Metronidazole is a substance that is active against anaerobic bacteria and some protozoa. Currently, it is a golden agent used in the treatment of diseases caused by the above-mentioned microorganisms. Its molecule is small and has a very good absorption. It penetrates well into tissues, even passing through the body's barriers, such as the placenta or the blood-brain barrier.

Metronidazole - action

To properly understand how metronidazole kills anaerobic bacteria and protozoa, it is important to understand its mechanism of action. Metronidazole is a small molecule that easily penetrates into bacterial and protozoal cells. Although this substance is able to pass even through the membranes of aerobic bacteria, it is not effective in fighting this group of bacteria.

The mechanism of action of metronidazoleis based on its low redox potential. Metronidazole transforms into a reduced form in a bacterial cell. Its presence in the cell in this form causes the breakdown of the DNA chain of anaerobic bacteria and the subsequent death of the cell.

Metronidazole is effective against bacteria of the following type:

  • Bacteroides- these are sticks responsible mainly for purulent infections and endogenous infections, i.e. those resulting from the displacement of physiological bacterial flora from the natural place in the body to the sterile areas. This can happen during surgery or an injury.
  • Fusobacterium -similarly to the group mentioned above, it is present in the physiological bacterial flora and is responsible for endogenous infections.
  • Clostridium -infection with this group of bacteria is often treated with metronidazole and in terms of antibiotic therapy it is the target group of metronidazole. Bacteria from the groupClostridiumare responsible for serious infections such as gangrene, tetanus, botulism, antibiotic-induced diarrhea, and pseudomembranous enteritis.Clostridium difficileis by far one of the most common causes of nosocomial infections and post-antibiotic diarrhea. Infection with this bacterium occurs as a resultovergrowthC. difficilefrom the physiological microbial flora or from the environment.
  • Eubacterium
  • Gardnerella vaginalis -is the most common factor in bacterial vaginosis caused by anaerobic bacteria.

Protozoa are also sensitive to metronidazole:

  • Trichomonas , this group includesT. vaginalisso-called vaginal trichomoniasis. It is the most common cause of non-viral STDs.
  • Entamoeba histolytica , or amoeba which causes amoebiasis, a disease of the gastrointestinal tract. It is an infection that Poles most often bring from trips to the tropics, where there is a low sanitary standard. It is a common disease in developing countries. The reason why dysentery amoebiasis is so common in these places is the ability of its cysts to survive in tap water, even when chlorine is used to disinfect it.
  • Giardia lamblia -LikeEntamoeba histolyticacauses travelers' diarrhea.
  • Balantidium.

Metronidazole - indications

Metronidazole - the leaflet of this drug informs that it is a drug used in infections with the above-mentioned anaerobic bacteria and protozoa.

Additionally, it is used to reduce the risk of postoperative infection.

Metronidazole is administered to patients in such cases as:

  • sepsis
  • bacteremia
  • peritonitis
  • brain abscess
  • pneumonia
  • osteomyelitis
  • puerperal fever
  • pelvic abscess
  • Parrotitis
  • infection of wounds after surgery due to infection with anaerobic bacteria
  • genitourinary trichomoniasis in both sexes
  • bacterial vaginosis
  • amoebiasis
  • giardiaza / giardiaza
  • acute ulcerative gingivitis
  • acute periodontal infection
  • ulceration of limbs and pressure ulcers caused by anaerobic bacteria
  • infectionHelicobacter pylori .

Because trichomoniasis is such a common non-viral STD, treatment regimens have already been developed. Although infection with this parasite is asymptomatic in most patients, treatment should be undertaken to reduce the transmission of the protozoan to other sexual partners.

Metronidazole belongs to the only group of drugs to which trichomoniasis reacts. Oral metronidazole is the recommended therapy. The drug is found ingel form, but does not reach therapeutic concentrations in the urogenital tract as an alternative to oral administration. Unfortunately, recent studies indicate a slight increase in trichomoniasis resistance to metronidazole. About 10 percent of trichomoniasis are resistant to treatment with the standard dose of metronidazole. Then the specialist decides to modify the dosage.

