ketotifen (systemic)

Action and Spectrum

Actions and Spectrum: 

ketotifen (systemic) is a medication primarily used as an antihistamine and mast cell stabilizer. It is commonly used to treat various allergic conditions and asthma.  

Action: 

• Antihistamine: ketotifen blocks the effects of histamine. Histamine is responsible for causing symptoms like itching, sneezing, runny nose, and watery eyes. 
• Mast cell stabilizer: ketotifen stabilizes mast cells, which are cells involved in releasing histamine and other inflammatory substances during allergic reactions. By stabilizing mast cells, ketotifen helps reduce the release of these substances and mitigates allergic symptoms. 

The spectrum of use: 

• Allergic rhinitis: ketotifen is used to relieve symptoms of allergic rhinitis, including sneezing, runny or itchy nose, and itchy or watery eyes. 
• Allergic conjunctivitis: It is used to treat symptoms of allergic conjunctivitis, such as red, itchy, and watery eyes. 
• Asthma: ketotifen may be used as an add-on therapy in managing mild to moderate persistent asthma, especially in children, to help reduce the frequency and severity of asthma attacks. 
• Chronic urticaria (hives): It can alleviate symptoms and reduce the frequency of hives in people with chronic urticaria. 
• Eczema (atopic dermatitis): ketotifen may be a supplementary treatment to help control itching and inflammation associated with eczema. 

Drug Interaction

Adverse Reaction

Frequency not defined 

Dry mouth. 

Trouble sleeping. 

Feeling irritable. 

Upset stomach. 

Feeling dizzy or sleepy. 

Feeling nervous and excitable. 

Headache. 

Weight gain. 

Black Box Warning

Black Box Warning: 

None 

Contraindication / Caution

Contraindication/Caution: 

Contraindication 

• Hypersensitivity: ketotifen should not be used in individuals with a known hypersensitivity or allergic reaction to the drug or its components. Allergic reactions to ketotifen can range from mild skin rashes to severe reactions, such as anaphylaxis, a life-threatening allergic response. 
• Pregnancy and breastfeeding: The safety of ketotifen during pregnancy and breastfeeding has not been established. Therefore, it is generally not recommended for use in pregnant or breastfeeding women unless the potential benefits outweigh the risks and only under the supervision of a healthcare professional. 
• Children under three years of age: ketotifen is not recommended for use in children under three, as safety and efficacy data in this age group are limited. 
• Severe liver impairment: ketotifen is metabolized in the liver, and its use may need to be avoided or adjusted in individuals with severe liver impairment. 
• Severe kidney impairment: In cases of severe kidney impairment, ketotifen may need to be avoided or adjusted due to potential changes in drug clearance. 
• Closed-angle glaucoma: ketotifen may cause changes in eye pressure, and its use is contraindicated in individuals with closed-angle glaucoma, a type of glaucoma characterized by increased eye pressure. 
• Concurrent use of monoamine oxidase inhibitors (MAOIs): Combining ketotifen with an antidepressant, may lead to increased sedation and other adverse effects. Therefore, concurrent use is generally not recommended. 

Caution 

• Central Nervous System (CNS) effects: ketotifen may cause drowsiness, dizziness, or affect mental alertness in some individuals. Caution is advised while driving, operating machinery, or performing tasks that require mental alert until you know how the medication affects you. 
• Alcohol and sedatives: Combining ketotifen with alcohol or other sedatives can enhance the CNS depressant effects of the drug, increasing drowsiness and impairing coordination. Avoid alcohol and consult your doctor before using other sedative medications while taking ketotifen. 
• Diabetes: ketotifen may alter blood sugar levels in some individuals. Diabetic patients should carefully monitor their blood glucose levels while using ketotifen. 
• Cardiovascular effects: ketotifen may have mild cardiovascular effects, such as increased heart rate. People with pre-existing heart conditions should use ketotifen cautiously and inform their healthcare provider about their medical history. 
• Renal impairment: In individuals with mild to moderate kidney impairment, caution is advised when using ketotifen, as it may require dosage adjustments. ketotifen may need to be avoided altogether for those with severe kidney impairment. 
• Hepatic impairment: ketotifen is metabolized in the liver, and individuals with liver impairment may require dose adjustments or monitoring. 
• Pregnancy and breastfeeding: As mentioned before, the safety of ketotifen during pregnancy and breastfeeding is not well-established. Consult a healthcare professional before using ketotifen if you are pregnant or breastfeeding. 
• Asthma exacerbation: While ketotifen can benefit some individuals with asthma, it may not be suitable for relieving acute asthma attacks. Patients should have a separate, fast-acting rescue inhaler to manage acute asthma symptoms. 
• Eye conditions: ketotifen may cause blurred vision or other visual disturbances. Use caution when performing tasks that require clear vision. 
• Allergic reactions: Though rare, hypersensitivity reactions to ketotifen can occur.  
• Interactions with other medications: Inform your healthcare provider about all the medications you are taking to avoid potential drug interactions, including over-the-counter drugs and herbal supplements. 

Pregnancy / Lactation

Pregnancy consideration:  

US FDA pregnancy category: Not assigned 

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: 

ketotifen (systemic) is a medication with dual pharmacological actions. As an antihistamine, it competes with histamine for H1 receptors, blocking their activation and reducing allergic symptoms like itching, sneezing, and runny nose. Additionally, as a mast cell stabilizer, ketotifen inhibits the release of the inflammatory mediators from mast cells, helping to prevent the cascade of allergic reactions. It is primarily used to treat allergic conditions, such as allergic rhinitis, allergic conjunctivitis, and chronic urticaria.

ketotifen is also an add-on therapy for mild to moderate persistent asthma, though it is not intended for acute asthma attacks. The medication is generally well-tolerated, with common side effects being drowsiness and mild gastrointestinal disturbances. However, it is contraindicated in individuals with known hypersensitivity to the drug and in pregnancy and breastfeeding. It requires caution in patients with certain medical conditions, such as liver or kidney impairment. 

Pharmacodynamics: 

Mechanism of action: Ketotifen (systemic) exerts its pharmacological effects through a dual mechanism of action as an antihistamine and a mast cell stabilizer. These actions are essential in reducing the symptoms associated with allergic reactions and inflammation. 

• Antihistamine Action: ketotifen competes with histamine for binding to histamine H1 receptors on various cells, including those in the respiratory tract, blood vessels, and skin. By binding to these receptors, ketotifen prevents histamine from exerting its effects. Histamine is a chemical released by the mast cells during an allergic response and is responsible for causing symptoms such as itching, sneezing, runny nose, and watery eyes. By blocking the H1 receptors, ketotifen helps reduce these allergic symptoms. 
• Mast Cell Stabilization: ketotifen has an additional role as a mast cell stabilizer. Mast cells are immune cells found in tissues throughout the body, especially in areas prone to allergic reactions. When exposed to allergens, mast cells release inflammatory mediators, including histamine and other substances, into the surrounding tissues. This process triggers the allergic response. ketotifen works by inhibiting the release of these inflammatory mediators from mast cells, thus preventing or reducing the cascade of allergic reactions. By stabilizing mast cells, ketotifen helps dampen the allergic response and provides longer-term relief from allergic symptoms. 

The dual mechanism of action of ketotifen makes it effective in managing various allergic conditions, including allergic rhinitis, allergic conjunctivitis, chronic urticaria (hives), and as an add-on therapy for mild-moderate persistent asthma. It is important to note that ketotifen is not a rescue medication for acute asthma attacks and should not be used for immediate relief. Instead, it is intended for prophylactic use to prevent asthma symptoms over time. 

Pharmacokinetics: 

Absorption 

After oral administration, ketotifen is well absorbed from the gastrointestinal tract. The absorption rate is relatively slow, with peak plasma concentrations typically reached within 2 to 4 hours after ingestion. 

Distribution 

ketotifen has a moderate volume of distribution, indicating that it distributes throughout the body tissues. It readily crosses the BBB (blood-brain barrier), which is one of the reasons it can cause central nervous system (CNS) effects like drowsiness and sedation. 

Metabolism 

ketotifen undergoes extensive metabolism in the liver, primarily via the cytochrome P450 enzyme system. The main metabolite is N-desmethyl ketotifen, which also exhibits some pharmacological activity. These metabolites are then excreted from the body. 

Elimination and Excretion 

ketotifen and its metabolites are eliminated primarily through the kidneys. The drug and its metabolites are typically excreted in the urine, with only a small fraction being eliminated via the feces. 

Adminstartion

Administration: 

ketotifen (systemic) is available in various forms, such as tablets or oral solutions. The specific administration instructions may vary depending on the formulation and the treated condition. Always follow your doctor’s instructions and the directions on the medication label.  

• Dosage: The dosage may vary based on the individual’s condition and response to treatment. For children, the dosage is typically lower and is determined by the child’s age and weight. 
• Timing: ketotifen is usually taken orally with or without food. It is commonly administered in the morning and evening to maintain stable blood levels throughout the day. Taking it at the same time each day can help improve its effectiveness. 
• Swallowing the tablet: If you take ketotifen in tablet form, swallow the whole tablet with a glass of water. Do not crush or chew the tablet unless your doctor specifically instructs you. 
• Oral solution: If you use the oral solution, carefully measure the prescribed amount using a medicine dropper or dosing spoon provided with the medication. If the solution needs to be diluted before administration, follow the instructions provided by your healthcare provider or pharmacist. 
• Duration of use: ketotifen treatment may vary depending on the condition. It is key to follow your doctor’s advice regarding the length of treatment. 
• Missed dose: If a dose is missed, taking it as soon as possible is generally recommended. However, if the next scheduled dose is missed, it should be skipped and the following dose should be taken at the appropriate time. It is important to avoid taking a double dose of the medication to compensate for the missed dose. 
• Store properly: Store ketotifen at room temperature, away from direct sunlight and moisture. Keep it out of reach of children and pets. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: ketotifen (systemic) 

Why do we use ketotifen (systemic)? 

ketotifen (systemic) has several medical uses, primarily as an antihistamine and mast cell stabilizer. It is commonly prescribed to treat various allergic conditions and asthma.  

• Allergic Rhinitis: ketotifen relieves allergic rhinitis symptoms, commonly known as hay fever. It can help alleviate sneezing, runny or itchy nose, and watery eyes caused by exposure to allergens like pollen, dust mites/pet dander. 
• Allergic Conjunctivitis: ketotifen is effective in treating symptoms of allergic conjunctivitis, which is inflammation of the conjunctiva (the thin, clear tissue covering the white part of the eyes and the inner eyelids). It can help reduce redness, itching, and watering of the eyes due to allergic reactions. 
• Asthma: ketotifen may be an add-on therapy in managing mild to moderate persistent asthma, especially in children. It is not a rescue inhaler or intended to provide immediate relief during acute asthma attacks. Instead, it helps prevent asthma symptoms and reduce the frequency of attacks over time. 
• Chronic Urticaria (Hives): ketotifen can alleviate symptoms and reduce the frequency of hives in people with chronic urticaria, a condition characterized by itchy, raised welts on the skin that can last for more than six weeks. 
• Atopic Dermatitis (Eczema): ketotifen may be a supplementary treatment to help control itching and inflammation associated with atopic dermatitis (eczema).