MINOPHYLLINE S.R. 300 MG (THEOPHYLLINE) – SUSTAINED-RELEASE TABLETS

Minophylline S.R. contains Theophylline 300 mg, a bronchodilator belonging to the methylxanthine class. It is formulated as a sustained-release tablet designed to provide prolonged theophylline delivery.

It is used in the management of certain respiratory conditions characterized by reversible airway narrowing, helping to relax bronchial smooth muscles and improve airflow.

Composition

• Active ingredient: Theophylline anhydrous 300 mg.
• Pharmaceutical form: Sustained-release (S.R.) oral tablets.
• Pack size: 30 tablets.

Mechanism of Action

Theophylline is a methylxanthine bronchodilator that works by:

• Relaxing bronchial smooth muscles, resulting in bronchodilation.
• Helping reduce airway narrowing and improve airflow.
• Enhancing diaphragmatic muscle contractility.
• Producing additional prophylactic effects against airway hyperresponsiveness.

Indications

Minophylline S.R. may be prescribed for:

• Bronchial asthma: Long-term management and prevention of bronchospasm.
• Chronic obstructive pulmonary disease (COPD): Management of persistent airflow obstruction.
• Chronic bronchitis: Management of associated bronchospasm and respiratory symptoms.
• Selected cases of cardiac failure, according to the Egyptian National Drug Formulary.

Note: Theophylline is generally not considered a first-line treatment for asthma or COPD because of its narrow therapeutic index and potential adverse effects.

Benefits / Therapeutic Effects

• Helps relax bronchial smooth muscles.
• Supports improved airflow and respiratory function.
• Helps reduce symptoms associated with reversible airway obstruction.
• Sustained-release formulation provides prolonged drug delivery.
• May improve diaphragmatic muscle contractility.

Dosage & Administration

• Adults: The Egyptian National Drug Formulary lists an initial maintenance regimen of 200 mg every 12 hours, which may be adjusted to 300–400 mg every 12 hours according to therapeutic response.
• The appropriate dose must be individualized according to clinical response and serum theophylline concentrations.
• Take orally as prescribed.
• Swallow tablets whole with water.
• Do not crush, chew, or break sustained-release tablets, as this may cause rapid drug release and increase the risk of toxicity.

Important: The 300 mg strength does not mean that every patient should take one tablet twice daily. The prescribed regimen must be determined by the treating physician.

Possible Side Effects

Commonly reported adverse effects include:

• Nausea and vomiting.
• Headache.
• Insomnia and sleep disturbances.
• Restlessness and irritability.
• Tremors.
• Palpitations and increased heart rate.

Signs of potential toxicity:

• Persistent or severe vomiting.
• Marked tachycardia or irregular heartbeat.
• Severe agitation or confusion.
• Seizures.

Medical attention is required if symptoms of theophylline toxicity develop.

Contraindications & Precautions

• Hypersensitivity to theophylline or any of the product's ingredients.
• Contraindicated in patients with porphyria.
• Use cautiously in patients with:
  • Cardiac disorders or arrhythmias.
  • Epilepsy or a history of seizures.
  • Peptic ulcer disease.
  • Liver disorders.
  • Hyperthyroidism.
  • Severe hypertension.
• Elderly patients may require lower doses and closer monitoring.
• Smoking cessation, fever, and certain infections can alter theophylline levels and may require dose adjustment.
• Pregnancy and breastfeeding require medical assessment before use.

Drug Interactions

Theophylline has clinically significant drug interactions. Particular attention is required with:

• Erythromycin: May increase theophylline concentrations.
• Cimetidine: May increase the risk of theophylline toxicity.
• Carbamazepine: May decrease theophylline concentrations.
• Rifampicin: May decrease theophylline concentrations.
• Other xanthine derivatives: May increase the risk of adverse effects and toxicity.

Patients should inform their healthcare provider about all medications and supplements they are taking.

Monitoring

• Serum theophylline concentrations should be monitored to ensure safe and effective treatment.
• Heart rate and cardiac rhythm should be assessed when clinically indicated.
• Monitor for gastrointestinal and central nervous system adverse effects.
• Additional monitoring may be necessary following changes in medication, smoking habits, or clinical condition.

Storage

• Store at a temperature not exceeding 30°C.
• Keep in a dry place.
• Keep out of reach of children.

References

1. Egyptian Drug Authority (EDA): Egyptian National Drug Formulary – Respiratory Medicines, 2026, Theophylline monograph, pages 101–103.
2. U.S. National Library of Medicine (DailyMed): Theophylline Extended-Release Tablets – Official Drug Label.
3. U.S. Department of Veterans Affairs: VA/DoD Clinical Practice Guideline for the Management of Asthma, 2025.
4. National Institute for Health and Care Excellence (NICE): COPD Diagnosis and Management Guidelines.

​Patient Disclaimer:

This information is provided for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Minophylline S.R. is a prescription medication and should only be used under medical supervision. Do not start, discontinue, or adjust the dose without consulting your healthcare professional. Theophylline has a narrow therapeutic index, and inappropriate dosing may lead to serious toxicity.