Amotrex 200 mg/5 ml Oral Suspension (Metronidazole) – ACI Limited

1. About Amotrex 200 mg/5 ml Oral Suspension

Amotrex 200 mg/5 ml Oral Suspension contains Metronidazole 200 mg per 5 ml, the liquid formulation of the essential nitroimidazole antibiotic-antiprotozoal, manufactured by ACI Limited, Bangladesh. This oral suspension is specifically designed for paediatric patients and adults who have difficulty swallowing tablets, providing accurate weight-based dosing in a pleasant flavoured liquid form.

Metronidazole oral suspension is one of the most important paediatric antimicrobials in Bangladesh for treating amoebiasis, giardiasis, and anaerobic bacterial infections in children — conditions with high prevalence rates in the country due to environmental and sanitation factors. The suspension allows precise dosing by weight (mg/kg) for children from toddlers to adolescents.

2. Mechanism of Action

Metronidazole is a nitroimidazole prodrug activated selectively within anaerobic organisms and protozoa:

• Reductive activation by low-redox proteins: Ferredoxin and pyruvate:ferredoxin oxidoreductase in anaerobes reduce the nitro group of metronidazole, generating cytotoxic radical intermediates
• DNA strand breakage: These reactive metabolites cause irreversible double-strand DNA breaks and helix disruption — rapidly killing susceptible organisms
• Selective toxicity: Aerobic human cells cannot generate these reactive intermediates, making metronidazole selectively lethal to anaerobic bacteria and protozoa
• Antiprotozoal spectrum: Highly effective against Entamoeba histolytica, Giardia lamblia, and Trichomonas vaginalis — the main protozoal pathogens in Bangladesh's paediatric population

3. Indications

Amotrex 200 mg/5 ml Oral Suspension is indicated for:

• Amoebiasis in children: Intestinal amoebiasis (amoebic dysentery — bloody diarrhoea, abdominal pain) and amoebic liver abscess caused by Entamoeba histolytica — highly prevalent in Bangladeshi children
• Giardiasis in children: Giardia lamblia infection causing chronic watery diarrhoea, malabsorption, and failure to thrive — very common paediatric infection in Bangladesh
• Trichomoniasis: Trichomonas vaginalis (adolescents)
• Bacterial Vaginosis: Adolescent females where oral treatment preferred
• Anaerobic Bacterial Infections in children: Intra-abdominal, pelvic, or dental anaerobic infections
• Surgical Prophylaxis in children: Pre- and peri-operative cover for colorectal/abdominal surgery
• Adults: Adults unable to swallow tablets — providing equivalent bioavailability in liquid form

4. Dosage and Administration

Paediatric weight-based dosing (200 mg/5 ml = 40 mg/ml):

Amoebiasis:

• Children: 35–50 mg/kg/day in 3 divided doses for 5–10 days
• Example: 20 kg child = 700–1000 mg/day = 17.5–25 ml/day in 3 doses = ~6–8 ml three times daily

Giardiasis:

• Children: 15 mg/kg/day in 3 divided doses for 5 days
• Example: 20 kg child = 300 mg/day = 7.5 ml/day in 3 doses = 2.5 ml three times daily

Anaerobic infections:

• Children: 7.5 mg/kg every 8 hours (max 400 mg per dose) for 7–10 days

Adult dosing using suspension (equivalent to tablet regimens):

• Amoebiasis: 10–20 ml (400–800 mg) 3 times daily for 5–10 days
• Giardiasis: 10 ml (400 mg) 3 times daily for 5 days
• Bacterial vaginosis: 10 ml (400 mg) twice daily for 7 days

How to give the suspension:

1. Shake the bottle well before each dose — the suspension settles on standing
2. Use the oral syringe or measuring spoon provided — never estimate using a household teaspoon
3. Give with or after food to reduce nausea
4. Do NOT give with any alcohol-containing preparations

5. Contraindications

• Hypersensitivity to metronidazole or other nitroimidazoles
• First trimester of pregnancy in mother (if used for adult females)
• Concurrent disulfiram within 2 weeks
• Alcohol ingestion — absolute contraindication (including alcohol-containing preparations)

6. Warnings and Precautions

Alcohol contraindication: Even the small amounts of alcohol in some paediatric medicines (cough syrups, tonics, vitamin preparations) can trigger a disulfiram-like reaction in children receiving metronidazole. Check all concurrent medications for alcohol content.

Paediatric neuropathy risk: Peripheral neuropathy risk with prolonged courses. Avoid unnecessarily extended treatment in children.

Accurate dose measurement: Always use the supplied measuring device. Underdosing reduces efficacy; overdosing risks CNS toxicity in small children.

Complete the course: Stopping early — especially in amoebiasis — risks relapse and resistance. The child may feel better before the infection is eradicated.

Hepatic impairment: Reduce dose in children with significant liver disease.

