Clinical & Dosing Information
This information complements the calculator and is intended for healthcare professionals. It is not a substitute for clinical judgment or professional medical advice.
About This Calculator
The Adderall to Vyvanse conversion calculator is an educational tool designed to estimate an approximate equivalent starting dose of Vyvanse (lisdexamfetamine) for a patient currently taking a stable total daily dose of Adderall (mixed amphetamine salts). The conversion is based on data from prescribing information and established clinical practice.
Outputs
The tool provides a single primary output: an estimated once-daily dose of Vyvanse in milligrams (mg). This calculated dose should be considered a starting point. The patient’s dose must be titrated up or down based on their individual clinical response, efficacy, and tolerability under the supervision of a qualified healthcare provider.
How to Use
To use the calculator, a clinician must input the patient’s total daily dose of Adderall in milligrams. For example, if a patient takes Adderall IR 15 mg twice a day, the total daily dose entered should be 30 mg. The specific formulation (IR vs. XR) is noted for context but does not alter the total daily dose calculation.
Dosing Overview
Vyvanse (lisdexamfetamine) is a long-acting central nervous system (CNS) stimulant. It is a prodrug that is enzymatically converted to dextroamphetamine. This process results in a gradual onset of action (approx. 1.5-2 hours) and an extended duration of effect (up to 14 hours). It is administered once daily in the morning. Commercially available strengths include 10, 20, 30, 40, 50, 60, and 70 mg.
Adderall (mixed amphetamine salts) contains both dextroamphetamine and levoamphetamine. It is available in an immediate-release (IR) formulation with a duration of 4-6 hours and an extended-release (XR) formulation lasting 10-12 hours.
Switching Medications
When switching a patient from Adderall to Vyvanse, it is essential to consider the pharmacokinetic differences. The prodrug nature of Vyvanse provides a smoother drug delivery profile, which may reduce the “ups and downs” experienced by some patients on IR formulations. This conversion is not based on a simple milligram-for-milligram equivalency but on established dose correspondence tables from the manufacturer’s literature. Close follow-up is required after any medication switch to assess for efficacy and adverse effects.
Missed Dose Protocol
If a patient misses a dose of Vyvanse, they should take it as soon as they remember. However, if it is already late in the afternoon or evening, they should skip the missed dose and resume their normal schedule the next morning. Taking a dose late in the day can cause insomnia. Patients should be counseled never to take two doses to “catch up.”
Safety Alerts
CNS stimulants, including Adderall and Vyvanse, have a high potential for abuse and dependence. Prescribers should assess the risk of abuse prior to prescribing and monitor for signs of abuse and dependence during treatment.
- Cardiovascular Risks: Sudden death, stroke, and myocardial infarction have been reported in adults with CNS stimulant treatment at usual doses. Patients with pre-existing structural cardiac abnormalities or other serious heart problems should generally not be treated with stimulants.
- Psychiatric Risks: Stimulants may exacerbate symptoms of behavior disturbance and thought disorder in patients with a pre-existing psychotic disorder. They may also induce a manic or mixed episode in patients with bipolar disorder.
Frequently Asked Questions (FAQ)
This is due to differences in the molecular weight and bioavailability of lisdexamfetamine (the prodrug) compared to the mixed amphetamine salts in Adderall. The conversion accounts for the amount of active dextroamphetamine that is delivered from a dose of Vyvanse.
The maximum recommended dose of Vyvanse for ADHD is 70 mg per day. The calculator will not recommend a dose higher than this, even for high doses of Adderall.
The calculation is based on an interpolation of the conversion chart provided in the official Vyvanse prescribing information, which correlates specific Adderall daily doses to equivalent Vyvanse doses.
No. This tool is exclusively for converting between Adderall (mixed amphetamine salts) and Vyvanse (lisdexamfetamine). Conversions from methylphenidate-based products require different calculations.
No, the conversion is based on the total daily dose of amphetamine salts, regardless of whether it is taken as an IR or XR formulation. The key input is the total milligrams consumed over a 24-hour period.
Vyvanse has a slower onset of action (around 1.5-2 hours) compared to Adderall IR (around 30-60 minutes) due to its prodrug metabolism. Its duration is generally longer and smoother than both Adderall IR and XR.
Common side effects of stimulants include decreased appetite, insomnia, dry mouth, and anxiety. Monitor the patient to see if these effects emerge or change in intensity after the switch, and adjust the dose as needed.
Typically, the patient would take their last dose of Adderall one day and begin Vyvanse the following morning. There is usually no need for a washout period, but this should be determined by the prescribing clinician.
References
- VYVANSE® (lisdexamfetamine dimesylate) Prescribing Information. U.S. Food and Drug Administration.
- ADDERALL XR® (mixed salts of a single-entity amphetamine product) Prescribing Information. U.S. Food and Drug Administration.
- Vyvanse Professional Website for Healthcare Professionals. Takeda Pharmaceutical Company Limited.
- Wolraich, M. L., et al. (2019). Clinical Practice Guideline for the Diagnosis, Evaluation, and Treatment of Attention-Deficit/Hyperactivity Disorder in Children and Adolescents. Pediatrics, 144(4), e20192528.
Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions you may have regarding a medical condition or medication.
