Pemirolast

Class: Antiallergic Agents
VA Class: OP300
Chemical Name: 9-Methyl-3-(1H-tetrazol-5-yl)-4H-pyrido[1,2a]pyrimidin-4-one potassium salt
Molecular Formula: C₁₀H₇KN₆O
CAS Number: 100299-08-9
Brands: Alamast

Medically reviewed by Drugs.com on Aug 23, 2021. Written by ASHP.

Introduction

Mast-cell stabilizer.

Uses for Pemirolast

Allergic Conjunctivitis

Prevention of ocular itching associated with allergic conjunctivitis.

Pemirolast Dosage and Administration

Administration

Ophthalmic Administration

Apply topically to the eye as an ophthalmic solution. Not for injection or oral use.

Avoid contamination of the solution container.

Dosage

Available as pemirolast potassium; dosage expressed in terms of the salt.

Initiate therapy before and continue throughout pollen season.

Pediatric Patients

Allergic Conjunctivitis

Ophthalmic

Children ≥3 years of age: 1 or 2 drops of a 0.1% solution in the affected eye(s) 4 times daily.

Symptomatic response (i.e., decreased itching) may be evident within a few days following initiation but frequently requires up to 4 weeks of therapy.

Adults

Allergic Conjunctivitis

Ophthalmic

1 or 2 drops of a 0.1% solution in the affected eye(s) 4 times daily.

Symptomatic response (i.e., decreased itching) may be evident within a few days following initiation but frequently requires up to 4 weeks of therapy.

Cautions for Pemirolast

Contraindications

Known hypersensitivity to pemirolast or any ingredient in the formulation.

Warnings/Precautions

Specific Populations

Pregnancy

Category C.

Lactation

Distributed into milk in rats; not known whether distributed into human milk. Caution if used in nursing women.

Pediatric Use

Safety and efficacy not established in children <3 years of age.

Common Adverse Effects

Headache, rhinitis, cold/flu symptoms.

Interactions for Pemirolast

No formal drug interaction studies to date.

Pemirolast Pharmacokinetics

Absorption

Bioavailability

Following topical application to both eyes (0.1% solution 4 times daily for 2 weeks), peak plasma concentrations were attained within about 25 minutes, but were substantially lower than those following a single (10 mg) oral dose.

Elimination

Elimination Route

10–15% of topical ophthalmic dose excreted unchanged in urine.

Half-life

About 4.5 hours.

Stability

Storage

Ophthalmic

Solution

15–25°C.

Actions

Suppresses the release of mediators from cells involved in hypersensitivity reactions, including mast cells, and decreases chemotaxis and activation of eosinophils.
Reportedly blocks calcium channels in mast cell membranes.

Advice to Patients

Importance of learning and adhering to proper administration techniques to avoid contamination of the product.
Importance of removing soft contact lenses prior to administration of each dose. Delay reinsertion for 10 minutes after administration if eyes are not red; do not wear contact lenses if eye(s) are red. Not indicated for contact lens-related irritation.
Importance of reporting any worsening of symptoms or new-onset ocular pain/discomfort.
Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.
Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.