Recommended Topic Related To:

Vira-A

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Vira-A

Discontinued Warning IconPlease Note: This Brand Name drug is no longer available in the US.
(Generic versions may still be available.)

Warnings
Precautions

WARNINGS

Normally, corticosteroids alone are contraindicated in Herpes simplex virus infections of the eye. If VIRA-A (vidarabine) Ophthalmic Ointment, 3%, is administered concurrently with topical corticosteroid therapy, corticosteroid-induced ocular side effects must be considered.

These include corticosteroid-induced glaucoma or cataract formation and progression of a bacterial or viral infection.

VIRA-A (vidarabine) is not effective against RNA virus or adenoviral ocular infections. It is also not effective against bacterial, fungal, or chlamydial infections of the cornea or nonviral trophic ulcers.

Although viral resistance to VIRA-A (vidarabine) has not been observed, this possibility may exist.

PRECAUTIONS

General

The diagnosis of keratoconjunctivitis due to Herpes simplex virus should be established clinically prior to prescribing VIRA-A (vidarabine) Ophthalmic Ointment, 3%.

Patients should be forewarned that VIRA-A (vidarabine) Ophthalmic Ointment, 3%, like any ophthalmic ointment, may produce a temporary visual haze.

Carcinogenesis

Chronic parenteral (IM) studies of vidarabine have been conducted in mice and rats.

In the mouse study, there was a statistically significant increase in liver tumor incidence among the vidarabine-treated females. In the same study some vidarabine-treated male mice developed kidney neoplasia. No renal tumors were found in the vehicle-treated control mice or the vidarabine-treated female mice.

In the rat study, intestinal, testicular, and thyroid neoplasia occurred with greater frequency among the vidarabine-treated animals than in the vehicle-treated controls. The increases in thyroid adenoma incidence in the high-dose (50 mg/kg) males and the low-dose (30 mg/kg) females were statistically significant.

Hepatic megalocytosis, associated with vidarabine treatment, has been found in short and long-term rodent (rat and mouse) studies. It is not clear whether or not this represents a preneoplastic change.

The recommended frequency and duration of administration should not be exceeded (see DOSAGE AND ADMINISTRATION).

Mutagenesis

Results of in vitro experiments indicate that vidarabine can be incorporated into mammalian DNA and can induce mutation in mammalian cells (mouse L5178Y cell line). Thus far, in vivo studies have not been as conclusive, but there is some evidence (dominant lethal assay in mice) that vidarabine may be capable of producing mutagenic effects in male germ cells.

It has also been reported that vidarabine causes chromosome breaks and gaps when added to human leukocytes in vitro. While the significance of these effects in terms of mutagenicity is not fully understood, there is a well-known correlation between the ability of various agents to produce such effects and their ability to produce heritable genetic damage.

Pregnancy Category C

VIRA-A (vidarabine) parenterally is teratogenic in rats and rabbits. Ten percent VIRA-A (vidarabine) ointment applied to 10% of the body surface during organogenesis induced fetal abnormalities in rabbits. When 10% VIRA-A (vidarabine) ointment was applied to 2% to 3% of the body surface of rabbits, no fetal abnormalities were found. This dose greatly exceeds the total recommended ophthalmic dose in humans. The possibility of embryonic or fetal damage in pregnant women receiving VIRA-A (vidarabine) Ophthalmic Ointment, 3%, is remote. The topical ophthalmic dose is small, and the drug relatively insoluble. Its ocular penetration is very low. However, a safe dose for a human embryo or fetus has not been established. There are no adequate and well-controlled studies in pregnant women. VIRA-A (vidarabine) should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nursing Mothers

It is not known whether VIRA-A (vidarabine) is secreted in human milk. Because many drugs are excreted in human milk and because of the potential for tumorigenicity shown for VIRA-A (vidarabine) in animal studies, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. However, breast milk excretion is unlikely because VIRA-A (vidarabine) is rapidly deaminated in the gastrointestinal tract.

Pediatric Use

The safety and effectiveness in pediatric patients below the age of 2 years have not been established.

Last reviewed on RxList: 4/8/2009
This monograph has been modified to include the generic and brand name in many instances.

Warnings
Precautions
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