theophylline(redirected from T-phyl)
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Pharmacologic class: Xanthine derivative
Therapeutic class: Bronchodilator, spasmolytic
Pregnancy risk category C
Relaxes bronchial smooth muscles, suppressing airway response to stimuli. Also inhibits phosphodiesterase and release of slow-reacting substance of anaphylaxis and histamine.
Capsules (immediate-release): 100 mg, 200 mg
Capsules (extended-release, 8 to 12 hours): 50 mg, 60 mg, 65 mg, 75 mg, 100 mg, 125 mg, 130 mg
Capsules (extended-release, 12 hours): 50 mg, 125 mg, 130 mg, 250 mg, 260 mg
Capsules (extended-release, 24 hours): 100 mg, 200 mg, 300 mg, 400 mg
Elixir: 80 mg/15 ml
Injection (with dextrose): 0.4 mg/ml, 0.8 mg/ml, 1.6 mg/ml, 2 mg/ml, 3.2 mg/ml, 4 mg/ml
Syrup (cherry): 80 mg/15 mg, 150 mg/15 ml
Tablets (immediate-release): 100 mg, 125 mg, 200 mg, 250 mg, 300 mg
Tablets (extended-release, 12 to 24 hours): 100 mg, 200 mg, 300 mg, 400 mg, 450 mg, 600 mg
Tablets (extended-release, 24 hours): 400 mg, 600 mg
Indications and dosages
➣ Acute bronchospasm in patients not receiving theophylline
Adults (otherwise healthy nonsmokers): Initially, 6 mg/kg P.O., followed in next 12 to 16 hours by 3 mg/kg P.O. q 6 hours for two doses, then a maintenance dosage of 3 mg/kg P.O. q 8 hours
Children ages 9 to 16; young adult smokers: Initially, 6 mg/kg P.O., followed in next 12 to 16 hours by 3 mg/kg P.O. q 4 hours for three doses, then a maintenance dosage of 3 mg/kg P.O. q 6 hours
Children ages 1 to 9: Initially, 6 mg/kg P.O., followed in next 12 to 16 hours by 4 mg/kg P.O. q 4 hours for three doses, then a maintenance dosage of 4 mg/kg P.O. q 6 hours
➣ Acute bronchospasm in patients receiving theophylline
Adults and children: Loading dose based partly on time, amount, and administration route of last dose and on expectation that each 0.5 mg/kg will produce 1 mcg/ml rise in theophylline blood level. In significant respiratory distress, loading dose may be 2.5 mg/kg P.O. or I.V. to increase theophylline level by approximately 5 mcg/ml.
➣ Chronic bronchospasm
Adults and children: Immediate-release forms-16 mg/kg or 400 mg P.O. daily (whichever is lower) in three to four divided doses q 6 to 8 hours. Timed-release forms-12 mg/kg or 400 mg P.O. daily (whichever is lower) in three to four divided doses q 8 to 12 hours. May increase dosage of either immediate- or timed-release form at 2- to 3-day intervals, to a maximum of 13 mg/kg or 900 mg daily (whichever is lower) in patients older than age 16, 18 mg/kg daily in children ages 12 to 16, 20 mg/kg daily in children ages 9 to 12, or 24 mg/kg daily in children up to age 9.
• Cor pulmonale or heart failure
• Elderly patients
• Young adults
• Essential tremor
• Apnea and bradycardia in premature infants
• Hypersensitivity to drug or other xanthines (such as coffee, theobromine)
• Active peptic ulcer
• Seizure disorder
Use cautiously in:
• alcoholism; heart failure or other cardiac or circulatory impairment; hypertension; renal or hepatic disease; COPD; hypoxemia; hyperthyroidism; diabetes mellitus; glaucoma; peptic ulcer disease
• elderly patients
• children younger than age 1.
• For I.V. delivery, use infusion solution designed for drug, or mix with dextrose 5% in water. Administer by controlled infusion pump.
