Drug Interaction Report

Using bismuth subsalicylate together with tetracycline may decrease the effects of tetracycline. Administration of tetracycline and bismuth subsalicylate should be separated by two to three hours. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Consumer information for this interaction is not currently available.

MONITOR: The concomitant use of acetylcholinesterase inhibitors (ACHEIs) (e.g., donepezil, galantamine, benzgalantamine physostigmine, rivastigmine, tacrine) with nonsteroidal anti-inflammatory drugs (NSAIDs) may increase the risk of gastrointestinal (GI) bleeding. ACHEIs can increase gastric acid secretion due to their cholinergic effects and NSAIDS may increase the risk of GI bleeding and ulceration. In a Swedish retrospective case study of 70,060 patients aged 65 years and older with new prescriptions for both ACHEIs and NSAIDs, 1500 persons were diagnosed with incident peptic ulcer. The results suggested that the risk of peptic ulcer was significantly increased for the combination of ACHEIs and NSAIDs compared to NSAIDs alone. No increased risks were found for the use of ACHEIs alone.


MANAGEMENT: Caution and clinical monitoring are recommended if concomitant use of ACHEIs and NSAIDs is required, especially in patients with a prior history of peptic ulcer disease, the elderly, or debilitated patients. Patients should be advised to seek prompt medical attention if they experience symptoms that could indicate the occurrence gastrointestinal bleeding such as black or tarry stools, bright red blood in vomit, coffee ground like vomit, abdominal pain or cramping, diarrhea, dizziness or lightheadedness, weakness or fatigue and pale skin.

Consumption of alcoholic beverages or products containing alcohol or propylene glycol during treatment with metroNIDAZOLE is not recommended. Doing so may occasionally trigger a reaction in some patients similar to the disulfiram reaction, which includes unpleasant effects such as flushing, throbbing in head and neck, throbbing headache, difficulty breathing, nausea, vomiting, sweating, thirst, chest pain, rapid heartbeat, palpitation, low blood pressure, dizziness, lightheadedness, blurred vision, and confusion. Rarely, more severe reactions may include abnormal heart rhythm, heart attack, heart failure, unconsciousness, convulsions, and even death. Patients treated with metroNIDAZOLE should continue to avoid using any products containing alcohol or propylene glycol for at least 3 days until after completion of therapy. Talk to your doctor or pharmacist if you have questions on how to take this or other medications you are prescribed. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Do not take iron supplements, multivitamins, calcium supplements, antacids, or laxatives within 2 hours before or after taking tetracycline. These products can make tetracycline less effective in treating your infection. Do not take tetracycline with milk or other dairy products, unless your doctor has told you to. Dairy products can make it harder for your body to absorb the medication.

Consumer information for this interaction is not currently available.

GENERALLY AVOID: The oral bioavailability of quinolone and tetracycline antibiotics may be reduced by concurrent administration of preparations containing polyvalent cations such as aluminum, calcium, iron, magnesium, and zinc. Therapeutic failure may result. The proposed mechanism is chelation of quinolone and tetracycline antibiotics by di- and trivalent cations, forming an insoluble complex that is poorly absorbed from the gastrointestinal tract. Reduced gastrointestinal absorption of the cations should also be considered.

MANAGEMENT: Concomitant administration of oral quinolone and tetracycline antibiotics with preparations containing aluminum, calcium, iron, magnesium, and/or zinc salts should generally be avoided. Otherwise, the times of administration should be staggered by as much as possible to minimize the potential for interaction. Quinolones should typically be dosed either 2 to 4 hours before or 4 to 6 hours after polyvalent cation preparations, depending on the quinolone and formulation. Likewise, tetracyclines and polyvalent cation preparations should typically be administered 2 to 4 hours apart. The prescribing information for the antibiotic should be consulted for more specific dosing recommendations.