Theophylline

A to Z Drug Facts

(thee-AHF-ih-lin)

Accurbron, Aerolate, Aquaphyllin, Asmalix, Bronkodyl, Constant-T, Elixomin, Elixophyllin, Elixophyllin SR, Lanophyllin, Quibron-T Dividose, Quibron-T/SR Dividose, Respbid, Slo-bid, Gyrocaps, Slo-Phyllin, Slo-Phyllin Gyrocaps, Sustaire, T-Phyl, Theo-24, Theo-Dur, Theo-Sav, Theobid Duracaps, Theobid Jr. Duracaps, Theochron, Theoclear L.A., Theoclear-80 Syrup, Theolair, Theolair-SR, Theospan-SR, Theovent, Theo-X, Uni-Dur, Uniphyl, Apo-Theo LA, Novo-Theophyl SR, Pulmophylline, Quibron-T/SR, Somophyllin-12, Theochron SR, Theolixir, Theo-SR

Class: Bronchodilator/Xanthine derivative

 Action Relaxes bronchial smooth muscle and stimulates central respiratory drive.

 Indications Prevention or treatment of reversible bronchospasm associated with asthma or chronic obstructive pulmonary disease. Unlabeled use(s): Treatment of apnea and bradycardia of prematurity; reduction of essential tremor.

 Contraindications Hypersensitivity to xanthines; seizure disorders not adequately controlled with medication.

 Route/Dosage

Dosage based on lean body weight.

Acute Therapy in Patients Not Currently Receiving Theophylline

Loading dose: ADULTS & CHILDREN: PO 5 mg/kg. Maintenance: CHILDREN 9–16 YR & YOUNG ADULT SMOKERS: PO 3 mg/kg q 6 hr. CHILDREN 1–9 YR: PO 4 mg/kg q 6 hr. ELDERLY & COR PULMONALE PATIENTS: PO 2 mg/kg q 8 hr. PATIENTS WITH CHF: PO 1–2 mg/kg q 12 hr. NONSMOKING ADULTS: PO 3 mg/kg q 8 hr.

Acute Therapy in Patients Receiving Theophylline

Each 0.5 mg/kg theophylline administered as a loading dose will increase serum theophylline concentration by about 1 mcg/ml. If a serum theophylline concentration can be obtained rapidly, defer the loading dose. If this is not possible, clinical judgment must be exercised, using close monitoring. Maintenance doses as per above.

Chronic Therapy

Slow clinical titration preferred. Initial dose: 16 mg/kg/24 hr or 400 mg/24 hr, whichever is less. Increasing dose: Increase the above dosage by 25% increments at 3 day intervals as long as the drug is tolerated or until the following maximum dose is reached (not to exceed 900 mg, whichever is less). MAXIMUM DOSE (WHERE SERUM CONCENTRATION IS NOT MEASURED): Do not attempt to maintain any dose that is not tolerated. ADULTS & CHILDREN > 16 YR: 13 mg/kg/day. CHILDREN 12–16 YR: 18 mg/kg/day. CHILDREN 9–12 YR: 24 mg/kg/day. CHILDREN 1–9 YR: 24 mg/kg/day.

Adjustments Based on Serum Theophylline Concentrations (Recommended for Final Adjustments in Dosage)

If serum theophylline concentration is within the desired range (10–20 mcg/ml), maintain dosage if tolerated. If too high (20–25 mcg/ml) decrease doses by about 10% and recheck in 3 days; (25–30 mcg/ml) skip the next dose, decrease subsequent doses by about 25% and recheck after 3 days; (over 30 mcg/ml) skip the next 2 doses, decrease subsequent doses by about 50% and recheck in 3 days. If too low (< 10 mcg/ml) increase dosage by 25% at 3 day intervals until either the desired clinical response or serum concentration is achieved.

Infant Guidelines

INFANTS 26–52 WK: Dosing interval is q 6 hr. INFANTS £ 26 WK: Dosing interval is q 8 hr. INFANTS 6–52 WK: PO 24 hr dose in mg [(0.2 × age in wk) + 5] × weight in kg. PREMATURE INFANTS > 24 DAYS: PO 1.5 mg/kg q 12 hr. PREMATURE INFANTS £ 24 DAYS: PO 1 mg/kg q 12 hr. Final dosage guided by serum concentration after steady state is achieved.

