Usage
This combination medication is primarily prescribed to address vertigo (a spinning sensation) and motion sickness, often alongside nutritional supplementation to prevent or treat folic acid deficiency. Meclizine, an antihistamine, targets the vestibular system to alleviate dizziness, nausea, and vomiting. Folic acid is crucial for cell growth and development, particularly during pregnancy, to prevent neural tube defects.
Pharmacological Classification:
- Meclizine: Antiemetic, Antihistamine
- Folic Acid: Water-soluble Vitamin, Nutritional Supplement
Mechanism of Action:
Meclizine acts as an antagonist at H1 histamine receptors and muscarinic acetylcholine receptors. This inhibits vestibular stimulation and suppresses the chemoreceptor trigger zone in the brain, reducing nausea and vomiting. Folic acid is converted into tetrahydrofolic acid, a coenzyme essential for various metabolic processes, including DNA synthesis and cell division.
Alternate Names
While “Folic Acid + Meclizine” is a descriptive name, the individual components have alternate names. Folic acid is also known as folate, pteroylmonoglutamic acid, and vitamin B9. Meclizine may be referred to as meclizine hydrochloride.
Brand Names:
Brand names for meclizine include Antivert®, Bonine®, and Dramamine Less Drowsy®. Combinations with folic acid might be marketed under different brand names depending on the region and manufacturer. Examples include Meczine and Mexzine, though these might not be available in all markets.
How It Works
Pharmacodynamics:
Meclizine primarily affects the central nervous system, targeting the vestibular system and the chemoreceptor trigger zone. It reduces the sensitivity to motion and diminishes the signals that trigger nausea and vomiting. Folic acid participates in numerous metabolic pathways related to cell growth and division, impacting hematopoiesis (blood cell formation) and the development of the nervous system.
Pharmacokinetics:
- Meclizine: Well-absorbed orally, extensively metabolized in the liver (primarily via CYP2D6), and excreted through urine and feces. Half-life is approximately 6 hours.
- Folic Acid: Absorbed primarily in the jejunum, metabolized in the liver, and excreted in urine and bile.
Mode of Action/Receptor Binding/Enzyme Inhibition/Neurotransmitter Modulation:
Meclizine acts as an antagonist at H1 histamine receptors and muscarinic acetylcholine receptors. It doesn’t inhibit CYP enzymes significantly. Folic acid is itself a substrate for dihydrofolate reductase, which converts it to its active form, tetrahydrofolic acid.
Elimination Pathways:
Meclizine is eliminated through both renal and hepatic routes. Folic acid is eliminated through renal excretion and biliary elimination.
Dosage
The dosage for this combination medication is determined by the individual components.
Standard Dosage
Adults:
- Meclizine (for vertigo): 25-100 mg per day, divided into multiple doses.
- Meclizine (for motion sickness): Initial dose: 25-50 mg one hour before travel, repeated every 24 hours as needed.
- Folic acid: 400 mcg (0.4 mg) daily for general supplementation. Higher doses (e.g., 4 mg/day) might be prescribed for specific conditions like preventing neural tube defects.
Children:
- Meclizine: Not generally recommended for children under 12 years. If necessary, consult a pediatrician for appropriate dosing adjustments. For children 12 and older, follow adult motion sickness dosing.
- Folic Acid: Dosing varies depending on age and specific requirements; consult pediatric resources or a pediatrician.
Special Cases:
- Elderly Patients: Start with lower doses and monitor carefully due to potential for increased sensitivity.
- Patients with Renal Impairment: Use with caution; dose adjustments might be needed based on creatinine clearance.
- Patients with Hepatic Dysfunction: Use with caution; reduced doses might be necessary due to decreased metabolism.
- Patients with Comorbid Conditions: Consider existing conditions, especially glaucoma, asthma, and prostatic hypertrophy.
Clinical Use Cases
The primary clinical use cases are vertigo and motion sickness. Folic acid supplementation is for deficiency prevention or treatment. The provided sources do not mention dosages for clinical scenarios like intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations.
