";
outputHtml += "Note: Tablets may need to be split. Consult your pharmacist on the best way to achieve this dose.";
break;
case "tab_80":
tmpPerTablet = 80;
var minNumberOfTablets_ss = minSingleDoseTMP / tmpPerTablet;
var maxNumberOfTablets_ss = maxSingleDoseTMP / tmpPerTablet;
outputHtml += "Using Single Strength Tablets (80mg TMP), the dose per administration is:";
outputHtml += "
";
outputHtml += "Note: Tablets may need to be split. Consult your pharmacist on the best way to achieve this dose.";
break;
case "tab_160":
tmpPerTablet = 160;
var minNumberOfTablets_ds = minSingleDoseTMP / tmpPerTablet;
var maxNumberOfTablets_ds = maxSingleDoseTMP / tmpPerTablet;
outputHtml += "Using Double Strength Tablets (160mg TMP), the dose per administration is:";
outputHtml += "
";
outputHtml += "Note: Tablets may need to be split. Consult your pharmacist on the best way to achieve this dose.";
break;
}
outputHtml += "
DISCLAIMER: This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with any questions you may have regarding a medical condition or medication.
";
resultDiv.innerHTML = outputHtml;
}
Understanding Co-trimoxazole Dosing in Children
Co-trimoxazole, known by brand names like Bactrim® or Septra®, is a combination antibiotic used to treat a variety of bacterial infections. It contains two active ingredients: Trimethoprim (TMP) and Sulfamethoxazole (SMX). These two drugs work together to block two crucial steps in the bacterial production of folic acid, effectively stopping their growth and replication.
In pediatrics, accurate dosing is paramount. A child's body metabolizes drugs differently than an adult's, and dosages must be carefully calculated based on body weight to ensure the medication is both effective and safe. Underdosing can lead to treatment failure, while overdosing increases the risk of side effects. This calculator is designed to help understand how these doses are determined based on established medical guidelines.
How to Use the Pediatric Dose Calculator
To use the calculator, you will need three key pieces of information:
Child's Weight (kg): This is the most critical factor. Ensure you have an accurate, recent weight for the child in kilograms.
Indication for Use: The reason for treatment dramatically affects the dosage. Our calculator includes the most common pediatric indications, which have different dosing regimens.
Medication Formulation: Co-trimoxazole is available in various strengths of oral suspensions and tablets. You must select the exact formulation prescribed by your doctor to calculate the correct volume (mL) or number of tablets.
Dosing Guidelines Explained
Pediatric dosing for co-trimoxazole is based on the trimethoprim (TMP) component. The total daily dose is calculated in milligrams of TMP per kilogram of the child's body weight (mg/kg/day).
Standard Infections (e.g., Urinary Tract Infections – UTI): The typical dose is 6-12 mg/kg/day of TMP, divided into two doses given every 12 hours.
Pneumocystis jirovecii Pneumonia (PJP) Prophylaxis: For prevention in immunocompromised children, the dose is 5-10 mg/kg/day of TMP, usually divided into two doses every 12 hours.
Pneumocystis jirovecii Pneumonia (PJP) Treatment: To treat an active PJP infection, a much higher dose of 15-20 mg/kg/day of TMP is required, divided into four doses given every 6 hours.
Example Calculation
Let's see how the calculation works for a practical scenario:
Child's Weight: 18 kg
Indication: Standard Infection (UTI)
Formulation: Oral Suspension (40mg TMP / 5mL)
1. Calculate the total daily dose range of TMP:
18 kg × 6 mg/kg/day = 108 mg/day (minimum)
18 kg × 12 mg/kg/day = 216 mg/day (maximum)
2. Calculate the single dose range (divided into 2 doses):
108 mg ÷ 2 = 54 mg per dose (minimum)
216 mg ÷ 2 = 108 mg per dose (maximum)
3. Convert the single dose in mg to a volume in mL:
(54 mg ÷ 40 mg) × 5 mL = 6.75 mL per dose (minimum)
(108 mg ÷ 40 mg) × 5 mL = 13.5 mL per dose (maximum)
Result: The child should receive a dose between 6.75 mL and 13.5 mL every 12 hours. The prescribing physician will determine the exact dose within this range.
IMPORTANT MEDICAL DISCLAIMER: This tool provides calculations based on standard guidelines and is for educational purposes only. It does not constitute medical advice. A physician may adjust the dose based on the child's specific clinical condition, kidney function, and severity of the infection. Never administer medication to a child without a prescription and direct guidance from a qualified healthcare professional.
Frequently Asked Questions (FAQ)
Q: Why is the dose calculated based on Trimethoprim (TMP)? A: The TMP component is the primary determinant for dosing co-trimoxazole. The ratio of TMP to SMX is fixed in all formulations (typically 1:5), so calculating the dose based on TMP automatically determines the correct amount of SMX.
Q: What should I do if my child has a sulfa allergy? A: Co-trimoxazole contains sulfamethoxazole, which is a sulfa drug. It should NOT be given to anyone with a known sulfa allergy. Inform your doctor immediately about any allergies before starting a new medication.
Q: What are common side effects? A: Common side effects can include nausea, vomiting, loss of appetite, and skin rash. More serious side effects can occur. If you notice any adverse reactions, especially a rash, contact your healthcare provider immediately.