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The older we get, the more infections we get, and the more infections we get, the more likely it is that doctors will treat us with multiple, intravenously administered (IV) antibiotics. These life-saving medications can interact with common drugs.
Of all the commonly prescribed antibiotics, clarithromycin probably causes the greatest number of adverse interactions. Marketed under the trade names Biaxin and Prevpac (which combines clarithromycin with amoxicillin and lansoprazole), clarithromycin is used to treat pneumonia, severe bacterial bronchitis, Lyme disease, Legionnaire's disease, cat scratch fever, and peptic and duodenal ulcers caused by infections with the bacterium Helicobacter pylori.
Clarithromycin can be a lifesaving drug, but it can also interfere with the way the body processes a very long list of medications.
- Cisapride (Propulsid, for gastroesphogeal reflux disease), colchicine (Colcrys, for gout), dihydroergotamine (DHE 45, Migranal,for migraine headaches), ergotamine (Ergomar, in Cafergot, in Migergot, also for migraine, and also to stop severe bleeding after childbirth), lovastatin (Mevacor, in Advicor, for lowering cholesterol), pimozide (Orap, an antipsychotic drug), simvastatin (Zocor, part of Vytorin, also used to lower cholesterol) react with clarithromycin so violently they should never be mixed at all. This is also true of the herbal remedy red yeast rice, used for controlling cholesterol.
- Combining clarithromycin with other statin drugs increases the risk of rhabdomyolysis, breaking down muscle tissue, especially when the user engages in vigorous exercise.
- Combining clarithromycin with calcium channel blockers, used to control high blood pressure, a class of medications including amlopidine (Norvasc), felopidine (Plendil), and nifedipine (Adalat, Procardia), can result in extremely low pressure, kidney failure, and even death, due to interference with the liver enzymes that break down the calcium channel blocker.
- Combining clarithromycin with the medication Tegretol (carbamazepine, used to treat epilepsy and neuropathy pain) can double the amount of Tegretol in the bloodstream. High Tegretol titers can result in double vision (diplopia), extremely low sodium levels (hyponatremia), and nausea.
- Combining clarithromycin with busiprone (Buspar, used to treat anxiety in patients who have psychoses) can cause serotonin syndrome: extreme anxiety, headache, elevated blood pressure, diarrhea, vomiting, and psychotic episodes.
Potentially fatal drug interactions sometimes occur when clarithromycin is given to elderly patients who take a class of medications known as glyburides for type 2 diabetes.
The glyburides work by stimulating the pancreas to release more insulin. Clarithromycin, as well as the other antibiotics mentioned in this article, stops the liver from breaking down the anti-diabetes medications so they stimulate the pancreas to release more and more insulin. Blood sugar levels can go very low. This can cause very obvious symptoms like loss of consciousness, or it can cause subtler symptoms such as inappropriate emotions, accident-prone behaviors, and bad judgment.
Older persons whose mental faculties are actually impaired by low blood sugar levels, due to drug interaction, may be misdiagnosed as suffering dementia, and inappropriately confined to hospital or nursing home care. It is much better simply to test blood sugar levels more frequently when someone is getting antibiotics, and to give more carbohydrate in the diet, than to deal with the consequences of misdiagnosing a drug interaction as delirium or senile dementia.
- Parekh TM, Raji M, Lin YL, Tan A, Kuo YF, Goodwin JS. Hypoglycemia after antimicrobial drug prescription for older patients using sulfonylureas. JAMA Intern Med. 2014 Oct.174(10):1605-12. doi: 10.1001/jamainternmed.2014.3293.
- Photo courtesy of samantha celera via Flickr: www.flickr.com/photos/scelera/2307998410
- Photo courtesy of a-md via Flickr: www.flickr.com/photos/angela_sleeping/6833986386
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