Action and Spectrum

Actions and Spectrum: 

The actions of meclizine include: 

• Antihistamine: meclizine blocks the action of histamine in the body, which helps reduce allergic reactions. 
• Antiemetic: meclizine helps prevent nausea and vomiting associated with motion sickness and vertigo. 
• Vestibular suppressant: meclizine can suppress activity in the vestibular system, which is responsible for our sense of balance and spatial orientation. This can help alleviate symptoms of vertigo. 

The spectrum of meclizine includes: 

• Motion sickness: meclizine is often used to prevent and treat motion sickness, particularly in situations where there is a lot of movement, such as on boats, planes, or in cars. 
• Vertigo: meclizine is also commonly used to treat vertigo, a condition characterized by dizziness and a sensation of spinning or whirling. 
• Allergic reactions: meclizine can help alleviate symptoms of allergic reactions, such as itching, hives, and swelling. 
• Other conditions: meclizine may also be used to treat other conditions, such as nausea and vomiting caused by other medications or medical treatments, or as a sleep aid. 

Drug Interaction

Adverse Reaction

Frequency not defined 

Drowsiness 

Acute glaucoma attack 

Blurred vision  

Constipation 

Fatigue 

Vomiting 

Urinary retention 

Xerostomia 

Headache 

Black Box Warning

Contraindication / Caution

Contraindication/Caution: 

meclizine has several contraindications and precautions that should be taken into consideration before using this medication. These include: 

• Hypersensitivity: meclizine should not be used by individuals who have a known hypersensitivity or allergy to the medication. 
• Glaucoma: meclizine should be used with caution in individuals with glaucoma, a condition characterized by increased pressure in the eye. 
• Urinary retention: meclizine may worsen urinary retention, which is the inability to empty the bladder fully. 
• Respiratory depression: meclizine may cause respiratory depression, particularly in individuals who are also taking other medications that depress the central nervous system, such as opioids. 
• Pregnancy and breastfeeding: meclizine should be used with caution during pregnancy and breastfeeding, as its safety has not been fully established in these populations. 
• Children: meclizine is not recommended for use in children under 12 years old, as its safety and efficacy have not been established in this age group. 
• Elderly: meclizine should be used with caution in elderly individuals, as they may be more susceptible to the side effects of the medication, such as drowsiness and confusion. 

Pregnancy / Lactation

Pregnancy consideration:  

Category B 

Breastfeeding warnings:  

meclizine is not known for its secretion in breast milk  

Pregnancy category: 

• Category A: Satisfactory and well-controlled studies show no risk to the fetus in the first or later trimester. 
• Category B: There is no affirmation of risk to the fetus found in animal reproduction studies, and there are not enough studies on pregnant women. 
• Category C: Adverse effects on the fetus found with evidence in animal reproduction studies and no adequate evidence for a product in humans; Pregnant women must take care of the potential risks. 
• Category D: There is adequate data available with sufficient evidence of human fetal risk from various platforms. However, despite potential dangers may be used only in emergency cases for potential benefits. 
• Category X: Drugs listed in this category outweigh risks over benefits. The drug is not for pregnant women. 
• Category N: No data is available for the drug under this category. 

Pharmacology

Pharmacology: 

meclizine is a first-generation antihistamine that also has anticholinergic and antiemetic properties. Its pharmacological effects are mediated through its antagonism of histamine H1 receptors in the central nervous system, as well as its antagonism of muscarinic acetylcholine receptors. 

The antihistamine effect of meclizine is responsible for its ability to reduce symptoms of allergic reactions, such as itching, redness, and swelling. By blocking the action of histamine in the body, meclizine can help alleviate these symptoms. 

The anticholinergic effect of meclizine is responsible for its ability to reduce symptoms such as nausea, vomiting, and vertigo. By blocking the action of acetylcholine in the body, meclizine can help reduce the activity of the vestibular system in the inner ear, which is responsible for our sense of balance and spatial orientation. 

meclizine is well-absorbed after oral administration and reaches peak plasma concentrations within 3 to 4 hours. Its half-life is approximately 6 hours, and it is primarily metabolized in the liver and excreted in the urine. 

meclizine is available in various forms, including tablets, chewable tablets, and oral solutions. The dosage and administration of meclizine may vary depending on the individual’s medical history, age, and condition being treated, and should be determined by a healthcare provider. 

Pharmacodynamics: 

The pharmacodynamics of meclizine involve its actions on various receptors and neurotransmitters in the body, including: 

• Histamine H1 receptors: meclizine blocks the action of histamine on H1 receptors in the central nervous system, which helps reduce allergic reactions, such as itching, redness, and swelling. 
• Muscarinic acetylcholine receptors: meclizine blocks the action of acetylcholine on muscarinic receptors in the central nervous system, which helps reduce symptoms such as nausea, vomiting, and vertigo. 
• Serotonin receptors: meclizine has been shown to have some activity at serotonin receptors, particularly 5-HT3 receptors, which may contribute to its antiemetic effects. 
• Dopamine receptors: meclizine has been shown to have some activity at dopamine receptors, particularly D2 receptors, which may contribute to its antiemetic effects. 

Pharmacokinetics: 

Absorption 

The onset of action is 30-60 min 

The duration of action is 12-24 hours 

Peak plasma concentration is achieved in 3 hours 

Distribution 

The volume of distribution is 7 L/kg 

Metabolism 

The drug is dominantly metabolized by CYP2D6  

Elimination and Excretion 

The half-life is 5 hours 

The drug is excreted in urine and feces 

Adminstartion

Administration: 

meclizine is usually administered orally and is available in various forms, including tablets, chewable tablets, and oral solutions. The dosage and administration of meclizine may vary depending on the individual’s medical history, age, and condition being treated and should be determined by a healthcare provider. 

meclizine should be taken as directed by a healthcare provider or as indicated on the product label. It is typically taken with or without food, depending on the individual’s preference. meclizine should be swallowed whole and not crushed or chewed unless it is a chewable tablet. 

For the treatment of motion sickness, meclizine is typically taken 1 hour before travel and then every 24 hours as needed. The usual adult dose is 25-50 mg orally once daily, while the dose for children aged 12 years and above is 25 mg orally once daily. 

For the treatment of vertigo, the usual adult dose is 25-100 mg orally in divided doses throughout the day, while the dose for children aged 12 years and above is 25-50 mg orally in divided doses throughout the day. 

It is important to talk to a healthcare provider before using meclizine to ensure that it is safe and appropriate for your individual needs and medical history. Do not exceed the recommended dose or use meclizine for a longer duration than prescribed without consulting a healthcare provider. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: meclizine 

Pronounced: MEK-li-zeen 

Why do we use meclizine? 

meclizine is primarily used for the prevention and treatment of motion sickness and vertigo, which are conditions characterized by symptoms such as nausea, vomiting, and dizziness. 

Motion sickness occurs when the inner ear and eyes send conflicting signals to the brain about the body’s movement and position, leading to symptoms such as nausea, vomiting, and dizziness. meclizine works by blocking the action of histamine in the central nervous system and reducing activity in the vestibular system of the inner ear, which helps alleviate these symptoms. 

Vertigo is a sensation of spinning or movement, often accompanied by nausea and dizziness. meclizine is also used to treat vertigo by reducing activity in the vestibular system of the inner ear.