Usage
Chlorpheniramine Maleate + Phenylephrine is primarily prescribed for the short-term symptomatic relief of common cold, hay fever (allergic rhinitis), and sinusitis. This combination targets symptoms like runny nose, sneezing, itchy or watery eyes, itchy nose or throat, and nasal congestion. It is categorized as an antihistamine/decongestant.
The medication works through a dual mechanism: Chlorpheniramine maleate, an antihistamine, blocks histamine H1 receptors, reducing allergic symptoms like sneezing, runny nose, and itching. Phenylephrine hydrochloride, a decongestant, constricts blood vessels in the nasal passages, relieving nasal congestion.
Alternate Names
While “Chlorpheniramine Maleate + Phenylephrine Hydrochloride” represents the generic name, numerous brand names exist, varying by region and manufacturer. Popular brand names include Actifed Cold and Allergy, Allerest PE, Ed A-Hist, NoHist LQ, Suphedrine PE Sinus Plus Allergy, and Sinarest AF New.
How It Works
Pharmacodynamics: Chlorpheniramine competes with histamine for H1-receptor sites, primarily in blood vessels, gastrointestinal smooth muscle, and respiratory tract. This competitive antagonism counteracts histamine’s effects, diminishing vasodilation, capillary permeability, and smooth muscle contraction. Phenylephrine acts as an alpha-adrenergic receptor agonist, constricting blood vessels in the nasal mucosa and reducing congestion.
Pharmacokinetics: Both drugs are absorbed orally. Chlorpheniramine undergoes hepatic metabolism, primarily by CYP450 enzymes, and its metabolites are renally excreted. Phenylephrine is also metabolized in the liver by monoamine oxidase (MAO) and excreted in the urine. Absorption is faster in children, leading to a shorter half-life and duration of action (around 4-6 hours).
Mode of Action: At the molecular level, chlorpheniramine binds to the H1 receptor, preventing histamine from binding and triggering downstream effects like vasodilation and increased capillary permeability. Phenylephrine binds to alpha-adrenergic receptors on vascular smooth muscle, activating a signaling cascade that leads to vasoconstriction and reduced nasal congestion.
Elimination Pathways: Both drugs are primarily metabolized in the liver and excreted through the kidneys. Specific CYP enzymes involved in chlorpheniramine metabolism are not consistently specified in available sources.
Dosage
Standard Dosage
Adults:
For adults and children 12 years and older, the usual dose is one tablet or 5 mL (1 teaspoon) of liquid containing 4 mg chlorpheniramine and 10 mg phenylephrine, taken every 4 to 6 hours. The maximum daily dose should not exceed 6 tablets or 30 mL.
Children:
- 6 to 11 years: Half a tablet or 2.5 mL every 4 hours (maximum 3 tablets or 15 mL per day). For liquids containing 1 mg chlorpheniramine and 2.5 mg phenylephrine per 5 mL, 2.5 mL every 6 hours (maximum 4 doses in 24 hours).
- Under 6 years: Consult a pediatrician for appropriate dosing. For drops containing 1 mg chlorpheniramine and 2.5 mg phenylephrine per 1 mL:
- 2-5 years: 1.25 mL syrup or drops every 4 to 6 hours (maximum 7.5 mL per day)
- Under 2 years: Use is not recommended for certain formulations; consult a pediatrician.
Special Cases:
- Elderly Patients: Start with a lower dose due to potential increased sensitivity. Close monitoring is recommended.
- Patients with Renal Impairment: Dosage adjustment may be necessary based on creatinine clearance.
- Patients with Hepatic Dysfunction: Reduced dosage or increased dosing intervals are usually required.
- Patients with Comorbid Conditions: Pre-existing conditions like asthma, glaucoma, hypertension, diabetes, thyroid disease, cardiovascular disease, and prostatic hypertrophy require careful evaluation and potential dosage adjustments.
Clinical Use Cases
Chlorpheniramine + Phenylephrine is not typically used in clinical settings such as intubation, surgical procedures, mechanical ventilation, or ICU care. Its use is generally limited to outpatient management of mild to moderate cold and allergy symptoms.
Dosage Adjustments
Dose adjustments are necessary for patients with renal/hepatic dysfunction, elderly patients, and those with certain comorbid conditions. Consultation with a doctor is crucial in such cases.
Side Effects
Common Side Effects:
Drowsiness, dizziness, dry mouth/nose/throat, blurred vision, upset stomach, constipation, difficulty urinating, and trouble sleeping.
Rare but Serious Side Effects:
Allergic reactions (rash, itching, swelling, difficulty breathing), mental/mood changes (confusion, hallucinations), rapid/irregular heartbeat, seizures, high blood pressure, tremor, and difficulty urinating.
