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Tinidazole Pharmacology

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Tinidazole is a synthetic nitroimidazole, an antiprotozoal, antibacterial agent used to treat certain types of vaginal infections and also used to treat certain types of parasite infections (giardiasis, amebiasis).

Pregnancy category: C

Pharmacological data

Tinidazole is active against both protozoa and anaerobic bacteria. The activity against protozoa involves trichomonas vaginalis, Entamoeba histolytica, and giardia lamblia.

Mechanism of Action of tinidazole

The mode of action of tinidazole against anaerobic bacteria and protozoa involves penetration of the drug into the cell of the microorganisms. Once inside the cell, it undergoes intracellular chemical reduction during anaerobic metabolism.

After tinidazole is reduced, it damages DNA’s helical structure and breaks its strands, which inhibits the bacterial nucleic acid synthesis and causes cell death

It is active against Helicobacter pylori, Gardnerella vaginalis and most anaerobic bacteria including Bacteroides flagilis, Bacteroides melaninogenicus, Bacteroides species., clostridium spp., Eubacterium spp. And veilonella spp.

Therapeutic indications.

Eradication of helicobacter pylori associated with duodenal ulcers, in the presence of antibiotics and acid suppression therapy.

Anaerobic infections such as

  • Intraperitoneal infections ie peritonitis, abscess
  • Gynecological infections ie endometritis, endomyometritis, tub ovarian abscess
  • Bacterial septicemia
  • Post-operative wound infections
  • Skin and soft tissue infections
  • Upper and lower respiratory tract infections, pneumonia, empyema, and lung abscess
  • Nonspecific vaginitis
  • Acute ulcerative gingivitis
  • Urogenital trichomoniasis in both male and female patients
  • Giardiasis
  • Intestinal amoebiasis
  • Amoebic involvement of the liver

Prophylaxis

The prevention of postoperative infections caused by anaerobic bacteria especially those associated with the colonic, gastrointestinal bacteria and gynecological surgery

Contraindications

As with other drugs of similar structure, tinidazole is contraindicated in patients who have a history of blood dyscrasias, although no persistent hematological abnormalities have been noted in clinical studies

It should be avoided in patients with neurological disorders

Tinidazole and other 5 nitroimidazole derivatives or any components of tinidazole should not be administered to patients with a known allergic reaction.

The use of tinidazole is contraindicated for use in the first trimester of pregnancy and lactating mothers.

Warnings and contraindications

Alcoholic beverages should be avoided when using tinidazole because of the possibility of developing disulfiram-like reaction (flushing, abdominal cramps, tachycardia, and vomiting). Alcohol should be avoided for at least 72 hours after the last dose of tinidazole

Drugs of a similar chemical structure have also produced various neurological disturbances such as dizziness, vertigo, ataxia, and incoordination. You should stop the therapy is these features occur.

Although carcinogenicity data is not there for tinidazole, the two drugs are structurally related and therefore there is a potential for similar biologic effects, mutagenicity results with tinidazole were mixed that is positive and negative. The use of tinidazole for longer treatment than usually should be carefully considered.

Side effects of tinidazole

The reported side effects have been infrequent, mild and self-limiting.

Blood and lymphatic system disorders such as leukopenia.

Nervous system: ataxia, convulsions, dizziness, headache, hyperesthesia, paresthesia, peripheral neuropathy, sensory disturbance, vitiligo, metallic taste, and flushing.

Gastrointestinal disorders; abdominal pain, anorexia, diarrhea, furry tongue, stomatitis, glossitis, vomiting, and nausea.

Skin and subcutaneous tissue disorders; hypersensitivity reactions occasionally severe, may occur in rare cases as skin rash, pruritus, urticaria, and angioneurotic edema.

Renal and urinary tract disorders: dark urine

General disorders and administration site conditions are fever and tiredness.

Drug interactions

Alcohol: Concurrent use of alcohol and tinidazole may produce a disulfiram-like reaction and should be therefore avoided.

Anticoagulants. Drugs of similar chemical structures have shown to potentiate the effects of oral anticoagulants. Prothrombin times should be closely monitored and adjusted to the dose of anticoagulants made as necessary.

May increase INR with warfarin.

Do not give at the same time as cholestyramine.

cholestyramine: Possibly decreased the bioavailability of tinidazole

cimetidine, ketoconazole: Possibly delayed elimination and increased blood level of tinidazole

cyclosporine, tacrolimus: Possibly increased serum cyclosporine and tacrolimus levels

disulfiram: Possibly combined toxicity, resulting in confusion and psychosis

fluorouracil: Possibly decreased fluorouracil clearance

lithium: Possibly increased serum lithium levels

oxytetracycline: Possibly diminished the effect of tinidazole

phenobarbital, phenytoin, rifampin: Possibly increased metabolism and decreased the blood level of tinidazole

Posology and administration

The route of administration is oral with food.

Tell the patient to take tinidazole with food to minimize gastric discomfort.

Instruct patient unable to swallow tablets to crush tinidazole and mix in artificial cherry syrup and then take with food

Tinidazole is readily absorbed and permeates all tissues by simple diffusion. Intracellular concentrations rapidly approach extracellular levels. Peak plasma concentrations are reached in 1–3 hours.

Protein binding is low (10–20%); the half-life of unchanged drug is 12–14 hours.

Dosage of tinidazole

Eradication of h pylori associated with duodenal ulcers

Adults: the usual dose is 500 mg twice daily co-administered with omeprazole 20 mg twice daily and clarithromycin 350 mg twice daily for a duration of seven days.

Anaerobic infections

Adults: an initial dose of 2 grams the first day followed by 1 gram daily given as a single dose or as 500 mg twice daily. Routine clinical and laboratory observation is recommended if is considered necessary to continue therapy for seven days or more.

Non-specific vaginitis

A single oral dose of 2 grams. The higher cure rate is observed with 2 grams single dose as on two consecutive days.

Ulcerative gingivitis

2 grams single dose

Urogenital trichomoniasis

2 grams single dose in adults and 50- 75 mg/kg of body weight in children.

Giardiasis

Single-dose of 2 grams and in children 50- 70mg/kg body weight

Intestinal amoebiasis

An adult dose is 2 grams for 2 to 3 days and in children 50 – 70 mg/kg body weight on every three successful days.

Amoebic involvement of the liver.

For adults, a total of 4.5 to 12 grams depending on the virulence of Entamoeba histolytica. Initiate treatment with 1.5 grams to 2 grams as a single dose for three days. Occasionally when a three-day dose is ineffective, treatment may be continued for up to six days.

In children a single dose of 50 – 60mg/kg body weight per day for five successive days.

Give iodoquinol/paromomycin after treatment for amebic dysentery or liver abscess.

Dose modification is not generally necessary for patients with renal failure.

For patients undergoing hemodialysis: Give supplemental dose after the dialysis session.

Prevention of post-operative infection

Adults get a single dose of 2 grams approximately 12 hours before surgery

There is no data available for use in children < 12 years of age.

There is no special consideration in the use of elderly

Overdose

There is no reported overdose of tinidazole. In case it occurs treat the patient symptomatically and supportively

Gastric lavage may be useful.

Tinidazole is easily dialyzable


Post References

  • Katzung basic and clinical pharmacology

  • Revised on: 2021-06-24 09:33:07