pemirolast

Action and Spectrum

Actions and Spectrum: 

pemirolast is a medication primarily used to treat allergic conditions, particularly allergic conjunctivitis (inflammation of the eye) and asthma. It belongs to a class of drugs known as mast cell stabilizers. Mast cells are the cells of the immune system that release inflammatory substances, such as histamine, when exposed to allergens. pemirolast works by preventing mast cells from releasing these inflammatory substances, thereby reducing the allergic response. 

Action: 

• Mast cell stabilization: pemirolast stabilizes mast cells, inhibiting their activation and preventing the release of inflammatory mediators like histamine, leukotrienes, and prostaglandins. By reducing the release of these substances, it helps to alleviate allergy-related symptoms. 

Spectrum:  

pemirolast is primarily used in treating allergic conjunctivitis (seasonal and perennial allergic conjunctivitis) and has been shown to effectively reduce itching, redness, and eye irritation associated with allergies. 

Drug Interaction

Adverse Reaction

Frequency not defined 

Painful menstrual bleeding 

Stomach pain and cramping 

Runny or stuffy nose 

Headache  

Pain and tenderness 

Cough  

Troubled breathing 

Tightness in chest 

Black Box Warning

Black Box Warning: 

None 

Contraindication / Caution

Contraindication/Caution: 

Contraindication 

• Hypersensitivity: pemirolast should not be used in individuals with known hypersensitivity or allergy to the drug or its components. Allergic reactions can be severe, including rash, itching, swelling, dizziness, and difficulty breathing. 
• Pregnancy and breastfeeding: The safety of pemirolast use during pregnancy condition and breastfeeding has not been adequately studied. Therefore, it is generally not recommended for use during these periods unless specifically directed by a healthcare professional, and the potential benefits outweigh the risks. 
• Children: The safety and efficacy of pemirolast in children below a certain age may not be established, and medication use in this population may not be recommended. 
• Severe renal impairment: pemirolast is metabolized by the liver and excreted through the kidneys. The drug may accumulate in patients with severe renal impairment, leading to potentially adverse effects. Dose adjustments may be necessary for individuals with impaired kidney function. 
• Severe hepatic impairment: pemirolast is metabolized in the liver, and severe hepatic impairment may alter drug metabolism and clearance. It should be used cautiously and under close medical supervision in patients with severe liver dysfunction. 
• Concurrent use of other medications: pemirolast may interact with other medications, and some drug combinations may lead to adverse effects or reduced effectiveness.  

Caution 

• Allergic reactions: While pemirolast treats allergic conditions, some individuals may still experience allergic reactions to the medication. If you develop signs of an allergic reactions like rash, hives, itching, swelling, dizziness, or difficulty breathing, discontinue using pemirolast and seek immediate medical attention. 
• Contact lenses: If you use contact lenses, remove them before applying pemirolast eye drops and wait at least 10-15 minutes before reinserting them. This precaution helps to avoid potential interactions between eye drops and contact lenses. 
• Pre-existing eye conditions: pemirolast should be used with caution in individuals with certain pre-existing eye conditions, such as inflammation or infection of the eye. Consult an eye care professional before using pemirolast if you have any eye problems. 
• Pregnancy and breastfeeding: As mentioned earlier, the safety of pemirolast during pregnancy and breastfeeding has not been well-established.  
• Pediatric use: The safety and efficacy of pemirolast in children below a certain age may not be fully established. The use of pemirolast in pediatric patients should be carefully considered under the guidance of a healthcare professional. 
• Driving and operating machinery: pemirolast eye drops may cause temporary blurred vision or other visual disturbances. If you experience these effects, avoid driving or operating heavy machinery until your vision returns normal. 
• Drug interactions: pemirolast may interact with other medications. Inform your healthcare provider about all your drugs, supplements, or herbal products to prevent potential interactions. 
• Liver and kidney function: pemirolast is metabolized in the liver and excreted through the kidneys. In individuals with impaired liver/kidney function, the dose of pemirolast may need to be adjusted. Close monitoring and medical supervision are essential in such cases. 

Pregnancy / Lactation

Pregnancy consideration:  

US FDA pregnancy category: C 

Lactation:   

Excreted into human milk: Not known. 

Pregnancy category: 

• Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester. 
• Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 
• Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    
• Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.    
• Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    
• Category N: There is no data available for the drug under this category. 

