Pheniramine Maleate (Avil)

Pheniramine Maleate, commonly marketed under the brand name Avil, is a first-generation antihistamine widely used to treat allergic reactions. As a potent H1 receptor antagonist, Pheniramine Maleate works by blocking histamine activity, alleviating symptoms such as sneezing, runny nose, itching, and skin rashes. Due to its mild sedative effect, it is also employed in cases of motion sickness and insomnia.

Uses of Pheniramine Maleate

Pheniramine Maleate is extensively used for various allergic conditions and other medical purposes, including:

Treatment of seasonal allergic rhinitis (hay fever)
Relief from urticaria (hives) and eczema
Management of insect bites and stings
Adjunct therapy for anaphylaxis alongside epinephrine
Treatment of drug and food allergies
Motion sickness and nausea
Sedative purposes in minor cases of insomnia
Used in combination with other medications for cold and flu relief

Dosage and Administration

Pheniramine Maleate dosage varies based on age, condition, and severity.

General Dosage Guidelines:

Adults: 25–50 mg orally, up to three times daily
Children (5-10 years): 10–15 mg, up to three times daily
Children (above 10 years): 15–30 mg, up to three times daily
Elderly Patients: Dose should be adjusted due to increased susceptibility to sedation and dizziness

Pheniramine Maleate is available in various forms such as tablets, syrups, and injectables. It should be taken with or without food but is best avoided with alcohol due to its sedative effects.

Dose Adjustment in Different Diseases

Hepatic Impairment: Requires dose reduction due to potential liver metabolism issues.
Renal Impairment: Adjustments needed for those with moderate to severe kidney dysfunction to prevent toxicity.
Cardiovascular Disease: Used with caution due to potential arrhythmia risk.
Pregnancy and Lactation: Should be avoided unless prescribed by a physician.

Drug Combinations in Use

Pheniramine Maleate is often combined with other drugs to enhance therapeutic effects:

Combination Drug	Purpose
Paracetamol	Used in cold and flu medications for fever and pain relief
Caffeine	Helps counteract sedation caused by Pheniramine Maleate
Phenylephrine	Used in decongestants to relieve nasal congestion
Codeine	Found in cough syrups for suppressing severe cough

Presentation or Form

Pheniramine Maleate is available in the following forms:

Tablets (25 mg, 50 mg) – Used for oral administration
Syrup (2 mg/ml) – For pediatric and geriatric patients
Injectable solution (45.5 mg/ml) – Used in emergency allergic reactions

Pharmacokinetics of Pheniramine Maleate

Absorption: Rapidly absorbed from the gastrointestinal tract
Onset of Action: 30 minutes post-administration
Peak Plasma Concentration: Achieved within 1–3 hours
Metabolism: Primarily hepatic metabolism
Excretion: Eliminated via the kidneys with a half-life of approximately 16–19 hours

Pharmacodynamics of Pheniramine Maleate

Pheniramine Maleate exerts its effects by blocking H1 histamine receptors, preventing histamine-induced symptoms such as itching, swelling, and vasodilation. It also has mild anticholinergic and sedative properties, contributing to drowsiness and dry mouth.

Drug Interactions

Pheniramine Maleate interacts with several drugs, leading to enhanced or diminished effects:

Central Nervous System Depressants (e.g., alcohol, benzodiazepines): Increased sedation
Monoamine Oxidase Inhibitors (MAOIs): Potentiated antihistaminic effects
Anticholinergic Drugs: Increased risk of dry mouth, constipation, and urinary retention
Beta-Blockers: May exacerbate hypotension

Comparison with Other Drugs of the Same Category

Drug Name	Sedation Level	Duration of Action	Uses
Pheniramine Maleate	Moderate	16-19 hours	Allergies, motion sickness, insomnia
Diphenhydramine	High	4-8 hours	Insomnia, severe allergies
Loratadine	Low	24 hours	Seasonal allergies
Cetirizine	Low	24 hours	Allergies, urticaria

Precautions and Special Considerations

Should not be used while operating heavy machinery or driving due to drowsiness
Not recommended in patients with severe hypertension or arrhythmias
Avoid alcohol consumption to prevent excessive sedation
Should be used cautiously in asthmatic patients as it may thicken bronchial secretions

Toxicity and Overdose

Overdose symptoms of Pheniramine Maleate include:

Extreme drowsiness
Confusion and agitation
Hallucinations
Seizures
Respiratory depression

Antidote

In case of an overdose, symptomatic and supportive treatment is recommended. Gastric lavage, activated charcoal administration, and IV fluids may be necessary. Severe cases may require mechanical ventilation.

Effects of Pheniramine Maleate

Positive Effects: Effective relief from allergies, itching, and inflammation
Negative Effects: Drowsiness, dizziness, dry mouth, nausea, blurred vision
Long-Term Effects: Prolonged use can lead to tolerance, dependency, and cognitive impairment in elderly patients

Recent Updates (2025) and Guidelines

2025 Guidelines: Recent studies suggest Pheniramine Maleate should be used cautiously in the elderly due to increased fall risk.
New Formulations: Research is exploring a controlled-release version to reduce drowsiness while maintaining efficacy.
Regulatory Updates: Certain countries are considering restricting over-the-counter availability due to misuse.

Facts to Remember

Pheniramine Maleate is a first-generation antihistamine.
It has sedative properties unlike second-generation antihistamines.
It is often used in cold and flu medications.
Available in tablet, syrup, and injectable forms.
Overdose can cause serious CNS depression and cardiac toxicity.

References

British National Formulary (BNF) 2025
World Health Organization (WHO) Allergy Treatment Guidelines
National Institute for Health and Care Excellence (NICE) Guidelines
European Medicines Agency (EMA) Drug Safety Report
Recent Clinical Trials on Antihistamines – PubMed Database (2025)

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