Mebastin50 mg

Established / Labeled Uses

• Allergic rhinitis (seasonal/perennial hay fever, vasomotor rhinitis) — Mebastin 50 mg is used for symptomatic relief of sneezing, nasal itching, and rhinorrhea.
• Urticaria (hives) and pruritus — Mebastin 50 mg relieves itching and skin wheals associated with allergic skin reactions.
• Allergic dermatoses and eczema — used adjunctively for itching related to allergic skin conditions.
• Allergic conjunctivitis — for itching and irritation of the eyes due to allergy.
• Insect bite reactions and drug rash — for symptomatic relief of localized allergic itching/swelling.

Guideline/Adjunct Use

• Allergic (extrinsic) asthma — Mebastin 50 mg may be used as an adjunct to standard bronchodilator/anti-inflammatory asthma therapy for allergic symptom relief; it is not a substitute for controller asthma therapy.

Note: Mebastin 50 mg is not marketed or FDA-approved in the United States; the uses above reflect labeling and clinical use in countries where it is marketed (including Bangladesh).

Each tablet commonly contains 50 mg of Mebastin 50 mg as the active ingredient, formulated with standard pharmaceutical excipients. Mebastin 50 mg is also available in some markets as an oral suspension/syrup for pediatric use.

Mebastin 50 mg is a first-generation (older, sedating) antihistamine belonging to the H1-receptor antagonist class of drugs. It is used for the symptomatic relief of allergic conditions caused by histamine release, such as itching, hives, and allergic rhinitis.

Mebastin 50 mg works by competitively blocking histamine at H1 receptors, reducing symptoms such as itching, sneezing, watery eyes, and skin wheals. Like other first-generation antihistamines, it crosses the blood-brain barrier and commonly causes sedation.

Mebastin 50 mg belongs to the first-generation (sedating) H1-antihistamine class, also categorized as an antiallergic / antipruritic agent.

Mebastin 50 mg is a competitive, reversible antagonist at peripheral and central histamine H1 receptors. By blocking H1 receptors, it prevents histamine-mediated increases in capillary permeability, smooth muscle contraction, and sensory nerve stimulation, thereby reducing itching, wheal-and-flare responses, sneezing, and rhinorrhea.

Mebastin 50 mg also possesses mild anticholinergic (antimuscarinic) activity, which can contribute to side effects such as dry mouth and urinary retention. As a first-generation antihistamine, it penetrates the blood-brain barrier and produces central nervous system depression, manifesting clinically as drowsiness and sedation. Onset of action is generally within 15-60 minutes of oral administration.

Mebastin 50 mg tablets are taken orally, generally with or after meals to minimize stomach upset. Swallow tablets with water; for young children, tablets may be crushed and mixed with a small amount of soft food or liquid immediately before giving. Doses should be spaced evenly across the day as directed. Do not exceed the prescribed dose or frequency (see Dosage and Administration for exact amounts).

• CNS depressants (alcohol, sedatives, hypnotics, opioids): Mebastin 50 mg can add to the sedative effects of these agents, causing pronounced drowsiness and impaired coordination; concurrent use should be avoided.
• Anticholinergic drugs (e.g., atropine, tricyclic antidepressants): Mebastin 50 mg may enhance anticholinergic effects (dry mouth, urinary retention, constipation, blurred vision) when combined with other anticholinergic agents.
• Ototoxic drugs (e.g., aminoglycoside antibiotics): Mebastin 50 mg, like other antihistamines, may mask early symptoms of ototoxicity (tinnitus, dizziness), potentially delaying recognition of hearing damage; caution is advised when co-administered with ototoxic medicines.
• Monoamine oxidase inhibitors (MAOIs): may theoretically prolong and intensify the anticholinergic and sedative effects of Mebastin 50 mg; concurrent use should be approached with caution.

The most common adverse effect is sedation/drowsiness, which is typically dose-related. Other reported side effects include:

• Dizziness, headache, and muscular weakness
• Dry mouth, blurred vision, and other mild anticholinergic effects
• Gastrointestinal upset: nausea, vomiting, epigastric pain, diarrhea, or constipation
• Hypotension (uncommon)
• Tinnitus
• Paradoxical CNS stimulation or, rarely, depression/mood changes

Severe allergic reactions (e.g., rash, angioedema) to Mebastin 50 mg itself are rare but should prompt immediate discontinuation and medical attention.

