Theophylline, Ephedrine, Guaifenesin, and Phenobarbital (Systemic)

Before Using This Medicine

For theophylline, ephedrine, guaifenesin, and phenobarbital combination medicine, the following should be considered:

Allergies - Tell your doctor if you have ever had any unusual or allergic reaction to aminophylline, oxtriphylline, or theophylline; ephedrine or medicines like ephedrine such as albuterol, amphetamines, epinephrine, isoproterenol, metaproterenol, norepinephrine, phenylephrine, phenylpropanolamine, pseudoephedrine, or terbutaline; or phenobarbital or other barbiturates. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Diet - Make certain your health care professional knows if you are on any special diet, such as a high-protein, low-carbohydrate or low-protein, high-carbohydrate diet.

Pregnancy - Theophylline is used to treat asthma in pregnant women. Although there are no studies on birth defects in humans, problems have not been reported. However, some studies in animals have shown that theophylline can cause birth defects when given in doses many times the usual human dose.

Because your ability to clear theophylline from your body may decrease later in pregnancy, your doctor may want to take blood samples during your pregnancy to measure the amount of medicine in the blood. This will help your doctor decide whether the dose of this medicine should be changed.

Theophylline crosses the placenta. Use of this medicine during pregnancy may cause unwanted effects, such as fast heartbeat, irritability, jitteriness, or vomiting, in the newborn infant if the amount of medicine in your blood is too high.

Ephedrine has been shown to cause birth defects in humans when used during the first trimester.

Phenobarbital taken during pregnancy has been shown to increase the chance of birth defects in humans. Also, taking phenobarbital regularly during the last 3 months of pregnancy may cause the baby to become dependent on the medicine. This may lead to withdrawal symptoms in the baby after birth. In addition, one study in humans has suggested that phenobarbital taken during pregnancy may increase the chance of brain tumors in the baby.

Breast-feeding - Theophylline, ephedrine, and phenobarbital pass into the breast milk and may cause unwanted effects such as drowsiness, irritability, fretfulness, or trouble in sleeping in babies of mothers taking this medicine. Guaifenesin has not been reported to cause problems in nursing babies.

Children - Newborn infants may be especially sensitive to the effects of theophylline, ephedrine, guaifenesin, and phenobarbital combination medicine. This may increase the chance of side effects during treatment.

Older adults - Patients older than 60 years of age may be especially sensitive to the effects of theophylline, ephedrine, guaifenesin, and phenobarbital combination medicine. This may increase the chance of side effects during treatment.

Other medicines - Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking theophylline, ephedrine, and phenobarbital combination medicine, it is especially important that your health care professional know if you are taking any of the following:

• Anticoagulants (blood thinners) or
• Carbamazepine or
• Corticosteroids (cortisone-like medicines) or
• Corticotropin - The effects of these medicines may be decreased by phenobarbital

• Beta-adrenergic blocking agents including those used in the eyes (acebutolol [e.g., Sectral], atenolol [e.g., Tenormin], betaxolol [e.g., Betoptic, Kerlone], bisoprolol [e.g., Zebeta], carteolol [e.g., Cartrol], labetalol [e.g., Normodyne], levobunolol [e.g., Betagan], metipranolol [e.g., OptiPranolol], metoprolol [e.g., Lopressor], nadolol [e.g., Corgard], oxprenolol [e.g., Trasicor], penbutolol [e.g., Levatol], pindolol [e.g., Visken], propranolol [e.g., Inderal], sotalol [e.g., Sotacor], timolol [e.g., Blocadren, Timoptic]) - These medicines may prevent theophylline from working properly

• Central nervous system (CNS) depressants - The effects of these medicines or phenobarbital may be increased

• Cimetidine (e.g., Tagamet) or
• Ciprofloxacin (e.g., Cipro) or
• Clarithromycin (e.g., Biaxin) or
• Enoxacin (e.g., Penetrex) or
• Erythromycin (e.g., E-Mycin) or
• Fluvoxamine (e.g., Luvox) or
• Interferon alpha or
• Mexiletine (e.g., Mexitil) or
• Pentoxifylline (e.g., Trental) or
• Tacrine (e.g., Cognex) or
• Thiabendazole or
• Ticlopidine (e.g., Ticlid) or
• Troleandomycin (e.g., TAO) - These medicines may increase the effects of theophylline

• Cocaine or
• Tricyclic antidepressants (amitriptyline [e.g., Elavil], amoxapine [e.g., Asendin], clomipramine [e.g., Anafranil], desipramine [e.g., Norpramin], doxepin [e.g., Sinequan], imipramine [e.g., Tofranil], nortriptyline [e.g., Aventyl], protriptyline [e.g., Vivactil], trimipramine [e.g., Surmontil]) - The effects of ephedrine on the heart and blood vessels may be increased

• Divalproex sodium or
• Valproic acid - Using these medicines with phenobarbital may change the amount that you need to take of any of these medicines

• Guanadrel or
• Guanethidine or
• Methyldopa (e.g., Aldomet) - These medicines may increase the chance of high blood pressure caused by ephedrine

• Medicines that lower the acidity of urine, such as antacids containing calcium or magnesium, carbonic anhydrase inhibitors (e.g., Diamox, Neptazine), citrates (e.g., Bicitra, Polycitra), or sodium bicarbonate (e.g., baking soda) - These medicines may increase the chance of side effects of ephedrine

• Monoamine oxidase (MAO) inhibitor activity (isocarboxazid [e.g., Marplan], phenelzine [e.g., Nardil], procarbazine [e.g., Matulane], selegiline [e.g., Eldepryl], tranylcypromine [e.g., Parnate]) - Taking ephedrine while you are taking or within 2 weeks of taking monoamine oxidase (MAO) inhibitors may increase the effects of MAO inhibitors

• Moricizine (e.g., Ethmozine) or
• Phenytoin (e.g., Dilantin) or
• Rifampin (e.g., Rifadin) - These medicines may decrease the effects of theophylline

• Oral contraceptives (birth control pills) containing estrogen - Phenobarbital may decrease the birth control effects of these medicines; use of another method of birth control may be necessary while you are taking this combination medicine

• Rauwolfia alkaloids (e.g., reserpine) - These medicines may prevent ephedrine from working properly

Other medical problems - The presence of other medical problems may affect the use of theophylline, ephedrine, and phenobarbital combination medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Angle-closure glaucoma or
• Convulsions (seizures) or
• Heart or blood vessel disease or
• High blood pressure or
• Underactive adrenal gland - This combination medicine may make the condition worse

• Diabetes mellitus (sugar diabetes) - Barbiturates may make the condition worse; your doctor may need to change the dose of your diabetes medicine
• History of drug abuse or
• Liver disease - The effects of theophylline may be increased

• Pain - Phenobarbital may cause unusual excitement in the presence of pain