Vyvanse Mechanism of Action
Vyvanse (lisdexamfetamine) is a prodrug that is enzymatically converted to dextroamphetamine in the blood, which then blocks the reuptake of dopamine and norepinephrine while simultaneously increasing their release into the synaptic space. 1
How Lisdexamfetamine Works
Prodrug Conversion
Lisdexamfetamine consists of the amino acid lysine chemically bonded to dextroamphetamine. The parent compound (lisdexamfetamine) is therapeutically inactive and does not bind to dopamine or norepinephrine transporters 1. After oral administration, it undergoes enzymatic hydrolysis primarily in the blood—not in the gastrointestinal tract—to release the active dextroamphetamine 2, 3. This conversion is unaffected by gastrointestinal pH or variations in normal transit times 3.
Active Mechanism: Dextroamphetamine Effects
Once converted, dextroamphetamine exerts its therapeutic effects through multiple mechanisms 1, 2:
- Blocks reuptake: Competitively inhibits the dopamine transporter (DAT) and norepinephrine transporter (NAT), preventing these neurotransmitters from being taken back into presynaptic neurons
- Increases release: Promotes the release of dopamine and norepinephrine by entering neuronal cells and acting on the vesicular monoamine transporter (VMAT2)
- Net effect: Substantially increases dopamine and norepinephrine concentrations in the synaptic cleft and extraneuronal space
Clinical Translation
The enhanced availability of dopamine and norepinephrine in the prefrontal cortex optimizes executive and attentional function 4. This translates to improvements in the core ADHD symptoms: attention, focus, impulse control, and reduction of hyperactivity 5, 2.
Pharmacokinetic Profile
The prodrug design creates a prolonged and controlled release pattern 5:
- Lisdexamfetamine reaches peak concentration (Tmax) at approximately 1 hour post-dose
- Dextroamphetamine reaches peak concentration at approximately 3.5-4.4 hours post-dose 1
- Duration of action extends 13 hours in children and 14 hours in adults 3
- Food does not significantly affect overall exposure but delays Tmax by approximately 1 hour 1
Important clinical note: The exact therapeutic mechanism in ADHD and binge eating disorder remains incompletely understood, though the monoaminergic effects are believed to be central 1.