Metronidazol Polpharma - (IR): composition and pharmaceutical form
One tablet contains 250 mg of metronidazole. Unlike the vaginal form, these tablets are intended to be taken by mouth and act systemically.
They can be taken independently of food. If necessary, the tablet may be crushed — this makes it easier to give to children. The composition includes glucose (6.60 mg per tablet), so the medicine is not suitable for patients with glucose-galactose malabsorption syndrome.
How Metronidazol Polpharma - (IR) works
Metronidazole penetrates easily into single-celled organisms, protozoa and bacteria, but does not penetrate into the cells of mammals. Its oxidation-reduction potential is lower than that of ferredoxin, the electron-carrying protein found in anaerobic organisms and in those living in an oxygen-poor environment. The difference in potentials leads to the reduction of the nitro group of metronidazole, and the reduced form breaks the DNA chain of the microorganism.
The medicine acts on protozoa: Trichomonas vaginalis, Giardia lamblia, Entamoeba histolytica and Balantidium coli. It has a strong bactericidal action on anaerobic bacteria — the Gram-negative rods of the genus Bacteroides, including B. fragilis, B. distasonis, B. ovatus, B. thetaiotaomicron and B. vulgatus, and also Fusobacterium; the Gram-positive rods Eubacterium and Clostridium; the Gram-positive cocci Peptococcus and Peptostreptococcus. On most aerobic and facultatively anaerobic bacteria, and on fungi and viruses, metronidazole has no effect.
Indications
The medicine is used in adults and children in infections caused by anaerobic bacteria of the genera Bacteroides, Fusobacterium, Clostridium, Eubacterium, by anaerobic cocci and by Gardnerella vaginalis, and also by protozoa — trichomonads, Entamoeba histolytica, Giardia lamblia and balantidia. These include sepsis, bacteraemia, peritonitis, brain abscess, pneumonia, osteomyelitis, puerperal fever, pelvic abscess, parametritis and infections of surgical wounds.
Separate indications are the prevention of postoperative infections caused by anaerobic bacteria, above all of the genera Bacteroides and Streptococcus; trichomoniasis of the genitourinary tract in women and men; bacterial vaginosis; amoebiasis; giardiasis; acute ulcerative gingivitis and acute periodontal infections; ulcers of the lower limbs and pressure sores infected with anaerobic bacteria. As part of a combined regimen metronidazole is also used in peptic ulcer disease associated with Helicobacter pylori infection. When choosing an antibacterial agent, the official recommendations are taken into account.
Method of use and dosage
The dosage depends on the infection and on the patient's age. The average length of treatment of anaerobic infections does not exceed 7 days.
| Indication | Scheme for adults and adolescents |
|---|---|
| Anaerobic infections | 1–2 tablets 3 times a day, usually 7 days |
| Prevention of postoperative infections | 1000 mg as a single dose, then 250 mg 3 times a day until the preoperative fast |
| Trichomoniasis | 2000 mg as a single dose, or 250 mg 3 times a day for 7 days, or 500 mg twice a day for 5–7 days |
| Bacterial vaginosis | 500 mg morning and evening for 7 days or 2000 mg as a single dose |
| Amoebiasis | 750 mg 3 times a day for 5–10 days |
| Giardiasis | 250 mg 3 times a day for 5–7 days or 2000 mg once a day for 3 days |
| Eradication of Helicobacter pylori | 500 mg 2–3 times a day for 7–14 days in combination with other medicines |
| Acute ulcerative gingivitis, periodontal infections | 250 mg 2–3 times a day, 3 days in gingivitis and 3–7 days in periodontal infections |
Children and special situations
In children the dose is calculated by body weight: in anaerobic infections, children over 8 weeks and up to 12 years are usually given 20–30 mg per kilogram a day — as a single dose or 7.5 mg/kg every 8 hours — and if necessary up to 40 mg/kg a day. Children under 8 weeks are given 15 mg/kg a day as a single dose or 7.5 mg/kg every 12 hours. In newborns born before the 40th week of gestation, metronidazole can accumulate during the first week of life, so after a few days of treatment its serum concentration is checked. In trichomoniasis the treatment is necessarily given to both sexual partners at the same time. In infants and children weighing less than 10 kg the doses are reduced proportionately.
Contraindications
The medicine is not used in hypersensitivity to metronidazole, to other 5-nitroimidazole derivatives or to any excipient, nor in the first trimester of pregnancy.
In the second and third trimesters it is prescribed only when the expected benefit to the mother outweighs the risk to the foetus, and during breastfeeding the medicine is not used.
Special warnings and precautions
Metronidazole has no effect on aerobic and facultatively anaerobic bacteria, so a gonococcal infection may persist even after the successful treatment of trichomoniasis. It is worth knowing separately that the medicine colours the urine a darker shade — this is harmless. Because the data on mutagenicity in humans are insufficient, the question of treating for longer than the usually recommended period is settled with particular care.
