Althrocin 125 syrup is erythromycin 125 mg/5 mL, so it contains 25 mg per mL.

For a 16 kg, 4-year-old child, a common erythromycin dosing range is 30 to 50 mg/kg/day, divided into 3 or 4 doses, depending on the infection and prescriber's plan.

A practical usual lower-end dose is therefore 5 mL every 6 hours, but do not start or choose the higher dose without the child’s clinician, because the correct dose and duration depend on the diagnosis, severity, allergies, liver history, and other medicines. The product information describes 30 mg/kg/day in divided doses, up to 50 mg/kg/day for severe infections erythromycin prescribing information.

Use an oral syringe, not a kitchen spoon. Seek medical advice urgently for persistent vomiting, severe/watery or bloody diarrhea, rash/swelling, fainting/palpitations, or breathing difficulty.

Althrocin 125 syrup contains erythromycin 125 mg per 5 mL.

For a 16 kg child, usual pediatric erythromycin dosing is 30 to 50 mg/kg/day, split into 4 doses, but the exact dose depends on the infection and must follow the prescribing clinician.

So, 5 mL every 6 hours is a common lower-range weight-based dose for a 16 kg child, only if erythromycin was prescribed for the child and this matches the prescription. Do not use 8 mL or change frequency without medical direction. Product guidance supports 30 mg/kg/day in divided doses, up to 50 mg/kg/day for severe infections erythromycin product information.

Shake well and measure with an oral syringe. Give the full prescribed course. Get urgent advice for rash or facial swelling, breathing trouble, fainting/palpitations, yellow eyes/skin, or severe/persistent diarrhea.

Do you mean difference between the doses, or are you asking about something else?