Pharmacology
Summary
NNRTIs, or non-nucleoside reverse-transcriptase inhibitors, include drugs such as nevirapine, efavirenz, and delavirdine. Unlike NRTIs, NNRTIs don't require activating phosphorylation steps. Instead, NNRTIs bind directly to the HIV reverse transcriptase, inhibiting the synthesis of viral DNA.
Adverse effects of NNRTIs include flu-like symptoms, abdominal pain, jaundice, and fever, which hint at hepatic failure – a potentially life-threatening condition. Moreover, efavirenz has adverse effects on the central nervous system resulting in dizziness, drowsiness, insomnia, nightmares, headache, and psychiatric symptoms. Stevens-Johnson syndrome, a skin rash that may result from NNRTIs, is a rare but important side effect. NNRTIs are noted to have numerous drug-drug interactions because of varying effects on the liver cytochrome P450 system.
Lesson Outline
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FAQs
Some reported side effects of NNRTIs include insomnia, nightmares, and CNS symptoms such as dizziness, drowsiness, headache, and psychosis. More severe adverse reactions such as Stevens-Johnson syndrome have also been documented. It's essential to monitor patients regularly for symptoms while on these medications.
NNRTIs work by direct binding and allosteric inhibition of HIV reverse transcriptase, a vital enzyme in the life cycle of HIV. By doing this, they stop the enzyme's DNA polymerase activity. This effectively prevents the virus from reproducing, thereby reducing the load of HIV in the body.
No, NNRTIs function directly and do not need to be phosphorylated by intracellular enzymes to be active. This is one notable characteristic that distinguishes them from the NRTIs.
Liver failure can occur within six weeks of starting therapy with NNRTIs like nevirapine and efavirenz. Therefore, liver function tests are a critical part of care when these specific drugs are included in a patient's regimen. If signs of liver failure occur, the medication may need to be discontinued.
NNRTIs have varying effects on the cytochrome P-450 system, which plays a crucial role in drug metabolism. Some NNRTIs can inhibit or induce this system, potentially affecting the metabolism of other drugs the patient may be taking. This makes it necessary to carefully consider potential drug-drug interactions when prescribing NNRTIs.
