Usage
This combination medication is primarily used for the temporary relief of symptoms associated with the common cold and allergies, particularly those affecting the upper respiratory tract. These symptoms include nasal congestion, runny nose, sneezing, and cough. It is also used to treat dry cough associated with allergic reactions.
Pharmacological Classification: This product combines drugs from different classes:
- Phenylephrine: Decongestant (alpha-1 adrenergic agonist)
- Pholcodine: Cough suppressant (opioid antitussive)
- Promethazine: Antihistamine (H1 receptor antagonist) and antiemetic
Mechanism of Action:
- Phenylephrine: Constricts blood vessels in the nasal mucosa, reducing swelling and congestion.
- Pholcodine: Suppresses the cough reflex by acting on the cough center in the medulla oblongata.
- Promethazine: Blocks the effects of histamine, relieving allergic symptoms like sneezing and runny nose. It also possesses antiemetic properties via action on the chemoreceptor trigger zone.
Alternate Names
This combination may be referred to as Promethazine-Phenylephrine-Pholcodine. No widely recognized international non-proprietary name (INN) exists. Brand names vary regionally. An example is Kidylinctus.
How It Works
Pharmacodynamics:
- Phenylephrine: Acts as a vasoconstrictor, primarily affecting alpha-1 adrenergic receptors in the nasal mucosa. This leads to reduced blood flow and edema, relieving nasal congestion.
- Pholcodine: Acts centrally on the cough center in the brain to suppress the cough reflex.
- Promethazine: Antagonizes the H1 histamine receptors, reducing the effects of histamine release, thus relieving allergy symptoms. It also has anticholinergic effects, contributing to its sedative properties.
Pharmacokinetics:
- Absorption: All three components are absorbed orally.
- Metabolism: Primarily hepatic metabolism for all components.
- Elimination: Mainly renal excretion.
Mode of Action:
- Phenylephrine: Stimulates alpha-1 adrenergic receptors, causing vasoconstriction.
- Pholcodine: Depresses the cough reflex at the level of the medulla.
- Promethazine: Competes with histamine for H1 receptor sites, preventing histamine from binding and exerting its effects.
Receptor Binding, Enzyme Inhibition, or Neurotransmitter Modulation:
- Phenylephrine: Alpha-1 adrenergic receptor agonist.
- Pholcodine: Acts on opioid receptors in the cough center, though it is less potent than codeine.
- Promethazine: H1 receptor antagonist.
Elimination Pathways:
- Primarily renal excretion for all three drugs, though hepatic metabolism plays a role.
Dosage
Standard Dosage
Adults:
5 mL (1 teaspoonful) every 4 to 6 hours, not to exceed 30 mL in a 24-hour period.
Children:
- Under 2 years: Contraindicated due to risk of respiratory depression.
- 2 to under 6 years: 1.25 to 2.5 mL (¼ to ½ teaspoonful) every 4 to 6 hours.
- 6 to under 12 years: 2.5 to 5 mL (½ to 1 teaspoonful) every 4 to 6 hours, not exceeding 30 mL in 24 hours.
- 12 years and over: Adult dosage applies.
Special Cases:
- Elderly Patients: Initiate with lower dose due to potential increased sensitivity to sedative and anticholinergic effects, as well as age-related decline in hepatic and renal function. Close monitoring is essential.
- Patients with Renal Impairment: Dose adjustment may be necessary. Monitor renal function.
- Patients with Hepatic Dysfunction: Dose reduction may be required. Monitor liver function tests.
- Patients with Comorbid Conditions: Use cautiously in patients with cardiovascular disease, hypertension, diabetes, hyperthyroidism, glaucoma, prostatic hypertrophy, or asthma. Adjust dosage accordingly.
Clinical Use Cases
The combination of phenylephrine, pholcodine, and promethazine is generally not indicated for use in specialized clinical settings like intubation, surgical procedures, mechanical ventilation, or the ICU. Its primary use is for symptomatic relief of common cold and allergy symptoms in an outpatient setting.
Dosage Adjustments
Dose adjustments should be considered based on patient-specific factors like age, renal and hepatic function, and the presence of comorbid conditions.
Side Effects
Common Side Effects
Drowsiness, dizziness, dry mouth, blurred vision, constipation, nausea, and vomiting.
Rare but Serious Side Effects
Respiratory depression (especially in children under 2), allergic reactions (including anaphylaxis), seizures, hallucinations, extrapyramidal symptoms (e.g., dystonia, oculogyric crisis), neuroleptic malignant syndrome, jaundice, and blood dyscrasias (leukopenia, thrombocytopenia, agranulocytosis).
Long-Term Effects
Tardive dyskinesia with prolonged promethazine use is a concern.
Adverse Drug Reactions (ADR)
Severe allergic reactions, respiratory depression, neuroleptic malignant syndrome, and severe dystonias require immediate medical attention.
Contraindications
Hypersensitivity to any of the components, comatose states, severe respiratory impairment, children under 2 years old, concurrent use of MAO inhibitors. Use with caution in patients with narrow-angle glaucoma, prostatic hypertrophy, cardiovascular disease, hypertension, and asthma.
Drug Interactions
Alcohol, CNS depressants (e.g., sedatives, hypnotics, opioids), anticholinergics, MAOIs, tricyclic antidepressants, and antihypertensives can interact with this combination. Concurrent use should be avoided or carefully monitored. Inform patients to avoid alcohol during treatment.
Pregnancy and Breastfeeding
Pregnancy: Use with caution only if clearly needed. Promethazine is FDA Pregnancy Category C. Its use near term may inhibit platelet aggregation in the newborn. Phenylephrine may reduce uterine blood flow.
Breastfeeding: These drugs may be excreted in breast milk. Use with caution. Promethazine may suppress lactation. Safer alternatives may be preferred.
Drug Profile Summary
- Mechanism of Action: Phenylephrine: Alpha-1 adrenergic agonist causing vasoconstriction. Pholcodine: Central cough suppressant. Promethazine: H1 receptor antagonist and antiemetic.
- Side Effects: Drowsiness, dizziness, dry mouth, blurred vision, constipation. Rarely: respiratory depression, seizures, neuroleptic malignant syndrome.
- Contraindications: Children under 2, hypersensitivity, comatose states, severe respiratory impairment, MAOI use.
- Drug Interactions: Alcohol, CNS depressants, anticholinergics, MAOIs, tricyclic antidepressants, antihypertensives.
- Pregnancy & Breastfeeding: Use with caution. Potential risks to fetus and newborn.
- Dosage: Adults: 5 mL every 4-6 hours (max 30 mL/24 hours). Pediatric dosage varies by age; contraindicated under 2 years.
- Monitoring Parameters: Respiratory rate, blood pressure, mental status, liver and renal function if used long-term.
Popular Combinations
This combination itself is a commonly used formulation. However, individual components may be combined with other medications. For example, promethazine can be combined with codeine for cough suppression.
Precautions
- General Precautions: Evaluate for pre-existing conditions, drug allergies, and concurrent medications.
- Specific Populations: Close monitoring in children, the elderly, and those with renal or hepatic impairment. Avoid use in children under 2.
- Lifestyle Considerations: Avoid alcohol, operating machinery, and driving.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Phenylephrine + Pholcodine + Promethazine?
A: Adults: 5 mL every 4-6 hours, not exceeding 30 mL/24 hours. Children: Dosage varies by age; contraindicated under 2 years. Elderly: Start with a lower dose.
Q2: Can this combination be used in children under 2?
A: No, it’s contraindicated due to the risk of potentially fatal respiratory depression.
Q3: What are the most common side effects?
A: Drowsiness, dizziness, dry mouth, blurred vision, and constipation.
Q4: What are the serious side effects to watch out for?
A: Respiratory depression, allergic reactions, seizures, neuroleptic malignant syndrome.
Q5: What are the contraindications to using this medicine?
A: Hypersensitivity, comatose states, severe respiratory impairment, children under 2, concurrent MAOI use.
Q6: Can this medication be taken with alcohol?
A: No, alcohol can potentiate the sedative effects and should be avoided.
Q7: Can pregnant or breastfeeding women take this medication?
A: Use with caution only if clearly needed. Discuss risks and benefits with the patient and consider safer alternatives.
Q8: What should patients be advised regarding lifestyle modifications while taking this medication?
A: Avoid driving, operating machinery, and other activities requiring alertness due to potential drowsiness. Avoid alcohol.
Q9: What are the key drug interactions to be aware of?
A: CNS depressants, anticholinergics, MAOIs, tricyclic antidepressants, and antihypertensives.
Q10: What is the mechanism of action of each component in this combination?
A: Phenylephrine: vasoconstriction. Pholcodine: cough suppression. Promethazine: H1 receptor antagonism and antiemetic effect.
