mizolastine

Action and Spectrum

Actions and Spectrum: 

mizolastine is an antihistamine medication with a specific action and a spectrum of use primarily focused on alleviating allergic symptoms.  

Action: 

Its action centers on its role as a selective histamine H1 receptor antagonist. When the body encounters allergens, such as pollen or pet dander, it triggers an allergic response, releasing histamine. mizolastine competitively binds to histamine H1 receptors on various cells throughout the body, effectively blocking histamine’s action. Doing so mitigates or prevents the allergic symptoms caused by histamine, including sneezing, runny or itchy nose, nasal congestion, and itchy/watery eyes. Significantly, mizolastine has limited penetration of the blood-brain barrier, resulting in a reduced likelihood of causing sedation or drowsiness compared to older-generation antihistamines. 

Spectrum: 

The spectrum of use for mizolastine is primarily centered on allergic conditions. It is commonly prescribed to treat allergic rhinitis, both seasonal and perennial, providing relief from symptoms such as sneezing, nasal congestion, and itchy, watery eyes. Additionally, mizolastine is used to manage chronic urticaria, a skin condition characterized by hives and itching, offering relief from itching and reducing the appearance of new hives.

It may also be employed for other allergy-related symptoms, including itching associated with various allergic skin conditions and allergic conjunctivitis. mizolastine’s non-sedating properties and effectiveness in managing allergic symptoms make it a valuable choice for individuals seeking relief from allergy-related discomfort without the drowsiness often associated with some antihistamines. 

Drug Interaction

Adverse Reaction

Frequency not defined 

Increased appetite 

Nausea 

Increased weight 

Dry mouth 

Transient drowsiness 

Diarrhea 

Abdominal pain 

Transient asthenia 

CNS depression 

Headache 

Dizziness 

Dyspepsia 

QT prolongation 

Black Box Warning

Black Box Warning: 

None 

Contraindication / Caution

Contraindication/Caution: 

Contraindication 

• Hypersensitivity or Allergy: mizolastine should not be used in individuals with a known hypersensitivity or allergy to mizolastine or its components. Allergic reactions can be severe, including rash, itching, swelling, and difficulty breathing. 
• Severe Liver Impairment: mizolastine is metabolized by the liver, and its elimination half-life may be prolonged in individuals with severe liver impairment. It is generally contraindicated in patients with severe hepatic (liver) dysfunction. Dose adjustments or alternative treatments may be necessary for individuals with mild to moderate liver impairment. 
• Children Under 12 Years: mizolastine is typically not recommended for use in children under 12, as its safety and efficacy in this age group have not been well established.  
• Pregnancy and Breastfeeding: The safety of mizolastine during pregnancy condition and breastfeeding has not been adequately studied. It is generally recommended to avoid using mizolastine during pregnancy condition unless the potential benefits outweigh the risks and under the supervision of a healthcare professional.  
• Elderly Patients: While not a strict contraindication, caution is advised when using mizolastine in elderly patients, as they may be more sensitive to its effects, including the potential for drowsiness or impaired coordination. Lower doses or alternative treatments may be considered. 
• Alcohol Use: mizolastine can potentiate the sedative effects of alcohol. Patients are generally advised to avoid excessive alcohol consumption while taking mizolastine, as it may increase the risk of drowsiness and impaired alertness. 

Caution 

• Driving and Operating Machinery: mizolastine can cause drowsiness in some individuals, although it is considered less sedating than older-generation antihistamines. Patients should generally exercise caution when engaging in activities requiring mental alertness, like driving or operating heavy machinery, especially when starting treatment or using higher doses. 
• Alcohol Use: Combining alcohol with mizolastine can potentiate the medication’s sedative effects. It is advisable to limit/avoid alcohol consumption while taking mizolastine to reduce the risk of drowsiness and impaired coordination. 
• Elderly Patients: Elderly individuals may be more sensitive to the effects of mizolastine, including the potential for drowsiness or impaired coordination. Lower doses may be considered in older patients to minimize these effects. 
• Renal Impairment: mizolastine is primarily excreted through the kidneys, and its elimination half-life may be prolonged in individuals with severe renal (kidney) impairment. Caution is advised in patients with moderate-severe renal impairment; dose adjustments may be necessary. 
• Cardiovascular Effects: Although mizolastine is generally considered non-drowsy, it may still have the potential to cause minor cardiovascular effects such as changes in heart rate. Patients with pre-existing cardiovascular conditions should use mizolastine with caution. 
• Other Medications: mizolastine has the potential to interact with other medications.  
• Pregnancy and Breastfeeding: The safety of mizolastine during pregnancy and breastfeeding has not been well established. Pregnant or breastfeeding individuals should consult the healthcare provider before using mizolastine, and alternative treatments may be considered. 
• Allergic Reactions: Although rare, allergic reactions to mizolastine can occur. If you experience symptoms such as rash, itching, swelling/difficulty breathing, stop taking the medication immediately and seek medical attention. 
• Duration of Use: mizolastine is typically intended for short-term use to relieve allergy symptoms. Prolonged or excessive use should be avoided, as it may lead to tolerance or diminished effectiveness. 

Pregnancy / Lactation

Pregnancy consideration:  

US FDA pregnancy category: Not assigned. 

Lactation:   

Excreted into human milk is 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: 

mizolastine is a second-generation antihistamine with a selective affinity for histamine H1 receptors. Its pharmacological action involves blocking the effects of histamine, an endogenous chemical mediator released during the allergic reactions, by competitively binding to H1 receptors on target cells in various tissues.

