Trifluridine

INDICATIONS AND USAGE: Trifluridine Ophthalmic Solution is indicated for the treatment of primary keratoconjunctivitis and recurrent epithelial keratitis due to herpes simplex virus, types 1 and 2.

CLINICAL PHARMACOLOGY: Trifluridine is a fluorinated pyrimidine nucleoside with in vitro and in vivo activity against herpes simplex virus, types 1 and 2 and vacciniavirus. Some strains of adenovirus are also inhibited in vitro . Trifluridine is also effective in the treatment of epithelial keratitis that has not responded clinically to the topical administration of idoxuridine or when ocular toxicity or hypersensitivity to idoxuridine has occurred. In a smaller number of patients found to be resistant to topical vidarabine, trifluridine was also effective. Trifluridine interferes with DNA synthesis in cultured mammalian cells. However, its antiviral mechanism of action is not completely known. In vitro perfusion studies on excised rabbit corneas have shown that trifluridine penetrates the intact cornea as evidenced by recovery of parental drug and its major metabolite, 5-carboxy-2´-deoxyuridine, on the endothelial side of the cornea. Absence of the corneal epithelium enhances the penetration of trifluridine approximately two-fold. Intraocular penetration of trifluridine occurs after topical instillation of trifluridine into human eyes. Decreased corneal integrity or stromal or uveal inflammation may enhance the penetration of trifluridine into the aqueous humor. Unlike the results of ocular penetration of trifluridine in vitro , 5-carboxy-2´-deoxyuridine was not found in detectable concentrations within the aqueous humor of the human eye. Systemic absorption of trifluridine following therapeutic dosing with trifluridine appears to be negligible. No detectable concentrations of trifluridine or 5-carboxy-2´-deoxyuridine were found in the sera of adult healthy normal subjects who had trifluridine instilled into their eyes seven times daily for 14 consecutive days. Clinical Studies: During a controlled multicenter clinical trial, 92 of 97 (95%) patients (78 of 81 with dendritic and 14 of 16 with geographic ulcers) responded to therapy with trifluridine as evidenced by complete corneal re-epithelialization within the 14-day therapy period. Fifty-six of 75 (75%) patients (49 of 58 with dendritic and 7 of 17 with geographic ulcers) responded to idoxuridine therapy. The mean time to corneal re-epithelialization for dendritic ulcers (6 days) and geographic ulcers (7 days) was similar for both therapies. In other clinical studies, trifluridine was evaluated in the treatment of herpes simplex virus keratitis in patients who were unresponsive or intolerant to the topical administration of idoxuridine or vidarabine. Trifluridine was effective in 138 of 150 (92%) patients (109 of 114 with dendritic and 29 of 36 with geographic ulcers) as evidenced by corneal re-epithelialization. The mean time to corneal re-epithelialization was 6 days for patients with dendritic ulcers and 12 days for patients with geographic ulcers. The clinical efficacy of trifluridine in the treatment of stromal keratitis and uveitis due to herpes simplex virus or ophthalmic infections ca

DOSAGE AND ADMINISTRATION: Instill one drop of Trifluridine Ophthalmic Solution onto the cornea of the affected eye every 2 hours while awake for a maximum daily dosage of nine drops until the cornea ulcer has completely re-epithelialized. Following re-epithelialization, treatment for an additional 7 days of one drop every 4 hours while awake for a minimum daily dosage of five drops is recommended. If there are no signs of improvement after 7 days of therapy or complete re-epithelialization has not occurred after 14 days of therapy, other forms of therapy should be considered. Continuous administration of trifluridine for periods exceeding 21 days should be avoided because of potential ocular toxicity.

ADVERSE REACTIONS: The most frequent adverse reactions reported during controlled clinical trials were mild, transient burning or stinging upon instillation (4.6%) and palpebral edema (2.8%). Other adverse reactions in decreasing order of reported frequency were superficial punctate keratopathy, epithelial keratopathy, hypersensitivity reaction, stromal edema, irritation, keratitis sicca, hyperemia, and increased intraocular pressure.

WARNINGS: The recommended dosage and frequency of administration should not be exceeded (See DOSAGE AND ADMINISTRATION ).

CONTRAINDICATIONS: Trifluridine Ophthalmic Solution is contraindicated for patients who develop hypersensitivity reactions or chemical intolerance to trifluridine.

OVERDOSAGE: Overdosage by ocular instillation is unlikely because any excess solution should be quickly expelled from the conjunctival sac. Acute overdosage by accidental oral ingestion of trifluridine has not occurred. However, should such ingestion occur, the 75 mg dosage of trifluridine in a 7.5 mL bottle of Trifluridine Ophthalmic Solution is not likely to produce adverse effects. Single intravenous doses of 1.5 to 30 mg/kg/day in children and adults with neoplastic disease produce reversible bone marrow depression as the only potentially serious toxic effect and only after three to five courses of therapy. The acute oral LD 50 in the mouse and rat was 4379 mg/kg or higher.