Dosage Adjustments
Dosage adjustments are required for elderly patients, and patients with hepatic or renal impairments.
Side Effects
Common Side Effects:
- Drowsiness
- Dry mouth
- Blurred vision
- Headache
- Fatigue
Rare but Serious Side Effects:
- Allergic reactions (anaphylaxis, bronchospasm)
- Seizures
- Confusion
- Depression
Long-Term Effects:
Long-term effects of meclizine use, especially in the elderly, may include cognitive impairment.
Adverse Drug Reactions (ADR):
ADRs requiring immediate intervention include allergic reactions and seizures.
Contraindications
- Hypersensitivity to meclizine or any component of the formulation
- Narrow-angle glaucoma
- Prostatic hypertrophy
- Urinary retention
- Pyloric or duodenal obstruction
Drug Interactions
- Alcohol (increases drowsiness)
- CNS depressants (e.g., sedatives, opioids)
- Anticholinergic drugs (additive anticholinergic effects)
- Other medications metabolized by CYP2D6
Pregnancy and Breastfeeding
- Pregnancy: Meclizine is classified as Pregnancy Category B. While animal studies haven’t shown fetal harm, human data are limited. Use only if clearly needed. Folic acid is generally recommended during pregnancy to prevent neural tube defects.
- Breastfeeding: Meclizine passes into breast milk. Use with caution and only if clearly necessary. Folic acid is considered safe during breastfeeding.
Drug Profile Summary
- Mechanism of Action: Meclizine: Antihistamine, antiemetic; Folic Acid: Essential vitamin.
- Side Effects: Drowsiness, dry mouth, blurred vision.
- Contraindications: Hypersensitivity, glaucoma, prostatic hypertrophy.
- Drug Interactions: Alcohol, CNS depressants, anticholinergic drugs.
- Pregnancy & Breastfeeding: Meclizine: use with caution; Folic Acid: generally safe.
- Dosage: See detailed dosage section above.
- Monitoring Parameters: Liver function, renal function (especially in long-term use).
Popular Combinations
A popular combination is meclizine with folic acid, as prescribed to address both vertigo/motion sickness and ensure adequate folic acid levels.
Precautions
- Monitor for drowsiness and avoid activities requiring alertness.
- Pre-existing conditions (glaucoma, asthma, prostatic hypertrophy) necessitate caution.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Folic Acid + Meclizine?
A: The dosage varies depending on individual needs and the condition being treated. See the Dosage section for detailed information.
Q2: Can this combination be used in children?
A: Meclizine is generally not recommended for children under 12. Folic acid dosing in children is age-dependent; consult pediatric resources.
Q3: What are the common side effects?
A: Common side effects include drowsiness, dry mouth, blurred vision, and headache.
Q4: Are there any contraindications?
A: Yes, contraindications include hypersensitivity, glaucoma, and prostatic hypertrophy. See the Contraindications section for a complete list.
Q5: What should patients do if they miss a dose?
A: Take the missed dose as soon as remembered, unless it is close to the next scheduled dose. Do not double the dose.
Q6: How should this medication be stored?
A: Store at room temperature, away from light and moisture.
Q7: Can pregnant or breastfeeding women take this combination?
A: Consult a doctor before using during pregnancy or breastfeeding. Meclizine should be used cautiously during pregnancy. Folic acid is generally recommended during pregnancy.
Q8: Does Meclizine interact with alcohol?
A: Yes, alcohol can increase the sedative effects of meclizine. Avoid alcohol while taking this medication.
Q9: What are the potential drug interactions with meclizine?
A: Meclizine may interact with other CNS depressants, anticholinergic drugs, and certain medications metabolized by CYP2D6. Provide a complete medication list to your doctor.
Q10: How does renal impairment affect Meclizine dosage?
A: Renal impairment can affect the elimination of Meclizine. Dose adjustments might be needed; consult a doctor.
