Lamivudine/Zidovudine

A to Z Drug Facts

 Action Inhibits replication of HIV by incorporation into HIV DNA and producing an incomplete, nonfunctional DNA.

 Indications Treatment of HIV infection.

 Contraindications Hypersensitivity to any component of the product; use in patients requiring dosage adjustment (eg, renal function impairment with Ccr less than 50 mL/min, body weight less than 50 kg or 110 lb).

 Route/Dosage

Adults and Children at least 12 yr: PO One combination tablet bid.

 Interactions

Ganciclovir, interferon-alpha, other bone marrow suppressives or cytotoxic agents: Increased hematologic toxicity of zidovudine. Note: Although pharmacokinetic interactions are reported with the following drugs, routine dose modification of lamivudine and zidovudine is not warrented: atovaquone, fluconazole, methadone, nelfinavir, probencid, ritonovir, trimethoprim-sulfamethoxazole, valproic acid.

 Lab Test Interferences None well documented.

 Adverse Reactions

CNS: Headache; fatigue; neuropathy; insomnia; dizziness; depression. DERMATOLOGIC: Rash. EENT: Nasal symptoms. GI: Nausea; diarrhea; vomiting; anorexia; abdominal pain; abdominal cramps; dyspepsia. HEMATOLOGIC: Anemia; neutropenia; thrombocytopenia. HEPATIC: Elevated liver enzymes. RESPIRATORY: Cough. OTHER: Malaise; fever; chills; myalgia; arthralgia; musculoskeletal pain.

 Precautions

Pregnancy: Category C. Lactation: Undetermined. HIV-infected mothers should not breastfeed infants. Children: Not indicated in children less than 12 yr because it is a fixed-dose combination that prevents dosage adjustment. Bone marrow suppression: Use with caution in patients who have bone marrow compromise evidenced by granulocyte count less than 1000 cells/cm or hemoglobin less than 9.5 g/dL. Monitoring: Frequent blood counts are recommended when using this drug combination in patients with advanced HIV disease; periodic blood counts are recommended when using in patients with asymptomatic or early HIV disease. Hepatic function impairment or known risk factors for liver disease: Use with caution; suspend treatment in any patient who develops clinical or labortory findings suggestive of lactic acidosis or hepatotoxicity. Fixed-dose combination: Does not allow for dose reduction; do not use in patients requiring lamivudine or zidovudine dosage reduction (eg, children less than 12 yr; renal impairment with Ccr less than 50 mL/min; low body weight; or those patients experiencing dose-limiting side effects).

 Administration/Storage

• Adhere strictly to the prescribed dosage schedule.
• Administer without regard to food.
• Store tablets and oral solution at room temperature (36° to 76°F) in a tight, dry container.

 Assessment/Interventions

• Obtain patient history, including drug history.
• Assess for signs and symptoms of the major toxicities, including neutropenia and anemia, especially in patients with advanced disease.
• Administer with caution to patients with liver disease. Assess patient for clinical symptoms that might suggest the onset of lactic acidosis or severe hepatomegaly with steatosis (fatty degeneration).
• Monitor BUN, serum creatine, LFTs, amylase, and CBC during the course of therapy.
• Monitor for signs and symptoms of infection or neurological changes. Assess patient for change in severity of symptoms.
• Monitor the patient for increased risk of adverse effects that included headache, fatigue, nausea, neuropathy, nasal signs and symptoms, cough, skin rashes, and musculoskeletal pain.

 Patient/Family Education

• Provide patient information pamphlet.
• Teach patient that this medication is for oral use only and to take only as prescribed.
• Instruct the patient to avoid OTC medicines unless approved by health care provider.
• Stress the inportance of regular exams and laboratory work.
• Inform patient that this medication is not a cure for the HIV infection and that the patient may continue to develop opportunistic infections and other complications of HIV infection. Patients will need to remain under the close observation of health care providers experienced in the treatment of patients with HIV-associated diseases.
• Caution patient not to discontinue use of drug even when feeling better.
• Caution patient that long-term effects of this medicine is not known.
• Instruct patient to notify health care provider of signs of infection, including sore throat, fever, cough, and respiratory congestion.
• Instruct family to notify health care provider of changes in neurological status such as memory loss or confusion.
• Advise patient that it may take at least 4 wk for maximum effect.
• Warn patient that the risk of transmission of HIV to others through sexual contact or exposure to the patient's blood is still present. Instruct patient in methods to prevent transmission of the HIV virus.
• Caution mothers to discontinue nursing if receiving this medication.
• Instruct women to inform health care provider immediately if suspecting pregnancy.
• Inform patient that the major toxicities are neutropenia and anemia and to have blood counts monitored closely.

Books@Ovid
Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts