HIV in Children

ANTIRETROVIRAL DRUGS

Dr. Ira Shah
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Last Updated : 1st September 2012
Antiretrovirals are a group of drugs that are used in the treatment of HIV infected individuals to decrease the viral burden. They are potent inhibitors of viral replication. As of August 2010, 22 antiretroviral drugs are approved for use in HIV-infected adults and adolescents; 17 of these have an approved pediatric treatment indication and 15 are available as a pediatric formulation or capsule size. These drugs fall into 3 major classes – Nucleoside Reverse Transcriptase Inhibitors (NRTIs), Non-nucleoside Reverse Transcriptase Inhibitors (NNRTIs) and Protease Inhibitors (PIs).

Nucleoside Reverse Transcriptase Inhibitors (NRTIs)


The NRTIs were the first class of antiretroviral drugs that became available for treatment of HIV. They inhibit the reverse transcriptase enzyme (See the Chapter on Transmission and Pathogenesis). They have activity against both HIV-1 and HIV-2. The parent compounds need to undergo intracellular phosphorylation to become active against HIV. NRTIs act by competing with normal nucleoside triphosphates for incorporation into the growing proviral DNA chain. The abnormal nucleoside prevents the addition of further nucleosides to the chain, and viral replication ceases. Dual NRTI is the backbone of current combination of various antiretroviral therapies.
Drugs in this class include:
  • Zidovudine (AZT/ZDV)

  • Lamivudine (3TC)

  • Stavudine (d4T)

  • Didanosine (ddI)

  • Abacavir (ABC)

  • Zalcitabine (ddC) - It is not available in India.

  • Emtricitabine (FTC)

  • Tenofovir (TDF)

    – It is a nucleotide reverse transcriptase inhibitor (NtRTI). It affects the bone mineral density thus potentially limiting its use in pre-pubertal children. It also acts against Hepatitis B.

Non-nucleoside Reverse Transcriptase Inhibitors (NNRTIs)


NNRTIs  were the second class of anti-HIV agents to be developed. The parent compounds are the active moieties, and are therefore immediately active on entering the cell. They inhibit HIV-1 reverse transcriptase by binding to a hydrophobic pocket on the enzyme close to the active site, thereby locking the enzyme in an inactive conformation. The NNRTI class of drugs rapidly reduce viral load; however drug resistance develops quickly after initiation of monotherapy and cross-resistance between drugs in this class is common. There are currently 3 NNRTIs used for treatment of HIV infection.
  • Nevirapine (NVP)

  • Efavirenz (EFV)

  • Etavirine:

    It was approved in January 2008 in adults and is considered a ‘second generation’ NNRTI, in part because it retains activity against HIV-1 isolates which are resistant to other NNRTIs.Stavudine (d4T)


ANTIRETROVIRAL DRUGS
Dr. Ira Shah
Incharge Pediatric HIV and TB Clinic, B.J.Wadia Hospital for Children, Mumbai, India Consultant in Pediatric Infectious Diseases, Nanavati Hospital, Mumbai, India.
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