Medical Editor: John P. Cunha, DO, FACOEP Last updated on RxList: 2/23/2022
Drug Description

What is Alamast and how is it used?

Alamast is a prescription medicine used to treat the symptoms of Allergy Medication, such as itching. Alamast may be used alone or with other medications.

Alamast belongs to a class of drugs called Ophthalmic Antihistamines and Decongestants.

It is not known if Alamast is safe and effective in children younger than 3 years of age.

What are the possible side effects of Alamast?

Alamast may cause serious side effects including:

  • hives,
  • difficulty breathing,
  • swelling of your face, lips, tongue, or throat,
  • eye burning or discomfort,
  • itching of the eye,
  • feeling as if something in your eye,
  • dry eyes,
  • other eye discomfort,
  • itching,
  • back pain, and
  • fever

Get medical help right away, if you have any of the symptoms listed above.

The most common side effects of Alamast include:

  • headache,
  • runny nose,
  • sneezing, and
  • cold or flu symptoms

Tell the doctor if you have any side effect that bothers you or that does not go away.

These are not all the possible side effects of Alamast. For more information, ask your doctor or pharmacist.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


ALAMAST® (pemirolast potassium ophthalmic solution) is a sterile, aqueous ophthalmic solution with a pH of approximately 8.0 containing 0.1% of the mast cell stabilizer, pemirolast potassium, for topical administration to the eyes.

Pemirolast potassium is a slightly yellow, water-soluble powder with a molecular weight of 266.3.

The chemical structure is presented below:

ALAMAST® (pemirolast potassium) Structural Formula Illustration


Chemical name

9-methyl-3-(1H-tetrazol-5-yl)-4H-pyrido[1,2-α] pyrimidin-4-one potassium

Each mL contains: ACTIVE: pemirolast potassium 1 mg (0.1%); PRESERVATIVE: lauralkonium chloride 0.005%; INACTIVES: glycerin, dibasic sodium phosphate, monobasic sodium phosphate, phosphoric acid and/or sodium hydroxide to adjust pH, and purified water. The osmolality of ALAMAST® (pemirolast potassium ophthalmic solution) oph-thalmic solution is approximately 240 mOsmol/kg.

Indications & Dosage


ALAMAST® (pemirolast potassium ophthalmic solution) ophthalmic solution is indicated for the prevention of itching of the eye due to allergic conjunctivitis. Symptomatic response to therapy (decreased itching) may be evident within a few days, but frequently requires longer treatment (up to four weeks).


The recommended dose is one to two drops in each affected eye four times daily.

Symptomatic response to therapy (decreased itching) may be evident within a few days, but frequently requires longer treatment (up to four weeks).


ALAMAST® (pemirolast potassium ophthalmic solution) 0.1% is supplied as follows:

10 mL in a white, low density polyethylene bottle with a controlled dropper tip, and a white polyethylene screw cap.

NDC 68669-711-10 10 mL fill in 11 cc container


Store at 15°–25°C (59°–77°F).

Manufactured by: Santen Oy, PO Box 33, FIN-33721 Tampere, Finland. February 2005 Version. Marketed by: VISTAKON® Pharmaceuticals, LLC Jacksonville, FL 32256 USA. Licensed from Mitsubishi Pharma Corporation Japan. FDA revision date: 5/12/2005


Pink Eye (Conjunctivitis) Symptoms, Causes, Treatments See Slideshow
Side Effects & Drug Interactions


In clinical studies lasting up to 17 weeks with ALAMAST® (pemirolast potassium ophthalmic solution) ophthalmic solution, headache, rhinitis, and cold/flu symptoms were reported at an incidence of 10–25%. The occurrence of these side effects was generally mild. Some of these events were similar to the underlying ocular disease being studied.

The following ocular and non-ocular adverse reactions were reported at an incidence of less than 5%:

Ocular: burning, dry eye, foreign body sensation, and ocular discomfort.

Non-Ocular: allergy, back pain, bronchitis, cough, dysmenorrhea, fever, sinusitis, and sneezing/nasal congestion.


