Usage
- Dexchlorpheniramine + Phenylpropanolamine is prescribed for the temporary relief of symptoms associated with the common cold, allergies, and sinusitis, such as runny nose, sneezing, itchy and watery eyes, and nasal congestion.
- Pharmacological Classification: This combination medication includes a first-generation antihistamine (dexchlorpheniramine) and a decongestant (phenylpropanolamine).
- Mechanism of Action: Dexchlorpheniramine blocks the action of histamine, reducing allergic symptoms. Phenylpropanolamine constricts blood vessels in the nasal passages, relieving congestion.
Alternate Names
- While the generic name is Dexchlorpheniramine + Phenylpropanolamine, specific brand names can vary regionally. Some examples might include formulations containing these ingredients under different product names (e.g., containing variations with chlorpheniramine maleate instead of dexchlorpheniramine). Due to safety concerns related to phenylpropanolamine, this exact combination might not be readily available in some regions.
How It Works
- Pharmacodynamics: Dexchlorpheniramine acts as an inverse agonist at the H1 histamine receptor, reducing the effects of histamine release. Phenylpropanolamine acts as an alpha-adrenergic agonist, constricting blood vessels in the nasal mucosa.
- Pharmacokinetics: Both drugs are absorbed orally. Dexchlorpheniramine is metabolized in the liver, primarily by CYP2D6 enzymes, and has a half-life of 20-30 hours. Phenylpropanolamine is also metabolized in the liver and excreted in the urine.
- Mode of Action: Dexchlorpheniramine competes with histamine for H1 receptor sites, thereby reducing the effects of histamine on blood vessels, smooth muscle, and glands. Phenylpropanolamine stimulates alpha-adrenergic receptors, causing vasoconstriction in the nasal mucosa.
- Elimination Pathways: Dexchlorpheniramine is primarily eliminated via hepatic metabolism with subsequent urinary excretion of metabolites. Phenylpropanolamine is predominantly excreted in the urine.
Dosage
Standard Dosage
Adults:
- Dexchlorpheniramine: 2 mg every 4-6 hours.
- Phenylpropanolamine: 12.5-25 mg every 4-6 hours (not to exceed 150mg/day). Note: Formulations containing phenylpropanolamine may not be available in all regions due to safety concerns.
Children:
- Dosing varies based on age and weight. Consult a pediatrician or refer to specific product labeling for pediatric dosing guidelines.
- Pediatric Safety Considerations: Use with caution in young children as they may be more susceptible to side effects such as excitement, nervousness, and irritability.
Special Cases:
- Elderly Patients: Start with a lower dose and monitor closely for adverse effects like dizziness, confusion, and urinary retention.
- Patients with Renal Impairment: Dosage adjustments may be necessary.
- Patients with Hepatic Dysfunction: Dosage adjustments may be necessary due to altered metabolism.
- Patients with Comorbid Conditions: Caution should be exercised in patients with hypertension, cardiovascular disease, hyperthyroidism, glaucoma, and prostatic hyperplasia.
Clinical Use Cases
Due to potential safety concerns, this combination is generally not recommended for use in clinical settings such as intubation, surgical procedures, mechanical ventilation, intensive care units, or emergency situations. Other medications are generally preferred for these specific scenarios.
Dosage Adjustments
Adjustments may be needed based on renal or hepatic impairment, age, and other concomitant medications. Consider therapeutic drug monitoring where appropriate.
Side Effects
Common Side Effects
- Drowsiness
- Dizziness
- Dry mouth
- Blurred vision
- Constipation
- Nausea
Rare but Serious Side Effects
- Allergic reactions (e.g., rash, itching, swelling)
- Cardiovascular events (e.g., increased heart rate, palpitations, hypertension)
- Seizures
- Difficulty urinating
Long-Term Effects
Chronic use of phenylpropanolamine has been associated with a potential increased risk of hemorrhagic stroke, though this is rare.
