Generic Name

Vidarabine

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Classification

FDA Approved Indications

• Herpes simplex virus (HSV) infections of the eye

Mechanism of Action

Vidarabine is a nucleoside analog that inhibits viral DNA synthesis by competing with natural nucleotides, leading to chain termination during viral DNA replication.

Dosage and Administration

Adult: Apply 1% ophthalmic ointment to the affected eye every 3 hours during the day and every 4 hours during the night, for 7-14 days.

Pediatric: Same as adult dosing; dosages are based on the severity of the infection and patient response.

Geriatric: No specific adjustments; follow standard dosing unless renal or hepatic impairment present.

Renal Impairment: Use with caution; no specific dose adjustment provided, but monitor renal function.

Hepatic Impairment: Use with caution; no specific dose adjustment provided.

Pharmacokinetics

Absorption: Poor oral absorption; topical administration for ocular use.

Distribution: Limited systemic absorption; mostly localized effect.

Metabolism: Metabolized by deamination.

Excretion: Primarily renally excreted.

Half Life: Approximately 20-25 minutes systemically; topical ocular half-life varies.

Contraindications

• Hypersensitivity to vidarabine or any component

Precautions

• Use with caution in immunocompromised patients.
• Potential for neurotoxicity if used systemically.

Adverse Reactions - Common

• Local irritation, burning, or stinging of the eye (Frequent)
• Conjunctivitis or eyelid inflammation (Occasional)

Adverse Reactions - Serious

• Neurotoxicity (e.g., seizures, altered consciousness) if systemically absorbed (Rare)

Drug-Drug Interactions

• None well-documented; check for other ocular medications.

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Use medication exactly as prescribed.
• Avoid touching the tip of the tube to any surface.
• Report any eye pain, vision changes, or Allergic reactions.

Special Considerations

Black Box Warnings: N/A

Genetic Factors: None specified.

Lab Test Interference: None known.

Overdose Management

Signs/Symptoms: Local ocular irritation or systemic neurotoxicity in case of significant systemic absorption.

Treatment: Discontinue drug; provide symptomatic and supportive care.

Storage and Handling

Storage: Store at room temperature, protected from light.

Stability: Stable as per manufacturer; discard after expiration.