Cough and Expectorant Medicines: A Detailed Guide

Cough and Expectorant Medicines: A Detailed Guide

This article provides detailed information about cough and expectorant medicines, including their mechanisms of action, types, indications, side effects, and precautions for use.

1. Cough Medicines

Cough medicines can act peripherally and centrally to reduce cough intensity and frequency.

a. Peripheral Action:

• Cough Receptor Sensitizers: Irritants/volatiles such as camphor and menthol act on cough receptors, reducing the sensation of irritation and stimulation in the respiratory tract.

b. Central Action:

• Cough Center Inhibition: Some medications act directly on the cough center in the medulla oblongata, suppressing the cough reflex.

• Opioid Derivatives: Codeine, ethylmorphine, pholcodin, dextromethorphan, noscapin, levopropoxyphen, and H1 antihistamines are common opioid derivatives used to suppress the cough center.

• Note: The use of centrally acting medications in children and the elderly should be exercised with utmost caution due to the risk of side effects.

2. Medications Acting on the Cough Center:

a. Codeine:

• Mechanism: Codeine acts on the mu opioid receptor and the cough center in the medulla oblongata.

• Effects: Mild pain relief, inhibition of bowel motility (can cause constipation), suppression of the cough center.

• Indications: Dry cough, mild to moderate pain.

• Side Effects: Constipation, respiratory depression, drowsiness (high doses).

• Contraindications: Driving, operating machinery, asthma, respiratory failure. Not to be used in children.

b. Ethylmorphine:

• Effects: Cough suppression, respiratory depression, less constipation than codeine.

c. Pholcodin:

• Mechanism: An opium alkaloid, lacks analgesic effects, addictive.

• Effects: Suppresses the respiratory center (less respiratory depression than codeine).

• Indications: Dry cough.

d. Morphine and Methadone:

• Indications: Intractable cough in bronchial carcinoma.

e. Non-opioid: Dextromethorphan:

• Mechanism: Central NMDA antagonist.

• Effects: Effective for acute nocturnal cough.

• Side Effects: Dizziness, nausea, drowsiness. High doses can cause hallucinations and ataxia.

f. Non-opioid: Noscapin:

• Mechanism: An alkaloid from opium resin, suppresses the cough center similarly to codeine.

• Effects: Negligible analgesic effects, no respiratory depression, non-addictive.

g. Levopropoxyphen:

• Effects: No analgesic or antitussive effects.

• Side Effects: Drowsiness, dizziness, nausea, urticaria.

h. H1 Antihistamines:

• Mechanism: Sedative and anticholinergic effects.

• Indications: Nocturnal cough.

• Note: Thickens phlegm, avoid use for coughs with phlegm.

• Side Effects: Sedation, dry mouth, visual disturbances.

• Includes: Chlorpheniramine, diphenhydramine, promethazine.

3. Topical Cough Medicines:

• Benzonatate: A local anesthetic, reduces the activity of cough receptors in the respiratory tract and pleura.

• Side Effects: Dizziness, dysphagia, severe allergic reactions in patients allergic to para-aminobenzoic acid.

• Eucalyptol (Cineol): Relieves mild cough, antiseptic, treats fever.

• Side Effects: Nausea, vomiting, hot sensation (especially in children).

• Contraindications: Not to be used in patients with respiratory failure, asthma, children under 30 months of age.

• Camphor, Menthol: Chest and neck rubs help reduce cough. Camphor is commonly used in vaporizer inhalers, menthol is used in lozenges.

• Lidocaine: Provides surface anesthesia, used for coughs due to endoscopy, respiratory mucosal injury.

4. Bronchodilators:

• Ipratropium, Albuterol: Used for coughs due to asthma and COPD.

5. Expectorant Medicines:

• Mechanism: Stimulate the secretory glands in the inner lining of the trachea, increasing the volume and reducing the viscosity of tracheal secretions.

• Includes: Sodium benzoate, terpin hydrate, guaifenesin.

6. Mucolytics:

• Mechanism: Breaks disulfide bonds of glycoproteins in phlegm, antioxidant.

• Includes: N-acetyl cysteine, carbocysteine, bromhexine, ambroxol.

7. Cysteine Derivatives:

• Rapid absorption, primarily excreted by the kidneys.

• Note: Use with caution in patients with peptic ulcer disease, PNCT, and CCB.

Note:

• The information above is for informational purposes only, consult a healthcare professional before using any medication.

• Self-medication can be hazardous to your health.

• Always follow the instructions of your doctor and the manufacturer when using medication.

• Store medication as instructed.

• Do not use expired medication.

• Keep medication out of reach of children.