7. Side Effects

Common in children:

• Nausea, vomiting — give with food or milk
• Metallic or bitter taste — harmless, resolves on stopping
• Diarrhoea, abdominal discomfort
• Dark brown/reddish urine — harmless metabolite excretion

Less common:

• Headache, dizziness
• Skin rash

Rare/Serious:

• Seizures — stop medication and seek immediate medical attention
• Peripheral neuropathy with prolonged use
• Severe allergic reactions

8. Drug Interactions

• Alcohol (in any preparation): Severe disulfiram-like reaction — absolute contraindication
• Warfarin: Markedly increases anticoagulant effect — monitor INR in anticoagulated patients
• Phenytoin: Increased phenytoin levels — monitor
• Phenobarbitone: Reduces metronidazole levels — may reduce efficacy
• Lithium: Increased lithium toxicity risk

9. Pharmacokinetics

Absorption: Oral bioavailability ~80–100% from suspension — equivalent to tablet formulation when shaken and dosed accurately. Tmax ~1–2 hours.

Distribution: Excellent paediatric tissue penetration including CSF, peritoneal fluid, bile, and abscess cavities. Low protein binding (~20%) means high free fraction reaches site of infection.

Metabolism: Hepatic — active hydroxy metabolite formed. Half-life in children is similar to adults (~6–9 hours) but may be shorter in older children due to higher metabolic rates.

Elimination: Primarily renal. Neonates have significantly longer half-lives due to immature hepatic metabolism — dosing should be carefully supervised in neonates and young infants.

10. Paediatric Amoebiasis and Giardiasis in Bangladesh

Amoebiasis and giardiasis together represent major causes of morbidity in Bangladeshi children under 10 years:

• Entamoeba histolytica affects 1–10% of the Bangladeshi population at any time — children in endemic areas face repeated infections. Presentation: bloody/mucoid diarrhoea, abdominal cramps, fever. Amotrex suspension for 5–10 days is curative for intestinal disease; liver abscess also responds to metronidazole.
• Giardia lamblia is a leading cause of persistent diarrhoea and malabsorption in Bangladeshi children — contributing significantly to undernutrition and developmental delay. Presentation: fatty/frothy stools, bloating, poor weight gain, fatigue. A 5-day course of Amotrex suspension is highly effective.
• Luminal agents: After completing metronidazole for amoebiasis, follow-up treatment with diloxanide furoate (500 mg 3 times daily for adults; 20 mg/kg/day in children, for 10 days) eliminates intestinal cysts and reduces risk of recurrence and spread.

11. When to See a Doctor

Seek medical review if the child:

• Develops seizures, severe vomiting, confusion, or difficulty walking during treatment
• Has persistent or worsening diarrhoea after completing the course
• Develops signs of dehydration (sunken eyes, dry mouth, decreased urination)
• Has high fever, severe abdominal pain, or right upper quadrant pain (may indicate liver abscess)
• Is under 1 year of age — paediatric specialist supervision recommended

12. Storage

• Store below 30°C in a cool, dry place
• Protect from direct sunlight — do not refrigerate (may cause the suspension to thicken)
• Shake well before each use
• Keep cap tightly closed after use
• Use within the period specified after opening (usually 7–14 days — check bottle label)
• Keep out of reach of children
• Do not use after expiry date on the bottle

Frequently Asked Questions (FAQ)

Q1: What is Amotrex suspension used for in children?

Amotrex 200 mg/5 ml Suspension (Metronidazole) is used to treat protozoal and anaerobic bacterial infections in children. In Bangladesh, the most common uses are: amoebiasis (amoebic dysentery — Entamoeba histolytica infection causing bloody diarrhoea and abdominal cramps), giardiasis (Giardia lamblia — chronic watery diarrhoea, bloating, poor weight gain), and anaerobic bacterial infections. The suspension allows accurate weight-based dosing that tablets cannot provide for small children. It is taken with food, 2–3 times daily for 5–10 days depending on the infection.

Q2: How do I measure the correct dose for my child?

Always use the oral syringe or measuring spoon that comes with the bottle — never use a household teaspoon as its volume is inaccurate. Amotrex suspension contains 200 mg metronidazole per 5 ml (40 mg per ml). For weight-based dosing: your doctor will calculate the dose in mg/kg based on your child's weight — ask your pharmacist to mark the syringe at the correct volume for each dose. Shake the bottle thoroughly before measuring each dose as the suspension settles on standing. Give the dose with food or milk to reduce stomach upset.

Q3: How long does Amotrex suspension take to work for diarrhoea?

Most children with amoebic dysentery or giardiasis notice significant improvement in diarrhoea and abdominal pain within 2–4 days of starting Amotrex. However, it is absolutely essential to complete the full course (5–10 days as prescribed) even after symptoms resolve. Stopping early leaves surviving parasites that can re-establish infection and become harder to treat. For amoebiasis, follow-up treatment with diloxanide furoate is recommended to eliminate intestinal cysts and prevent recurrence.

Q4: Is Amotrex suspension safe for young children and toddlers?

Metronidazole oral suspension is established as safe and effective for children including toddlers when dosed correctly by weight and used for the appropriate duration. It is widely used for paediatric amoebiasis and giardiasis in Bangladesh and globally. The key safety considerations are: (1) dose accurately by weight using a measuring device; (2) avoid all alcohol-containing preparations during treatment; (3) do not use for unnecessarily long periods; (4) for infants under 1 year, use only under specialist paediatric supervision as metronidazole metabolism is slower in very young infants. Report any unusual side effects including seizures immediately.