Know Your HIV Drugs: NNRTIs
June 1, 2000
Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
NNRTIs are another class of FDA-approved HIV antiviral drugs. There are currently three drugs approved for use in this class. NNRTIs work by targeting the structure of reverse transcriptase to inhibit enzyme activity. By inhibiting the enzymatic activity necessary for reverse transcription, NNRTIs successfully interfere with a one of the steps of the HIV life-cycle and prevent the virus from being able to reproduce. You may recall this is the same point in the life cycle interfered with by NRTIs. The difference is that NNRTIs simply do it in a different way.
Although NNRTIs are very potent antiretrovirals, a significant drawback is that resistance can develop quickly if the drugs are not taken exactly as prescribed, and once resistance develops to one drug in the class you will probably be resistant to all the drugs in that class. Many combination therapies include one NNRTI plus two or more drugs in another class.
Commonly known as Viramune, this was the first FDA-approved NNRTI. Viramune is usually taken as one 200-mg tablet twice a day. There are no food restrictions with this drug. Lead-in dosing for the first 14 days of therapy is recommended at one 200-mg tablet once a day. The most common side effect associated with Viramune is a rash, and the rash seems to be more prevalent in women than in men. The lead-in dosing regimen is prescribed to help minimize the rash. Do not stop taking Viramune if you experience a mild rash without any other symptoms. If you do experience a rash, be sure to notify your provider or pharmacist immediately. Viramune can have an adverse drug interaction with various antihistamines, sedatives, and anti-fungal medications, so be sure your doctor and pharmacist know all of the medications you are taking when on Viramune.
Commonly called Sustiva, this drug is usually taken as three 200-mg tablets once a day. Food restriction is to avoid high-fat meals two hours before or one hour after taking the medication. Sustiva can cause rash, nausea, headache, diarrhea, and insomnia. The most common side effects of Sustiva are central nervous system (CNS) side effects. CNS side effects can include a feeling of "euphoria," dizziness, insomnia, drowsiness, poor concentration, and abnormal dreams that may occur in up to 50% of people. As a result, many physicians recommend taking the medication at bedtime. If you have any underlying psychiatric disorders (bipolar disorder, mania, depression, etc.) Viramune may worsen these symptoms. Drug interactions can occur with Hismanal, Propulsid, Versed and Halcion. Additionally, the medications commonly used to treat migraine headaches that are called "ergot medications" may cause serious and life-threatening side effects when taken with Sustiva.
Commonly called Rescriptor, this drug is usually taken as four 100-mg tablets three times a day. There are no food restrictions. Common side effects are headache, hypertension, rash, fever, nausea, and changes in liver function. Severe rash can be life threatening and signs of this include fever, blistering, sores in the mouth, and joint pains. See your doctor or go to the emergency room immediately if these symptoms develop. Drug interactions can occur with Seldane, Hismanal, Xanax, and Propulsid. Also, the same warning for "ergot medications" as indicated for Sustiva applies to Rescriptor. Finally, antacids can decrease absorption of the drug so avoid taking Rescriptor with antacids. Also, since the NRTI "ddI" has a built-in antacid, Rescriptor is best taken one hour apart from this drug.
This completes the list of currently approved NNRTIs for use in combination therapy for HIV. Detailed fact sheets are available on each of these drugs. E-mail us your full name and mailing address, with the name of the drug you are interested in, to request a copy. E-mail to: firstname.lastname@example.org.
This article was provided by Seattle Treatment Education Project. It is a part of the publication STEP Ezine.