- severe bullous skin reactions, sometimes with a fatal outcome, have been described: Stevens-Johnson syndrome and toxic epidermal necrolysis; most cases of Stevens-Johnson syndrome arose in the first 7 weeks of treatment, and with flu-like symptoms accompanied by a spreading rash, blisters or involvement of the mucous membranes the medicine is withdrawn;
- in active and chronic diseases of the central and peripheral nervous system caution is needed: an intensification of neurological symptoms is possible, so the appearance of paraesthesia, ataxia, dizziness and seizures is watched for;
- if numbness, tingling in the limbs or seizures appear during treatment, it is continued only when the benefit exceeds the risk of complications;
- caution is necessary in severe hepatic failure and hepatic encephalopathy, in renal failure, and also in patients receiving corticosteroids and those prone to oedema;
- during treatment the blood picture is monitored, above all the white cell count; with a course longer than 10 days such monitoring is obligatory;
- during use candidiasis of the mouth, the vagina and the gastrointestinal tract is possible and requires separate treatment;
- alcohol is excluded during treatment and for at least 48 hours after it ends — a disulfiram-like reaction is possible;
- in patients with Cockayne syndrome cases of severe hepatotoxicity and acute liver failure have been described, including fulminant and fatal ones: the medicine is prescribed only when there are no alternatives, liver tests are done before, during and after treatment, and with a considerable rise in the values the medicine is stopped.
Metronidazole can alter the results of some laboratory tests — AST, ALT, LDH, triglycerides and glucose. The patient is warned of possible drowsiness, dizziness, disorientation, hallucinations, seizures and transient visual disturbances: with such symptoms one must not drive or operate machinery.
Drug interactions
With coumarin anticoagulants metronidazole prolongs the prothrombin time. Agents that activate the liver microsomal enzymes — phenytoin and phenobarbital — speed up its elimination and lower its serum concentration, while those that inhibit these enzymes, for example cimetidine, prolong its half-life.
The medicine raises the serum concentration of lithium and enhances its toxic action, so with concomitant use the lithium and creatinine levels are monitored. Alcohol during treatment causes a disulfiram-like reaction — a feeling of heat, sweating, headache, nausea, vomiting, pain in the upper abdomen — and combination with disulfiram can lead to acute psychoses and disorientation: treatment with metronidazole is not started until two weeks after it has been withdrawn. An interaction with busulfan is possible. As an inhibitor of the enzyme CYP3A4, metronidazole slows the metabolism of medicines that this enzyme breaks down.
Pregnancy and breastfeeding
Data on the use of metronidazole in pregnant women are scarce. It crosses the placental barrier, and in the first trimester of pregnancy its use is contraindicated.
In the second and third trimesters the medicine is used only on condition that the possible benefit to the mother is greater than the risk of a harmful influence on the foetus. Metronidazole passes into breast milk in concentrations close to those in plasma, so during breastfeeding it is not prescribed; if treatment is necessary, a decision is taken to stop feeding.
Adverse effects
Severe undesirable reactions are rare when the recommended schemes are observed. In children the frequency, nature and severity of the reactions are the same as in adults. In the prolonged treatment of chronic conditions the doctor separately weighs the benefit against the risk of peripheral neuropathy.
- very rare — agranulocytosis, neutropenia, thrombocytopenia, pancytopenia;
- very rare — psychotic disorders, including confusion and hallucinations;
- very rare — encephalopathy with confusion, fever, headache, hallucinations, photosensitivity, disturbances of vision and movement, and also a subacute cerebellar syndrome with disturbance of coordination, speech and gait, nystagmus and tremor — both conditions may resolve after the medicine is withdrawn;
- very rare — drowsiness, dizziness, seizures, headache, visual disturbances including double vision and short-sightedness, usually transient;
- very rare — raised activity of the liver enzymes, cholestatic or mixed hepatitis, damage to the liver cells, jaundice and pancreatitis, resolving after withdrawal;
- very rare — rash, pustular eruptions, itching, redness, pain in the muscles and joints, a darker colour of the urine;
- rare — anaphylaxis; frequency not known — angioedema, urticaria, fever;
- frequency not known — disturbances of taste, stomatitis, "hairy" tongue, nausea, vomiting, pain in the upper abdomen and diarrhoea, loss of appetite, low mood, leucopenia, peripheral sensory neuropathy, aseptic meningitis, optic neuritis, erythema multiforme, Stevens-Johnson syndrome and toxic epidermal necrolysis.
Overdose
The fatal dose of metronidazole for humans is unknown. In isolated cases, after taking 6–10.4 g by mouth every other day for 5–7 days, neurotoxic phenomena were seen, including convulsive states and peripheral neuropathies.
After a single dose of 15 g, nausea, vomiting and impaired coordination of movements were noted. In poisoning, symptomatic treatment is given and the vital functions are supported.
How to get a prescription for Metronidazol Polpharma - (IR) online
Metronidazole is dispensed on prescription: the scheme and the length of the course differ greatly depending on the infection — from a single dose in trichomoniasis to a two-week course in the Helicobacter pylori eradication regimen.
During the online consultation the doctor will establish the diagnosis and the test results, will choose the dose, will warn about the ban on alcohol and, if there are no contraindications, will issue an electronic prescription — the medicine can be collected from a pharmacy using its code.
