NELVEX-250 250MG TABLET

Indications

• HIV infection
• AIDS-related complex
• Prevention of HIV transmission in high-risk populations

Dosage

Children: Paediatric dosing should be based on weight and age. Refer to the BNF for Children for detailed dosing information.

Adults: Dosage should be individualized based on treatment guidelines and patient response. Refer to the BNF for specific dosing recommendations.

Mechanism of action

Nelvinavir exerts its antiviral effect by specifically inhibiting the HIV-1 protease enzyme. This enzyme is responsible for cleaving the viral polyprotein into functional proteins necessary for the formation of new virions. By blocking this process, nelvinavir prevents the maturation of viral particles, leading to the production of immature and non-infectious virions.

Pharmacodynamics

Nelvinavir demonstrates dose-dependent antiviral activity against HIV-1. It shows synergistic effects when combined with other antiretroviral agents. Its pharmacodynamic properties include inhibition of viral replication, measured by reductions in plasma viral load and improvements in CD4 cell counts in patients undergoing treatment. Resistance can develop through various mutations in the HIV protease gene, which may diminish the drug's efficacy.

Pharmacokinetics

After oral administration, nelvinavir is absorbed with a peak plasma concentration occurring within 1 to 3 hours. It has a bioavailability of approximately 90%, significantly influenced by food intake. The drug is extensively metabolized in the liver via cytochrome P450 enzymes, particularly CYP3A4. Its elimination half-life ranges from 3 to 5 hours, and it is excreted mainly through the feces. Renal clearance plays a minor role in its elimination, making it suitable for patients with renal impairment.

Contra-indications

• Hypersensitivity to nelvinavir or any of its components
• Severe hepatic impairment
• Concurrent use with certain drugs that are known to cause significant drug interactions

Adverse effects

• Diarrhea
• Nausea
• Vomiting
• Abdominal pain
• Headache
• Fatigue
• Rash
• Elevated liver enzymes
• Hyperlipidemia
• Lipid abnormalities

Interactions

• Caution with drugs metabolized by CYP450 enzymes as nelvinavir may inhibit or induce these pathways
• Increased risk of toxicity with certain antiretrovirals
• Potential interactions with anticonvulsants, antihistamines, and other medications that use the same metabolic pathways

Precautions

• Monitor liver function tests regularly due to potential hepatotoxicity
• Assess for signs of hypersensitivity reactions
• Use caution in patients with a history of pancreatitis
• Monitor for signs of metabolic abnormalities, including hyperlipidemia

Pregnancy

Use during pregnancy only if the potential benefit justifies the potential risk to the fetus. Consult guidelines for antiretroviral therapy in pregnancy.

Breast-feeding

Nelvinavir is excreted in breast milk. The decision to continue breastfeeding should consider the mother's need for the drug and the potential risks to the infant.

Storage

Store at room temperature, away from moisture and heat. Keep in a tightly closed container.

Formulations

• Tablets
• Oral suspension