What Is the Difference between Metronidazole and Tinidazole?

The differences between metronidazole and tinidazole include, antimicrobial action, methods of administration, and prescribed dosages. While both anti-infective agents treat bacterial and protozoal organisms, they exhibit effective action against different organisms. Physicians may prescribe mthese medications for oral use, but metronidazole can also be administered intravenously or topically. Patients typically require a higher dosage of tinidazole but take the medication for a shorter length of time. Studies indicate that both anti-infectives have carcinogenic properties and similar side effects and that both will interact with other drugs.

Uses of metronidazole and tinidazole include the treatment of gastrointestinal or systemic infections and sexually transmitted diseases caused by susceptible gram-negative, gram-positive, and amebic organisms. Metronidazole eliminates Bacteroides and Clostridium along with Trichomonas. The medication enters the cells and undergoes a molecular change that releases free radicals, causing cell death.

Tinidazole also an effective treatment for Trichomonas, but physicians also prescribe this medication for the Gardnerella and Haemophilas genuses of bacteria. After entering the cell, tinidazole breaks down and produces nitrites that harm the cell. It also breaks the organism's deoxyribonucleic acid (DNA) chains and alters DNA formation. The combination of these actions causes cell death.

Metronidazole dose depends on the organism requiring treatment. Patients with sexually transmitted organisms require 375 milligrams (mg) twice a day for up to seven days. Systemic bacterial or protozoal infections require 7.5 mg per kilogram (1 kg = 2.2 pounds) of body weight every six hours for up to 10 days. Amebic infections require 750 mg three times a day for 5 to 10 days. In topical gel, lotion, or ointment preparation, patients generally apply the anti-infective once or twice daily for the prescribed number of days.

Patients generally take one oral 2-gram tinidazole dose daily for up to three days. Instructions advise taking the medication with food. Metronidazole and tinidazole interact with alcohol, and patients may experience abdominal cramping, nausea, vomiting, and headaches. Taking the medications with warfarin increases the anticoagulant effects of the drug. Using metronidazole and tinidazole with phenobarbital or phenytoin hastens elimination of the anti-infective medications.

Side effects of metronidazole and tinidazole include nausea, vomiting, and diarrhea or constipation. Patients taking either medication may develop a metallic taste in their mouths. The medications also contribute to systemic yeast overgrowth. Patients may experience allergic reactions with a range of symptoms including skin rashes to anaphylaxis. Both anti-infectives have the potential to cause central nervous system symptoms, which produce drowsiness, dizziness, and fatigue or generalized weakness.

Some patients experience convulsions in addition to seizures and aseptic meningitis. Other adverse effects include numbness and tingling from peripheral nerve damage. Both formulations may adversely affect the liver, causing darkened urine and nausea, along with joint and muscle discomfort.