Switching From or To Vyvanse: Protocols, Dose Conversions, and Clinical Evidence

How Vyvanse Works: The Prodrug Mechanism That Affects Switching

Lisdexamfetamine is not an active stimulant when swallowed. The molecule is L-lysine bonded to d-amphetamine, and it requires enzymatic hydrolysis in red blood cells before d-amphetamine is released into circulation 1. This rate-limited conversion is why plasma d-amphetamine concentrations rise gradually over 1 to 2 hours, peak around 3.5 hours post-dose, and sustain therapeutic levels for 12 to 13 hours 2.

That pharmacokinetic profile matters when switching. Patients moving from an immediate-release amphetamine (which peaks in roughly 2 hours and covers 4 to 6 hours) will experience a noticeably different onset curve on their first Vyvanse dose. The reverse is also true. A patient stepping down from Vyvanse to IR amphetamine may perceive a faster, more abrupt peak.

Because the prodrug conversion happens in the blood rather than the gut or liver, first-pass hepatic metabolism does not significantly alter lisdexamfetamine bioavailability 1. Food slows the time to peak concentration (Tmax) by about one hour but does not reduce total exposure, so patients can take Vyvanse with or without breakfast during a switch period without worrying about dose inconsistency 3.

One practical consequence: crushing the capsule contents and mixing them with water or yogurt does not accelerate absorption, because the rate-limiting step is enzymatic, not dissolution-based. This built-in abuse deterrence also means that dose dumping during a switch is not a clinical concern.

Dose Equivalence: Converting Between Vyvanse and Other Stimulants

No FDA-approved conversion table exists for switching between stimulants. Published approximations, however, are consistent enough to guide clinical practice. The FDA prescribing information for Vyvanse provides the following pharmacokinetic basis: 30 mg lisdexamfetamine delivers approximately 8.9 mg of d-amphetamine base after hydrolysis [3].

Working from that conversion:

• Vyvanse 30 mg approximates mixed amphetamine salts (Adderall) 10 mg (which contains 7.5 mg total amphetamine base as a 3:1 d-to-l ratio)
• Vyvanse 30 mg approximates dextroamphetamine (Dexedrine) 10 mg
• Vyvanse 50 mg approximates mixed amphetamine salts 20 mg
• Vyvanse 70 mg approximates mixed amphetamine salts 20 to 25 mg

Methylphenidate-to-amphetamine conversions are less precise because the drugs act through different mechanisms (dopamine reuptake inhibition vs. vesicular release). A commonly applied clinical ratio is 2:1 to 3:1 (methylphenidate to amphetamine equivalent). A patient on Concerta (OROS-MPH) 36 mg, for example, might start Vyvanse at 30 mg or 40 mg based on clinician judgment.

These are starting-point estimates. Every patient requires individualized titration after the switch.

Switching from Immediate-Release Amphetamine to Vyvanse

This is the most common intra-class switch, typically prompted by one of three reasons: inconsistent afternoon coverage, twice-daily dosing burden, or concerns about misuse potential. A 2018 network meta-analysis in The Lancet Psychiatry (N=10,068 children/adolescents across 133 trials) found amphetamines as a class to be the most efficacious pharmacotherapy for childhood ADHD, with lisdexamfetamine showing the highest effect size among amphetamine formulations 4.

Protocol:

1. Calculate the patient's total daily amphetamine dose. A patient taking Adderall IR 10 mg twice daily has a total daily dose of 20 mg mixed salts.
2. Match to the nearest Vyvanse equivalent. Twenty mg mixed salts approximates Vyvanse 50 mg.
3. Discontinue the IR amphetamine after the last evening dose. Start Vyvanse the next morning. No washout is needed.
4. Schedule a follow-up at 7 to 14 days. Adjust in 10 mg increments (Vyvanse is available in 10, 20, 30, 40, 50, 60, and 70 mg capsules).

The 2019 American Academy of Pediatrics (AAP) clinical practice guideline states: "Clinicians should titrate doses of ADHD medication to achieve maximum benefit with tolerable side effects" 5. That directive applies equally during a medication switch, where underdosing on the new agent because of excessive caution is a common reason for perceived treatment failure.

Switching from Methylphenidate (Concerta, Ritalin, Focalin) to Vyvanse

Cross-class switching (methylphenidate to amphetamine) is warranted when a patient has had an inadequate response or intolerable side effects on methylphenidate. The SPD489-325 head-to-head trial (N=196 children, ages 6 to 17) compared lisdexamfetamine directly against OROS-methylphenidate and found lisdexamfetamine to be statistically superior on the ADHD-RS-IV total score (effect size 0.80 vs. 0.61 for OROS-MPH, P=0.0188) 6.

Dr. David Coghill, the trial's lead investigator, noted: "Lisdexamfetamine dimesylate was significantly more effective than OROS-methylphenidate, and both active treatments were significantly more effective than placebo" 6.

Protocol:

1. Stop methylphenidate after the last dose.
2. Start Vyvanse the next morning. Use the approximate 2.5:1 conversion (total daily methylphenidate dose divided by 2.5 gives the equivalent amphetamine dose, then match to the nearest Vyvanse capsule strength).
3. Example: Concerta 54 mg delivers approximately 15 mg methylphenidate equivalents over 12 hours. Divide 54 by 2.5 to get roughly 22 mg amphetamine. This suggests starting Vyvanse at 50 mg (which yields approximately 14.8 mg d-amphetamine).
4. If the patient was on dexmethylphenidate (Focalin), the conversion ratio is closer to 1.25:1, because dexmethylphenidate is the active d-threo enantiomer.

Some clinicians prefer a conservative start at one dose step below the calculated equivalent, then titrate upward at the first follow-up. This approach reduces the risk of overstimulation but may leave the patient symptomatic for one to two weeks during the adjustment window.