Pharmacology

Pharmacology: 

pemirolast is a mast cell stabilizer with pharmacological properties primarily focused on its antiallergic effects. Upon topical administration as eye drops, it exerts its action by stabilizing mast cells, inhibiting the release of inflammatory mediators, like histamine, leukotrienes, and prostaglandins.

By doing so, pemirolast reduces the conjunctiva’s allergic response and effectively alleviates allergic conjunctivitis symptoms, including itching, redness, tearing, and eye irritation. pemirolast’s targeted mechanism of action makes it a valuable treatment option for managing allergic conjunctivitis and relieving patients suffering from this allergic eye condition. 

Pharmacodynamics: 

Mechanism of action: pemirolast is a mast cell stabilizer, and its mechanism of action is primarily centered around its antiallergic effects. pemirolast acts locally on the eye surface when administered as eye drops for allergic conjunctivitis. 

• Mast cell stabilization: pemirolast stabilizes mast cells, immune cells involved in the allergic response. When exposed to allergens, mast cells release inflammatory mediators such as histamine, leukotrienes, and prostaglandins. These mediators cause the characteristic symptoms of allergic reactions, including itching, redness, tearing, and eye irritation in the case of allergic conjunctivitis. By stabilizing mast cells, pemirolast prevents them from releasing these inflammatory substances, thereby reducing the allergic response. 
• Inhibition of allergic cascade: pemirolast also inhibits the activation of other inflammatory cells, like eosinophils and neutrophils, which play a role in the allergic cascade. Modulating the immune response helps dampen the overall allergic reaction and alleviate the associated symptoms. 
• Anti-inflammatory effects: pemirolast has anti-inflammatory properties that contribute to its beneficial effects in allergic conjunctivitis. Reducing inflammation in the eye tissues helps alleviate redness, swelling, and discomfort caused by the allergic response. 

Pharmacokinetics: 

Absorption 

pemirolast is available as eye drops for topical use in the eyes. When applied to the eye surface, the drug is absorbed into the surrounding tissues through the cornea and conjunctiva. The systemic absorption of pemirolast from the eye is minimal, which reduces the risk of systemic side effects. 

Distribution 

pemirolast, after absorption, undergoes distribution in the body through the bloodstream. However, due to its minimal systemic absorption from the eye, the distribution to other tissues and organs is limited. 

Metabolism 

pemirolast undergoes hepatic metabolism, primarily through cytochrome P450 enzymes, to form various metabolites. The specific details of the metabolic pathways are not extensively studied, but hepatic metabolism contributes to eliminating the drug from the body. 

Elimination and Excretion 

After metabolism, the metabolites of pemirolast are excreted from the body primarly through the renal route (via the urine). Some excretion may also occur through the feces. 

Adminstartion

Administration: 

Ophthalmic administration 

pemirolast is typically administered as an ophthalmic (eye) solution in the form of eye drops.  

• Wash your hands thoroughly with soap and water before handling the eye drops to prevent contamination. 
• If you use contact lenses, remove them before instilling the eye drops. Wait 10-15 minutes before reinserting your contact lenses to avoid potential interactions. 
• Hold the eye drop bottle upside down with the dropper tip pointing downward. Be careful that not to touch your eye, eyelid, or other surface with the dropper tip to prevent contamination. 
• Gently squeeze the bottle to instill the prescribed quantity of drops into the pocket formed by your lower eyelid. Follow your healthcare provider’s instructions regarding the dosage and frequency of eye drops. 
• After instilling the drops, close your eyes gently and press lightly on the inner corner of your eye with your finger for about 1-2 minutes. This helps to avert the eye drops from draining into the tear duct, which can reduce the effectiveness of the medication. 
• If using other eye medications, wait at least 5 minutes before instilling them to avoid potential interactions between eye drops. 
• If you have been prescribed pemirolast for both eyes, repeat the process for the other eye. 
• After using the eye drops, close the bottle tightly with the cap to prevent contamination. 
• Rewash your hands after administering the eye drops to remove residual medication. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: pemirolast 

Pronounced: [ pem-IR-oh-last ] 

Why do we use pemirolast? 

pemirolast is primarily used for treating allergic conjunctivitis, a condition which is characterized by inflammation of the conjunctiva due to an allergic reaction. pemirolast is available in the form of eye drops and is used to relieve the symptoms associated with allergic conjunctivitis.  

• Allergic Conjunctivitis: pemirolast alleviates symptoms such as itching, redness, tearing, and eye irritation caused by allergic reactions to substances like pollen, pet dander, dust mites, and other allergens.