There are few alternatives in the pharmaceutical market that work to the same extent on trichomoniasis. Trichomoniasis may occur in pregnant women, so it is important to make the mother-to-be aware of the benefits and risks of metronidazole therapy. Infection with this parasite can cause premature birth or low birth weight in the baby. If the doctor and the patient decide to undergo treatment, metronidazole can be administered as a single dose of 2 g orally.

It should be noted that the treatment of trichomoniasis may protect the newborn child from infection. Although metronidazole crosses the placenta, it has not been proven to be mutagenic or teratogenic in the fetus. Therefore, women can be treated in the second and third trimesters of pregnancy. The safety of treatment of trichomoniasis in women in the first trimester of pregnancy should be consulted with a physician. When it comes to treating breastfeeding women, doctors agree that the safest solution is to stop breastfeeding for a few days while undergoing treatment.

Metronidazole passes into breast milk, its concentration in the body of a child is not higher than the recommended dose for children. Nevertheless, the doctor reduces the risk of side effects in your baby by taking a break from breastfeeding.

The condition in which doctors prescribe metronidazole to a patient is also bacterial vaginosis. The most common cause of this infection is Gardnerelia vaginalis. Infections with aerobic bacteria can occur, so it is important to get cultures and tests before starting treatment. During this disease, the physiological bacterial flora in the form of Lactobacillus is lost.

Instead, a pathological flora composed of anaerobic bacteria develops. The use of metronidazole in this condition is justified and the effectiveness of treatment is about 84-96%. Metronidazole does not destroy the he althy vaginal flora unlike clindamycin.

Unfortunately, there is an increasing resistance of the bacteria causing bacterial vaginosis to metronidazole. If treatment is not successful, the physician should assume that the strain is resistant to the antibiotic used and change the treatment or dosage.

Additionally, he is sensitive to metronidazoleHelicobacter pylori. This fact is used in multi-drug therapy aimed at eradication of H. pylori. The therapy is similar to tuberculosis therapy because a combination of three drugs, sometimes as many as four, is required to treat this ulcerative gastritis infection effectively. The antibiotics used in therapy include metronidazole. It acts on H. pylori independently of the pH of the environment, unlike clarithromycin and amoxicillin. Unfortunately, bacterial resistance to metronidazole is quite high.

Before making a decision about treatment, you should take into account all current treatment guidelines for the diseases mentioned.

Metronidazole - contraindications

One of thecontraindications to the use of metronidazoleis the first trimester of pregnancy, while international literature and specialists, before rejecting metronidazole as a therapeutic drug, take into account the patient's condition and the benefit-to-risk ratio.

Hypersensitivity to metronidazole or other 5-nitroimidazole derivatives is also a contraindication to the use of this substance.

Metronidazole - precautions

According to the current summary of product characteristics, there are situations in which the use of metronidazole should be carefully considered by a doctor.

  1. Please note that metronidazole is not bactericidal against aerobic bacteria and may not be fully effective against relative anaerobes.
  2. There is a risk that the infection will recur after treatment with metronidazole, which may not be because the bacteria or protozoa are resistant, but because the patient is not taking the medicine correctly. In a situation where the patient did not follow the recommendations, omitted to take the drug, or took the drug irregularly, not only no improvement, but also an increase in the resistance of the microorganism to metronidazole, may occur.
  3. Animal studies do not conclude whether this drug is mutagenic, therefore it is not recommended to use the drug for longer than necessary.
  4. Stevens-Johnson syndrome has been reported with the use of metronidazole. This is a violent, heterogeneous skin reaction. During this reaction, epidermal cell apoptosis occurs, which leads to erosion and further tissue necrosis. This condition is life threatening. The attending physician should instruct the patient about the risk and recommend monitoring of skin reactions. If these symptoms occur, treatment with metronidazole should be discontinued and therapy strategies changed.
  5. Because metronidazole can worsen neurological symptoms and it lasts longertreatment can lead to neuropathy, adherence to the prescribed treatment period is recommended. Do not use the drug in people with diseases of the peripheral or central nervous system. Any decision to treat must be made by the treating physician. Some situations leave no doubt that the risk of therapy should be taken, e.g. treatment of a brain abscess.
  6. Caution should be exercised when treating metronidazole in people with liver damage or hepatic encephalopathy. Then, metronidazole and its metabolites accumulate in the body.
  7. Dosage adjustment may be necessary when treating a patient with hepatic or renal insufficiency.
  8. There is an additional risk of edema in patients receiving concomitant use of corticosteroids and metronidazole.
  9. Specialists recommend checking the patient's blood picture during and after therapy. Especially if the treatment takes more than 10 days.
  10. The use of metronidazole may result in oral, vaginal and digestive candidiasis. It is important to use oral and vaginal probiotics after treatment.
  11. Alcohol must not be consumed while taking metronidazole as a disulfiram reaction may occur and alcohol toxicity is increased. Symptoms to watch out for in this case are: headache, feeling hot with sweating, nausea and vomiting.
  12. Patients with Cockayne syndrome developed severe hepatotoxicity and acute liver failure during treatment with this compound.