Switching from Vyvanse to Other Stimulants

Patients may switch away from Vyvanse for several reasons: formulary exclusion, cost (brand Vyvanse carried a list price above $400 per month before generic entry in 2023), or preference for a shorter-acting agent that allows flexible afternoon dosing.

Vyvanse to Adderall XR: Both are amphetamine-based and provide extended coverage. The switch is straightforward. Calculate the d-amphetamine equivalent from the current Vyvanse dose and select the nearest Adderall XR strength. A patient on Vyvanse 50 mg (14.8 mg d-amphetamine) would start Adderall XR 20 mg. The subjective experience may differ because Adderall XR uses a bead-based pulsatile release (two peaks) rather than the steady enzymatic curve of lisdexamfetamine 3.

Vyvanse to Concerta: This is a cross-class switch. Multiply the d-amphetamine equivalent by 2.5 to estimate the methylphenidate dose. Vyvanse 50 mg becomes roughly 37 mg methylphenidate, suggesting Concerta 36 mg as the starting point.

Vyvanse to IR stimulants: Some patients need to switch to immediate-release formulations for scheduling flexibility or to add a short-acting afternoon booster. Use the same dose conversion, split across two or three daily doses, and counsel the patient about the shorter duration per dose.

Switching from Vyvanse to Non-Stimulants

When stimulants produce intolerable cardiovascular effects (resting heart rate increase of >20 bpm, blood pressure above 95th percentile in children), or when patients have active substance use disorder, a non-stimulant may be appropriate. The two primary options are atomoxetine (Strattera) and alpha-2 agonists (guanfacine ER, clonidine ER).

The Newcorn et al. head-to-head trial (N=267 children, ages 6 to 17) compared lisdexamfetamine against atomoxetine and found that lisdexamfetamine produced a significantly greater reduction in ADHD-RS-IV total score at week 9. The standardized effect size was 0.96 for lisdexamfetamine versus 0.44 for atomoxetine (P<0.001) 7.

Dr. Jeffrey Newcorn, lead investigator, stated: "Lisdexamfetamine dimesylate showed a significantly greater treatment effect compared with atomoxetine on multiple measures of ADHD symptom severity" 7.

Protocol for switching to atomoxetine:

1. Begin atomoxetine at 0.5 mg/kg/day while the patient is still taking Vyvanse.
2. After 7 days, increase atomoxetine to the target dose of 1.2 mg/kg/day.
3. Taper Vyvanse over the following week (reduce by one dose step every 3 to 4 days) or discontinue once the atomoxetine target dose is reached.
4. Atomoxetine requires 4 to 6 weeks to reach full effect, so patients should be counseled that the early transition period may involve suboptimal symptom control.

Protocol for switching to guanfacine ER (Intuniv):

1. Start guanfacine ER at 1 mg/day, titrating by 1 mg/week to the target (typically 0.05 to 0.12 mg/kg/day).
2. Overlap Vyvanse during the first 2 to 3 weeks of guanfacine titration.
3. Taper and stop Vyvanse once guanfacine reaches the therapeutic range.
4. Monitor blood pressure and heart rate at each titration step, as alpha-2 agonists can cause hypotension and bradycardia.

What to Monitor After Any Stimulant Switch

The first 30 days after a switch are the highest-risk window for treatment failure, side-effect emergence, and patient dropout. A structured monitoring plan reduces all three.

Week 1: Contact the patient (phone or telehealth) to assess symptom coverage across the day. Ask specifically about morning onset ("How long after taking the new medication do you notice it working?") and late-afternoon wear-off. Record resting heart rate and blood pressure if possible 5.

Week 2: Repeat symptom check. If the patient reports inadequate coverage, adjust the dose by one step. For Vyvanse, each step is 10 mg. Do not adjust more than once per week.

Week 4: Formal reassessment using a validated rating scale (ADHD-RS-5 or Conners 3). Compare scores to the pre-switch baseline. The AAP guideline recommends: "Clinicians should evaluate for target behavior improvements as well as adverse effects by obtaining specific information from the parent/guardian and teacher" 5.

Ongoing: Monitor weight, height (in children), appetite, and sleep quality at every follow-up. Wigal et al. found that lisdexamfetamine maintained ADHD symptom reduction for 12 to 13 hours in an analog classroom setting, but the tail end of that coverage can cause insomnia in some patients if the dose is taken too late in the morning 2.

Special Populations: Switches That Require Extra Caution

Adults with comorbid anxiety: Amphetamine switches can transiently worsen anxiety during dose adjustment. Consider overlapping a stable anxiolytic (SSRI or buspirone) through the switch window rather than changing two medications simultaneously.

Patients with binge eating disorder (BED): Vyvanse is the only stimulant FDA-approved for BED at doses of 50 to 70 mg/day 3. Switching away from Vyvanse in a BED patient should involve a discussion about the loss of this specific indication. No other stimulant carries BED approval.

CYP2D6 poor metabolizers taking atomoxetine: Atomoxetine is extensively metabolized by CYP2D6. Poor metabolizers (roughly 7% of Caucasians) achieve plasma levels 5 to 10 times higher than extensive metabolizers at the same dose. If a Vyvanse-to-atomoxetine switch is planned in a known or suspected poor metabolizer, start atomoxetine at 0.5 mg/kg/day and hold at that dose for 4 weeks before considering an increase 8.

Pregnancy: The 2019 AAP guideline does not address adult ADHD treatment during pregnancy, but the FDA label for Vyvanse lists amphetamines as associated with premature delivery and low birth weight in human data. Any switch during pregnancy should be managed by a maternal-fetal medicine specialist in coordination with a psychiatrist.