Disclaimer: This calculator is for educational and verification purposes only. Always verify calculations with prescribing information and institutional protocols. Gamunex-C is a 10% solution (100mg/mL).
Understanding Gamunex-C Infusion Rates
Gamunex-C (Immune Globulin Injection [Human], 10% Caprylate/Chromatography Purified) is indicated for the treatment of Primary Humoral Immunodeficiency (PI), Chronic Immune Thrombocytopenic Purpura (ITP), and Chronic Inflammatory Demyelinating Polyneuropathy (CIDP). Correctly calculating the infusion rate is critical for patient safety, primarily to mitigate adverse reactions associated with rapid infusion.
Key Conversion Factor: Gamunex-C is supplied as a 10% solution. This means there are 100 mg of protein per 1 mL of solution (or 1 gram per 10 mL).
Standard Titration Schedule
Infusions are typically initiated at a low rate and increased incrementally if the patient tolerates the infusion well. A common protocol for PI involves:
Initial Rate: 1 mg/kg/min (0.01 mL/kg/min) for the first 30 minutes.
Incremental Increase: If tolerated, the rate may be increased to 2 mg/kg/min, then 4 mg/kg/min.
Maximum Rate: The maximum recommended rate is typically 8 mg/kg/min (0.08 mL/kg/min).
The Mathematics of the Calculation
To determine the pump setting in milliliters per hour (mL/hr), one must convert the weight-based dosing rate (mg/kg/min) using the patient's weight and the solution concentration.
Consider a patient weighing 165 lbs (75 kg) starting their infusion.
Convert Weight: 165 lbs ÷ 2.2 = 75 kg.
Determine Rate: Initial rate is 1 mg/kg/min.
Calculate Flow: 75 × 1 × 0.6 = 45 mL/hr.
If the patient tolerates this for 30 minutes, the nurse might increase the rate to 2 mg/kg/min. The new pump setting would be:
75 × 2 × 0.6 = 90 mL/hr.
Clinical Considerations
Always ensure adequate hydration prior to the initiation of the infusion. For patients with risk factors for thrombosis or renal dysfunction, the infusion should be administered at the minimum practicable rate. Always refer to the full Prescribing Information for complete dosage and administration guidelines.
function toggleCustomRate() {
var select = document.getElementById("infusionRate");
var customGroup = document.getElementById("customRateGroup");
if (select.value === "custom") {
customGroup.style.display = "block";
} else {
customGroup.style.display = "none";
}
}
function calculateInfusion() {
// 1. Get Inputs
var weightInput = document.getElementById("patientWeight").value;
var unit = document.getElementById("weightUnit").value;
var totalDoseGrams = document.getElementById("totalDose").value;
var rateSelect = document.getElementById("infusionRate").value;
// 2. Validate Inputs
if (!weightInput || weightInput <= 0) {
alert("Please enter a valid patient weight.");
return;
}
// 3. Logic: Convert Weight to kg
var weightKg = parseFloat(weightInput);
if (unit === "lbs") {
weightKg = weightKg / 2.20462;
}
// 4. Logic: Determine Rate in mg/kg/min
var rateMgKgMin = 0;
if (rateSelect === "custom") {
var customRate = document.getElementById("customRateValue").value;
if (!customRate || customRate 0) {
// Gamunex-C is 10% (10g/100mL or 1g/10mL)
totalVolume = parseFloat(totalDoseGrams) * 10;
if (flowRate > 0) {
estTimeHours = totalVolume / flowRate;
var hours = Math.floor(estTimeHours);
var minutes = Math.round((estTimeHours – hours) * 60);
timeDisplay = hours + " hr " + minutes + " min";
}
} else {
totalVolume = "N/A";
}
// 7. Display Results
document.getElementById("flowRateResult").innerText = flowRate.toFixed(1) + " mL/hr";
document.getElementById("weightKgResult").innerText = weightKg.toFixed(1) + " kg";
if (typeof totalVolume === 'number') {
document.getElementById("totalVolumeResult").innerText = totalVolume.toFixed(1) + " mL";
} else {
document.getElementById("totalVolumeResult").innerText = "–";
}
document.getElementById("estTimeResult").innerText = timeDisplay;
document.getElementById("resultsArea").style.display = "block";
}