Adult: Recommended dose: 400 mg bid-tid. Max: 1,200 mg daily. Elderly: Reduce dose to 200 mg bid-tid. Child: As syr: <12 years 6-9 mg/kg bid; ≥12 years 200 mg bid-tid. Dosage recommendations may vary among countries and individual products (refer to specific product guidelines).
Special Patient Group
Patient with CHF or concomitant infection: Dose reduction may be required.
Smokers: Dose adjustment may be necessary.
Renal Impairment
Dose reduction may be required.
Hepatic Impairment
Dose reduction may be required.
Contraindications
Acute MI, hypotension. Lactation.
Special Precautions
Patient with CV disease (e.g. cardiac arrhythmias, angina pectoris, chronic right ventricular failure, CHF, hypertension), COPD; active or history of peptic ulcer and/or GERD; hyperthyroidism, hypoxaemia, concomitant infection, inflammation, history of seizure disorder. Smokers (including after cessation of smoking). Hepatic and renal impairment. Children and elderly. Pregnancy.
Adverse Reactions
Cardiac disorders: Tachycardia, extrasystoles, palpitations. Gastrointestinal disorders: Nausea, vomiting, epigastric pain. Metabolism and nutrition disorders: Hyperglycaemia. Nervous system disorders: Headache. Rarely, seizures. Psychiatric disorders: Irritability, insomnia. Renal and urinary disorders: Albuminuria. Respiratory, thoracic and mediastinal disorders: Tachypnoea.
Symptoms: Nausea, vomiting, gastrointestinal bleeding, hypotension, seizures, and severe arrhythmia. Management: Symptomatic and supportive treatment. May induce emesis or perform gastric lavage, followed by administration of activated charcoal or cathartic. In case of seizures, establish adequate airway and give IV diazepam and/or phenobarbital.
Drug Interactions
Increased half-life and decreased clearance with cimetidine, allopurinol, erythromycin, ciprofloxacin, troleandomycin, lincomycin, clindamycin, ranitidine, propranolol, and flu vaccines. Decreased half-life and increased clearance with phenytoin and other anticonvulsants. Increased risk of synergistic toxicity with ephedrine and other sympathomimetics. May potentiate hypokalaemia caused by hypoxia with β2-agonists, corticosteroids, and diuretics.
Food Interaction
Caffeine-containing products may enhance the adverse effect of doxofylline; avoid concomitant use.
Action
Description: Mechanism of Action: Doxofylline, a theophylline derivative, is a bronchodilator. It inhibits phosphodiesterase enzymes which increase cyclic adenine monophosphate (cAMP), thereby causing bronchial smooth muscle relaxation leading to bronchodilation. Pharmacokinetics: Absorption: Rapidly absorbed. Absolute bioavailability: 62.6%. Time to peak plasma concentration: 1.19 hours. Distribution: Volume of distribution: 1 L/kg. Plasma protein binding: Approx 48%. Metabolism: Extensively metabolised in the liver (approx 90%) into the inactive metabolite, hydroxyethyltheophylline. Excretion: Via urine (<4% as unchanged drug). Elimination half-life: 7-10 hours.
Chemical Structure
Doxofylline Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 50942, Doxofylline. https://pubchem.ncbi.nlm.nih.gov/compound/Doxofylline. Accessed Apr. 26, 2022.
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