Metronidazole: Instructions For Use Of The Antibiotic

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Metronidazole: Instructions For Use Of The Antibiotic
Metronidazole: Instructions For Use Of The Antibiotic
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Video: How and When to use Metronidazole (Flagyl, Metrogel) - Doctor Explains 2023, February

Metronidazole is a broad-spectrum antibiotic used in gynecology and urology. Metronidazole is highly effective and affordable, but at the same time, the drug has a number of contraindications that you must familiarize yourself with.

The content of the article:

  • 1 Pharmacological action of Metronidazole
  • 2 Pharmacokinetics
  • 3 Indications for Metronidazole use
  • 4 Method of administration and dosage

    4.1 Oral suspension

  • 5 Side effects
  • 6 Special instructions
  • 7 Metronidazole - Restrictions on use
  • 8 Application during pregnancy and lactation
  • 9 Interaction of Metronidazole with other drugs
  • 10 Conditions for dispensing from pharmacies
  • 11 Metronidazole - Storage conditions and shelf life

Pharmacological action of Metronidazole

Antiprotozoal and antimicrobial drug derived from 5-nitroimidazole. The mechanism of action consists in the biochemical reduction of the 5-nitro group of metronidazole by intracellular transport proteins of anaerobic microorganisms and protozoa. The reduced 5-nitro group of metronidazole interacts with the DNA of the cell of microorganisms, inhibiting the synthesis of their nucleic acids, which leads to the death of bacteria.

Instructions for use of the antibiotic Metronidazole
Instructions for use of the antibiotic Metronidazole

Active against Trichomonas vaginalis, Entamoeba histolytica, Gardnerella vaginalis, Giardia intestinalis, Lamblia spp., As well as obligate anaerobes Bacteroides spp. (including Bacteroides fragilis, Bacteroides distasonis, Bacteroides ovatus, Bacteroides thetaiotaomicron, Bacteroides vulgatus), Fusobacterium spp., Veillonella spp., Prevotella (Prevotella bivia, Prevotella and gram-positive microorganisms) Clostridium spp., Peptococcus spp., Peptostreptococcus spp.). The MIC for these strains is 0.125-6.25 μg / ml.

In combination with amoxicillin, it is active against Helicobacter pylori (amoxicillin inhibits the development of resistance to metronidazole).

Aerobic microorganisms and facultative anaerobes are insensitive to metronidazole, but in the presence of mixed flora (aerobes and anaerobes), metronidazole acts synergistically with antibiotics effective against conventional aerobes.

It increases the sensitivity of tumors to radiation, causes disulfiram-like reactions, and stimulates reparative processes.


Absorption - high (bioavailability at least 80%). It has a high penetrating ability, reaching bactericidal concentrations in most tissues and body fluids, including lungs, kidneys, liver, skin, cerebrospinal fluid, brain, bile, saliva, amniotic fluid, abscess cavities, vaginal secretions, semen, breast milk, penetrates through blood-brain and placental barrier. Vd in adults is about 0.55 l / kg, in newborns - 0.54-0.81 l / kg. Cmax of the drug in the blood ranges from 6 to 40 μg / ml, depending on the dose. Time to reach Cmax - 1-3 hours. Plasma protein binding - 10-20%. In the body, about 30-60% of metronidazole is metabolized by hydroxylation, oxidation and glucuronidation.

Metronidazole. The main metabolite (2-oxymetronidazole) also has antiprotozoal and antimicrobial effects. T1 / 2 with normal liver function - 8 hours (from 6 to 12 hours), with alcoholic liver damage - 18 hours (from 10 to 29 hours), in newborns born at a gestational age of 28-30 weeks - about 75 hours, 32-35 weeks - 35 hours, 36-40 weeks - 25 hours. Excreted by the kidneys 60-80% (20% unchanged), through the intestines - 6-15%. Renal clearance - 10.2 ml / min.

In patients with impaired renal function, after repeated administration, accumulation of mstronidazole in the blood serum may be observed (therefore, in patients with severe renal insufficiency, the frequency of administration should be reduced).

Metronidazole and the main metabolites are rapidly removed from the blood during hemodialysis (T1 / 2 is reduced to 2.6 hours). With peritoneal dialysis, it is excreted in small quantities.

Indications for the use of Metronidazole

Instructions for use of the antibiotic Metronidazole
Instructions for use of the antibiotic Metronidazole
  • Protozoal infections: extraintestinal amebiasis, including amoebic liver abscess, intestinal amebiasis (amoebic dysentery), trichomoniasis, giardiasis, balantidiasis, giardiasis, cutaneous leishmaniasis, trichomonas vaginitis, trichomonas urethritis.
  • Infections caused by Bacteroides spp. (including Bacteroides fragilis, Bacteroides distasonis, Bacteroides ovatus, Bacteroides thetaiotaomicron, Bacteroides vulgatus): infections of bones and joints, infections of the central nervous system, incl. meningitis, brain abscess, bacterial endocarditis, pneumonia, empyema and lung abscess, sepsis.
  • Infections caused by Clostridium spp., Peptococcus and Peptostreptococcus species: infections of the abdominal cavity (peritonitis, liver abscess), infections of the pelvic organs (endometritis, abscess of the fallopian tubes and ovaries, infections of the vaginal vault).
  • Pseudomembranous colitis (associated with the use of antibiotics).
  • Gastritis or duodenal ulcer associated with Helicobacter pylori.
  • Prevention of postoperative complications (especially interventions on the colon, near-rectal region, apendectomy, gynecological operations).
  • Radiation therapy for patients with tumors - as a radiosensitizing drug in cases where tumor resistance is due to hypoxia in tumor cells.

