Antimicrobials 4- Metronidazole Antimicrobials 4- Metronidazole Pharmacology -1 DSX 215 DSX 215 Dr/ Abdulaziz Saeedan Pharmacy College Pharmacy College 1

Metronidazole Metronidazole (Flagyl) is a synthetic nitroimidazole antibiotic that acts against anaerobic bacteria and some protozoa. ► i. e. Antibacterial & Antiprotozoal Agent.Spectrum: Metronidazole has a broad spectrum activity, It acts against anaerobic bacteria and some protozoa as Amoeba and Giardia. Anaerobic bacteria cause infections in some areas of the body such as the gum, pelvic cavity, intestine and bones because they do not need oxygen to grow and multiply. 2

Metronidazole- Action & Mechanism of action  Action:  Action: Metronidazole has bactericidal activity.  Mechanism of action flavodoxins ferredoxinsanaerobic protozoa Metronidazole is selectively absorbed then activated (reduced) by the microbial proteins (flavodoxins and ferredoxins) found in anaerobic bacteria and certain protozoa. Once activated, the reduction product of the drug oxidizes DNA causing cell death. NOTE: Mammalian cells are unharmed because they lack flavodoxins and ferredoxins that reduce the nitro group of metronidazole. 3

 HOW should this drug be taken? Metronidazole can be given orally or IV. Oral metronidazole can be taken with or without food.  What should you do if you FORGET a dose? If you miss a dose of metronidazole, take it as soon as possible. However, if it is the time for your next dose, do not double the dose. 4

Metronidazole - indications  Metronidazole is indicated for the treatment of: 1- Acute gingivitis and periapical abscess. ► Often used in conjunction with Amoxicillin. 2- Vaginal infections, commonly associated with overgrowth of anaerobes. 3- Abscesses in the liver, pelvis and abdomen that caused by anaerobic bacteria. 4- Used to treat Helicobacter pylori (H. pylori) that causes stomach ulcers. 5- Diarrhea caused by Entamoeba histolytica (Amoebiasis - amebic dysentery) OR Giardia (Giardiasis). ► Metronidazole is the drug of choice for the treatment of all tissue infections with Entamoeba histolytica. ► Metronidazole is the treatment of choice for giardiasis. Efficacy after a single treatment is about 90% 5

Metronidazole – Adverse Effects 1- Minor side effects include: a)Gastrointestinal disturbance in the form of nausea, vomiting, diarrhea, abdominal cramping and constipation. ► Taking the drug with meals lessens gastrointestinal irritation b) Unpleasant metallic taste, furry tongue, glossitis, dry mouth and stomatitis. ► These may be associated with a sudden overgrowth of Candida which may occur during therapy 2- Serious side effects: include seizures and damage of nerves resulting in numbness of extremities. ► Metronidazole should be stopped if these symptoms appear. 3- High doses and/or long-term treatment with metronidazole is associated with the development of leukopenia. NOTE: Although metronidazole has been shown to be teratogenic in some animals, it has not been associated with this effect in humans 6