Levothyroxine Theophylline

Antidepressants selective serotonin reuptake inhibitors, tricyclic antidepressants Antihypertensives felodipine Antibiotics quinolones, isoniazid Bronchodilators albuterol, theophylline Corticosteroids prednisone Dopa agonists levodopa Herbals ma huang, ginseng, ephedra Nonsteroidal anti-inflammatory drugs ibuprofen Stimulants amphetamines, methylphenidate, caffeine, cocaine Sympathomimetics pseudoephedrine Thyroid hormones levothyroxine Toxicity anticholinergics, antihistamines, digoxin Withdrawal alcohol, sedatives... 

Noninterfering acetaminophen, N-acetylprocainamide, amikacin, amitriptyline, amlodi-pine, carbamazepine, cefotaxime, ceftazidime, chloramphenicol, ciprofloxacin, cisapride, clindamycin, clonidine, codeine, cyclosporine, digoxin, diphenhydramine, disopyramide, ethosuximide, fluconazole, gentamicin, gentamicin, heparin, labetalol, levothyroxine, li-docaine, lithium, methotrexate, metronidazole, minoxidil, nafcillin, nifedipine, phenobar-bital, phenobarbital, phenytoin, phenytoin, primidone, procainamide, propranolol, quini-dine, ranitidine, salicylic acid, theophylline, tobramycin, tobramycin, valproic acid, warfarin... 

The serum theophylline level of an asthmatic patient was found to have doubled, from 15.2 to 30.9 mg/L, accompanied by toxicity, 3 months after treatment for hyperthyroidism with radioactive iodine ( I). At this point the patient was hypothyroid, and after treatment with levothyroxine was started, his serum theophylline returned to approximately the same level as before radioactive iodine treatment (13.9 mg/L). Another patient with Graves disease treated with a combination of thiamazole (methimazole)... 

It is established that changes in thyroid status may affect how the body handles theophylline. Monitor the effects and anticipate the possible need to begin to reduce the theophylline dosage if treatment for hyperthyroidism is started (e.g. with radioactive iodine, carbimazole, thiamazole, propylthiouracil, etc.). Similarly, anticipate the possible need to increase the theophylline dosage if treatment is started for hypothyroidism (e.g. with levothyroxine). Stabilisation of the thyroid status may take weeks or even months to achieve so that if monitoring of the theophylline dosage is considered necessary, it will need to extend over the whole of this period. 

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