Mechanism of Action

Pemirolast potassium is a mast cell stabilizer that inhibits the in vivo Type I immediate hypersensitivity reaction.

In vitro and in vivostudies have demonstrated that pemirolast potassium inhibits the antigen-induced release of inflammatory mediators (e.g., histamine, leukotriene C₄,D₄,E₄) from human mast cells.

In addition, pemirolast potassium inhibits the chemotaxis of eosinophils into ocular tissue and blocks the release of mediators from human eosinophils.

Although the precise mechanism of action is unknown, the drug has been reported to prevent calcium influx into mast cells upon antigen stimulation.

Pharmacokinetics

Topical ocular administration of one to two drops of ALAMAST® (pemirolast potassium ophthalmic solution) ophthalmic solution in each eye four times daily in 16 healthy volunteers for two weeks resulted in detectable concentrations in the plasma. The mean (±SE) peak plasma level of 4.7 ±0.8 ng/mL occurred at 0.42 ±0.05 hours and the mean t1/2 was 4.5 ±0.2 hours. When a single 10 mg pemirolast potassium dose was taken orally, a peak plasma concentration of 0.723 μ g/mL was reached.

Clinical Studies

In clinical environmental studies, ALAMAST® (pemirolast potassium ophthalmic solution) was significantly more effective than placebo after 28 days in preventing ocular itching associated with allergic conjunctivitis.

Last reviewed on RxList: 12/30/2008
This monograph has been modified to include the generic and brand name in many instances.