 Interactions

Allopurinol, nonselective beta-blockers, calcium channel blockers, cimetidine, oral contraceptives, corticosteroids, disulfiram, ephedrine, influenza virus vaccine, interferon, macrolide antibiotics (eg, erythromycin), mexiletine, quinolone antibiotics (eg, ciprofloxacin), thyroid hormones: Increase theophylline levels. Aminoglutethimide, barbiturates, hydantoins, ketoconazole, rifampin, smoking (cigarettes and marijuana), sulfinpyrazone, sympathomimetics: Decrease theophylline levels. Benzodiazepines and propofol: Theophylline may antagonize sedative effects. Beta-agonists: Cardiovascular adverse effects may be additive. However, may be used together for additive beneficial effects. Carbamazepine, isoniazid and loop diuretics: May increase or decrease theophylline levels. Halothane: Coadministration has caused catecholamine-induced arrhythmias. Ketamine: Coadministration may result in seizures. Lithium: Theophylline may reduce lithium levels. Nondepolarizing muscle relaxants: Theophylline may antagonize neuromuscular blockade. INCOMPATIBILITIES: Do not mix following solutions with theophylline in IV fluids: scorbic acid; chlorpromazine; corticotropin; dimenhydrinate; epinephrine HCl; erythromycin gluceptate; hydralazine; hydroxyzine HCl; insulin; levorphanol tartrate; meperidine; methadone; methicillin sodium; morphine sulfate; norepinephrine bitartrate; oxytetracycline; papaverine; penicillin G potassium; phenobarbital sodium; phenytoin sodium; procaine; prochlorperazine maleate; promazine; promethazine; etracycline; vancomycin; vitamin B complex with C.

 Lab Test Interferences None well documented.

 Adverse Reactions

CV: Palpitations; tachycardia; hypotension; arrhythmias. CNS: Irritability; headache; insomnia; muscle twitching; seizures. GI: Nausea; vomiting; gastroesophageal reflux; epigastric pain. GU: Proteinuria; diuresis. RESP: Tachypnea; respiratory arrest. OTHER: Fever; flushing; hyperglycemia; inappropriate antidiuretic hormone secretion; sensitivity reactions (exfoliative dermatitis and urticaria).

 Precautions

Pregnancy: Category C. Lactation: Excreted in breast milk. Cardiac effects: Theophylline may cause or worsen pre-existing arrhythmias. GI effects: Theophylline may cause or worsen pre-existing ulcers or gastroesophageal reflux. Toxicity: Patients with liver impairment, cardiac failure or > 55 yrs of age are at greatest risk; monitor theophylline levels to prevent toxicity.

 Administration/Storage

• Some sustained release preparations should be given on empty stomach to avoid rapid drug release.
• Do not crush or allow patient to chew sustained release preparations.
• If GI irritation occurs, give with food or full glass of water.
• When administering parenterally, use a pump or controller to maintain a constant infusion rate.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Carefully monitor patients with history of arrhythmias, seizures, peptic ulcer or gastroesophageal reflux.
• Monitor theophylline levels. The usual therapeutic range is 7 to 20 mcg/ml but some toxicity may be noted at the upper end of this range.
• Assess baseline LFT results.
• Implement cardiac monitoring as ordered for patients receiving IV form of theophylline.
• Monitor vital signs and I&O.

 Patient/Family Education

• Emphasize importance of follow-up with physician to monitor drug levels.
• Explain to patient that the medication is used to prevent asthma attacks and should be used continuously.
• Explain that some sustained release forms should be taken on empty stomach. Sustained release products should not be crushed or chewed.
• Explain that low-protein, high-carbohydrate diets may increase theophylline levels while high-protein, low-carbohydrate diets and charcoal-broiled foods may decrease theophylline levels.
• Alert patients to common adverse reactions including stomach upset, nausea, insomnia, tremors, palpitations, exfoliative dermatitis and urticaria.
• Tell patient to avoid food products containing caffeine.
• Instruct patient not to take extra doses of theophylline for acute asthma attack.
• Advise patient to consult with physician before taking any otc preparations.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts