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Metronidazole
Metronidazole is a synthetic antiprotozoal and antibacterial agent commonly used to treat various anaerobic infections, including C. difficile and bacterial vaginosis, with a mechanism that disrupts microbial DNA synthesis. It is available in multiple forms, such as tablets and creams, with key pharmacokinetic properties including 80% GI absorption and varying half-lives based on patient condition. Potential side effects include epigastric distress and peripheral neuropathy, and it should be used cautiously in pregnant individuals.
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Introduction to Metronidazole, its contents, and structure as an antibacterial agent.
Dosage forms, trade names, and pharmacokinetics including absorption, metabolism, and elimination.
Describes how Metronidazole disrupts microbial DNA synthesis, primarily affecting anaerobic cells.
Indications for use include various anaerobe infections and conditions like C. difficile and bacterial vaginosis.
Lists side effects such as seizures, metallic taste, and rare conditions like Stevens-Johnson syndrome.
Interactions with alcohol, anticoagulants, and other drugs affecting Metronidazole's efficacy.
Pregnancy category B; recommends caution in lactation due to excretion in human milk.
Consequences of missing a dose and its impact on treatment effectiveness.
Important patient inquiries before dispensing, including pregnancy status and medication history.
Cites sources for further reading and reference on pharmacology and Metronidazole.
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Metronidazole
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- 2. CONTENTS •INTRODUCTION •DOSAGE FORMS &TRADE NAMES •PHARMACOKINETICS •MECHANISM OF ACTION •INDICATIONS •SIDE EFFECTS OF METRONIDAZOLE •DRUG INTERACTIONS •PREGNANCY & LACTATION •WHAT HAPPENS IF ONE MISSES THE DOSE •IMPORTANT THINGS TO REMEMBER
- 3. INTRODUCTION •Metronidazole (flagyl) isa synthetic antiprotozoal and antibacterial agent,( l-β-hydroxyethyl)-2-methyl-5-nitroimidazole, which has the following structural formula: •It belongs to the group of nitro imidazoles. •Other members related to metronidazole are tinidazole and others.
- 4. DOSAGE FORMS &TRADE NAMES •Trade names: Flagyl, Flagyl ER. Dosage Forms: Tablet, Gel, Cream, Capsule, Tablet, Suspension •Flagyl tablets contain 250 mg or 500 mg of metronidazole. • Inactive ingredients include cellulose, hydroxypropyl cellulose.
- 5. PHARMACOKINETICS •Absorption • Bioavailability: 80%absorption from GI tract (PO) • Protein binding (<20%) • Peak serum time: 1-2 hr •Distribution • Widely distributed; similar pattern for PO and IV •Metabolism • Liver • Enzymes inhibited: Hepatic CYP2C9 •Elimination • Half-life: 25-75 hr (neonates); 8 hr (others); prolonged in patients with hepatic impairment • Excretion: Urine (77%); feces (14%)
- 6. MECHANISM OF ACTION •Metronidazole acts by inhibiting nucleic acid synthesis by disrupting the DNA of microbial cells. • This function only occurs when metronidazole is partially reduced, and because this reduction usually happens only in anaerobic cells, it has relatively little effect upon human cells or aerobic
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- 8. INDICATIONS Anaerobe infections C. difficile H.pylori Bacterial vaginosis Trichomonas vaginitis Amebiasis Giardiasis
- 9. SIDE EFFECTS OF METRONIDAZOLEEpigastricdistress Seisures Metallic taste Darkening of urine Peripheral neuropathy Pancreatitis Hepatitis Fever Reversible neutropenia •Stevens–Johnson syndrome: Metronidazole alone rarely causes Stevens–Johnson syndrome, but is reported to occur at high rates when combined with mebendazole. Very rare Fewer than 20K US cases per year
- 10. DRUG INTERACTIONS DRUG INTERACTION ALCOHOLMild disulfiram like reaction (Nausea, headache, vomiting, abdominal cramps) ANTICOAGULANTS (WARFARIN) Prolonged PT(Prothrombin time) CIMETIDINE Prolong half life & decrease clearance of Metronidazole PHENYTOIN & PHENOBARBITONE Decrease serum concentration and increase metabolism of Metronidazole
- 11. PREGNANCY & LACTATION •Pregnancycategory: B •May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. •Lactation •Excreted in human milk; not recommended •Following PO administration, concentrations in human milk are similar to concentrations in plasma
- 12. WHAT HAPPENS IFONE MISSES THE DOSE •The decision of drug dose is a practical issue after many complicated trials both in-vitro and in-vivo •Missing a dose in any cause of treatment will disturb the optimal therapeutic concentration which in turn may compromise treatment, and hence impair healing.
- 13. IMPORTANT THINGS TO REMEMBERBEFORE DISPENSING METRONIDAZOLE•Any woman in child bearing age should be asked if she is pregnant. •Any old man should be asked about history of chronic illness, especially hepatic and renal diseases. •Social history must inquire alcohol consumption of the patient. •Patient should be asked about other medications he/she is taking as well as other important questions like allergies and intolerances.
- 14. REFERENCES •Katzung & Trevor'sPharmacology Examination and Board Review,10th Edition (Katzung & Trevor's Pharmacology Examination & Board Review), ISBN- 13: 978-0071789233 •Lippincott Illustrated Reviews: Pharmacology 6th edition (Lippincott Illustrated Reviews Series), ISBN-13: 978-1451191776 •www.reference.medscape.com •www.nlm.nih.gov •www.webmd.com •www.medicinenet.com