• Know that for acute bronchospasm, theophylline preferably is given I.V. as 20 mg/ml of theophylline (or 25 mg/ml of aminophylline).
• Don't give timed-release form to patient with acute bronchospasm.
CNS: irritability, dizziness, nervousness, restlessness, headache, insomnia, reflex hyperexcitability, seizures
CV: palpitations, marked hypotension, sinus tachycardia, extrasystole, circulatory failure, ventricular arrhythmias
GI: nausea, vomiting, diarrhea, hematemesis, gastroesophageal reflux
GU: increased diuresis, proteinuria
Metabolic: hyperglycemia, syndrome of inappropriate antidiuretic hormone secretion
Musculoskeletal: muscle twitching
Respiratory: tachypnea, respiratory arrest
Skin: urticaria, rash, alopecia, flushing
Other: fever, hypersensitivity reaction
Drug-drug. Allopurinol, calcium channel blockers, cimetidine, corticosteroids, disulfiram, ephedrine, hormonal contraceptives, influenza virus vaccine, interferon, macrolides, mexiletine, nonselective beta-adrenergic blockers, quinolones, thiabendazole: increased theophylline blood level, greater risk of toxicity
Aminoglutethimide, barbiturates, ketoconazole, rifampin, sulfinpyrazone, sympathomimetics: decreased theophylline blood level and effects
Carbamazepine, isoniazid, loop diuretics: increased or decreased theophylline blood level
Halothane: increased risk of arrhythmias
Hydantoins: decreased hydantoin blood level
Lithium: decreased therapeutic effect of lithium
Nondepolarizing muscle relaxants: reversal of neuromuscular blockade
Propofol: antagonism of propofol's sedative effects
Tetracyclines: increased risk of adverse reactions to theophylline
Drug-diagnostic tests. Glucose: increased level
Drug-food. Any food: altered bioavailability and absorption of some timed-release theophylline forms, causing rapid release and possible toxicity
Caffeine- or xanthine-containing foods and beverages: increased theophylline blood level and greater risk of adverse CNS and cardiovascular reactions
Diet high in protein and charcoal-broiled beef and low in carbohydrates: increased theophylline elimination, decreased efficacy
High-carbohydrate, low-protein diet: decreased theophylline elimination, increased risk of adverse reactions
Drug-herbs. Caffeine-containing herbs (such as cola nut, guarana, maté): increased theophylline blood level, greater risk of adverse CNS and cardiovascular reactions
Ephedra (ma huang): increased stimulant effect
St. John's wort: decreased theophylline blood level and efficacy
Drug-behaviors. Nicotine (in cigarettes, gum, transdermal patches): increased theophylline metabolism, decreased efficacy
• Monitor for signs and symptoms of hypersensitivity reaction, including rash and fever.
• Assess respiratory status. Monitor pulmonary function tests to gauge drug efficacy and identify adverse effects.
• Monitor cardiovascular and neurologic status carefully.
• Assess glucose level in diabetic patient.
• Advise patient to take oral form with 8 oz of water 1 hour before or 2 hours after meals.
• Tell patient not to crush or chew timed-release form.
• Caution patient not to use different drug brands interchangeably.
Instruct patient to immediately report worsening dyspnea and other respiratory problems.
• Teach patient to recognize and report adverse neurologic reactions.
• Tell patient that all nicotine forms (including cigarettes, patches, and gum) decrease drug efficacy. Discourage nicotine use.
• Advise patient that a diet high in protein and charcoal-broiled beef and low in carbohydrates makes drug less effective.
• Tell patient that a high-carbohydrate, low-protein diet increases risk of adverse reactions, as do products containing caffeine.
• Caution patient to avoid herbs, especially ephedra and St. John's wort.
• Advise patient not to take over-the-counter drugs without prescriber's approval. Tell him to inform all prescribers he's taking drug, because it interacts with many other drugs.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, herbs, and behaviors mentioned above.