How does Xanthine Derivatives Works?

Type of Drug.

Bronchodilators; theophylline products; drugs that make breathing easier by relaxing and widening certain breathing passages (bronchial tubes) of the lung.

How the Drug Works:

The xanthine derivatives directly relax the smooth muscle surrounding the bronchial tubes (air passages) of the lungs, allowing the tubes to widen, making breathing easier. These drugs may improve contraction of the diaphragm (the major breathing muscle) in patients with chronic obstructive airway disease.

Uses:

To prevent and relieve symptoms of bronchial asthma. Not for use by them­selves in an acute attack (status asthmaticus).

To treat bronchospasm (spasm in breathing tubes) associated with chronic bronchitis and emphysema.

Unlabeled Uses: Occasionally doctors may prescribe xanthine bronchodilators for other breathing problems and slow heart rates in premature infants.

Precautions:

Acute asthma attacks (status asthmaticus) are a medical emergency and are not rapidly responsive to usual doses of conventional bronchodilators. Therapy frequently requires IV medication and close monitoring .These products alone are not appropriate treatment for an acute asthma attack.

Pregnancy: There are no adequate and well-controlled studies in pregnant women. Use only if clearly needed and potential benefits outweigh the possible hazards to the fetus.

Breastfeeding: Xanthines appear in breast milk. Because of the potential for serious adverse reactions in nursing infants, decide whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. Consult your doctor before you begin breastfeeding.

Children: Safety and effectiveness of aminophylline and theophylline for use in children younger than 1 year of age have not been establish Caution should be exercised for younger children who cannot of side effects. If used in children younger than 1 year of age, strict;' attention should be directed at dosing and monitoring of serum levels I However, some dosage forms of theophylline are not recommonclod 101 certain age groups. Please check individual dosing and adiministration in package inserts. Oxtriphylline is not recommended for children younger than 6 years of age. Dyphylline is not recommended for cl1idren.

Elderly: Reduced theophylline elimination has been documented in patient older than 55 years of age, particularly in males with chronic lung disease, congestive heart failure, or liver disease. It is important to consider reduclloll of dosage and frequent measurement of serum theophyillne levels in these individuals, as they experience toxicity more easily.

Lab Tests: Lab tests may be necessary. High blood levels of xanthine bronchodilators may cause severe side effects. Therapy is monitored with lab tests to maintain nontoxic levels of medication, as serious toxicity is not reliably preceded by less severe side effects. Lung function measurements before and after a period of treatment may also be necessary to determine therapy effectiveness. Note that dyphylline is not converted to theophylline; thus, theophylline blood levels cannot be used to monitor its use.

Drug Interactions:

Tell your doctor or pharmacist if you are taking or planning to take any over­ the-counter or prescription medications or dietary supplements while taking xanthine bronchodilators. Doses of one or both drugs may need to be modified or a different drug may need to be prescribed. The following drugs and drug classes interact with xanthine bronchodilators:

These drugs increase the effects of xanthine broncobusters (increasing side effects)

• Alcohol allopurinol (eg, Zyloprim)

• Beta blockers (nonselective) (eg, propranolol)

• Carbamazepine (eg, Tegretol cimetidine (eg, Tagamet)

• Clarithromycin (Biaxin) contraceptives, oral estrogen­containing (eg, Ortho-Novum)

• Corticosteroids (eg, hydrocortisone)

• Disulfiram (Antabuse) ephedrine (eg, Sudafed)

• Erythromycin (eg, Eryc)

• Fluoroquinolones (eg, ciprofloxacin, enoxacin, norfloxacin, ofloxacin)

• Fluvoxamine (Luvox)

• Influenza vaccine (eg, Fluzone)

• Interferon, human recombinant alpha-A

• Isoniazid (eg, Laniazidl methotrexate (eg, Rheumatrex)

• Mexiletine (Mexitil) pentoXifylline (Trental) propafenone (Rythmol) propranolol (eg, lnderal)

• Tacrine (Cognex) thiabendazole (Mintezol thyroid hormones (eg, levothyroxine)

• Ticlopidine (Ticlid) troleandomycin (Tao) verapamil (eg, Verelan)

Side Effects:

Every drug is capable of producing side effects. Many xanthine bronchodilator users experience no, or minor, side effects, particularly if serum theophylline levels are less than 20 mcg/mL. The frequency and severity of side effects depend on many factors including dose, duration of therapy, and individual susceptibility. High blood levels (generally higher than 30 mcg/mL) of these medications will cause serious side effects, although high blood levels and serious toxicity are not always preceded by side effects. Possible side effects include:

Digestive Tract: Stomach pain; nausea; vomiting; vomiting of blood; diarrhea; gastroesophageal reflux (nocturnal).

Nervous System: Seizures; headache; sleeplessness; irritability; restless­ness; muscle twitching; reflex hyperexcitability; agitation.

Circulatory System: Decreased blood pressure; abnormal heart beat; pounding in the chest (palpitations); fast heartbeat.

Skin: Flushing; rush; hair loss.

Other: Increased urination; high blood sugar; rectal irritation or bleeding (suppository only); muscle tremors or twitching.

Guidelines for Use:

• Take exactly as prescribed. Individual doses are determined by response (decrease in symptoms) and blood levels (except with dyphylline). Do not take a different dose, take the drug more often, or for a longer time than prescribed.

• Immediate Release Tablets and Liquids: Take at regular intervals around the clock. If a dose is missed, take it as soon as possible. If several hours have passed or if it is nearing time for the next dose, do not double the dose in order to catch up, unless advised to do so by your doctor. If more than one dose is missed or it is necessary to establish a new dosage schedule, contact your doctor or pharmacist.

• Sustained, Extended, or Controlled Release Products: Take 8- to 12-hour release products at regular intervals (8 or 12 hours) around the clock. Try to take at the same time each day. Take 12- to 24-hour release products generally every 12 hours. However, a few patients may be able to take once a day. Take 24-hour release products once daily, preferably in the morning. Try to take at the same time each day. Although normally given once daily, patients who require very large doses may be asked to split the dose and take 2 doses per day. In this event, the second dose should be taken 10 to 12 hours after the first dose and before the evening meal. If a does Is missed, take the next dose at the usually scheduled time. Do not make up the the missed dose.

• Brand interchange - Do not change from one brand of this drug to another without consulting your pharmacist or doctor. Products are not equivalent on a weight basis and cannot be interchanged without adjusting the dose.

• If stomach upset occurs with liquid preparations or non-sustained release forms, take with food.

• Do not crush or chew enteric coated or sustained, extended, or con­trolled release tablets or capsules.

• Taking theophylline immediately after a high-fat meal or a fasting period may alter its rate of absorption.

• Do not use for an acute episode of bronchospasm.

• If rash, nausea, vomiting, restlessness, irregular heartbeat, or convulsions occur, contact your doctor immediately.

• Inform your doctor of bothersome side effects such as headache, stomach pain, sleeplessness, or jitteriness.

• Notify your doctor if respiratory symptoms return repeatedly near the end of the dosing interval.

• Avoid large amounts of caffeine-containing beverages, such as tea, coffee, cocoa, and cola drinks, or eating large amounts of chocolate. These products may increase side effects.

• Tell your doctor if you are a smoker. Smoking increases the clearance rate of theophylline and may decrease overall effect. Nicotine replacement therapy (NRT) used in smoking cessation programs does not adversely affect theophylline clearance.

• Uniphyl, Theolair SR - Take this drug consistently with respect to food, either with meals or fasting (at least 2 hours pre- or 2 hours post­meals).

• Theo-24 - In patients receiving once-daily doses of 900 mg or more, avoid eating a high-fat morning meal or take at least 1 hour before eating. If you cannot comply with this regimen, talk to your doctor about alternative therapy.

• Lab tests will be required. Be sure to keep appointments. Blood levels must be checked regularly to avoid underdosing and overdosing.

• Store oral dosage forms at room temperature (59° to 86°F) in a tightly closed container. Store suppositories between 36° to 46°F (refrigerated).