Xanthine Bronchodilators (Aminophylline)

• Prescribed for: Relief of bronchial asthma and spasms of bronchial muscles associated with emphysema, bronchitis, and other diseases. May also be prescribed to treat essential tremors and chronic obstructive pulmonary disease (COPD).

Xanthine Bronchodilators (Aminophylline) General Information

Xanthine bronchodilators are a mainstay of therapy for bronchial asthma and similar diseases. Although the dose of each of these drugs is different, they all work by relaxing bronchial muscles and helping reverse spasms in these muscles, though the exact way in which they work is not known.

Timed-release products allow the xanthine bronchodilators to act throughout the day, minimizing possible drug side effects by avoiding peaks and valleys associated with short-acting xanthine drugs. This also allows you to reduce the total number of daily doses.

The initial treatment with a xanthine bronchodilator requires your doctor to take blood samples to assess how much of the drug is in your blood. For Theophylline, the standard against which all other members of the group are compared, a level of between 10 and 20 micrograms per milliliter (quantity per blood volume) is generally considered desirable. For Dyphylline, the minimum effective level is 12 micrograms per milliliter. Dosage adjustments may be required based on these blood tests and your response to the therapy.

Because Dyphylline is not eliminated by the liver, it is not subject to many of the drug interactions or limitations placed on the other xanthine bronchodilators. However, dosage must be altered in the presence of kidney failure.

Xanthine Bronchodilators (Aminophylline) Cautions and Warnings

Do not use a xanthine bronchodilator if you are allergic or sensitive to any of these medicines. If you have a stomach ulcer, congestive heart failure, heart disease, liver disease, low blood-oxygen levels, or high blood pressure, or are an alcoholic, you should use this drug with caution. People with seizure disorders should not take a Xanthine bronchodilator unless they are receiving appropriate anticonvulsant medicines. Theophylline may cause or worsen preexisting abnormal heart rhythms. Any change in heart rate or rhythm warrants your doctor’s immediate attention.

Status asthmaticus, a medical condition in which the breathing passages are virtually completely closed, does not respond to oral bronchodilators. Victims of this condition must be taken to a hospital emergency room at once for treatment. Serious side effects, including convulsions, serious arrhythmias, and death, may be among the initial signs of drug toxicity. Periodic monitoring by your physician is mandatory if you are taking one of these medicines.

Xanthine Bronchodilators (Aminophylline) Possible Side Effects

Drug side effects are directly related to the amount of drug in your blood. As long as you stay in the proper range (below 20 micrograms per milliliter of blood), you should experience few, if any, problems.

• The first side effects you may experience when you exceed this level are nausea, vomiting, stomach pain, diarrhea, irritability, restlessness, and difficulty sleeping. Other possible drug side effects include rectal irritation or bleeding (especially with suppositories) and rapid breathing.
• As drug levels increase (over 35 micrograms per milliliter), you may experience excitability, high blood sugar, muscle twitching or spasms, heart palpitations, seizures, b rai n dam a g e, or death.
• Rare: vomiting blood, regurgitating stomach contents while lying down, fever, headache, rash, hair loss, and dehydration.

Xanthine Bronchodilators (Aminophylline) Drug Interactions

• Taking two xanthine bronchodilators together may increase side effects.
• Xanthine bronchodilators are often given in combination with a stimulant drug, such as Ephedrine. Such combinations can cause excessive stimulation and should be used only as specifically directed by your doctor.
• Reports have indicated that combining Erythromycin, flu vaccine, Allopurinol, beta blockers, calcium channel blockers, Cimetidine (and, rarely, Ranitidine), oral contraceptives, corticosteroids, Disulfiram, Ephedrine, Interferon, Mexiletine, quinolone antibacterials, or Thiabendazole with a xanthine bronchodilator will increase blood levels of the xanthine bronchodilator. Higher blood levels mean the possibility of more side effects. Tetracycline may also increase the chances for xanthine bronchodilator side effects.
• The following drugs may decrease Theophylline levels: Aminoglutethimide, barbiturates, charcoal, Phenytoin and other hydantoin anticonvulsants (the hydantoin level may also be reduced), Ketoconazole, Rifampin, Sulfinpyrazone, and sympathomimetic drugs.
• Smoking cigarettes or marijuana makes xanthine bronchodilators (except Dyphylline) less effective by increasing the rate at which your liver breaks them down.
• Drugs that may either increase or decrease xanthine bronchodilator levels include Carbamazepine, Isoniazid, and Furosemide and other loop diuretics. Persons combining a xanthine bronchodilator with one of these drugs must be evaluated individually. Again, consult your doctor when combining xanthine bronchodilators with any of these drugs.
• People with an overactive thyroid clear xanthine bronchodilators faster and may require a larger dose. People with an underactive thyroid have the opposite reaction. Normalizing thyroid function through medical or surgical treatment will normalize your response to a xanthine bronchodilator.
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• xanthine bronchodilator may counteract the sedative effect of Valium and other benzodiazepine tranquilizers.
• Xanthine bronchodilators may. interfere with or interact with a number of different drugs used during anesthesia. Your doctor may temporarily alter your bronchodilator dose or change drugs to avoid this problem.
• Blood-lithium levels may be lowered by xanthine bronchodilators.
• Probenecid may increase the effects of Dyphylline by interfering with its removal from the body through the kidneys.
• Xanthine bronchodilators may counteract the sedative effects of Propofol.

Food Interactions

To obtain a consistent effect from your medicine, take it at the same time each day on an empty stomach (at least 1 hour before or 2 hours after meals).

