aminophylline

Absorption: Aminophylline releases theophylline after administration.

Distribution: Widely distributed as theophylline; crosses the placenta; breast milk concentrations are 70% of plasma levels; not distributed into adipose tissue.

Metabolism/Excretion: Aminophylline is converted to theophylline; theophylline is metabolized by the liver (90%) to caffeine, which may accumulate in neonates; metabolites are renally excreted; 10% excreted unchanged by the kidneys.

Half-Life: Theophylline: Premature infants: 20–30 hr; Term infants: 11–25 hr; Children 1–4 yr: 3.4 hr; Children 6–17 yr: 3.7 hr; Adults: 9–10 hr (↑ in patients >60 yr, patients with HF or liver disease; ↓ in cigarette smokers ).

Time/Action Profile ⬆ ⬇

(bronchodilation)

ROUTE	ONSET‡	PEAK	DURATION
IV	rapid	end of infusion	6–8 hr

‡Provided that a loading dose has been given and steady-state blood levels exist.

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity to aminophylline or theophylline.

Use Cautiously in:

Cardiac arrhythmias;
Heart failure, liver disease, or hypothyroidism (dose ↓ required);
Peptic ulcer disease;
Seizure disorder;
OB: /Safety not established;
Pedi: Dose required in children 1 yr;
Geri: Initial dose may be necessary in geriatric or debilitated patients.

Adv. Reactions/Side Effects ⬆ ⬇

CV: tachycardia, angina, ARRHYTHMIAS, palpitations

Derm: rash

GI: nausea, vomiting, anorexia

Neuro: anxiety, headache, insomnia, irritability, SEIZURES, tremor

Interactions ⬆ ⬇

Drug-drug:

Additive CV and CNS side effects with adrenergics (sympathomimetic).
May ↓ the therapeutic effect of lithium and phenytoin.
Smoking, barbiturates, carbamazepine, phenytoin, nevirapine and rifampin may ↑ metabolism and may ↓ effectiveness.
Erythromycin, beta blockers, clarithromycin, calcium channel blockerscimetidine,hormonal contraceptives, disulfiram, doxycycline, estrogens, fluvoxamine, isoniazid, ketoconazole, mexiletine, nefazodone, protease inhibitors, quinidine, some fluoroquinolones, and large doses of allopurinol↓ metabolism and may lead to toxicity.

Drug-Natural Products:

Caffeine-containing herbs (cola nut, guarana, mate, tea, coffee) may ↑ serum levels and risk of CNS and CV side effects.
↓serum levels and effectiveness with St. John’s wort.

Excessive regular intake of charcoal-broiled foods may ↓ effectiveness.

Route/Dosage ⬆ ⬇

Dose should be determined by theophylline serum level monitoring. Loading dose should be decreased or eliminated if theophylline preparation has been used in preceding 24 hr. Aminophylline is 80% theophylline (100 mg aminophylline = 80 mg theophylline).
IV (Adults ): Loading dose: 6 mg/kg (4.7 mg/kg of theophylline) given over 20–30 min, followed by 0.7 mg/kg/hr (0.56 mg/kg/hr of theophylline) via continuous infusion (non-smoking adults); an infusion rate of 0.9 mg/kg/hr (0.72 mg/kg/hr of theophylline) should be used for adults who smoke.
IV Geriatric Patients and Adult Patients with Cor Pulmonale): Loading dose: 6 mg/kg (4.7 mg/kg of theophylline) given over 20–30 min, followed by 0.6 mg/kg/hr (0.47 mg/kg/hr of theophylline) via continuous infusion.
IV (Adults with HF or Liver Failure): Loading dose: 6 mg/kg (4.7 mg/kg/hr of theophylline) given over 20–30 min, followed by 0.5 mg/kg/hr (0.39 mg/kg/hr of theophyliine) via continuous infusion.
IV (Children 12–16 yr): Loading dose: 6 mg/kg (4.7 mg/kg of theophylline) given over 20–30 min, followed by 0.7 mg/kg/hr (0.56 mg/kg/hr of theophylline) via continuous infusion.
IV (Children 9–12 yr): Loading dose: 6 mg/kg (4.7 mg/kg of theophylline) given over 20–30 min, followed by 0.9 mg/kg/hr (0.72 mg/kg/hr of theophylline) via continuous infusion.
IV (Children 1–9 yr): Loading dose: 6 mg/kg (4.7 mg/kg of theophylline) given over 20–30 min, followed by 1–1.2 mg/kg/hr (0.8–0.96 mg/kg/hr of theophylline) via continuous infusion.
IV (Children 6 mo–1 yr): Loading dose: 6 mg/kg (4.7 mg/kg of theophylline) given over 20–30 min, followed by 0.6–0.7 mg/kg/hr (0.48–0.56 mg/kg/hr of theophylline) via continuous infusion.
IV (Children 6 wk–6 mo): Loading dose: 6 mg/kg (4.7 mg/kg of theophylline) given over 20–30 min, followed by 0.5 mg/kg/hr (0.4 mg/kg/hr of theophylline) via continuous infusion.

