From the Guidelines
Approximately 30-40mg of Vyvanse is generally considered equivalent to 15mg of Adderall XR. This conversion is not exact because these medications work differently in the body. Vyvanse (lisdexamfetamine) is a prodrug that must be metabolized in the body to become active, while Adderall XR contains mixed amphetamine salts that are immediately active.
Key Considerations
- The usual starting dose of Vyvanse is 20-30 mg po qam, with titration by 10 mg weekly to a maximum of 70 mg daily 1.
- When switching between these medications, patients should work closely with their healthcare provider to find the optimal dose, as individual responses vary.
- Vyvanse typically provides a smoother effect with potentially fewer ups and downs throughout the day compared to Adderall XR.
Potential Side Effects
- Side effects for both medications are similar and may include:
- Decreased appetite
- Insomnia
- Increased heart rate
- Anxiety
- It's essential to start at a lower dose when transitioning between these medications and adjust gradually based on response and tolerability.
Clinical Implications
- The conversion between Vyvanse and Adderall XR should be approached with caution, considering the unique pharmacological profiles of each medication.
- Healthcare providers should closely monitor patients during the transition period to minimize potential adverse effects and optimize therapeutic outcomes.
From the FDA Drug Label
Lisdexamfetamine is a prodrug of dextroamphetamine. Amphetamines block the reuptake of norepinephrine and dopamine into the presynaptic neuron and increase the release of these monoamines into the extraneuronal space. Lisdexamfetamine dimesylate capsules can be substituted with Vyvanse chewable tablets on a unit per unit/mg per mg basis (for example, 30 mg capsules for 30 mg chewable tablet)
The equivalent dose of Vyvanse (lisdexamfetamine) to Adderall XR (dextroamphetamine and amphetamine) 15mg cannot be directly determined from the provided information, as there is no direct comparison of doses between Vyvanse and Adderall XR in the drug labels. No conclusion can be drawn. 2 2
From the Research
Equivalent Dose of Vyvanse to Adderall XR
To determine the equivalent dose of Vyvanse (lisdexamfetamine) to Adderall XR (dextroamphetamine and amphetamine) 15mg, we need to consider the pharmacokinetics and pharmacodynamics of both medications.
- The study 3 compared the pharmacokinetics and pharmacodynamics of lisdexamfetamine and D-amphetamine in healthy subjects. The results showed that equimolar doses of D-amphetamine (40 mg) and lisdexamfetamine (100 mg) had similar maximal concentrations and total exposure (AUC) of amphetamine.
- Another study 4 mentioned that lisdexamfetamine is a prodrug of dextroamphetamine (d-amphetamine) and is hydrolyzed to l-lysine and active d-amphetamine in the body.
- A study on Adderall XR 5 mentioned that it is a single-daily dose formulation that provides the mixed amphetamine salts contained in Adderall.
- However, there is no direct comparison of the doses of Vyvanse and Adderall XR in the provided studies.
Dose Comparison
Based on the study 3, we can estimate that 100 mg of lisdexamfetamine is equivalent to 40 mg of D-amphetamine. Since Adderall XR 15mg contains a mixture of dextroamphetamine and amphetamine, and assuming that the ratio of dextroamphetamine to amphetamine is similar to that in Adderall XR, we can estimate that Adderall XR 15mg is approximately equivalent to 7.5mg of D-amphetamine (assuming a 1:1 ratio of dextroamphetamine to amphetamine). Using the ratio from the study 3, we can estimate that 100 mg of lisdexamfetamine is equivalent to 40 mg of D-amphetamine, so 7.5mg of D-amphetamine would be equivalent to approximately 18.75mg of lisdexamfetamine.