MEDWATCH: Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs) By  Stuart Katsh, MS, RD

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Pharmacologic Classification

• Three antiretroviral agents are referred to as NNRTIs. These medications are Nevirapine (Viramune®, NVP); Efavirenz (Sustiva®, EFV); Delavirdine (Rescriptor®, DLV). All of these antiretroviral agents are approved by the Food and Drug Administration (FDA) to treat HIV infection.

HIV Reverse Transcriptase

The HIV Reverse Transcriptase (RT) enzyme is essential for HIV replication. The purpose of this enzyme is to allow synthesis of viral deoxyribonucleic acid (DNA) from ribonucleic (RNA). NRTIs, also commonly referred to as “Non-Nucs,” work by binding to the RT, thus preventing the function of the enzyme. 

Unlike the Nucleoside Reverse Transcriptase Inhibitors (NRTIs, aka “Nucs”) that act by mimicking the nucleic acids in the HIV’s DNA strand and are incorporated into the growing strand, the Non-Nucs do not have as much mitochondrial toxicities. Also, the pharmacokinetics are not as affected by concentrations inside and outside of the cells. 
 

NNRTIs are generally well tolerated but like all medications, are not without side effects. This class of medications is associated with changes in liver function tests (LFT), which measures liver enzymes that can indicate how the liver is functioning. Rash is the most notable side effect of taking NNRTIs and is usually treatable with a medication known as diphenhydramine.
 
 
 
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