Indications
This is indicated for the symptomatic treatment of reversible bronchoconstriction associated with bronchial asthma, chronic obstructive pulmonary emphysema, chronic bronchitis and related bronchospastic disorders.
Therapeutic Class
Theophylline & related drugs
Pharmacology
Theophylline is a bronchodilator, structurally classified as a Methylxanthine. Theophylline has two distinct actions in the airways of patients with reversible obstruction; smooth muscle relaxation and suppression of the response of the airways to stimuli. Theophylline also increases the force of contraction of diaphragmatic muscles. The half-life of Theophylline is influenced by a number of known variables. In adult nonsmokers with uncomplicated asthma the half-life ranges from 3 to 9 hours
Dosage & Administration
Dosages are adjusted to maintain serum theophylline concentrations that provide optimal relief of symptoms with minimal side effects. Most of the controlled release preparations may be administered every 12 hours in adults while administration every 8 hours may be necessary in some children with markedly rapid hepatic metabolism of theophylline. The recommended dosages for achieving serum theophylline concentrations within the accepted therapeutic range is as follow:
1-6 months: 10 mg/Kg/day
6 months-1 year: 15 mg/Kg/day
1-9 years: 24 mg/Kg/day
10-16 years: 18 mg/Kg/day
Adults: 10-15 mg/Kg/day
Interaction
Allopurinol, cimetidine, norfloxacin, ciprofloxacin, erythromycin, oral contraceptives and propranolol increase serum theophylline levels. Phenytoin, methotrexate and rifampicin lead to decreased serum theophylline levels
Contraindications
Hypersensitivity to xanthine derivatives. It is also contraindicated in patients with active peptic ulcer disease and in individuals with underlying seizure disorders (unless receiving appropriate anti-convulsing medication).
Theophylline should not be administered concurrently with other xanthine. Use with caution in patients with hypoxemia, hypertension, or those with history of peptic ulcer. Do not attempt to maintain any dose that is not tolerated.
Side Effects
The following side effects have been observed:
Gastrointestinal: Nausea, vomiting, epigastric pain and diarrhoea.
Central nervous system: Headache, irritability, restlessness, insomnia, muscles twitching.
Cardiovascular: Palpitation, tachycardia, hypotension. circulatory failure.
Respiratory: Tachypnoea.
Renal: Potentiation of diuresis.
Others: Alopecia, hyperglycemia, rash etc.
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