Metronidazole adverse effects

Metronidazole maybe administered orally as a single 2-g dose or 500 mg twice daily for 7 days.17 Pregnant women should be prescribed the single dose of metronidazole. Cure rates are greater than 90% when metronidazole is administered as either a single 2-g dose or a 7-day regimen. Possible adverse effects include an unpleasant metallic taste, reversible neutropenia, urticaria, rash, flushing, dry mouth, darkened urine, and a disulfiram-like reaction. 

GI complaints (e.g., anorexia, nausea, vomiting, diarrhea) are the most common adverse effects, with the single 2-g dose of metronidazole or... 

There are a number of factors that limit the effectiveness of regimens designed to eradicate H. pylori. The first, antibiotic resistance, is seen with metronidazole and clarithromycin but has not been reported with bismuth, amoxicillin, or tetracycline. Second, mild adverse effects (eg, diarrhea, metallic taste, black stools) do occur in approximately 30% to 50% of patients. Therefore, shorter treatment periods in this group of patients may be better tolerated. 

Oral bioavailability is almost 100%. Metronidazole is protein bound for less than 20% and is widely distributed, including the CNS. It is metabolized in the liver with an elimination half-life of 8 hours. Common adverse effects include nausea, headache and taste disturbances. With alcohol a severe disulfiram-like reaction, with flushing, sweating and abdominal cramps will occur. 

Adverse effects include nausea, vomiting, diarrhoea, myalgias and because of its serious side effects including cardiac arrhythmia, CHE and hypotension, they have been almost completely replaced by metronidazole. 

Adverse effects include nausea, diarrhea, stomatitis, and peripheral neuropathy with prolonged use. Metronidazole has a disulfiram-like effect, and patients should be instructed to avoid alcohol. Although teratogenic in some animals, metronidazole has not been associated with this effect in humans. Other properties of metronidazole are discussed in Chapter 52. 

Diloxanide furoate is considered by many the drug of choice for asymptomatic luminal infections. It is not available commercially in the USA, but can be obtained from some compounding pharmacies. It is used with a tissue amebicide, usually metronidazole, to treat serious intestinal and extraintestinal infections. Diloxanide furoate does not produce serious adverse effects. Flatulence is common, but nausea and abdominal cramps are infrequent and rashes are rare. The drug is not recommended in pregnancy. 

Clinical Use. Emetine and dehydroemetine (Mebadin) are used primarily to treat protozoal infections in the intestinal tract and extraintestinal sites such as the lungs and liver. These drugs are powerful amebicides and are generally reserved for severe, acute cases of intestinal amebiasis (dysentery).51 Because of the potential for adverse effects, these drugs are no longer marketed in the United States, and safer agents like metronidazole are often used in their place. Emetine and dehydroemetine are typically administered by deep subcutaneous injection or intramuscular injection. 

Adverse Effects. Gastrointestinal disturbances including nausea, vomiting, diarrhea, stomach pain, and an unpleasant taste in the mouth are relatively common with metronidazole. Other adverse effects such as hypersensitivity reactions, peripheral neuropathy, hematologic abnormalities, and genitourinary problems have been reported, but their incidence is relatively low. 

Common adverse effects are diarrhea, nausea, and skin rashes. Impaired liver function (with or without jaundice) and neutropenia sometimes occur. Severe diarrhea and enterocolitis have followed clindamycin administration. Antibiotic-associated colitis that has followed administration of clindamycin and other drugs is caused by toxigenic C difficile. This potentially fatal complication must be recognized promptly and treated with metronidazole, 500 mg orally or intravenously three times a day (the preferred therapy), or vancomycin, 125 mg orally four times a day (less desirable given the increasing prevalence of vancomycin-resistant enterococci). Relapse may occur. 

METRONIDAZOLE DIDANOSINE, STAVUDINE t adverse effects (e.g. peripheral neuropathy) with didanosine and possibly stavudine Additive effect Monitor closely for peripheral neuropathy during intensive or prolonged combination... 

METRONIDAZOLE PROTEASE INHIBITORS t adverse effects, e.g. disulfiram-like reaction, flushing, with ritonavir (with or without lopinavir) Ritonavir and lopinavir oral solutions contain alcohol Warn patient and give alternative preparation if possible... 

Corticosteroids are commonly prescribed for moderate to severe Crohn s disease with short term efficacy probably related to their effect on inflammation. Anti-bacterials are commonly used as primary therapy in Crohn s disease. Common adverse effects of metronidazole are nausea and a metallic taste, hov ever peripheral neuropathy may result from long term use. Ciprofloxacin and similar antibacterials can be beneficial in those patients intolerant to mefi onidazole. 

In contrast to ulcerative colitis, about 50% of patients with Crohn s colitis will respond to metronidazole given for up to 3 months, although adverse effects including alcohol intolerance, and peripheral neuropathy from such prolonged therapy often limit its use. The drug is also helpful in controlling perianal and small bowel disease and it decreases the incidence of anastamotic recurrence after surgery. Other antimicrobials, particularly ciprofloxacin may also be effective. 

