Look Up > Drugs > Aminophylline
Aminophylline
Pronunciation
U.S. Brand Names
Generic Available
Synonyms
Pharmacological Index
Use
Pregnancy Risk Factor
Adverse Reactions
Drug Interactions
Stability
Mechanism of Action
Pharmacodynamics/Kinetics
Usual Dosage
Dietary Considerations
Administration
Dental Health: Local Anesthetic/Vasoconstrictor Precautions
Dental Health: Effects on Dental Treatment
Patient Information
Nursing Implications
Dosage Forms
References

Pronunciation
(am in OFF i lin)

U.S. Brand Names
Phyllocontin®; Truphylline®

Generic Available

Yes


Synonyms
Theophylline Ethylenediamine

Pharmacological Index

Theophylline Derivative


Use

Bronchodilator in reversible airway obstruction due to asthma or COPD; increase diaphragmatic contractility; neonatal idiopathic apnea of prematurity


Pregnancy Risk Factor

C


Adverse Reactions

Uncommon at serum theophylline concentrations less than or equal to 20 mcg/mL

1% to 10%:

Cardiovascular: Tachycardia

Central nervous system: Nervousness, restlessness

Gastrointestinal: Nausea, vomiting

<1%:

Central nervous system: Insomnia, irritability, seizures

Dermatologic: Skin rash

Gastrointestinal: Gastric irritation

Neuromuscular & skeletal: Tremor

Miscellaneous: Allergic reactions


Drug Interactions

Decreased effect/increased toxicity: Changes in diet may affect the elimination of theophylline; charcoal-broiled foods may increase elimination, reducing half-life by 50%; see table for factors affecting serum levels.

Decreased theophylline level

Aminoglutethimide, barbiturates, carbamazepine, charcoal, high protein/low carbohydrate diet, hydantoins, isoniazid, I.V. isoproterenol, ketoconazole, loop diuretics, phenobarbital, phenytoin, rifampin, smoking (cigarettes, marijuana), sulfinpyrazone, sympathomimetics

Increased theophylline level

Allopurinol (>600 mg/day), beta-blockers, calcium channel blockers, carbamazepine, CHF, cimetidine, ciprofloxacin, cor pulmonale, corticosteroids, disulfiram, ephedrine, erythromycin, fever/viral illness, hepatic cirrhosis, influenza virus vaccine, interferon, isoniazid, loop diuretics, macrolides, mexiletine, oral contraceptives, propranolol, quinolones, thiabendazole, thyroid hormones, troleandomycin


Stability

Do not use solutions if discolored or if crystals are present


Mechanism of Action

Causes bronchodilatation, diuresis, CNS and cardiac stimulation, and gastric acid secretion by blocking phosphodiesterase which increases tissue concentrations of cyclic adenine monophosphate (cAMP) which in turn promotes catecholamine stimulation of lipolysis, glycogenolysis, and gluconeogenesis and induces release of epinephrine from adrenal medulla cells


Pharmacodynamics/Kinetics

Pharmacokinetic parameters are those of theophylline

Half-life: Highly variable and dependent upon age, liver function, cardiac function, lung disease, and smoking history

Time to peak serum concentration:

Oral: 1 hour

Uncoated tablet: 2 hours

Chewable tablet: 1-1.5 hours

Enteric-coated tablet: 5 hours

I.V.: Within 30 minutes


Usual Dosage

Neonates: Apnea of prematurity:

Loading dose: 5 mg/kg for one dose

Maintenance: I.V.:

0-24 days: Begin at 2 mg/kg/day divided every 12 hours and titrate to desired levels and effects

>24 days: 3 mg/kg/day divided every 12 hours; increased dosages may be indicated as liver metabolism matures (usually >30 days of life); monitor serum levels to determine appropriate dosages

Theophylline levels should be initially drawn after 3 days of therapy; repeat levels are indicated 3 days after each increase in dosage or weekly if on a stabilized dosage

Treatment of acute bronchospasm:

Loading dose (in patients not currently receiving aminophylline or theophylline): 6 mg/kg (based on aminophylline) administered I.V. over 20-30 minutes; administration rate should not exceed 25 mg/minute (aminophylline)

Approximate I.V. maintenance dosages are based upon continuous infusions; bolus dosing (often used in children <6 months of age) may be determined by multiplying the hourly infusion rate by 24 hours and dividing by the desired number of doses/day

6 weeks to 6 months: 0.5 mg/kg/hour

6 months to 1 year: 0.6-0.7 mg/kg/hour

1-9 years: 1-1.2 mg/kg/hour

9-12 years and young adult smokers: 0.9 mg/kg/hour

12-16 years: 0.7 mg/kg/hour

Adults (healthy, nonsmoking): 0.7 mg/kg/hour

Older patients and patients with cor pulmonale, patients with congestive heart failure or liver failure: 0.25 mg/kg/hour

Dosage should be adjusted according to serum level measurements during the first 12- to 24-hour period; avoid using suppositories due to erratic, unreliable absorption.

Rectal: Adults: 500 mg 3 times/day


Dietary Considerations

Food does not appreciably affect absorption; avoid extremes of dietary protein and carbohydrate intake; limit charcoal-broiled foods


Administration

Dilute with I.V. fluid to a concentration of 1 mg/mL and infuse over 20-30 minutes; maximum concentration: 25 mg/mL; maximum rate of infusion: 0.36 mg/kg/minute, and no greater than 25 mg/minute


Dental Health: Local Anesthetic/Vasoconstrictor Precautions

No information available to require special precautions


Dental Health: Effects on Dental Treatment

Prescribe erythromycin with caution to patients taking theophylline products. Erythromycin will delay the normal metabolic inactivation of theophyllines leading to increased blood levels; this has resulted in nausea, vomiting and CNS restlessness


Patient Information

Do not drink or eat large quantities of caffeine-containing beverages or food (colas, coffee, chocolate); remain in bed for 15-20 minutes after inserting suppository


Nursing Implications

Avoid I.M. injection, too painful; do not inject I.V. solution faster than 25 mg/minute; oral and I.V. should be administered around-the-clock rather than 4 times/day, 3 times/day, etc, (ie, 12-6-12-6, not 9-1-5-9) to promote less variation in peak and trough serum levels; do not crush sustained release drug products; do not crush enteric coated drug product; encourage patient to drink adequate fluids (2 L/day) to decrease mucous viscosity in airways

Monitor vital signs, I & O, serum concentrations, and CNS effects (insomnia, irritability)


Dosage Forms

Injection, I.V.: 25 mg/mL (10 mL, 20 mL)

Liquid, oral: 105 mg/5 mL (240 mL)

Suppository, rectal (Truphylline®): 250 mg, 500 mg

Tablet: 100 mg, 200 mg

Controlled release [12 hours] (Phyllocontin®): 225 mg


References

Delaforge M and Sartori E, "In Vivo Effects of Erythromycin, Oleandomycin, and Erythralosamine Derivatives on Hepatic Cytochrome P-450," Biochem Pharmacol, 1990, 40(2):223-8.

Ludden TM, "Pharmacokinetic Interactions of the Macrolide Antibiotics," Clin Pharmacokinet, 1985, 10(1):63-79.


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