Viramune XR (nevirapine extended-release) is an antiretroviral medicine used as part of combination treatment for HIV-1 infection. It belongs to the non-nucleoside reverse transcriptase inhibitor (NNRTI) class and works by blocking a key enzyme (reverse transcriptase) that HIV uses to copy its genetic material into human cells.

The XR (extended-release) formulation allows once-daily dosing, compared to the immediate-release (IR) version which requires twice-daily dosing.

Before starting Viramune XR, an 14-day lead-in period is required using nevirapine IR (immediate-release) 200 mg once daily. This slow introduction reduces the risk of serious rash.

After the 14-day lead-in, take one Viramune XR 400 mg tablet once daily, with or without food.

Take at the same time each day. Swallow the tablet whole. Do not crush, split, or chew the extended-release tablet.

Viramune XR must always be used in combination with other antiretroviral medicines.

Take the missed dose as soon as you remember. If it is nearly time for the next dose, skip and continue your schedule. Never take a double dose.

Contact your HIV specialist or a poison control centre.

• Store below 30°C
• Keep in the original container
• Keep out of reach of children

The most important side effects occur primarily in the first 18 weeks of treatment.

Common side effects:

• Rash: extremely common, occurring in about 50 percent of people. Most rashes are mild and manageable, but severe rash requires stopping nevirapine immediately
• Nausea
• Headache
• Fatigue

Serious side effects:

• Severe skin reactions: Stevens-Johnson syndrome and toxic epidermal necrolysis are rare but life-threatening. Stop immediately if you develop a rash with blistering, peeling, or sores in the mouth, eyes, or genitals, and seek urgent medical care
• Severe hepatotoxicity (liver damage): particularly in the first 18 weeks. Women with CD4 counts above 250 and men with CD4 counts above 400 are at higher risk. Report jaundice, dark urine, vomiting, or fatigue immediately. Stop nevirapine if signs of hepatitis develop
  

Liver function tests are mandatory before starting and regularly during the first 18 weeks of treatment.

Nevirapine is an inducer of CYP3A4 liver enzymes and reduces the levels of many medicines:

• Protease inhibitors: nevirapine significantly reduces levels of most PI-based regimens. Careful consideration required before combining
• Hormonal contraceptives: effectiveness of oral and other hormonal contraceptives is reduced. Alternative non-hormonal contraception must be used
• Rifampicin, St John's Wort: further reduce nevirapine levels
• Antifungals (ketoconazole, fluconazole): nevirapine reduces ketoconazole levels significantly

Always have your HIV pharmacist review your complete medicine list before starting or changing any medicine.

Why is there a 14-day lead-in period?

Nevirapine at full doses can cause a serious rash in a significant proportion of patients. Starting at a lower dose for 14 days induces liver enzymes and allows the body to gradually adapt, reducing the risk and severity of rash. It is an important safety step and must not be skipped. If rash develops during the lead-in period, do not progress to the full dose.

Who should avoid nevirapine?

Nevirapine carries a higher risk of serious liver toxicity in women with CD4 T-cell counts above 250 cells/mm3 and in men with CD4 counts above 400 cells/mm3. For this reason, it is not recommended as a starting medicine in these groups. Your HIV doctor will assess whether it is appropriate based on your CD4 count and treatment history.

Ace provides accurate and independent information medically reviewed on prescription medications. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment.