AMINOPHYLLINE (THEOPHYLLINE ETHYLENEDIAMIDE)

AMINOPHYLLINE (THEOPHYLLINE ETHYLENEDIAMIDE) (am-in-off'i-lin) Corophyllin , Paladron , Truphylline Classifications: bronchodilator; (respiratory smooth muscle relaxant); xanthine; Therapeutic: bronchodilator (respiratory smooth muscle relaxant) Prototype: Theophylline Pregnancy Category: C

Availability

100 mg, 200 mg tablets; 105 mg/5 mL oral liquid; 25 mg/mL injection; 250 mg, 500 mg suppositories

Action

A xanthine derivative that relaxes smooth muscle in the airways of the lungs and suppresses the response of the airways to stimuli that constrict them.

Therapeutic Effect

It is a respiratory smooth muscle relaxant that results in bronchodilation.

Uses

To prevent and relieve symptoms of acute bronchial asthma and treatment of bronchospasm associated with chronic bronchitis and emphysema.

Unlabeled Uses

As a respiratory stimulant in Cheyne-Stokes respiration; for treatment of apnea and bradycardia in premature infants; as cardiac stimulant and diuretic in treatment of CHF.

Contraindications

Hypersensitivity to xanthine derivatives or to ethylenediamine component; cardiac arrhythmias; pregnancy (category C); lactation.

Cautious Use

Severe hypertension, cardiac disease, arrhythmias; impaired hepatic function; diabetes mellitus; hyperthyroidism; glaucoma; prostatic hypertrophy; fibrocystic breast disease; history of peptic ulcer; neonates and young children, patients over 55 y; COPD, acute influenza or patients receiving influenza immunization.

Route & Dosage

Bronchospasm Adult: IV Loading Dose 6 mg/kg over 30 min IV Maintenance Dose Nonsmoker, 0.5 mg/kg/h; smoker, 0.8 mg/kg/h; CHF or cirrhosis, 0.1–0.2  mg/kg/h PO Nonsmoker, 0.5 mg/kg/h times 24 h in 4 divided doses; smoker, 0.75 mg/kg/h times 24 h in 4 divided doses; CHF or cirrhosis, 0.25 mg/kg/h times 24 h in 4 divided doses Child: IV Loading Dose 6 mg/kg IV over 30 min IV Maintenance Dose 1–9 y, 1 mg/kg/h; >9 y, 0.8 mg/kg/h PO 1–9 y, 1 mg/kg/h times 24 h in 4 divided doses; >9 y, 0.75 mg/kg/h times 24 h in 4 divided doses Infant: PO/IV 6–11 mo, 0.7 g/kg/h; 2–6 mo, 0.5 mg/kg/h Neonatal Apnea Neonate: PO/IV Loading Dose 5 mg/kg PO/IV Maintenance Dose 5 mg/kg/d divided q12h Geriatric Patients: PO 6.25 mg/kg loading dose, then 2.5 mg/kg q8h Obesity Dose on IBW.

Administration

• Note: All doses based on ideal body weight.

Oral

• Give with a full glass of water on an empty stomach (?–1 h before or 2 h after meals) for faster absorption, which is delayed but is not reduced with food.
• Minimize GI symptoms by taking immediately after a meal or with food.
• Do not chew or crush extended (controlled) release preparations before swallowing; however, if tablet is scored, it can be broken in half, then swallowed.
• Do mix contents of extended release capsules with soft, moist food to promote swallowing.

Suppository

• Note: Rectal preparations may be ordered when patient must fast or cannot tolerate the drug orally; absorption is enhanced if rectum is empty.

Intravenous Verify correct IV concentration and rate of infusion with physician for neonates, infants, and children. PREPARE: IV Infusion: • Dilute loading dose in 100–200 mL NS, D5W, D5/NS, or RL. For continuous or intermittent infusion dilute in 500–1000 mL.• Do not use aminophylline solutions if discolored or if crystals are present.  ADMINISTER: IV Infusion: Infuse at a rate not to exceed 25 mg/min.   INCOMPATIBILITIES Solution/additive: Amikacin, bleomycin, cephalosporins, chlorpromazine, ciprofloxacin, clindamycin, dimenhydrinate, dobutamine, doxorubicin, epinephrine, hydralazine, hydroxyzine, insulin, isoproterenol, meperidine, methylprednisolone, morphine, nafcillin, norepinephrine, papaverine, penicillin G, pentazocine, procaine, prochlorperazine, promazine, promethazine, verapamil, vitamin B complex with C, zinc. Y-site: Amiodarone, ciprofloxacin, clarithromycin, dobutamine, fenoldopam, hydralazine, lansoprazole, ondansetron, TPN, vinorelbine, warfarin.

• Store at 15°–30° C (59°–86° F) in tightly closed containers unless otherwise directed.
• Follow manufacturer's directions regarding storage of suppositories; some can be stored at room temperature; others must be refrigerated.

Adverse Effects (≥1%)

CNS: Nervousness, restlessness, depression, insomnia, irritability, headache, dizziness, muscle hyperactivity, convulsions. CV: Cardiac arrhythmias, tachycardia (with rapid IV), hyperventilation, chest pain, severe hypotension, cardiac arrest. GI: Nausea, vomiting, anorexia, hematemesis, diarrhea, epigastric pain.

Interactions

Drug: Increases lithium excretion, lowering lithium levels; cimetidine, high-dose allopurinol (600 mg/d), ciprofloxacin, erythromycin, troleandomycin can significantly increase theophylline levels.

Pharmacokinetics

Absorption: Most products are 100% absorbed from GI tract. Peak: IV 30 min; uncoated tablet 1 h; sustained release 4–6 h. Duration: 4–8 h; varies with age, smoking, and liver function. Distribution: Crosses placenta. Metabolism: Extensively in liver; by CYP1A2. Elimination: Parent drug and metabolites excreted by kidneys; excreted in breast milk. Half-Life: 3.7 h (child); 7.7 h (adult).

Nursing Implications

Assessment & Drug Effects

• Monitor for S&S of toxicity (generally related to theophylline serum levels over 20 mcg/mL). Observe patients receiving parenteral drug closely for signs of hypotension, arrhythmias, and convulsions until serum theophylline stabilizes within the therapeutic range.
• Note: High incidence of toxicity is associated with rectal suppository use due to erratic rate of absorption.
• Monitor & record vital signs and I&O. A sudden, sharp, unexplained rise in heart rate may indicate toxicity.
• Lab tests: Monitor serum theophylline levels.
• Note: Older adults, acutely ill, and patients with severe respiratory problems, liver dysfunction, or pulmonary edema are at greater risk of toxicity due to reduced drug clearance.
• Note: Children appear more susceptible to CNS stimulating effects of xanthines (nervousness, restlessness, insomnia, hyperactive reflexes, twitching, convulsions). Dosage reduction may be indicated.

Patient & Family Education

• Note: Use of tobacco tends to increase elimination of this drug (shortens half-life), necessitating higher dosage or shorter intervals than in nonsmokers.
• Report excessive nervousness or insomnia. Dosage reduction may be indicated.
• Note: Dizziness is a relatively common side effect, particularly in older adults; take necessary safety precautions.
• Do not take OTC remedies for treatment of asthma or cough unless approved by physician.

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Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug