Phyllocontin Side Effects

Generic name: aminophylline

Note: This document contains side effect information about aminophylline. Some of the dosage forms listed on this page may not apply to the brand name Phyllocontin.

Some side effects of Phyllocontin may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to aminophylline: oral solution, oral tablet, oral tablet extended release, rectal suppository

If you experience any of the following serious side effects, stop taking aminophylline (the active ingredient contained in Phyllocontin) and seek emergency medical attention:

• an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives);

• seizures;

• increased or irregular heartbeats; or

• severe nausea or vomiting.

Other, less serious side effects may also occur, although they are not common at appropriate doses. Continue to take aminophylline and talk to your doctor if you experience

• slight nausea, decreased appetite, or weight loss;

• restlessness, tremor, or insomnia; or

• headache, lightheadedness, or dizziness.

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

For Healthcare Professionals

Applies to aminophylline: compounding powder, intravenous solution, oral solution, oral tablet, oral tablet extended release, rectal suppository

General

Most of the side effects of aminophylline (the active ingredient contained in Phyllocontin) (theophylline) have been dependent on serum concentrations. Generally, theophylline serum concentrations ranging from 10 to 20 mcg/mL are considered therapeutic, and serum concentrations greater than 20 mcg/mL are associated with greater toxicity.

There are several factors which may predispose a patient to higher serum concentrations and, thus, toxicity. These factors may include increased age, concomitant drugs which reduce the clearance of theophylline, hypothyroidism, congestive heart failure, liver disease, renal failure, and alterations in smoking habits. One series of patients with theophylline intoxication had recent upper respiratory tract infections.

The nature of acute toxicity of theophylline differs from chronic toxicity. Acute overdose is associated with higher theophylline concentrations and younger patients. In acute overdose the severity of toxicity is correlated with peak serum concentrations. Chronic overdosage is seen more commonly in older patients, and severe toxicity may occur with serum concentrations which are much lower than those seen in severe acute toxicity. In these patients, age is a predictor of severe toxicity.

Gastrointestinal

Gastrointestinal side effects have included anorexia, nausea, vomiting, and abdominal pain. Aminophylline (the active ingredient contained in Phyllocontin) may also cause locally-mediated gastrointestinal upset.

Nervous system

The mechanism of theophylline-induced seizures has not been determined. Seizures are generally focal with secondary generalization. Permanent neurologic deficits have been reported and morbidity may be high, especially in the elderly, patients with severe underlying disease, and patients with prolonged, uncontrolled seizure activity. The onset of seizures is not always preceded by less severe symptoms of aminophylline (the active ingredient contained in Phyllocontin) toxicity. Patients with an abnormal neurologic history, including a history of seizures, cerebral infarct, or head trauma, may be predisposed to seizure activity. If theophylline is used in these types of patients, serum concentrations should be monitored closely and maintained in the low, therapeutic range.

Nervous system side effects have included generalized seizures, most commonly in patients with elevated serum concentrations, although seizures have occurred at therapeutic concentrations. Theophylline may also cause nervousness and tremor at therapeutic dosages, which become worse as serum concentrations increase.

Cardiovascular

Theophylline serum concentrations are a significant predictor of arrhythmias. One study reported multifocal atrial tachycardia in 8% and 16% of patients with a serum concentration between 10 and 20 mcg/mL and greater than 20 mcg/mL, respectively. The onset of serious arrhythmias is not always preceded by less severe signs of theophylline toxicity.

Cardiovascular side effects have included increased heart rate which has progressed to atrial tachycardia or ventricular tachycardia. Patients with a history of arrhythmias may be predisposed to this effect. Hypotension has occurred with rapid intravenous administration.

Hypersensitivity

Patients are frequently sensitized to ethylenediamine through topical use, as it is used as a preservative in some topical preparations. These patients are generally able to tolerate plain theophylline preparations.

Hypersensitivity side effects have included erythematous rash, pruritus, urticaria, and exfoliative erythroderma. These side effects have been more commonly reported in patients sensitive to ethylenediamine component of aminophylline.

Metabolic

In one group of patients with theophylline concentrations greater than 20 mcg/mL, hyperglycemia was present in approximately 50%, hypokalemia in 15%, and hypomagnesemia in 20%. Hyponatremia and hypophosphatemia were seen less frequently.

Metabolic side effects have included hypokalemia, hyperglycemia, respiratory alkalosis, hypophosphatemia, and hypomagnesemia. The magnitude of these abnormalities have been correlated with theophylline concentrations.

Genitourinary

Genitourinary side effects have included urinary retention.

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