Home Drug Guide Didanosine

Drug Guide

Generic Name

Didanosine

Brand Names Videx, Videx EC

Classification

Therapeutic: Antiretroviral agent for HIV infection

Pharmacological: Nucleoside Reverse Transcriptase Inhibitor (NRTI)

FDA Approved Indications

Treatment of HIV-1 infection in combination with other antiretroviral agents

Mechanism of Action

Didanosine is a nucleoside analog that inhibits HIV reverse transcriptase, leading to termination of viral DNA elongation during reverse transcription.

Dosage and Administration

Adult: Typically 250 mg once daily on an empty stomach (at least 30 minutes before or 2 hours after meals). Dosage may vary based on patient weight and clinical response.

Pediatric: Dosage varies based on body weight; usually 250 mg/m² once daily. Precise dosing must be individualized.

Geriatric: No specific dosage adjustment solely based on age; however, renal function should be monitored.

Renal Impairment: Dose adjustments are required in renal impairment; typically, the interval is prolonged.

Hepatic Impairment: No specific dosage adjustment; caution due to potential accumulation.

Pharmacokinetics

Absorption: Well absorbed orally.

Distribution: Widely distributed in body fluids and tissues.

Metabolism: Primarily hydrolyzed in tissues; minimal metabolism.

Excretion: Mostly excreted unchanged in urine.

Half Life: Approximately 4-6 hours.

Contraindications

Known hypersensitivity to didanosine or any components of the formulation

Precautions

Lactic acidosis and hepatic failure can occur, especially in pregnant women, women of childbearing age, and obese patients. Caution in patients with pre-existing pancreatitis or hepatic disease, including hepatitis B or C. Monitor for peripheral neuropathy, pancreatitis, and hepatic toxicity.

Adverse Reactions - Common

Headache (Common)
Nausea (Common)
Diarrhea (Common)
Peripheral neuropathy (Less common)

Adverse Reactions - Serious

Pancreatitis (Rare)
Lactic acidosis with hepatomegaly (Rare)
Hepatic failure (Rare)
Severe hypersensitivity reactions (Rare)

Drug-Drug Interactions

Allopurinol - may increase didanosine levels.
Zidovudine - potential antagonism in effect.
Alcohol - enhances lactic acidosis risk.

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor clinical response, check for signs of pancreatitis (abdominal pain, nausea), liver function tests, serum amylase, and serum lactate levels.

Diagnoses:

Risk for infection related to HIV status
Risk for lactic acidosis

Implementation: Administer on an empty stomach, instruct about adherence. Monitor for adverse effects.

Evaluation: Assess viral load reduction and CD4 counts; monitor for adverse reactions.

Patient/Family Teaching

Take medication exactly as prescribed, preferably on an empty stomach.
Report symptoms of pancreatitis (severe abdominal pain), lactic acidosis (weakness, nausea, fast breathing), or hepatic symptoms.
Do not abruptly stop medication.
Use contraception as advised; discuss pregnancy considerations.

Special Considerations

Black Box Warnings:

Lactic acidosis and severe hepatomegaly with steatosis, which can be fatal, have been reported. Use with caution.

Genetic Factors: No specific genetic testing required.

Lab Test Interference: May interfere with certain laboratory tests, including those for lactic acid levels.

Overdose Management

Signs/Symptoms: Severe nausea, vomiting, pancreatitis, hepatic failure.

Treatment: Supportive care; no specific antidote. Hemodialysis may be considered in severe cases to remove drug.

Storage and Handling

Storage: Store at room temperature, 20-25°C (68-77°F), away from moisture and light.

Stability: Stable within expiration date when stored properly.