Usage
Pholcodine is primarily prescribed for the relief of dry, non-productive coughs, often associated with upper respiratory tract infections. It is classified as a cough suppressant (antitussive) and belongs to the opioid class of drugs. Pholcodine works by suppressing the cough reflex through a direct action on the cough center located in the medulla oblongata, a part of the brainstem.
Alternate Names
Pholcodine is also known as morpholinylethylmorphine and homocodeine. Brand names vary depending on the region and manufacturer.
How It Works
Pharmacodynamics: Pholcodine acts centrally on the cough center in the medulla oblongata to suppress the cough reflex. It has mild sedative properties but minimal analgesic effects. Therapeutic doses typically don’t cause respiratory depression or CNS excitation commonly seen with other opioid narcotics.
Pharmacokinetics: Pholcodine is readily absorbed from the gastrointestinal tract and crosses the blood-brain barrier. It is metabolized in the liver and excreted primarily by the kidneys, with some eliminated unchanged. Its action might be prolonged in patients with hepatic insufficiency.
Mode of Action: Pholcodine binds to opioid receptors in the central nervous system, specifically those involved in the cough reflex pathway, decreasing their sensitivity and activity.
Elimination Pathways: Primarily renal excretion, with some hepatic metabolism.
Dosage
Standard Dosage
Adults: 5-10 mg three to four times daily or 10-15 mg every 8-10 hours. The maximum daily dose is generally around 60 mg.
Children:
- 6-12 years: 4 mg three times daily. Maximum treatment duration: 5 days.
- >12 years: Same as adult dose.
Special Cases:
- Elderly Patients: Reduced dosage is recommended due to potential age-related decline in hepatic and renal function.
- Patients with Renal Impairment: Dose adjustment may be necessary based on the degree of impairment.
- Patients with Hepatic Dysfunction: Contraindicated in patients with liver failure. Dose reduction necessary in patients with hepatic impairment.
- Patients with Comorbid Conditions: Caution is advised in patients with respiratory diseases like asthma, chronic bronchitis, COPD, bronchiolitis, or bronchiectasis. Consider potential drug interactions in patients with other comorbid conditions.
Clinical Use Cases
Pholcodine is not typically used in clinical settings such as intubation, surgical procedures, mechanical ventilation, ICU, or emergency situations. It’s mainly indicated for the symptomatic relief of a dry cough.
Dosage Adjustments
Dose adjustments are based on age, renal or hepatic impairment, and the presence of other medical conditions. Always consider potential drug interactions.
Side Effects
Common Side Effects:
- Nausea
- Vomiting
- Constipation
- Drowsiness
- Dizziness
- Skin rash
Rare but Serious Side Effects:
- Allergic reactions (including anaphylaxis)
- Respiratory depression (with high doses)
- Sputum retention (particularly in patients with chronic respiratory conditions)
Long-Term Effects:
- Adrenal insufficiency (long-term use)
- Infertility (long-term use)
Adverse Drug Reactions (ADR):
- Severe Cutaneous Adverse Reactions (SCARs), including acute generalized exanthematous pustulosis (AGEP)
Contraindications
- Hypersensitivity to pholcodine
- Respiratory failure or risk thereof
- Acute asthma attack
- Chronic bronchitis, COPD, bronchiolitis, bronchiectasis (due to risk of sputum retention)
- Liver failure
- Concurrent use of MAOIs or within 14 days of stopping MAOI therapy
- Children under 6 years of age
Drug Interactions
- MAOIs: Concurrent use can lead to serotonin syndrome.
- CNS Depressants (alcohol, benzodiazepines, other opioids): Enhanced CNS depression, increasing the risk of sedation, respiratory depression, and coma.
- Antihypertensives and Diuretics: May potentiate hypotensive effects.
- Neuromuscular Blocking Agents (NMBAs): Increased risk of anaphylactic reaction to NMBAs if pholcodine has been used within 12 months before general anesthesia.
Pregnancy and Breastfeeding
- Pregnancy: Limited data available. Use only if clearly needed and under medical supervision, especially during the first trimester.
- Breastfeeding: It’s unknown if pholcodine is excreted in breast milk. Use with caution and consider potential risks to the infant.
Drug Profile Summary
- Mechanism of Action: Centrally acting cough suppressant, primarily acting on the cough center in the medulla.
- Side Effects: Nausea, vomiting, constipation, drowsiness, dizziness, skin rash. Rarely: allergic reactions, respiratory depression, sputum retention.
- Contraindications: Hypersensitivity, respiratory failure, liver failure, concurrent MAOI use, children <6 years.
- Drug Interactions: MAOIs, CNS depressants, antihypertensives, NMBAs.
- Pregnancy & Breastfeeding: Use with caution; limited safety data.
- Dosage: Adults: 5-10 mg TID/QID or 10-15 mg every 8-10 hours. Children (6-12 yrs): 4 mg TID.
- Monitoring Parameters: Respiratory function (in patients with respiratory compromise) and skin reactions.
Popular Combinations
Pholcodine is not typically used in combination with other drugs for cough suppression. Due to its interaction profile, combination use is often avoided.
Precautions
- Assess respiratory function in patients with respiratory conditions.
- Monitor for allergic reactions.
- Caution in patients with renal or hepatic impairment.
- Avoid in patients with a history of drug abuse.
- Avoid alcohol during treatment.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Pholcodine?
A: Adults: 5-10 mg three to four times daily or 10-15 mg every 8-10 hours. Children (6-12 years): 4 mg three times a day. Dosages should be adjusted for elderly patients and those with renal or hepatic impairment.
Q2: How does Pholcodine work?
A: Pholcodine suppresses the cough reflex by acting directly on the cough center in the brain.
Q3: What are the common side effects of Pholcodine?
A: Common side effects include nausea, vomiting, constipation, drowsiness, dizziness, and skin rashes.
Q4: Who should not take Pholcodine?
A: Pholcodine is contraindicated in individuals with hypersensitivity, respiratory failure, liver failure, concurrent use of MAOIs, and children under 6 years.
Q5: Can Pholcodine be used during pregnancy?
A: Limited data exists on Pholcodine use during pregnancy. Use only if clearly needed and under medical supervision.
Q6: Does Pholcodine interact with other medications?
A: Yes, significant interactions can occur with MAOIs, CNS depressants, antihypertensives, and neuromuscular blocking agents.
Q7: What should patients be advised while taking Pholcodine?
A: Patients should be advised to avoid driving or operating machinery due to potential drowsiness. They should also avoid alcohol.
Q8: What is the mechanism of action of Pholcodine?
A: Pholcodine binds to opioid receptors in the CNS, reducing the sensitivity of the cough reflex pathway.
Q9: Is Pholcodine addictive?
A: While Pholcodine is an opioid, it has a lower potential for addiction compared to other opioids like codeine. However, caution is still advised, particularly in patients with a history of drug abuse.