This antagonism of histamine receptors reduces the allergic response, alleviating symptoms such as itching, sneezing, nasal congestion, and itchy or watery eyes. mizolastine is considered a non-sedating antihistamine, as it has minimal soothing effects due to its limited penetration of the blood-brain barrier, making it suitable for daytime use. It also has a relatively long duration of action, allowing for once-daily dosing in most cases, and is well-tolerated by patients with a low risk of causing drowsiness. 

Pharmacodynamics: 

Mechanism of action: 

mizolastine action is primarily related to its selective histamine H1 receptor antagonist role.  

Histamine and Allergic Reactions: When the body encounters an allergen, like pollen or pet dander, it triggers an allergic response. One of the essential chemicals in this response is histamine, released by specialized immune cells called mast cells and basophils. Histamine binds to its receptors, particularly the histamine H1 receptors, located on various cells throughout the body. 

Competitive Binding: mizolastine is classified as an antihistamine because it competes with histamine for binding to H1 receptors. It does this by binding to the same receptors on target cells, such as those in the respiratory tract, skin, and blood vessels. 

Blockade of Histamine Effects: By binding to H1 receptors and preventing histamine from binding, mizolastine effectively blocks the effects of histamine. This action results in the reduction or suppression of various allergic symptoms, including: 

Sneezing: mizolastine can help reduce sneezing caused by histamine’s effects on the respiratory tract. 

Runny or Itchy Nose: It can alleviate the symptoms of a runny or itchy nose, common in allergic rhinitis. 

Nasal Congestion: mizolastine may help relieve nasal congestion by diminishing the dilation of blood vessels in the nasal passages. 

Itchy or Watery Eyes: It can alleviate itching and watering of the eyes associated with allergies. 

Limited Central Nervous System (CNS) Penetration: mizolastine has limited penetration of the blood-brain barrier, which means it has a lower likelihood of causing sedation or drowsiness than older-generation antihistamines. 

Duration of Action: mizolastine has a relatively long duration of action, allowing for once-daily dosing in most cases. 

Pharmacokinetics: 

Absorption 

mizolastine is typically administered orally and is well-absorbed from the gastrointestinal tract after oral ingestion. It is rapidly absorbed, with the peak plasma concentrations reached within one to two hours after ingestion. Food intake generally does not affect the absorption of mizolastine, which means it can be taken with or without food. 

Distribution 

Once absorbed into the bloodstream, mizolastine is distributed throughout the body. It can somewhat bind to plasma proteins, but the binding is relatively weak. mizolastine is lipophilic, which allows it to cross cell membranes and enter various tissues. It can also cross the BBB (blood-brain barrier) to a limited extent. Still, its central nervous system (CNS) penetration is less than some other antihistamines, contributing to its non-sedating properties. 

Metabolism 

mizolastine undergoes extensive hepatic (liver) metabolism. The primary metabolic pathway involves the cytochrome P450 enzyme system, primarily CYP3A4 and, to a lesser extent, CYP2D6. These enzymes metabolize mizolastine into several metabolites. The primary active metabolite is desmethylmizolastine, contributing to the drug’s antihistamine effects. The metabolites are less pharmacologically active than the parent compound. 

Elimination and Excretion 

mizolastine and its metabolites are primarily eliminated through renal (kidney) excretion. Approximately 40-50% of the administered dose is excreted in the urine, primarily metabolites. The remainder of the drug and its metabolites are excreted in the feces. The elimination half-life of mizolastine is about 10-12 hours, allowing for once-daily dosing in most cases. 

Adminstartion

Administration: 

Oral administration 

mizolastine is an oral medication available in the form of tablets or syrup. It is typically taken by mouth, and the administration instructions may vary depending on the specific product and the individual’s age.  

Dosage: mizolastine tablets are available in various strengths. Your healthcare provider will determine the recommended dosage and frequency based on your age, weight, the severity of your condition, and other factors. 

mizolastine syrup is usually prescribed for pediatric patients who have difficulty swallowing tablets. Your healthcare provider will determine the dosage based on the child’s age, weight, and the severity of the condition. 

Take with Water: Swallow the tablet whole with a glass of water. Do not crush, chew/break the tablet, as this can affect the medication is absorption and effectiveness. 

Timing: mizolastine is typically taken once daily. It can be taken with or without food, although taking it on an empty stomach may lead to faster absorption. 

Consistency: Try to take mizolastine at the same time each day to maintain a consistent level of the medication in your body and maximize its effectiveness. 

Follow Instructions: Always follow your healthcare provider’s instructions regarding the dosage and duration of treatment. Do not change the dose or stop taking mizolastine without consulting your healthcare provider. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: mizolastine 

Why do we use mizolastine? 

mizolastine is an antihistamine medication primarily used for the treatment of allergic conditions.  

• Allergic Rhinitis: mizolastine is commonly prescribed to relieve the symptoms of allergic rhinitis, both seasonal (hay fever) and perennial (year-round). It can help alleviate symptoms such as sneezing, runny or itchy nose, nasal congestion, and itchy or watery eyes. 
• Chronic Urticaria: mizolastine is also used in the treatment of chronic urticaria, a skin condition characterized by the appearance of hives (raised, itchy welts) that can last for more than six weeks. It helps reduce itching and the appearance of new hives. 
• Other Allergic Conditions: In some cases, mizolastine may be prescribed for other allergic symptoms or conditions, such as itching associated with various skin conditions and allergic conjunctivitis (eye allergies). 
• Pruritus (Itching): mizolastine may relieve itching associated with various dermatological conditions, including eczema, atopic dermatitis, and contact dermatitis.