Metronidazol Polpharma: composition and pharmaceutical form
Metronidazol Polpharma comes as vaginal tablets. One tablet contains 500 mg of metronidazole and is intended for insertion into the vagina, not to be taken by mouth.
In rare cases, with marked vaginal dryness, the tablet may fail to dissolve and come out unchanged — the treatment will then be incomplete. To prevent this, it is recommended to moisten the tablet slightly with boiled, cooled water before inserting it.
How Metronidazol Polpharma works
Metronidazole is a 5-nitroimidazole derivative with antiprotozoal and antibacterial action. It penetrates easily into single-celled organisms, protozoa and bacteria, but does not penetrate into the cells of mammals. The oxidation-reduction potential of metronidazole is lower than that of ferredoxin, the protein that carries electrons in anaerobic organisms and in those living in an oxygen-poor environment. Because of this difference in potentials the nitro group of metronidazole is reduced, and the reduced form of the substance breaks the DNA chain of the microorganism.
Metronidazole acts on protozoa — Trichomonas vaginalis, Giardia lamblia, Entamoeba histolytica and Balantidium coli — and has a marked bactericidal action against anaerobic bacteria: the Gram-negative rods of the genus Bacteroides, including the B. fragilis group, and Fusobacterium, the Gram-positive rods Eubacterium and Clostridium, the Gram-positive cocci Peptococcus and Peptostreptococcus. As regards the vaginal flora, its activity is confirmed against Gardnerella vaginalis, bacteria of the genus Bacteroides and Mycoplasma hominis.
Indications
The medicine is intended for the local treatment of trichomoniasis caused by Trichomonas vaginalis.
The second indication is bacterial vaginosis caused by Gardnerella vaginalis, bacteria of the genus Bacteroides and Mycoplasma hominis. In both cases it is specifically a local treatment: the tablet works in the lumen of the vagina.
Method of use and dosage
Adolescents and adults are prescribed one vaginal tablet in the evening for 10 days. Treatment is not interrupted during menstruation.
In trichomoniasis treatment is given to both sexual partners at the same time: asymptomatic trichomoniasis in the man is a frequent cause of reinfection of the woman. In bacterial vaginosis simultaneous treatment of the partner is, as a rule, not required.
Contraindications
The medicine is not used in hypersensitivity to metronidazole, to other 5-nitroimidazole derivatives or to any excipient.
It is also contraindicated in the first trimester of pregnancy. In the second and third trimesters it is prescribed only when the expected benefit to the mother exceeds the risk of a harmful influence on the foetus.
Special warnings and precautions
Although the tablets are inserted into the vagina, part of the substance is absorbed, so the warnings concern general reactions too. Caution is needed in severe disturbances of liver function: in such patients metronidazole is metabolised slowly, and it itself, together with its metabolites, can accumulate in the body. In epilepsy and other neurological diseases caution is likewise required — with the systemic use of metronidazole peripheral neuropathy and seizures have been seen. Leucopenia deserves separate attention, including a past episode of it: with the vaginal tablets it can worsen or appear, especially with prolonged or repeated use.
- during treatment and for at least a day after it ends alcohol must not be consumed — unpleasant reactions are possible;
- during treatment a candidal inflammation of the cervix or the vagina may develop, requiring an antifungal medicine;
- metronidazole affects the results of some laboratory tests: AST, ALT, LDH, triglycerides, glucose measured by the hexokinase method and the white cell count;
- in patients with Cockayne syndrome, cases of severe hepatotoxicity and acute liver failure have been described with the systemic use of metronidazole, including fulminant ones with a fatal outcome;
- in this group of patients the medicine is used only after a careful assessment of the benefit and the risk and only when there is no alternative treatment;
- in trichomoniasis the treatment of both partners is obligatory, otherwise the risk of reinfection is high;
- treatment is not interrupted during menstruation;
- with vaginal dryness the tablet is moistened before insertion, otherwise it may fail to dissolve.
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 medicines that inhibit the liver enzymes, for example cimetidine, on the contrary prolong its half-life.
Metronidazole raises the serum concentration of lithium and increases its toxicity: if concomitant use is necessary, the lithium and creatinine levels are monitored. It also enhances the toxic action of alcohol — drinking during treatment can cause a feeling of heat, sweating, headache, nausea, vomiting and pain in the upper abdomen. Combination with disulfiram sometimes leads to acute psychoses and disorientation, so treatment with metronidazole is not started until two weeks after the end of disulfiram therapy. An interaction with busulfan is possible. In addition, metronidazole inhibits the enzyme CYP3A4 and can therefore slow the metabolism of medicines that this enzyme breaks down.
Pregnancy and breastfeeding
No well-controlled studies have been carried out in pregnant women. Metronidazole crosses the placental barrier and in the first trimester of pregnancy it is contraindicated.
In the second and third trimesters the medicine is used only in the case where the possible benefit to the mother outweighs the risk to the foetus. Metronidazole is excreted in breast milk in concentrations close to those in plasma, so breastfeeding women should not take it; if treatment is necessary, the question of stopping feeding is settled.
Adverse effects
Inserted into the vagina, metronidazole has a low toxicity and is on the whole well tolerated. The main undesirable reactions are local, and with prolonged use a fungal infection may develop.
- common — candidal inflammation of the cervix or the vagina: itching, pain during intercourse, thick white discharge with no smell or with a faint one;
- uncommon — headache, dizziness, neuropathy, disturbances of the coordination of movements, drowsiness, changes in taste;
- uncommon — diarrhoea, nausea or vomiting, a metallic taste, dry mouth, a coated tongue;
- rare — anaphylaxis;
- very rare — anaphylactic shock;
- very rare — agranulocytosis, neutropenia, thrombocytopenia, pancytopenia;
- very rare — mental disturbances, including disorientation and hallucinations;
- frequency not known — leucopenia, loss of appetite, low mood, nervousness.
Cases of severe irreversible hepatotoxicity and acute liver failure in patients with Cockayne syndrome have been noted separately — they have been described with the systemic use of metronidazole, including with a very rapid course and a fatal outcome.
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 of metronidazole, nausea, vomiting and impaired coordination of movements were noted. Treatment in poisoning is symptomatic and supportive.
How to get a prescription for Metronidazol Polpharma online
Metronidazole is dispensed on prescription: before prescribing it is important to understand which infection exactly is causing the symptoms and to decide whether the partner needs treatment.
During the online consultation the doctor will go through the complaints and the test results, will explain the rules for inserting the tablets and the ban on alcohol during the course and, if there are no contraindications, will issue an electronic prescription — the medicine can be collected from a pharmacy using its code.
