Carcinogenesis, mutagenesis, impairment of fertility
Metronidazole, a chemically-related nitroimidazole, has been reported to be carcinogenic in mice and rats but not hamsters. In several studies metronidazole showed evidence of pulmonary, hepatic, and lymphatic tumorigenesis in mice and mammary and hepatic tumors in female rats. Tinidazole carcinogenicity studies in rats, mice or hamsters have not been reported.
Tinidazole was mutagenic in the TA 100, S. typhimurium tester strain both with and without the metabolic activation system and was negative for mutagenicity in the TA 98 strain. Mutagenicity results were mixed (positive and negative) in the TA 1535, 1537, and 1538 strains. Tinidazole was also mutagenic in a tester strain of Klebsiella pneumonia. Tinidazole was negative for mutagenicity in a mammalian cell culture system utilizing Chinese hamster lung V79 cells (HGPRT test system) and negative for genotoxicity in the Chinese hamster ovary (CHO) sister chromatid exchange assay. Tinidazole was positive for in vivo genotoxicity in the mouse micronucleus assay.
In a 60-day fertility study, tinidazole reduced fertility and produced testicular histopathology in male rats at a 600 mg/kg/day dose level (approximately 3-fold the highest human therapeutic dose based upon body surface area conversions). Spermatogenic effects resulted from 300 and 600 mg/kg/day dose levels. The no observed adverse reaction level for testicular and spermatogenic effects was 100 mg/kg/day (approximately 0.5-fold the highest human therapeutic dose based upon body surface area conversions). This effect is characteristic of agents in the 5-nitroimidazole class.
Animal toxicology and/or pharmacology
In acute studies with mice and rats, the LD50 for mice was generally > 3,600 mg/kg for oral administration and was > 2,300 mg/kg for intraperitoneal administration. In rats, the LD50 was > 2,000 mg/kg for both oral and intraperitoneal administration.
A repeated-dose toxicology study has been performed in beagle dogs using oral dosing of tinidazole at 100 mg/kg/day, 300 mg/kg/day, and 1000 mg/kg/day for 28-days. On Day 18 of the study, the highest dose was lowered to 600 mg/kg/day due to severe clinical symptoms. The two compound-related effects observed in the dogs treated with tinidazole were increased atrophy of the thymus in both sexes at the middle and high doses, and atrophy of the prostate at all doses in the males. A no-adverse-effect level (NOAEL) of 100 mg/kg/day for females was determined. There was no NOAEL identified for males because of minimal atrophy of the prostate at 100 mg/kg/day (approximately 0.9-fold the highest human dose based upon plasma AUC comparisons).
Important Safety Information
WARNING: POTENTIAL RISK FOR CARCINOGENICITY
Carcinogenicity has been seen in mice and rats treated chronically with metronidazole, another nitroimidazole agent. Although such data have not been reported for tinidazole, the two drugs are structurally related and have similar biologic effects. Its use should be reserved for the conditions described in INDICATIONS AND USAGE.
Tindamax® is a prescription antibiotic used to treat certain infections caused by bacteria and parasites. It is approved for treating trichomoniasis, also known as "trich," and bacterial vaginosis, or "BV" (in non-pregnant, adult women). It is also approved for treating giardiasis, also known as "giardia," amebiasis, and amebic liver abscess in patients age 3 and older.
Important Safety Information
Tindamax® is not for everyone. You should not take Tindamax® if you are in the first trimester of pregnancy. If you are nursing, Tindamax® can pass through your breast milk, so you should not take it unless you stop breastfeeding during your prescription and for 3 days after your last dose.
Tindamax® can lead to a temporary reduction in your white blood cells, so if you have been diagnosed with a blood disorder, talk to your doctor before starting a prescription.
Do not take Tindamax® if you have a history of sensitivity to tinidazole or related drugs in the nitroimidazole family. Reactions can range from mild itching, hives, or fever to Stevens-Johnson syndrome, which is a rare, life-threatening skin condition.
Certain drugs may interact with Tindamax®, so always tell your doctor about the medications you're taking before you start a prescription.
Take each dose of Tindamax® with food to lessen the risk of stomach upset and other GI side effects. Avoid any alcoholic beverages while taking Tindamax® and for 3 days afterward.
If you are undergoing hemodialysis while taking Tindamax® on the same day, consult your doctor for the appropriate dose of Tindamax®. An additional half-dose of Tindamax® at the end of dialysis may be recommended.
Antibacterial drugs, including Tindamax®, do not treat viral infections such as the common cold. When taking Tindamax® to treat a bacterial infection, it is very common to feel better early in your prescription; however, you should keep taking the medication as directed and for as long as directed by your doctor. Skipping doses or not taking all of your medication can make Tindamax® less effective. It can also allow the bacteria to build up resistance to the drug, so that it won't be treatable with Tindamax® or similar drugs in the future.
The most common side effects of Tindamax® are a metallic or bitter taste, nausea, weakness, fatigue, discomfort, indigestion, cramps, vomiting, loss of appetite, headache, dizziness, and constipation.
Some patients taking Tindamax® may also develop a yeast infection, which can require treatment with an anti-fungal drug. Talk to your doctor if you notice any unusual symptoms.
Certain patients taking Tindamax® have experienced seizures or nerve problems, with symptoms such as numbness or tingling of the hands or feet. Other side effects included vertigo, unsteady movements, insomnia, or drowsiness. Stop taking Tindamax® if you develop any abnormal symptoms.
Tinidazole, the key ingredient in Tindamax®, is related to a drug called metronidazole, which has been linked to cancer in lab rats and mice that received the drug over long periods of time. Although these effects have not been reported for tinidazole, the two drugs are chemically related and have similar effects on the body. Therefore, Tindamax® should only be used to treat infections it has been approved to treat.
To report negative side effects, contact Mission Pharmacal Company at 1-800-298-1087 or the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