No information provided.

Warnings & Precautions


For topical ophthalmic use only. Not for injection or oral use.


Carcinogenesis, mutagenesis, impairment of fertility

Pemirolast potassium was not mutagenic or clasto-genic when tested in a series of bacterial and mammalian tests for gene mutation and chromosomal injury in vitro nor was it clastogenic when tested in vivo in rats.

Pemirolast potassium had no effect on mating and fertility in rats at oral doses up to 250 mg/kg (approximately 20,000 fold the human dose at 2 drops/eye, 40 μL/drop, QID for a 50 kg adult). A reduced fertility and pregnancy index occurred in the F1 generation when F0 dams were treated with 400 mg/kg pemirolast potassium during late pregnancy and lactation period (approximately 30,000 fold the human dose).


Teratogenic effects: Pregnancy Category C.

Pemirolast potassium caused an increased incidence of thymic remnant in the neck, interventricular septal defect, fetuses with wavy rib, splitting of thoracicvertebral body, and reduced numbers of ossified sternebrae, sacral and caudal vertebrae, and metatarsi when rats were given oral doses ≥ 250 mg/kg (approximately 20,000 fold the human dose at 2 drops/eye, 40 μL/drop, QID for a 50 kg adult) during organogenesis. Increased incidence of dilation of renal pelvis/ureter in the fetuses and neonates was also noted when rats were given an oral dose of 400 mg/kg pemirolast potassium (approximately 30,000 fold the human dose). Pemirolast potassium was not teratogenic in rabbits given oral doses up to 150 mg/kg (approximately 12,000 fold the human dose) during the same time period. There are no adequate and well-controlled studies in pregnant women. Because animal reproductive studies are not always predictive of human response, ALAMAST® (pemirolast potassium ophthalmic solution) ophthalmic solution should be used during pregnancy only if the benefit outweighs the risk.

Non-teratogenic effects

Pemirolast potassium produced increased pre- and post-implantation losses, reduced embryo/fetal and neonatal survival, decreased neonatal body weight, and delayed neonatal development in rats receiving an oral dose at 400 mg/kg (approximately 30,000 fold the human dose). Pemirolast potassium also caused a reduction in the number of corpus lutea, the number of implantations, and number of live fetuses in the F1 generation in rats when F0 dams were given oral dosages ≥ 250mg/kg (approximately 20,000 fold the human dose) during late gestation and the lactation period.

Nursing Mothers

Pemirolast potassium is excreted in the milk of lactating rats at concentrations higher than those in plasma. It is not known whether pemirolast potassium is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when ALAMAST® (pemirolast potassium ophthalmic solution) ophthalmic solution is administered to a nursing woman.

Pediatric Use

Safety and effectiveness in pediatric patients below the age of 3 years have not been established.

Overdose & Contraindications


No accounts of ALAMAST® (pemirolast potassium ophthalmic solution) ophthalmic solution overdose were reported following topical ocular application.

Oral ingestion of the contents of a 10 mL bottle would be equivalent to 10 mg of pemirolast potassium.


ALAMAST® (pemirolast potassium ophthalmic solution) ophthalmic solution is contraindicated in patients with previously demonstrated hypersensitivity to any of the ingredients of this product.

Clinical Pharmacology


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.


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.

Medication Guide


To prevent contaminating the dropper tip and solution, do not touch the eye-lids or surrounding areas with the dropper tip. Keep the bottle tightly closed when not in use.

Patients should be advised not to wear contact lenses if their eye is red. ALAMAST® (pemirolast potassium ophthalmic solution) should not be used to treat contact lens related irritation. The preservative in ALAMAST® (pemirolast potassium ophthalmic solution) , lauralkonium chloride,may be absorbed by soft contact lenses.Patients who wear soft contact lenses and whose eyes are not red should be instructed to wait at least ten minutes after instilling ALAMAST® (pemirolast potassium ophthalmic solution) before they insert their contact lenses.

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