About This Tool
The Epidiolex Dose Calculator is a clinical support tool designed to help healthcare professionals determine appropriate dosing based on official prescribing information. Epidiolex® (cannabidiol) is an oral solution indicated for the treatment of seizures associated with Lennox-Gastaut syndrome (LGS), Dravet syndrome (DS), and Tuberous Sclerosis Complex (TSC) in patients 1 year of age and older.
Calculator Outputs Explained
After entering the required patient data, the calculator provides the following key outputs for safe and effective administration:
- Volume to Administer (BID): The volume in milliliters (mL) of the 100 mg/mL oral solution to be given twice daily.
- Dose Per Administration (BID): The specific dose in milligrams (mg) for each of the two daily administrations.
- Total Daily Dose: The total amount of cannabidiol in milligrams (mg) the patient will receive per day.
- Sample Titration Schedule: For standard indications, a weekly dosing table is provided showing the dose in mg/kg/day, total daily dose, and volume per administration during the titration period up to the maintenance dose.
How to Use the Calculator
To ensure accurate calculations, follow these steps:
- Enter Patient Weight: Input the patient's weight and select the unit (kg or lbs). The tool will automatically convert lbs to kg for calculations. The minimum weight is 2 kg.
- Select Indication: Choose the appropriate indication (LGS, DS, or TSC). This sets the standard dosing and titration schedule. Select "Other" for manual dose entry.
- Set Target Dose: The tool pre-fills the recommended maintenance dose for the selected indication. This can be adjusted as needed based on clinical judgment and patient response.
- Specify Hepatic Impairment: Select the level of hepatic impairment (None, Mild, Moderate, or Severe). The calculator will automatically apply the necessary dose reductions as per official guidelines for moderate and severe cases.
Dosing Overview
Dosing for Epidiolex is based on body weight and administered orally twice daily (BID). The oral solution has a concentration of 100 mg/mL.
| Indication | Starting Dose (mg/kg/day) | Maintenance Dose (mg/kg/day) | Maximum Dose (mg/kg/day) |
|---|---|---|---|
| Lennox-Gastaut Syndrome (LGS) | 5 | 10 | 20 |
| Dravet Syndrome (DS) | 5 | 10 | 20 |
| Tuberous Sclerosis Complex (TSC) | 5 | 25 | 25 |
For LGS and DS, the initial dose of 2.5 mg/kg twice daily (5 mg/kg/day) is titrated after one week to a maintenance dose of 5 mg/kg twice daily (10 mg/kg/day). For TSC, the dose is titrated weekly to reach the recommended maintenance dose of 12.5 mg/kg twice daily (25 mg/kg/day).
Switching and Concomitant Use
Epidiolex is typically used as an adjunctive therapy with other anti-seizure medications. When adding Epidiolex to a patient's regimen, be aware of potential drug-drug interactions, particularly with clobazam, which may require dose adjustment of the other medication. Tapering or discontinuing concomitant anti-seizure medications should be done under the close supervision of a healthcare professional to minimize seizure risk.
Missed Dose Instructions
If a dose of Epidiolex is missed, the patient or caregiver should be instructed to take the missed dose as soon as they remember. However, if it is almost time for the next scheduled dose, they should skip the missed dose and resume the regular dosing schedule. Instruct them not to take two doses at the same time to make up for a missed one.
Safety Alerts
Clinicians should be aware of several key safety considerations when prescribing Epidiolex:
- Hepatic Impairment: Dose adjustment is required for patients with moderate (Child-Pugh B) or severe (Child-Pugh C) hepatic impairment. The starting, maintenance, and maximum recommended doses should be reduced by 50% for moderate and 75% for severe impairment.
- Hepatocellular Injury: Epidiolex can cause dose-related elevations of liver transaminases (ALT and AST). Obtain serum transaminase levels before starting treatment, at 1, 3, and 6 months, and periodically thereafter.
- Somnolence and Sedation: Epidiolex can cause somnolence, which may be more pronounced when used with other CNS depressants, including alcohol.
Frequently Asked Questions
What is the concentration of the Epidiolex oral solution used in calculations?
The calculator uses the standard concentration of Epidiolex oral solution, which is 100 mg of cannabidiol per mL.
How does the calculator adjust dosing for severe hepatic impairment?
For severe (Child-Pugh C) hepatic impairment, the tool automatically reduces the recommended starting, maintenance, and maximum doses by 75% in accordance with the prescribing information.
Does the calculator provide a titration schedule for Tuberous Sclerosis Complex?
Yes, when TSC is selected as the indication, the calculator generates a sample four-week titration schedule to guide the patient up to the recommended maintenance dose of 25 mg/kg/day.
Can I use this calculator for a patient weighing less than 2 kg?
No, the calculator enforces a minimum weight of 2 kg, as dosing for patients below this weight is not specified in standard guidelines.
What happens if I enter a dose higher than the recommended maximum?
The calculator will still compute the dose but will display a prominent warning message alerting you that the entered target dose exceeds the recommended maximum for the selected indication.
Why is the recommended maintenance dose different for TSC compared to LGS and DS?
The dosing regimens were established in separate clinical trials. The trials for TSC demonstrated efficacy and safety at a maintenance dose of 25 mg/kg/day, whereas the trials for LGS and DS used maintenance doses of 10 to 20 mg/kg/day.
Is the calculated dose administered once or twice daily?
All calculated doses for Epidiolex are intended to be divided into two equal administrations per day (twice daily, or BID).
How does the tool handle weight input in pounds (lbs)?
If you enter a weight in pounds, the calculator automatically converts it to kilograms (kg) using the standard conversion factor (1 lb ≈ 0.453592 kg) before performing any dose calculations.
References
- EPIDIOLEX® (cannabidiol) oral solution. U.S. Prescribing Information. Jazz Pharmaceuticals, Inc. May 2022.
- Epidyolex (cannabidiol). European Medicines Agency.
- Dosing and Administration. EPIDIOLEX® HCP Website. Jazz Pharmaceuticals.
- Thiele EA, Marsh ED, French JA, et al. Cannabidiol in patients with seizures associated with Lennox-Gastaut syndrome (GWPCARE4): a randomised, double-blind, placebo-controlled phase 3 trial. Lancet. 2018;391(10125):1085-1096.
