Pharmacology
Levocabastine is a potent, fast-acting and highly selective histamine H1-antagonist with a sustained duration of action.
Within 10 to 15 minutes of topical application to the eyes, levocabastine inhibits: itching, redness and chemosis induced by conjunctival provocation with histamine; itching, redness, chemosis, eyelid swelling, and tearing induced by conjunctival provocation with allergens; and itching and redness induced by conjunctival provocation with compound 48/80.
Orally-administered levocabastine provides a dose dependent inhibition of skin reactions to intradermal histamine. After topical application to the eyes levocabastine did not produce clinically significant systemic antihistamine effects in patients.
Levocabastine eye drops (2 drops/eye 3 times daily), under acute and steady state conditions, are devoid of CNS effects, as evaluated by objective and subjective psychoperformance tests and measures of general CNS activity.
Following topical application to the eyes, the absorption of levocabastine was incomplete and the absolute bioavailability of levocabastine instilled in the eyes could be estimated at approximately 30% in patients with allergic conjunctivitis and up to 60% in healthy volunteers.
Indications
The symptomatic management of seasonal allergic conjunctivitis.
Precautions
The safety and efficacy of topical levocabastine have not been established in patients greater than 65 years of age.
There are no clinical trials on the use of levocabastine eye drops in pregnant or nursing women; therefore, levocabastine eye drops should not be used during pregnancy, except if the potential benefit justifies the potential risk to the fetus.
Supplied
Each mL of white sterile ophthalmic microsuspension contains: levocabastine HCl equivalent to levocabastine 0.5 mg. Nonmedicinal ingredients: benzalkonium chloride 0.15 mg as preservative, disodium edetate, disodium phosphate, hypromellose, monosodium phosphate, polysorbate 80, propylene glycol and water. pH 6 to 8. Plastic bottles of 10 mL containing 5 mL of microsuspension. Store between 15 and 30°C.
Contraindications
In patients with hypersensitivity to any of the ingredients.
Warnings
Levocabastine is not recommended for use in children under the age of 12 years except on the advice of a physician. Clinical experience in children under 5 years of age is limited with ocular levocabastine.
Adverse Effects
The most frequent side effect encountered with levocabastine eye drops is eye irritation. Most side effects are transient and rarely necessitate discontinuation of therapy. See Table 1.
Overdose
Treatment should include general supportive measures.
Dosage
Adults and children (12 to 65 years old): 1 drop (15 µg/drop) instilled in each eye, 2 times daily. The dose may be increased to 1 drop 3 to 4 times daily.
It is not useful to continue the treatment for more than 3 days if no improvement is seen. There are no clinical studies to support continuous treatment durations of greater than 16 weeks.
As levocabastine eye drops are available as a microsuspension, the bottle should be shaken before each application. Levocabastine eye drops should be used within 1 month of the first opening of the bottle. Patients should be instructed to take appropriate measures to avoid contamination.