Availability ⬆ ⬇

(Generic available)

Injection: 25 mg/mL

Assessment ⬆ ⬇

Assess BP, pulse, respiratory status (rate, lung sounds, use of accessory muscles, number and severity of apnea spells in infants) before and throughout therapy. Ensure that oxygen therapy is correctly instituted during acute asthma attacks.
- Monitor intake and output ratios for an increase in diuresis or fluid overload.
- Monitor patients with a history of cardiovascular problems for chest pain and ECG changes (PACs, supraventricular tachycardia, PVCs, ventricular tachycardia). Resuscitative equipment should be readily available.
- Monitor pulmonary function tests before and periodically during therapy to determine therapeutic efficacy in patients with chronic bronchitis or emphysema.

Lab Test Considerations:

Monitor ABGs, acid-base, and fluid and electrolyte balance in patients receiving parenteral therapy or whenever required by patient’s condition.

Toxicity and Overdose:

Monitor drug levels routinely, especially in patients requiring high doses or during prolonged intensive therapy. Serum sample should be obtained at time of peak absorption. Peak levels should be evaluated 30 min after a 30 min IV loading dose, 12–24 hr after initiation of a continuous infusion and 1–2 hr after rapid-acting oral forms, and 4–12 hr after extended-release oral forms. Therapeutic plasma levels range from 10–15 mcg/mL for asthma and 6–14 mcg/mL for apnea of prematurity. Drug levels in excess of 20 mcg/mL are associated with toxicity. Caffeine ingestion may falsely elevate drug concentration levels.
- Observe for symptoms of drug toxicity (anorexia, nausea, vomiting, stomach cramps, diarrhea, confusion, headache, restlessness, flushing, increased urination, insomnia, tachycardia, arrhythmias, seizures). Notify health care professional immediately if these occur. Tachycardia, ventricular arrhythmias, or seizures may be the first sign of toxicity.
- Patients over 60 yr have ↑ risk of toxicity and sensitivity to toxic effects due to age-related pharmacodynamic and pharmacokinetic changes. Assess frequently.

Implementation ⬆ ⬇

Administer around the clock to maintain therapeutic plasma levels.

IV Administration:

IV: Diluent: May be diluted in D5W, D10W, D20W, 0.9% NaCl, 0.45% NaCl, D5/0.9% NaCl, D5/0.45% NaCl, D5/0.25% NaCl, or LR.Concentration: 1 mg/mL. Maximum concentrationis 25 mg/mL. Mixture is stable for 24 hr if refrigerated.
- Do not administer discolored or precipitated solution. Flush main IV line before administration.
- If extravasation occurs, local injection of 1% procaine and application of heat may relieve pain and promote vasodilation.
Loading Dose: Administer over 20–30 min.
Rate: Do not exceed 20–25 mg/min in adults or 0.36 mg/kg/min in children. Administer via infusion pump to ensure accurate dosage. Rapid administration may cause chest pain, dizziness, hypotension, tachypnea, flushing, arrhythmias, or a reaction to the solution or administration technique (chills; fever; redness, pain, or swelling at injection site).
Usually given as a loading dose in a small volume followed by continuous infusion in larger volume.
Rate: See Route and Dosage section for rates.

Patient/Family Teaching ⬆ ⬇

Encourage the patient to drink adequate liquids (2000 mL/day minimum) to decrease the viscosity of the airway secretions.
Advise patient to avoid OTC cough, cold, or breathing preparations without consulting health care professional. These medications may increase side effects and cause arrhythmias.
Encourage patients not to smoke. A change in smoking habits may necessitate a change in dose.
Advise patient to minimize intake of xanthine-containing foods or beverages (colas, coffee, chocolate) and not to eat charcoal-broiled foods daily.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇

Pharmacokinetics ⬆ ⬇