tinidazole

General

Pronunciation:
ti-nid-a-zole

Trade Name(s)

• Tindamax

Ther. Class.

antiprotozoals

Pharm. Class.

imidazoles

Indications

• Bacterial vaginosis.
• Trichomoniasis.
• Giardiasis.
• Amebiasis.

Action

Interaction with protozoa results in release of a free nitro radical that has antiprotozoal activity.

Therapeutic Effect(s):

Resolution of protozoal infections.

Spectrum:

Active against Bacteroides spp., Entamoeba histolytica, Gardnerella vaginalis, Giardia duodenalis (also known as Giardia lamblia), Prevotella spp., and Trichomonas vaginalis.

Pharmacokinetics

Absorption: Rapidly and completely absorbed following oral administration.

Distribution: Extensively distributed.

Metabolism and Excretion: Primarily metabolized by the liver via the CYP3A4 isoenzyme; 20–25% excreted unchanged in urine, 12% excreted in feces.

Half-life: 12–14 hr.

TIME/ACTION PROFILE (plasma concentrations)

Contraindication/Precautions

Contraindicated in:

• Hypersensitivity; cross-sensitivity with other imidazoles may occur;
• Cockayne syndrome (↑ risk of hepatotoxicity and death);
• Lactation: Lactation.

Use Cautiously in:

• CNS pathology;
• History of blood dyscrasias;
• Hemodialysis (removes significant amount of tinidazole; supplement postdialysis with additional 50% of dose);
• Hepatic impairment;
• Unrecognized candidiasis (requires concurrent antifungal therapy);
• OB:   Use during pregnancy only if potential maternal benefit justifies potential fetal risk;
• Pedi:  Children <3 yr (safety and effectiveness not established).

Adverse Reactions/Side Effects

GI: constipation, dyspepsia, metallic/bitter taste, vomiting

GU: ↓ fertility (males)

Hemat: transient leukopenia/neutropenia

Neuro: dizziness, headache, malaise

* CAPITALS indicate life-threatening.
Underline indicate most frequent.

Interactions

Drug-Drug

• ↑ risk of bleeding with  warfarin.
• Disulfiram-like reaction may occur with  alcohol  or  propylene glycol  disulfiram  should be avoided for ≥2 wk before tinidazole; alcohol should be avoided during therapy and for 3 days after therapy completed.
• May ↑ levels of  lithium,  cyclosporine,  tacrolimus,  fluorouracil, and  fosphenytoin  (observe/monitor for toxicity if administered concurrently).
•  CYP3A4 inhibitors, including  cimetidine  or  ketoconazole, may ↑ levels and risk of toxicity.
•  CYP3A4 inducers, including  phenobarbital,  rifampin,  phenytoin, and  fosphenytoin, may ↓ levels and effectiveness.
• Absorption is ↓ by  cholestyramine ; separate dosing.

Route/Dosage

Bacterial Vaginosis

PO (Adults): 1 g once daily for 5 days  or  2 g once daily for 2 days.

Trichomoniasis

PO (Adults): 2 g as a single dose.

Giardiasis

PO (Adults): 2 g as a single dose.

PO (Children ≥3 yr): 50 mg/kg (up to 2 g) as a single dose;

Intestinal Amebiasis

PO (Adults): 2 g once daily for 3 days.

PO (Children ≥3 yr): 50 mg/kg once daily for 3 days.

Amebic Liver Disease

PO (Adults): 2 g once daily for 3–5 days.

PO (Children ≥3 yr): 50 mg/kg once daily for 3–5 days.

Availability (generic available)

Tablets: 250 mg, 500 mg

Assessment

• Assess patient for symptoms of infection (discharge, itching) prior to and during therapy.
• Giardiasis: Monitor three stool samples taken several days apart, beginning 3–4 wk after treatment.

Lab Test Considerations:

May cause transient leukopenia and neutropenia. Monitor total and differential leukocyte counts if retreatment is necessary.

• May interfere with certain tests of serum chemistry values such as AST, ALT, LDH, and triglycerides.

Implementation

• Symptoms of known or previously unrecognized candidiasis may become worse during therapy and require treatment with an antifungal agent.
• For trichomoniasis, all sexual partners of the patient should be treated with the same dosing regimen.
• PO Administer with food to decrease GI upset. May be crushed and prepared as a suspension in cherry syrup by pharmacist for patients unable to swallow tablets. Shake well before administering.

Patient/Family Teaching

• Instruct patient to take medication as directed, even if feeling better. Do not skip doses or double up on missed doses. If a dose is missed, take as soon as remembered if not almost time for next dose.
• Advise patients treated for trichomoniasis that sexual partners may be asymptomatic sources of reinfection and should be treated concurrently. Patient should also refrain from intercourse or use a condom to prevent reinfection.
• Caution patient to avoid intake of alcoholic beverages or preparations containing alcohol during and for at least 3 days after treatment with tinidazole. May cause a disulfiram-like reaction (flushing, nausea, vomiting, headache, abdominal cramps).
• May cause dizziness or drowsiness. Caution patient to avoid driving or other activities requiring alertness until response to medication is known.
• Inform patient that medication may cause an unpleasant metallic taste.
• Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.
• Rep:  Advise females of reproductive potential to inform health care professional if pregnancy is planned or suspected and to avoid breastfeeding during and for 72 hr after taking tinidazole. May impair fertility in males.

Evaluation/Desired Outcomes

Resolution of signs and symptoms of infection.