Method of administration and dosage

Inside and parenteral.

Inside, during or after food (or with milk), without chewing.

Instructions for use of the antibiotic Metronidazole
Instructions for use of the antibiotic Metronidazole

With trichomoniasis - 250 mg 2 times a day for 10 days or 400 mg 2 times a day for 5-8 days. Women need to additionally prescribe metronidazole in the form of vaginal suppositories or tablets. If necessary, you can repeat the course of treatment or increase the dose to 0.75-1 g / day. Between courses, you should take a break of 3-4 weeks with repeated control laboratory tests. An alternative therapy regimen is the appointment of 2 g once to the patient and his sexual partner.

Children 2-5 years old - 250 mg / day; 5-10 years old - 250-375 mg / day, over 10 years old - 500 mg / day. The daily dose should be divided into 2 doses. The course of treatment is 10 days.

With giardiasis - 500 mg 2 times a day for 5-7 days.

Children under 1 year old - 125 mg / day, 2-4 years old - 250 mg / day, 5-8 years - 375 mg / day, over 8 years old - 500 mg / day (in 2 divided doses). The course of treatment is 5 days.

With giardiasis - 15 mg / kg / day in 3 divided doses for 5 days.

Adults: with asymptomatic amebiasis (if a cyst is detected), the daily dose is 1-1.5 g (500 mg 2-3 times a day) for 5-7 days.

In chronic amoebiasis, the daily dose is 1.5 g in 3 doses for 5-10 days, in acute amoebic dysentery - 2.25 g in 3 doses until symptoms stop.

Instructions for use of the antibiotic Metronidazole
Instructions for use of the antibiotic Metronidazole

With liver abscess, the maximum daily dose is 2.5 g in 1 or 2-3 doses, for 3-5 days, in combination with antibiotics (tetracyclines) and other methods of therapy.

Children 1-3 years old - 1/4 adult dose, 3-7 years old - 1/3 adult dose, 7-10 years old - 1/2 adult dose.

With balantidiasis - 750 mg 3 times a day for 5-6 days.

For ulcerative stomatitis, adults are prescribed 500 mg 2 times a day for 3-5 days; in this case, the drug is not indicated for children.

With pseudomembranous colitis - 500 mg 3-4 times a day.

For the eradication of Helicobacter pylori - 500 mg 3 times a day for 7 days (as part of a combination therapy, for example a combination of samoxycillin 2.25 g / day).

When treating anaerobic infection, the maximum daily dose is 1.5-2 g.

In the treatment of chronic alcoholism, 500 mg / day is prescribed for a period of up to 6 (no more) months.

Instructions for use of the antibiotic Metronidazole
Instructions for use of the antibiotic Metronidazole

For the prevention of infectious complications - 750-1500 mg / day in 3 doses 3-4 days before surgery or once 1 g on the first day after surgery. 1-2 days after surgery (when oral administration is already allowed) - 750 mg / day for 7 days.

In case of severe impaired renal function (CC less than 10 ml / min), the daily dose should be halved.

Oral suspension

Anaerobic bacterial infections: children - 7 mg / kg every 8 hours, the course of treatment is 7-10 days; giardiasis: children 2-5 years old - 200 mg / day, 5-10 years old - 300 mg / day, 10-15 years old - 400 mg / day. The duration of treatment for giardiasis is 5 days. The course of treatment can be repeated after 10-15 days.

Metronidazole. Parenteral Adults and children over 12 years old at an initial dose of 0.5-1 g intravenous drip (duration of infusion - 30-40 minutes), and then every 8 hours, 500 mg at a rate of 5 ml / min. With good tolerance, after the first 2-3 infusions, they switch to jet administration. The course of treatment is 7 days. If necessary, intravenous administration is continued for a longer time. The maximum daily dose is 4 g. According to indications, a transition is made to a maintenance intake in a dose of 400 mg 3 times a day. Children under the age of 12 are prescribed according to the same scheme in a single dose - 7.5 mg / kg.

With purulent-septic diseases, 1 course of treatment is usually carried out.

For prophylactic purposes, adults and children over 12 years of age are prescribed intravenous drip, 0.5-1 g on the eve of the operation, on the day of the operation and the next day - 1.5 g / day (500 mg every 8 hours). After 1-2 days, they switch to supportive therapy inside. For patients with chronic renal failure and CC less than 30 ml / min and / or liver failure, the maximum daily dose is no more than 1 g, the frequency of administration is 2 times a day.

