Action

Free nitro radical (generated from tinidazole reduction by Trichomonas cell extracts) may explain activity against Trichomonas species; activity against Giardia and Entamoeba species is unknown.

Availability

Tablets: 250 mg, 500 mg

Indications and dosages

➣ Trichomoniasis caused by Trichomonas vaginalis

Adults: Single dose of 2 g P.O. with food, given to both sexual partners simultaneously

➣ Bacterial vaginosis in nonpregnant females

Adults: 2 g P.O. once daily with food for 2 days, or 1 g P.O. once daily with food for 5 days

➣ Giardiasis caused by Giardia duodenalis (Giardia lamblia)

Adults: Single dose of 2 g P.O. with food

Children older than age 3: Single dose of 50 mg/kg (up to 2 g) with food

➣ Amebiasis caused by Entamoeba histolytica

Adults: 2 g P.O. daily with food for 3 days

Children older than age 3: 50 mg/kg (up to 2 g) P.O. daily with food for 3 days

➣ Amebic liver abscess caused by E. histolytica

Adults: 2 g P.O. daily with food for 3 to 5 days

Children older than age 3: 50 mg/kg (up to 2 g) P.O. daily with food for 3 to 5 days

Dosage adjustment

• Hemodialysis patients

Contraindications

• Hypersensitivity to drug, its components, or other nitroimidazole derivatives

• First trimester of pregnancy

Precautions

Use cautiously in:

• CNS disease, hepatic dysfunction

• history of blood dyscrasias

• elderly patients

• pregnant or breastfeeding patients

• children (except to treat giardiasis and amebiasis in children older than age 3).

Administration

• Give with food to minimize GI discomfort.

Adverse reactions

CNS: weakness, fatigue, malaise, dizziness, vertigo, ataxia, insomnia, drowsiness, giddiness, headache, transient peripheral neuropathy, seizures

CV: palpitations

GI: nausea, vomiting, diarrhea, constipation, dyspepsia, gastric discomfort, tongue discoloration, stomatitis, anorexia

Hematologic: transient neutropenia and leukopenia

Musculoskeletal: arthralgia, myalgia, arthritis

Other: altered taste, overgrowth of susceptible organisms, hypersensitivity reactions including angioedema

Interactions

Drug-drug. Cyclosporine, lithium, tacrolimus: possible increase in blood levels of these drugs

Cholestyramine: decreased oral bioavailability of tinidazole

CYP450 inducers (such as phenobarbital, rifampin): increased tinidazole elimination and decreased blood level

CYP450 inhibitors (such as cimetidine, ketoconazole): increased tinidazole blood level

Fluorouracil: decreased fluorouracil clearance

Fosphenytoin, phenytoin: prolonged half-life and reduced clearance of these drugs

Oxytetracycline: antagonism of therapeutic effects of tinidazole

Warfarin, other oral coumarin anticoagulants: increased effects of these drugs

Drug-diagnostic tests. Alanine aminotransferase, aspartate aminotransferase, hexokinase glucose, lactate dehydrogenase, triglycerides: interference with test results

Drug-behaviors. Alcohol use: disulfiram-like reaction during tinidazole therapy and for 3 days after

Patient monitoring

Closely monitor patient for neurologic abnormalities, such as seizures and peripheral neuropathy. If these occur, withdraw drug immediately.

• Monitor blood chemistry tests, especially liver function tests.

Patient teaching

• Advise patient to take drug with food.

• For child or other patient unable to swallow tablets, inform parent or caregiver that drug can be crushed in artificial cherry syrup and given with food.

Caution patient or caregiver to stop therapy and call prescriber immediately if seizures or numbness or tingling in extremities occurs.

• Instruct patient to avoid alcohol use during therapy.

• Advise female patient to avoid pregnancy during therapy.

• Counsel female patient to avoid breastfeeding during therapy and for 3 days after last dose.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and behaviors mentioned above.