Vidarabine


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Vidarabine
Vidarabine (Vira-A)
Vidarabine
(vye- DAIR-ah-been)
Pregnancy Category: C Vira-A (Rx)

Classification: Antiviral

See Also: See also Antiviral Agents and Anti-Infectives .

Action/Kinetics: Phosphorylated in the cell to arabinosyl adenosine monophosphate (ara-AMP) or the triphosphate (ara-ATP). These compounds cause inhibition of viral DNA polymerase, inhibition of virus-induced ribonucleotide reductase. The drug may also incorporate into the viral DNA molecule leading to chain termination. Due to low solubility, systemic absorption is not expected to occur after ophthalmic use. Trace amounts seen in the aqueous humor only if there is a corneal epithelial defect.

Uses: Acute keratoconjunctivitis and recurrent epithelial keratitis caused by HSV types 1 and 2. Superficial keratitis caused by HSV that is resistant to idoxuridine or when toxic or hypersensitivity reactions have resulted from idoxuridine. It is more effective than idoxuridine for deep recurrent infections.

Contraindications: Hypersensitivity to drug. Concomitant use of corticosteroids usually contraindicated. Use in presence of sterile trophic ulcers.

Side Effects: Photophobia, lacrimation, conjunctival infection, foreign body sensation, temporal visual haze, burning, irritation, superficial punctate keratitis, pain, punctal occlusion, sensitivity to bright light.

Laboratory Test Alterations: Bilirubin, AST.

How Supplied: Ophthalmic ointment: 3%

Dosage
?Ophthalmic Ointment, 3%
1/2 in. applied to lower conjunctival sac 5 times/day at 3-hr intervals. Continue therapy for 7 days after complete reepithelialization but at reduced dosage (e.g., b.i.d.). If there are no signs of improvement after 7 days or if complete reepithelialization has not occurred within 21 days, consider other therapy.