Theophylline is eliminated from the body faster if your diet is high in protein and low in carbohydrates. Eating charcoal-broiled beef also has this effect. On the other hand, the rate at which your body eliminates Theophylline is reduced by a high-carbohydrate, low-protein diet. You may take some food with a liquid or non-sustained-release xanthine bronchodilator if it upsets your stomach. Dyphylline is not affected in this way.

Caffeine (a xanthine derivative) may add to the side effects of the xanthine bronchodilators, except Dyphylline. Avoid large amounts of caffeine-containing products such as coffee, tea, cola, cocoa, and chocolate, while taking one of these drugs.

Usual Dose

AminophylUne
Each 100 mg of Aminophylline is equal in potency to 79 mg of Theophylline. Aminophylline dosage is calculated on the basis of Theophylline equivalents and must be tailored to your specific condition. The best dose for you is the lowest dose that will control your symptoms.
Adult: 100 to 200 mg every 6 hours.
Child (up to age 16): 50 to 100 mg every 6 hours, or 1 to 2.5 mg per pound of body weight every 6 hours.

Timed-Release Products
1 to 3 times per day, based on your symptoms and response to treatment. Usual dose is 200 to 500 mg per day.

Dyphylline
There is no established Theophylline equivalent dosage for Dyphylline. The usual dose is up to 7 mg per pound of body weight 4 times per day. Dosage must be reduced in the presence of kidney failure. Dyphylline dosage must, be tailored to your specific condition. The best dose is the lowest that will control your symptoms.

Oxtriphylline
Each 100 mg of Oxtriphylline is roughly equal to 64 mg of Theophylline. Oxtriphylline dosage is calculated on the basis of Theophylline equivalents and must be tailored to your specific condition.
Adult: about 2 mg per pound of body weight, 3 times per day. Sustained Action (SA): 400 to 600 mg every 12 hours.
Child (age 1 to 9): 2.8 mg for every pound of body weight taken 4 times per day.

Theophylline
These dosage guidelines may seem backward because children (1 year and older) require more drug per pound of body weight than adults. This is because children metabolize (chemically change) xanthine bronchodilators faster than adults do.

• Adult: up to 6 mg per pound of body weight per day, to a maximum daily dose of 900 mg.
• Adolescent (age 12 to 16): up to 8.1 mg per pound of body weight per day.
• Child (age 9 to 11): up to 9 mg per pound of body weight per day.
• Child (age 1 to 9): up to 10.9 mg per pound of body weight per day.
  Infant (6 to 52 weeks): The total daily dose in mg is calculated by the following: 0.2 times age in weeks + 5. Up to 6 months, give 1/3 the total dose every 8 hours. From age 26 weeks to 1 year, divide the daily total into 4 doses.
• Premature Infant (25 days or older): 0.68 mg per pound of body weight every 12 hours.
• Premature Infant (24 days or younger): 0.45 mg per pound of body weight every 12 hours.
  Timed-release products are usually taken 1 to 3 times per day at the same dose, depending on your response.

The best dose of xanthine bronchodilators is that which is tailored to your condition and is the lowest dose that will produce maximum control of your symptoms.

Overdosage

The first symptoms of overdosage are loss of appetite, nausea, vomiting, nervousness, difficulty sleeping, headache, and restlessness, followed by rapid or abnormal heart rhythms, unusual behavior patterns, extreme thirst, delirium, convulsions, very high temperature, and collapse. These serious toxic symptoms are rarely experienced after overdose by mouth, which produces loss of appetite, nausea, vomiting, and stimulation. The overdose victim should be taken to a hospital emergency room immediately. ALWAYS bring the medicine bottle with you.

Xanthine Bronchodilators (Aminophylline) Special Information

Do not chew or crush coated or sustained-release capsules or tablets before you take them. This could result in the immediate release of large amounts of medicine, which can cause serious drug side effects.
To ensure consistent effectiveness, take your medicine at the same time and in the same way each day (with or without food).
Call your doctor if you develop nausea, vomiting, heartburn or vomiting, sleeplessness, jitteriness, restlessness, headache, rash, severe stomach pain, convulsions, or a rapid or irregular heartbeat. Serious side effects, including convulsions, serious arrhythmias, and death, may be the first signs of drug toxicity. Periodic monitoring by your physician is mandatory if you are taking one of these medicines.
Do not change bronchodilator drug brands without notifying your doctor or pharmacist. Different brands of the same xanthine bronchodilator may not be identical in their effect on your body.
If you forget to take a dose of your xanthine bronchodilator, take it as soon as you remember. If it is almost time for your next dose, skip the one you forgot and continue with your regular schedule. Do not take a double dose.

Special Populations

Pregnancy/Breast-feeding
Xanthine bronchodilators pass into the circulation of the developing baby. They do not cause birth defects but may result in dangerous drug levels in the infant’s bloodstream. Babies born to mothers taking this medication may be nervous, jittery, and irritable, and may gag or vomit when fed. Women who must use this medication to control asthma or other conditions should talk with their doctor about the relative risks of using this medication versus its benefits.
These drugs pass into breast milk and it may cause a nursing infant to be nervous or irritable, or to have difficulty sleeping. Nursing mothers who must use one of these drugs should bottle-feed their babies.

Seniors
Older adults (especially men age 55 and older) may take longer to clear the xanthine bronchodilators from their bodies than younger adults. Older adults with heart failure or other cardiac conditions, chronic lung disease, a viral infection with fever, or reduced liver function may require a lower dosage of this medication to account for the clearance effect.