Carnidazole is an imidazole derivative, less potent than most other similar compounds (1). In early studies, its adverse effects were mild nausea and vomiting, abdominal discomfort, dry mouth, dizziness, headache, and tiredness were reported (SEDA-6,264). Metronidazole-Uke adverse effects should be anticipated. 

Among the imidazole derivatives, numerous case reports or studies have shown that ketoconazole, fluconazole, and itraconazole can inhibit ciclosporin metabolism and increase blood ciclosporin concentrations (267). Ketoconazole, which is undoubtedly the most potent inhibitor, has been used to reduce the dose, and therefore the cost or adverse effects, of ciclosporin (268-270). There was also a beneficial effect on the rate of rejection or infection. In contrast, interactions with metronidazole and miconazole have only been described in isolated case histories (SEDA-19, 351) (5). 

Diloxanide often causes flatulence and, occasionally, nausea, vomiting, diarrhea, urticaria, and pruritus. It is an excellent luminal amebicide and is indicated after treatment with the 5-nitroimidazole compounds, which have relatively weak activity on the cyst stage. Experience over 14 years has been summarized by the Centers for Disease Control and Prevention (CDC, Atlanta), confirming the minimal toxicity of diloxanide. Fewer adverse effects were reported in patients aged 20 months to 10 years than in those aged over 10 years. There is no record of interactions between diloxanide and either metronidazole or tinidazole (SEDA-13, 830) (SEDA-17, 333). 

The MACH-2 study has assessed the role of omeprazole in triple therapy in 539 patients with duodenal ulcers associated with H. pylori (3). The addition of omeprazole resulted in significantly higher eradication rates (over 90%) than antibiotics alone (amoxicillin plus clarithromycin about 25% clarithromycin plus metronidazole 70%), and reduced the impact of primary resistance to metronidazole. About one-third of the patients who took amoxicillin reported diarrhea/loose stools. The frequency of taste disturbance was dose-dependent with clarithromycin. Increased liver enzymes were more commonly reported in those taking metronidazole. The addition of omeprazole did not increase the frequency of reported adverse effects. 

The DU-MACH study assessed the efficacy of two omeprazole-based triple therapies (omeprazole, amoxicillin, clarithromycin versus omeprazole, metronidazole, clarithromycin) given for 1 week to 149 patients for eradicating H. pylori, healing duodenal ulcers, and preventing ulcer relapse over 6 months after treatment (4). Both regimens achieved high eradication rates (about 90%) and were well tolerated. Adverse effects were similar in the two groups, and included diarrhea, taste disturbance, headache, nausea, and dyspepsia. 

Ranitidine 300 mg bd and omeprazole 20 mg bd have been compared as components of triple therapies (combining them with either amoxicillin plus clarithromycin or amoxicillin plus metronidazole) in 320 patients with H. pylori (5). Omeprazole and ranitidine combined with two antibiotics for 1 week were equally effective in eradicating H. pylori. This result questions the role of profound acid suppression in eradication. There was no difference in the reported adverse effects, which included nausea, vomiting, diarrhea, metallic taste, skin rashes, and headache. 

Quadruple therapy (omeprazole, amoxicUhn, roxithromycin, and metronidazole for 1 week) has been studied in an open trial in 169 patients with H. pylori (8). This regimen achieved an eradication rate of 92%. It was also beneficial in patients infected with pretreatment resistant strains to the antibiotics, in which cases the eradication rates achieved (over 90%) were similar to eradication rates in patients infected with sensitive strains. Compliance was good and there was only one serious adverse effect, anaphylaxis, probably due to amoxicillin. Frequent adverse effects were abdominal distension (10%), glossitis (9%), and diarrhea (8%). 

Emetine, once the drug of choice for the treatment of amebiasis, despite marked cardiotoxicity, has largely been replaced by metronidazole and related compounds for this indication. Large doses of emetine can damage the heart, hver, kidneys, intestinal tract, and skeletal muscle. Allergic reactions and tumor-inducing effects have not been described. Dehydroemetine is a httle less toxic but also less effective than emetine its adverse effects are similar (SED-11, 594). 

The use of metronidazole against infections with anerobic bacteria has increased over the years, and with this indication the use of metronidazole in combination with many other drugs used by patients with conditions likely to develop secondary anaerobic bacterial infections. With increased use there is also a widespread and increasing incidence of resistance of various strains of bacteria. The use of metronidazole as an added medication merely to make assurance double sure is to be discouraged. It is to be especially discouraged in immunocompromised patients, because of the risk of emergence of resistant bacterial strains. With increased use there is also an increased number of reports of some more unusual adverse effects. Overall, metronidazole can still be considered safe, if used in generally recommended doses. 

In the eradication of Helicobacter pylori, metronidazole plus bismuth is effective, but causes more adverse effects than omeprazole plus amoxicillin plus either clarithromycin or metronidazole. 

A polyneuropathy is a well-recognized adverse effect of metronidazole (3). A 6% incidence of neuropathy... 

---