Metronidazole

About Metronidazole

Metronidazole is a nitroimidazole antimicrobial that stops the growth of bacteria; like other antibiotics, it does not treat viral infections such as the common cold. Its oral labels cover trichomoniasis in women and men, including treatment of sexual partners, acute intestinal amebiasis and amebic liver abscess in adults and children, and serious anaerobic infections in adults: intra-abdominal, skin, gynecologic, bone and joint, central nervous system and lower respiratory infections, bacterial septicemia and endocarditis. Trichomoniasis is treated with a one-day 2 g dose or a seven-day course; adults take 750 mg three times a day for 5 to 10 days for intestinal amebiasis, and 7.5 mg/kg every 6 hours (up to 4 g a day), usually for 7 to 10 days, for anaerobic infections. Bacterial vaginosis is labeled for the vaginal gels, and was for the extended-release tablets (Flagyl ER and its generics, now discontinued), but neither it nor Clostridioides difficile infection is on the immediate-release tablet, capsule or suspension labels, so treating them with these forms is not an FDA-approved use, and the prescriber decides.

The boxed warning says metronidazole has been shown to be carcinogenic in mice and rats, that unnecessary use should be avoided, and that it should be reserved for its labeled conditions. Encephalopathy, peripheral neuropathy (including optic neuropathy), seizures and aseptic meningitis have been reported; abnormal nerve or brain symptoms call for prompt review of whether to continue. It must not be taken by anyone allergic to it or other nitroimidazoles or with Cockayne syndrome, in whom fatal liver failure has occurred, and the tablet and capsule labels rule it out for trichomoniasis in the first trimester of pregnancy. Severe skin reactions such as Stevens-Johnson syndrome, and QT prolongation with other QT-prolonging drugs, have been reported, and yeast infections may flare during treatment. Nausea, sometimes with headache, loss of appetite and vomiting, is the most common side effect, and a sharp, unpleasant metallic taste is not unusual.

The labels say oral metronidazole is associated with a disulfiram-like reaction to alcohol (abdominal cramps, nausea, vomiting, headaches and flushing), so alcohol and products containing propylene glycol are stopped during treatment and for at least three days afterward. Because oral metronidazole is associated with psychotic reactions in alcoholic patients who were using disulfiram, it is not given to anyone who has taken disulfiram within the last two weeks. The Flagyl labels say a nursing mother may pump and discard milk during treatment and for 48 hours after the last dose. Pylera capsules combine metronidazole with bismuth subcitrate potassium and tetracycline and, with omeprazole, are labeled for Helicobacter pylori infection with duodenal ulcer disease. Skin products (MetroGel 1 percent gel, MetroLotion and generics) treat the inflammatory lesions of rosacea, and vaginal gels (Vandazole and other 0.75 percent gels, and Nuvessa 1.3 percent gel) treat bacterial vaginosis, with their own alcohol and disulfiram limits.

Taking Metronidazole

How to take it

Exactly as prescribed, finishing the course even if you feel better. Shake Likmez well and measure each dose with a calibrated oral dosing device, not a household spoon. Avoid alcohol and propylene glycol products until at least three days after the last dose.

If you miss a dose

Take it as soon as you remember, unless it is almost time for the next dose; then skip the missed dose and carry on as usual. Do not take a double dose.

Storage

Tablets and capsules at room temperature, away from light, excess heat and moisture. Keep Likmez at room temperature and discard it 60 days after opening.

Interactions to know about

It must not be taken within two weeks of disulfiram. It strengthens warfarin (prothrombin time and INR are checked), can raise lithium levels and is not given with busulfan unless the benefit outweighs the risk; phenytoin and phenobarbital can lower its levels, and cimetidine can slow its clearance.

This summarizes the official prescribing information. Your prescriber’s and pharmacist’s instructions, and the leaflet that comes with your medicine, take priority.

Why the cash price for Metronidazole differs from pharmacy to pharmacy

Generic tablets come from several makers, so quotes for the same course differ by each pharmacy’s dispensing fee and markup and by whether metronidazole is on its flat-price generic list; tablets, capsules and the suspension are different forms, filled as written.

Likmez has no generic, so it is quoted as the brand. Gels are quoted by tube or package and substituted only with a product rated equivalent to the one prescribed; Vandazole is not rated equivalent to the generic vaginal gels.

Ways to pay less for Metronidazole without insurance

• Ask whether metronidazole tablets are on the pharmacy’s flat-price generic list, and compare more than one pharmacy.
• For Likmez, ask the maker whether a savings or patient assistance program applies to someone paying cash.
• For a skin or vaginal gel, ask for a generic rated to the product prescribed.
• Upload the prescription to Script Unlock so licensed pharmacies can quote their cash price. You pay the pharmacy directly.

Questions to ask your pharmacist about Metronidazole

1. 1.How long after my last dose must I wait before drinking alcohol?
2. 2.Do any of my medicines contain alcohol or propylene glycol?
3. 3.Does it interact with my warfarin, lithium or other medicines?
4. 4.Which numbness, tingling or balance problems mean I should call?

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