Adverse Drug Reactions (ADR)
Severe allergic reactions, significant cardiovascular events, and neurological symptoms require immediate medical attention.
Contraindications
- Hypersensitivity to dexchlorpheniramine, phenylpropanolamine, or any component of the formulation.
- Newborns or premature infants.
- Breastfeeding mothers.
- Narrow-angle glaucoma.
- Urinary retention.
- Severe cardiovascular disease.
- Concomitant MAOI therapy.
- Severe hepatic or renal impairment.
Drug Interactions
- MAOIs
- Alcohol
- CNS depressants (e.g., sedatives, hypnotics, opioids)
- Antihypertensives
- Other sympathomimetics
Pregnancy and Breastfeeding
- Pregnancy Safety Category: C (FDA classification). Not recommended due to potential risks associated with phenylpropanolamine.
- Breastfeeding: Not recommended. Both drugs can be excreted in breast milk and may affect the nursing infant.
Drug Profile Summary
- Mechanism of Action: Dexchlorpheniramine: H1 receptor inverse agonist; Phenylpropanolamine: Alpha-adrenergic agonist.
- Side Effects: Drowsiness, dizziness, dry mouth, blurred vision, constipation, potential for serious cardiovascular effects with phenylpropanolamine.
- Contraindications: Hypersensitivity, newborns/premature infants, breastfeeding, MAOI use, severe liver/kidney disease, narrow-angle glaucoma, urinary retention.
- Drug Interactions: MAOIs, alcohol, CNS depressants, antihypertensives, sympathomimetics.
- Pregnancy & Breastfeeding: Not recommended.
- Dosage: Adults: 2 mg dexchlorpheniramine, 12.5-25 mg phenylpropanolamine every 4-6 hours; Pediatric: Consult product labeling.
- Monitoring Parameters: Blood pressure, heart rate.
Popular Combinations
Dexchlorpheniramine is often combined with other decongestants, such as phenylephrine, but the combination with phenylpropanolamine is less common due to safety concerns.
Precautions
- Screen for allergies, cardiovascular disease, glaucoma, and other contraindicated conditions.
- Avoid or use with caution in elderly, children, pregnant or breastfeeding women.
- Limit alcohol intake.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Dexchlorpheniramine + Phenylpropanolamine?
A: The typical adult dose is 2 mg dexchlorpheniramine and 12.5-25 mg phenylpropanolamine every 4-6 hours. Pediatric doses vary; consult product labeling. This combination might not be available in all regions.
Q2: What are the common side effects?
A: Common side effects include drowsiness, dizziness, dry mouth, blurred vision, and constipation.
Q3: Is this combination safe during pregnancy or breastfeeding?
A: No. Both are contraindicated in pregnancy and breastfeeding.
Q4: What are the serious side effects to watch out for?
A: Serious, although rare, side effects can include cardiovascular issues (hypertension, palpitations), allergic reactions, and difficulty urinating.
Q5: What medications should be avoided while taking this combination?
A: Avoid alcohol, MAOIs, and other CNS depressants. Use caution with antihypertensives and other sympathomimetics.
Q6: What are the contraindications for this drug?
A: Contraindications include hypersensitivity, newborns/premature infants, breastfeeding, narrow-angle glaucoma, urinary retention, severe cardiovascular disease, and concomitant MAOI therapy.
Q7: What conditions does this combination treat?
A: It’s used for symptomatic relief of common cold, allergy, and sinusitis symptoms such as nasal congestion, runny nose, sneezing, and itchy/watery eyes.
Q8: Are there any long-term risks associated with its use?
A: While rare, long-term use of phenylpropanolamine has been associated with a potential increased risk of hemorrhagic stroke.
Q9: Why might this specific combination not be available in my region?
A: Due to the risk of hemorrhagic stroke associated with phenylpropanolamine, the FDA has recommended against its use, leading to its removal from the market in some regions. This combination is less common than combinations containing other decongestants, such as phenylephrine.