Pregnancy: The safety of Mebastin 50 mg in pregnancy has not been well established through controlled human studies. Use during the first trimester is generally best avoided. Mebastin 50 mg should be used in pregnancy only if clearly needed and if the potential benefit justifies the potential risk to the fetus; a physician should always be consulted before use.

Lactation: It is not well established whether Mebastin 50 mg passes into breast milk. As a sedating first-generation antihistamine, there is a theoretical risk of drowsiness or irritability in the nursing infant. Mebastin 50 mg should be used during breastfeeding only under medical advice, weighing benefits against potential risks to the infant.

• Sedation: Mebastin 50 mg commonly causes drowsiness. Patients should avoid driving, operating machinery, or performing other tasks requiring mental alertness until they know how they respond.
• Alcohol and CNS depressants: Concurrent alcohol consumption should be avoided while taking Mebastin 50 mg, as it can significantly worsen sedation and impaired coordination.
• Narrow-angle glaucoma: Mebastin 50 mg has mild anticholinergic activity and should be used with caution in patients with narrow-angle glaucoma, as it may worsen intraocular pressure.
• Urinary retention/benign prostatic hyperplasia (BPH): Use with caution, as anticholinergic effects may worsen urinary retention.
• Asthma/COPD: Mebastin 50 mg may thicken bronchial secretions; use with caution in patients with asthma or chronic obstructive pulmonary disease.
• Elderly patients: Older adults are more sensitive to sedative and anticholinergic effects and are at increased risk of confusion, dizziness, and falls; use the lowest effective dose with close monitoring.
• Hepatic/renal impairment: Mebastin 50 mg should be used cautiously, as drug clearance may be reduced.

Overdose with Mebastin 50 mg may cause marked drowsiness or, particularly in young children, paradoxical CNS excitation (restlessness, tremor, hallucinations), along with anticholinergic effects such as dry mouth, flushing, fixed dilated pupils, urinary retention, and rapid heartbeat. Severe overdose can potentially cause seizures, loss of consciousness, or cardiorespiratory compromise.

If overdose with Mebastin 50 mg is suspected, seek immediate medical attention or contact a poison control center/emergency services right away. Treatment is generally supportive and should only be given in a medical facility; do not attempt specific home treatment.

Store at room temperature (below 30°C), away from light and moisture. Keep out of reach of children.

• Elderly: Increased sensitivity to sedative and anticholinergic effects; use the lowest effective dose with caution (see Precautions and Warnings).
• Pregnant and breastfeeding women: Use only if clearly needed under medical advice (see Pregnancy and Lactation).
• Children: Mebastin 50 mg should be dosed conservatively by age (see Pediatric Uses and Dosage and Administration); safety and efficacy in infants under 2 years are not firmly established.
• Hepatic/renal impairment: Use with caution; no formal dose-adjustment data are available.

Mebastin 50 mg is generally intended for short-term, symptomatic relief of acute allergic symptoms (typically a few days to about 2 weeks). For chronic or recurrent allergic conditions (e.g., chronic urticaria or persistent allergic rhinitis), the duration of treatment should be individualized and determined by the prescribing physician, with periodic reassessment. It should not be used continuously for prolonged periods without medical supervision.

First-generation (sedating) antihistamine; H1-receptor antagonist; antiallergic/antipruritic agent.

Mebastin 50 mg acts by competitively and reversibly antagonizing histamine at H1-receptor sites on effector cells (blood vessels, bronchial and gut smooth muscle, and sensory nerve endings), without preventing histamine release itself. This blocks the downstream allergic effects of histamine, including vasodilation, increased vascular permeability, and pruritus.

Mebastin 50 mg has been used in children for allergic symptoms based on local pediatric age-based dosing schedules (see Dosage and Administration), typically starting from around 2 years of age under medical guidance. Tablets may be crushed and mixed with food or liquid for children who cannot swallow them whole.

The safety and efficacy of Mebastin 50 mg in infants under 2 years of age, and especially in neonates, have not been well established, and use in this age group is generally not recommended except under direct physician supervision. As with other sedating antihistamines, children may show paradoxical excitation rather than sedation; parents/caregivers should be advised to monitor for unusual behavioral changes and to consult a physician before giving Mebastin 50 mg to young children.