Theophylline is a drug used primarily to treat respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD). It belongs to a class of medications known as xanthines and is closely related to caffeine and theobromine. Theophylline works by relaxing the muscles in the airways and reducing inflammation, thereby improving airflow and breathing.
Dosage Forms and Strengths
Theophylline is available in several dosage forms and strengths:
- Oral Tablets: Available in immediate-release and extended-release formulations, typically in strengths of 100 mg, 200 mg, 300 mg, and 400 mg.
- Oral Solution: Usually provided in concentrations such as 80 mg/15 mL or 100 mg/15 mL.
- Injectable Form: Available for intravenous administration, often in concentrations of 0.8% or 1.6%.
Brand and Generic Names
Theophylline is available under various brand names and as a generic medication. Some of the brand names include:
- Theo-Dur
- Theolair
- Elixophyllin
- Uniphyl
The generic name is simply "Theophylline."
Indications for Use
Theophylline is prescribed for:
- Asthma: To prevent and control symptoms of asthma, particularly in cases where other medications are not sufficient.
- Chronic Obstructive Pulmonary Disease (COPD): To help improve breathing in patients with COPD.
- Bronchitis: To manage chronic bronchitis and related conditions.
Mechanism of Action
Theophylline acts primarily through two mechanisms:
Phosphodiesterase Inhibition: Theophylline inhibits the enzyme phosphodiesterase, which leads to an increase in cyclic adenosine monophosphate (cAMP) levels. Elevated cAMP levels result in bronchodilation by relaxing smooth muscles in the airways.
Adenosine Receptor Antagonism: Theophylline also acts as an antagonist at adenosine receptors, which helps in reducing bronchoconstriction and inflammation.
These actions collectively improve airflow and reduce symptoms of respiratory conditions.
Administration and Dosage
Theophylline dosage is individualized based on the patient's condition, age, weight, and response to the medication.
- Immediate-Release Tablets: Typically administered every 6 to 8 hours. Dosage often starts at 200 mg to 400 mg daily, gradually adjusted based on serum levels and clinical response.
- Extended-Release Tablets: Generally taken once or twice daily. Dosage usually ranges from 300 mg to 800 mg daily.
- Oral Solution: Administered according to the prescribed dosage, typically every 6 to 8 hours.
- Injectable Form: Used in acute settings, dosage adjusted based on patient needs and monitored closely.
Monitoring of serum theophylline levels is crucial to avoid toxicity, with therapeutic levels typically between 5 and 15 µg/mL.
Effects and Precautions
Effects:
- Positive Effects: Theophylline can significantly improve lung function, reduce frequency and severity of asthma attacks, and improve overall quality of life in patients with respiratory conditions.
- Common Side Effects: Include gastrointestinal upset (nausea, vomiting), headache, insomnia, and jitteriness.
Precautions:
- Toxicity: Theophylline has a narrow therapeutic range, and its levels can be influenced by various factors such as age, smoking status, and interactions with other medications. Symptoms of toxicity include arrhythmias, seizures, and severe gastrointestinal disturbances.
- Drug Interactions: Theophylline can interact with several drugs, including certain antibiotics, antifungals, and other respiratory medications. These interactions may alter theophylline levels and efficacy.
- Liver and Kidney Function: Impaired liver or kidney function can affect theophylline metabolism and clearance, necessitating dosage adjustments and careful monitoring.
Conclusion
Theophylline remains a valuable medication in the management of respiratory diseases like asthma and COPD. Its ability to improve breathing and reduce symptoms has made it a mainstay in respiratory therapy. However, due to its narrow therapeutic range and potential for interactions, careful monitoring and individualized dosing are essential to ensure efficacy while minimizing the risk of adverse effects. Theophylline's role in modern medicine underscores the importance of understanding and managing chronic respiratory conditions effectively.