Pharmaceutical Grade Metronidazole Pharmacopoeia Standard Metronidazole API for Preparation with Content Above 99%

I. Pharmacopoeia Quality Standards for Pharmaceutical Grade Metronidazole

1. Description

- Appearance: White to slightly yellow crystals or crystalline powder.

- Solubility: Slightly soluble in ethanol, sparingly soluble in water; readily soluble in sodium hydroxide test solution.

2. Identification

- Chemical Identification:

- Take about 10 mg of the substance, which produces a yellow precipitate.

- Dissolve an appropriate amount in water and dilute to a solution containing about 10 μg per ml. Measure by ultraviolet-visible spectrophotometry, showing maximum absorption at 277 nm with an absorbance of about 0.35.

- Infrared Spectrophotometry: The infrared absorption spectrum should match the reference spectrum (Spectrum Set 122).

- Chromatographic Identification: Using high-performance liquid chromatography, the retention time of the main peak in the test solution should correspond to that of the reference solution.

3. Tests

- Related Substances: Determined by high-performance liquid chromatography to control impurities (such as 2-methyl-5-nitroimidazole, etc.). In the chromatogram of the test solution, the area of any individual impurity peak should not exceed 0.5 times the area of the main peak in the reference solution (0.5%), and the sum of the areas of all impurity peaks should not exceed the area of the main peak in the reference solution (1.0%).

- Loss on Drying: When dried to constant weight at 105°C, the loss in weight should not exceed 0.5%.

- Residue on Ignition: The residue should not exceed 0.1%.

- Heavy Metals: The content of heavy metals should not exceed 10 parts per million.

- Microbial Limits: Must comply with the pharmacopoeial standards for sterility or microbial control (depending on the type of preparation).

4. Assay

- Determined by high-performance liquid chromatography. Calculated on the dried basis, the content of C?H?N?O? should not be less than 99.0%.

Pharmaceutical Grade Metronidazole Pharmacopoeia Standard Metronidazole API for Preparation with Content Above 99%

II. Medical Uses of Pharmaceutical Grade Metronidazole

1. Anti-Anaerobic Bacterial Infections

- Indications: Used to treat systemic or local infections caused by anaerobic bacteria, such as abdominal infections (peritonitis, abdominal abscess), pelvic infections (pelvic inflammatory disease, cervicitis), skin and soft tissue infections, endocarditis, sepsis, etc.

- Mechanism of Action: After entering anaerobic bacterial cells, its nitro group is reduced to free radicals with cytotoxic effects, inhibiting DNA synthesis and leading to bacterial death.

2. Anti-Trichomoniasis

- Trichomonal Vaginitis: As the drug of choice, it can be administered orally or topically to kill Trichomonas vaginalis, alleviating symptoms such as itching and increased vaginal discharge.

3. Anti-Amoebiasis

- Intestinal Amoebiasis: Such as acute amoebic dysentery and asymptomatic amoebic cyst carriers, it can eliminate amoebic trophozoites in the intestinal lumen;

- Extraintestinal Amoebiasis: Such as amoebic liver abscess, requiring combination therapy with other drugs.

4. Combination Therapy for Helicobacter pylori Infection

- Often used in combination with proton pump inhibitors (e.g., omeprazole), amoxicillin, or clarithromycin, forming "triple therapy" or "quadruple therapy" to eradicate Helicobacter pylori, used in the treatment of gastric ulcers, duodenal ulcers, and chronic gastritis.

5. Other Uses

- Antibiotic-Associated Diarrhea (AAD): Effective for mild AAD caused by Clostridium difficile, but severe infections require priority use of vancomycin or fidaxomicin.

- Topical Application: Metronidazole gel or cream can be used to treat skin and mucosal infections such as rosacea and bacterial vaginosis.