Long-Term Effects:
Long-term continuous use is not generally recommended as it can lead to tolerance and rebound congestion. Specific long-term side effects from prolonged appropriate use have not been clearly identified.
Adverse Drug Reactions (ADR):
Severe allergic reactions, cardiac arrhythmias, significant CNS effects (e.g., hallucinations, seizures).
Contraindications
- Hypersensitivity to chlorpheniramine, phenylephrine, or any component of the formulation.
- Severe hypertension or coronary artery disease.
- Narrow-angle glaucoma or urinary retention due to prostatic hypertrophy.
- Concurrent or recent use of MAO inhibitors.
- Patients with severe cardiovascular conditions, hyperthyroidism, or a history of stroke.
- Children under a specific age (varies by formulation; some are not recommended for children under 4 years).
Drug Interactions
- MAO inhibitors: Can cause severe hypertensive crisis.
- Antihistamines, sedatives, tranquilizers, and alcohol: Increased drowsiness and CNS depression.
- Tricyclic antidepressants, anticholinergics: Additive anticholinergic effects (dry mouth, blurred vision, urinary retention).
- Beta-blockers: May enhance the pressor effects of phenylephrine.
- Other sympathomimetics: Additive effects, potential for hypertension.
- Antidepressants (e.g., isocarboxazid, linezolid, phenelzine, tranylcypromine): Increased risk of serotonin syndrome and hypertensive crisis.
Pregnancy and Breastfeeding
- Pregnancy: Use with caution, only if the benefits outweigh the risks. Phenylephrine can potentially reduce uterine blood flow.
- Breastfeeding: Chlorpheniramine and phenylephrine can be excreted in breast milk. Consult a doctor before using during breastfeeding, as they may affect milk production or cause adverse effects in the infant.
Drug Profile Summary
- Mechanism of Action: Antihistamine (chlorpheniramine) blocks histamine H1 receptors; decongestant (phenylephrine) constricts nasal blood vessels.
- Side Effects: Drowsiness, dry mouth, dizziness, blurred vision, potential for serious cardiovascular and CNS effects.
- Contraindications: Hypersensitivity, severe hypertension, MAOI use, narrow-angle glaucoma, urinary retention, specific age limits.
- Drug Interactions: MAOIs, CNS depressants, anticholinergics, beta-blockers, sympathomimetics.
- Pregnancy & Breastfeeding: Use with caution; potential risks.
- Dosage: See detailed dosage section above.
- Monitoring Parameters: Blood pressure, heart rate, respiratory status, mental status, and urinary output.
Popular Combinations
Chlorpheniramine and phenylephrine are often combined with other medications, such as ibuprofen or dextromethorphan, for broader symptom relief, although not all combinations are appropriate for all patients.
Precautions
- General Precautions: Patient evaluation should include allergy history, existing medical conditions, and current medications.
- Specific Populations: See “Special Cases” under “Dosage.”
- Lifestyle Considerations: Avoid alcohol and operating machinery due to potential drowsiness.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Chlorpheniramine Maleate + Phenylephrine?
A: See detailed dosage section above.
Q2: Can this combination be used in children under 4 years old?
A: Some formulations are contraindicated in children under 4 years. Always consult a pediatrician for appropriate dosing in children.
Q3: What are the serious side effects to watch out for?
A: Severe allergic reactions, changes in mental status, heart rhythm abnormalities, high blood pressure, seizures, and difficulty urinating require immediate medical attention.
Q4: Can patients with high blood pressure take this medication?
A: Patients with severe or uncontrolled hypertension should avoid this medication. Those with mild to moderate hypertension should use it with caution and under medical supervision.
Q5: Can pregnant or breastfeeding women use this medication?
A: Use during pregnancy or breastfeeding should be under medical guidance and only if the benefits clearly outweigh the risks.
Q6: What should patients avoid while taking this medicine?
A: Alcohol, operating machinery, and other CNS depressants should be avoided.
Q7: What are the potential drug interactions?
A: See detailed “Drug Interactions” section above.
Q8: Are there any long-term effects of using this combination?
A: Long-term continuous use is generally not recommended and can lead to tolerance and rebound congestion. Appropriate intermittent use for symptom relief has not been clearly associated with long-term adverse effects.
Q9: What should be done if a dose is missed?
A: Take the missed dose as soon as remembered unless it’s close to the time for the next dose. Do not double the dose.
Q10: How should this medication be stored?
A: Store at room temperature away from heat, moisture, and direct light. Keep out of reach of children.
