Abacavir Sulfate

 Action Converted by cellular enzymes to carbovir triphosphate, which inhibits HIV-1 transcriptase and interferes with DNA synthesis.

 Indications Treatment of HIV-1 in combination with other antiretroviral agents.

 Contraindications Standard considerations.

 Route/Dosage

Adults: PO 300 mg bid in combination with other antiretroviral agents. Adolescents and Children 3 mo to up to 16 yr: PO 8 mg/kg bid (max dose, 300 mg bid) in combination with other antiretroviral agents.

 Interactions

Ethanol: Increases exposure to abacavir by decreasing the elimination and prolonging the half-life. Methadone: Plasma levels of methadone may be decreased in some patients, reducing the therapeutic effect.

 Lab Test Interferences None well documented.

 Adverse Reactions

CNS: Insomnia; sleep disorders; headache (children). GI: Nausea; vomiting; diarrhea; loss of appetite; anorexia; pancreatitis. DERMATOLOGIC: Skin rashes (children). METABOLIC: Elevated blood glucose; elevated triglycerides. OTHER: Hypersensitivity reactions (eg, fever, rash, fatigue, GI symptoms, malaise, lethargy, myalgia, arthralgia, edema, shortness of breath, paresthesia, hypotension, death); fever (children).

 Precautions

Pregnancy: Category C. Lactation: Undetermined; however, HIV-infected mothers should not breastfeed infants. Children: Safety and efficacy not established in children under 3 mo. Elderly: Select dose with caution, reflecting greater frequency of decreased hepatic, renal, or cardiac function and comorbidity. Hypersensitivity: Fatal hypersensitivity reactions have been associated with therapy. Lactic acidosis/Severe hepatomegaly with steatosis: Lactic acidosis/severe hepatomegaly with steatosis have been reported.

 Administration/Storage

• Store the oral solution at room temperature (68° to 77° F). The solution may be refrigerated but do not freeze.
• Administer with or without meals.
• Always give in combination with other antiretroviral agents.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Monitor for signs of hypersensitivity and discontinue use of medicine immediately if signs of hypersensitivity are present.
• Monitor for physical signs of hypersensitivity such as lymphadenopathy, mucous membrane lesions (eg, conjunctivitis, mouth ulcerations), and rash.
• Do not restart therapy following a hypersensitivity reaction.
• Discontinue therapy in patients with signs and symptoms of lactic acidosis hepatic or hepatomegaly or steatosis (fatty degeneration).
• Monitor for elevation of LFTs, increased creatine, phosphokinase, or creatinine, and for decreased lymphocytes.
• Monitor for blood glucose and triglyceride elevation, which may require adjustment in therapy for some patients such as those with diabetes.
• Monitor for signs and symptoms of pancreatitis.

 Patient/Family Education

• Tell patient that abacavir tablets and oral solution are for oral ingestion only.
• Instruct patient to take abacavir at the same time each day as prescribed in combination with another antiviral agent and to not skip a dose, which could increase the viral load.
• Instruct patient to avoid OTC medications, unless prescribed by primary health care provider.
• Instruct patient that abacavir is not a cure for the HIV infection and he/she may continue to develop opportunistic infections and other complication of the HIV infection, and to remain under close observation by health care professionals experienced in the treatment of patients with HIV-associated diseases.
• Caution patient that long-term effects of abacavir and results from controlled-clinical trials evaluating therapeutic and adverse effects are not known. Therefore, report any problem to heath care provider.
• Warn patient of potential adverse effects and drug/drug interactions.
• Instruct patient to notify health care provider immediately if signs of a rash or a rash accompanied by fever, blistering, oral lesions, conjunctivitis, swelling, muscle or joints aches, or general malaise, infection (eg, sore throat, fever, cough), and respiratory congestion occur.
• Warn the patient of potential adverse or toxic effects if taken with alcohol, as alcohol decreases the elimination of the drug.
• Inform patient that abacavir has not been shown to reduce the risk of passing HIV to others through sexual contact or blood contamination. Encourage patient to abstain or practice safe sex and not share needles.
• Instruct patient in methods and precautions to prevent transmission of the HIV virus.
• Caution mothers to discontinue nursing while receiving abacavir as there is potential for adverse effect from the drug in nursing infants and well as transmission of the HIV virus.
• Caution women of childbearing age to inform health care provider if planning to become pregnant.
• Stress importance of regular exams and laboratory work.
• Encourage patient to comply with the treatment regimen and to take exactly as prescribed.