Metronidazole - interactions with other drugs

Interaction of metronidazole with other drugs:

  • metronidazole increases the effect of anticoagulants such as warfarin. Such a patient may experience a haemorrhage. It has been reported that the use of heparin during treatment with metronidazole is safe
  • drugs that increase the activity of microsomal enzymes in the liver may shorten the half-life of metronidazole. Drugs from this group are, for example, phenobarbital and phenytoin
  • drugs that reduce the activity of microsomal liver enzymes can extend the half-life of metronidazole in the body
  • in patients who are treated with lithium s alts, this element accumulates in the body after the administration of metronidazole, which may lead to kidney damage
  • simultaneous use of metronidazole and disulfiran may lead to mental disorders in the patient manifested by psychosis and confusion
  • metronidazole increases the toxicity of busulfan and 5-fluorouracil
  • metronidazoleincreases the concentration of cyclosporine in the body.

Metronidazole - side effects

Metronidazole may have the following side effects:

  • on the part of the nervous system: encephalopathy, subacute cerebellar syndrome, convulsions, however these symptoms disappear after discontinuation of therapy, neuropathies have been observed during long-term use of the drug, which also disappeared after drug discontinuation. Other less dangerous side effects include: drowsiness, dizziness, headache. Psychotic disorders, manifested by confusion and hallucinations, have also been reported after metronidazole.
  • blood and lymph: very rarely observed in patients: agranulocytosis, neutropenia, thrombocytopenia, pancytopenia.
  • the immune system's reaction to metronidazole may be anaphylactic shock, especially in people who are hypersensitive to this group of drugs.
  • patients very rarely complain of side effects in the eye, such as double vision or myopia. In both cases, the symptoms were transient.
  • from the liver there is a risk of elevated liver enzymes, hepatitis, jaundice and / or pancreatitis.
  • your urine may be darker.

Metronidazole - dosage

The dosage of metronidazole varies according to the type of infection and the patient's condition. Sometimes doctors observe the ineffectiveness of the therapy and modify the dose of metronidazole, or add additional medications to support the effect of metronidazole. The doctor should determine the most optimal treatment regimen with metronidazole with the patient and explain exactly how to take this drug.

Dosage also depends on the form of the drug. Metronidazole is currently available in the form of oral tablets, vaginal globules, pastes, there are also gels with metronidazole, as well as skin emulsions, solutions for infusion. In addition, on the market we can find metronidazole in combined preparations in vaginal tablets and capsules used in the treatment of H. pylori infection.

How much does metronidazole cost?

Metronidazole - price

Metronidazole can be obtained with a prescription. The price of metronidazole may vary slightly depending on the pharmacy.

Metronidazole in gelusually costs around PLN 13 for a 15 gram pack, whilemetronidazole in ointmentand costs PLN 60 for 100 I play.

A package containing 20 tablets of 250 mg of metronidazole costs an average of PLN 26, while a package of 28 tablets of 500 g of metronidazole will cost about PLN 57.

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