Drug Interaction Report

Talk to your doctor before using tetracycline together with amoxicillin. Combining these medications may reduce the effectiveness of amoxicillin. Your doctor may be able to prescribe alternatives that do not interact. 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.

Using bismuth subcitrate potassium together with tetracycline may decrease the effects of tetracycline. Administration of tetracycline and bismuth subcitrate potassium 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.

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.

ADJUST DOSING INTERVAL: Food may impair the gastrointestinal absorption and decrease the bioavailability of bismuth from the administration of bismuth subcitrate potassium (also known as colloidal bismuth subcitrate or tripotassium dicitratobismuthate). The clinical significance of this effect is unknown, as the relative importance of systemic versus local bismuth concentrations for antimicrobial activity against Helicobacter pylori has not been established. Investigators have suggested that the increased gastric retention time of bismuth in the presence of food may be beneficial by prolonging the local exposure of Helicobacter pylori to high concentrations of bismuth, although the amount of bismuth absorbed systemically and secreted back into the gastric fluid may also contribute to its therapeutic effect. When Pylera (a treatment preparation for Helicobacter pylori infection that contains bismuth subcitrate potassium 420 mg, metronidazole 375 mg, and tetracycline 375 mg per recommended dose) was administered after a standardized high-fat breakfast in 23 healthy volunteers, mean systemic exposure (AUC) for bismuth decreased by 60% compared to administration in the fasting state. Metronidazole and tetracycline AUC values were also reduced by 6% and 34%, respectively. However, these changes are not deemed clinically relevant, as eradication rates of Helicobacter pylori near 90% have been reported in trial patients administered Pylera routinely after meals.

MANAGEMENT: Pylera and generic equivalents should be administered after meals (breakfast, lunch, and dinner) and at bedtime (preferably with a snack). The manufacturers for some of the other bismuth subcitrate potassium products have recommended avoiding the ingestion of food, beverages, or other medications within one-half hour before and after each dose. The prescribing information or package labeling should be consulted for dosing and administration instructions that are appropriate for each product.

Iron can bind to tetracycline in the gastrointestinal tract, which may prevent their absorption into the bloodstream and possibly reduce their effectiveness. To avoid or minimize the interaction, iron-containing medications and tetracycline should preferably be taken at least three to four hours apart in most cases. Talk to your doctor if you have any questions or concerns, or if you have trouble separating the dosing times. Your doctor may be able to prescribe alternatives that do not interact. 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.