Adult: Patient not receiving theophylline preparation: Loading: 5 mg/kg or 250-500 mg by slow inj or infusion over 20-30 min. Maintenance: 0.5 mg/kg/hr infusion. Max rate: 25 mg/min. Patient already receiving theophylline preparation: Loading dose is deferred until serum theophylline levels are determined, or if admin is required, 3.1 mg/kg. Child: Loading: Same as adult dose. Maintenance: 6 mth to 9 yr 1 mg/kg/hr; 10-16 yr 0.8 mg/kg/hr. Elderly: Maintenance: 0.3 mg/kg/hr.
Oral Chronic bronchospasm
Adult: As aminophylline hydrate modified-release tab: Initially, 225-450 mg bid, increased as appropriate. Child: As aminophylline hydrate modified-release tab: >40 kg: Initially, 225 mg bid, increased to 450 mg bid after 1 wk as appropriate. Elderly: Dose reduction may be necessary.
Hepatic Impairment
Oral: Chronic bronchospasm: Dose reduction may be necessary.
Intravenous: Acute
severe bronchospasm: Maintenance: 0.2 mg/kg/hr.
Administration
Should be taken on an empty stomach. Take at least 1 hr before or 2 hr after meals.
Incompatibility
Incompatible w/ metals and drugs that are unstable in alkaline soln or that would lower the pH below 8. Y-site admin: Amiodarone, ciprofloxacin, dobutamine, fenoldopam, hydralazine, isoproterenol, ondansetron, vinorelbine, warfarin. Syringe: Ceftriaxone, dimenhydrinate, doxapram, K phosphate.
Contraindications
Acute porphyria. Concomitant use w/ other xanthine derivatives.
Special Precautions
Patient w/ cardiac arrhythmia or failure, COPD, severe asthma, acute pulmonary oedema, peptic ulcer, hypo- and hyperthyroidism, glaucoma, DM, HTN, CHF, severe hypoxaemia, coronary artery disease, history of seizure, active influenza infection, acute febrile illness, sepsis. Patient undergoing influenza immunisation or in chronic alcoholism. Simultaneous admin by >1 route/preparation. Hepatic and renal impairment. Childn, elderly. Pregnancy and lactation.
Monitor heart and resp rate, arterial/capillary blood gases, and serum K levels. Monitor serum theophylline levels prior to dose adjustment.
Overdosage
Symptoms: Tachycardia, fever, anorexia, nausea, vomiting, diarrhoea, haematemesis, restlessness, hypertonia, insomnia, irritability, headache, agitation, hallucinations, extreme thirst, dilated pupils, tinnitus, exaggerated limb reflexes, seizures, hypoxic encephalopathy, coma, palpitations, arrhythmias, hypotension, acute MI, cardiorespiratory arrest, hypokalaemia, hypomagnesaemia, hypophosphataemia, hyperglycaemia, albuminuria, hyperthermia, resp alkalosis, metabolic acidosis, rhabdomyolysis, increase creatine kinase, myoglobin, and leukocyte count. Management: Symptomatic and supportive treatment. Employ activated charcoal. Aggressive antiemetic therapy may be required. Treat seizures w/ IV diazepam 0.1-0.3 mg/kg (up to 10 mg). Restoration of fluid and electrolyte balance is necessary. Correct hypokalaemia w/ IV infusion of KCl. Administer IV propranolol to reverse extreme tachycardia, hypokalaemia, and hyperglycaemia except when patient has asthma. Charcoal haemoperfusion may be beneficial.
Drug Interactions
Increased clearance w/ aminoglutethimide, carbamazepine, moracizine, phenytoin, rifampicin, sulfinpyrazone, and barbiturates. Reduced clearance w/ allopurinol, carbimazole, cimetidine, ciprofloxacin, clarithromycin, diltiazem, disulfiram, erythromycin, fluconazole, interferon, isoniazid, isoprenaline, methotrexate, mexiletine, nizatidine, norfloxacin, oxpentifylline, propafenone, propranolol, ofloxacin, thiabendazole, verapamil, viloxazine HCl and OCs. May increase steady state concentration of phenytoin. Potentially Fatal: Increased risk of toxicity w/ other xanthine derivatives.
Food Interaction
Increased clearance w/ St. John’s wort. Reduced half-life by 50% when taken w/ charcoal-broiled foods. Clearance may be increased w/ chronic consumption, or decreased w/ single large dose of alcohol.
Action
Description: Aminophylline, a xanthine derivative, is a complex of theophylline and ethylenediamine. It blocks phosphodiesterase-3 (PDE III), the enzyme that degrades 3’-5’-adenosine monophosphate (cAMP), promoting catecholamine stimulation of lipolysis, glycogenolysis, and gluconeogenesis and inducing release of epinephrine from adrenal medulla cells. This results in bronchodilation, diuresis, CNS and cardiac stimulation, and gastric acid secretion. Pharmacokinetics: Absorption: Rapidly and completely absorbed (oral) (as theophylline). Time to peak plasma concentration: 1-2 hr (oral); w/in 30 min (IV). Distribution: Freely crosses the placenta and CSF; enters breast milk. Volume of distribution: 0.45 L/kg. Plasma protein binding: Approx 40%, mainly to albumin (as theophylline). Metabolism: Readily liberates theophylline in the body which is subsequently metabolised (approx 90%) in the liver via N-demethylation by CYP1A2 enzyme and hydroxylation by CPY2E1 and CYP3A4 to the active metabolites, caffeine and 3-methylxanthine. Excretion: Via urine (10% as unchanged). Elimination half-life: 8.7 hr (range: 6.1-12.8 hr).
Chemical Structure
Aminophylline Source: National Center for Biotechnology Information. PubChem Database. Aminophylline, CID=9433, https://pubchem.ncbi.nlm.nih.gov/compound/Aminophylline (accessed on Jan. 20, 2020)
Storage
Store between 20-25°C. Protect from light and moisture.
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