. Many women only present at clinics or hospitals once they are in labour, when it is too late to administer the AZT component. Nevirapine is administered during labour.

Benjamin Chi and colleagues published an article in the November edition of The Lancet demonstrating that a single dose of tenofovir and emtricitabine (together with the Nevirapine and AZT regimen) at delivery, halved resistance to the nucleoside reverse transcriptase inhibitor class of drugs at six weeks.

Studies have suggested that the resistance does disappear after six months.

‘€œTherefore this treatment should be considered as an addition to intrapartum nevirapine,’€ the researchers said.

All of the almost 400 women who participated in this Zambia study received short-course AZT and nevirapine.

Over and above the short-course regimen, about half of the women were given a single oral dose of tenofovir and emtricitabine at delivery while the other half received nothing extra.

Another study has show that a week-long course of AZT and lamivudine (3TC) instead of the tenofovir-emtricitabine regimen would also reduce resistance.

Professors James McIntyre of the University of the Witwatersrand and Shahin Lockman of the Harvard School of Public Health commented in The Lancet that Chi’€™s results provided strong evidence that the addition of single dose tenofovir/emtricitabine to short-course AZT and single-dose nevirapine was a ‘€œnew effective, and feasible’€ approach to reducing nevirapine resistance.

‘€œIt should be seriously considered for implementation,’€ they said.

Head of HIV in the health department Dr Nomonde Xundu said the National Essential Drug List Committee and ‘€œexperts’€ have decided on dual therapy without the ‘€œtail’€ because of ‘€œinadequate evidence’€.

However, she said additional evidence would be considered to inform the decision regarding the ‘€œtail’€.

South Africa’€™s updated regimen, which will be announced next week, is expected to include single dose nevirapine for the mother at the onset of labour, AZT twice daily from 32 weeks gestation (depending on the woman’€™s CD4 count) and a 7-day course of AZT syrup for the infant.

Currently transmission rates using single dose nevirapine are 8% at best and usually much higher. Research has shown that by using dual prophylaxis regimens or even triple therapy for all pregnant women, transmission will be reduced to 5% or lower.

The Western Cape is currently the only place in South Africa where dual therapy is used or pregnant women are put onto triple therapy if their CD4 counts are low. ‘€“ Health-e News Service

 

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