Instructions for use of the antibiotic Metronidazole
Instructions for use of the antibiotic Metronidazole

As a radiosensitizing drug, intravenous drip is administered at the rate of 160 mg / kg or 4-6 g / m2 of body surface 0.5-1 hours before the start of irradiation. Apply before each irradiation session for 1-2 weeks. During the remaining period of radiation treatment, metronidazole is not used. The maximum single dose should not exceed 10 g, course dose - 60 g. To relieve the intoxication caused by radiation, drip injection of 5% dextrose solution, Gemodez or 0.9% NaCl solution is used.

For cancer of the cervix and the body of the uterus, skin cancer, it is used in the form of local applications (3 g is dissolved in 10% DMSO solution), tampons are moistened, which are applied topically, 1.5-2 hours before irradiation). In case of poor tumor regression, applications are carried out during the entire course of radiation therapy. With positive dynamics of cleansing the tumor from necrosis - during the first 2 weeks of treatment.

Side effects

  • From the digestive system: diarrhea, decreased appetite, nausea, vomiting, intestinal colic, constipation, "metallic" taste in the mouth, dry mouth, glossitis, stomatitis, pancreatitis.
  • From the nervous system: dizziness, impaired coordination of movements, ataxia, confusion, irritability, depression, increased excitability, weakness, insomnia, headache, convulsions, hallucinations, peripheral neuropathy.
  • Allergic reactions: urticaria, skin rash, skin flushing, nasal congestion, fever, arthralgia.
  • From the urinary system: dysuria, cystitis, polyuria, urinary incontinence, candidiasis, urine staining red-brown.
  • Local reactions: thrombophlebitis (pain, hyperemia or swelling at the injection site).
  • Others: neutropenia, leukopenia, flattening of the T wave on the ECG.

special instructions

During the treatment period, ethanol is contraindicated (disulfiram-like reactions may develop: abdominal pain of a spastic nature, nausea, vomiting, headache, sudden flushing of the face).

In combination with amoxicillin, it is not recommended for use in patients under 18 years of age.

Instructions for use of the antibiotic Metronidazole
Instructions for use of the antibiotic Metronidazole

With prolonged therapy, it is necessary to control the blood picture.

With leukopenia, the possibility of continuing treatment depends on the risk of developing an infectious process.

The appearance of ataxia, dizziness and any other deterioration in the neurological status of patients requires discontinuation of treatment.

May immobilize treponemas and lead to false positive Nelson's test.

Metronidazole stains the urine dark.

Instructions for use of the antibiotic Metronidazole
Instructions for use of the antibiotic Metronidazole

When treating Trichomonas vaginitis in women and Trichomonas urethritis in men, it is necessary to refrain from sexual activity. Simultaneous treatment of sexual partners is mandatory. Treatment does not stop during menses. After trichomoniasis therapy, control tests should be carried out for 3 successive cycles before and after menstruation.

After treatment of giardiasis, if symptoms persist, 3 stool tests should be performed after 3-4 weeks at intervals of several days (in some successfully treated patients, lactose intolerance caused by invasion may persist for several weeks or months, resembling the symptoms of giardiasis).

If necessary, the appointment of the drug during lactation should stop breastfeeding.

Metronidazole - Restrictions on Use

Diseases of the liver (cumulation is possible), kidneys, central nervous system, pregnancy (II – III trimesters).

Application during pregnancy and lactation

Instructions for use of the antibiotic Metronidazole
Instructions for use of the antibiotic Metronidazole

Contraindicated in the first trimester of pregnancy, in the II-III trimesters - with caution (metronidazole passes through the placenta).

FDA category of action on the fetus - B.

Interaction of Metronidazole with other drugs

Strengthens the action of indirect anticoagulants, which leads to an increase in the time of prothrombin formation.

Similar to disulfiram, it causes intolerance to ethanol.

The simultaneous use of Metronidazole with disulfiram can lead to the development of various neurological symptoms (the interval between appointments is at least 2 weeks).

Metronidazole for intravenous administration is not recommended to be mixed with other drugs.

Instructions for use of the antibiotic Metronidazole
Instructions for use of the antibiotic Metronidazole

Cimetidine inhibits the metabolism of metronidazole, which can lead to an increase in its concentration in the blood serum and an increased risk of side effects.

The simultaneous administration of drugs that stimulate microsomal oxidation enzymes in the liver (phenobarbital, phenytoin) can accelerate the elimination of metronidazole, resulting in a decrease in its concentration in plasma.

With the simultaneous administration of Metronidazole with lithium preparations, the concentration of the latter in the plasma may increase and the development of symptoms of intoxication.

It is not recommended to combine treatment with Metronidazole with non-depolarizing muscle relaxants (vecuronium bromide).

Sulfonamides enhance the antimicrobial effect of metronidazole.

Terms of dispensing from pharmacies

The drug is available by prescription.

Metronidazole - Storage conditions and terms

List B. The drug is stored in a dry, dark place, out of the reach of children, at a temperature not exceeding 25 ° C. Shelf life is 2 years. It is recommended to use before the expiration date indicated on the package.

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