Pharmacology
Infections
What is the main mechanism of action of metronidazole:
Answer:
Metronidazole, of the nitroimidazole class, is a bacterial nucleic acid synthesis inhibitor. It has high activity against anaerobic bacteria and protozoa. Metronidazole is well absorbed orally and the intravenous route is normally reserved for severe infections.Metronidazole
Pharmacology / Infections
Last Updated: 26th March 2019
Mechanism of Action
Metronidazole, of the nitroimidazole class, is a bacterial nucleic acid synthesis inhibitor. It has high activity against anaerobic bacteria and protozoa. Metronidazole is well absorbed orally and the intravenous route is normally reserved for severe infections.
Indications
Indications include:
- Clostridium difficile colitis
- Helicobacter pylori eradication (with clarithromycin/amoxicillin and PPI)
- Bacterial vaginosis
- Pelvic inflammatory disease (with doxycycline and ceftriaxone or ofloxacin)
- Peritonitis (with cephalosporin or gentamicin)
- Acute oral infections
- Tetanus
- Rosacea and acne (topical)
- Surgical prophylaxis
- Protozoal infections
- Amoebic dysentery
- Giardiasis
- Trichomoniasis
Interactions
Metronidazole can cause a disulfiram-like reaction with alcohol causing symptoms such as flushing, headaches, dizziness, nausea/vomiting, tachypnoea and tachycardia.
Metronidazole enhances the anticoagulant effect of warfarin. If concurrent use cannot be avoided, consider reducing the warfarin dosage appropriately.
Side Effects
Common adverse effects include a metallic taste and gastrointestinal irritation (in particular nausea and vomiting). These are more common at higher doses. Patients should be advised that metronidazole should be taken with or after food.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
