Composition of Vyvanse (Lisdexamfetamine Dimesylate)
Active Pharmaceutical Ingredient
Vyvanse contains lisdexamfetamine dimesylate as its active ingredient, which is a prodrug that is enzymatically converted to dextroamphetamine (d-amphetamine) after ingestion. 1, 2
The chemical designation is (2S)-2,6-diamino-N-[(1S)-1-methyl-2-phenylethyl] hexanamide dimethanesulfonate, with molecular formula C15H25N3O∙(CH4O3S)2 and molecular weight of 455.60 2
Lisdexamfetamine dimesylate is a white to off-white powder that is highly soluble in water (792 mg/mL) 2
The prodrug structure consists of d-amphetamine covalently bonded to the amino acid L-lysine 3, 4
Conversion to Active Drug
Lisdexamfetamine remains pharmacologically inactive until it undergoes enzymatic hydrolysis predominantly in red blood cells, which cleaves the molecule to release d-amphetamine and lysine 4, 5
This conversion process occurs in the blood following oral administration, not in the gastrointestinal tract 3, 5
The parent drug lisdexamfetamine does not bind to dopamine or norepinephrine reuptake sites; only the converted d-amphetamine is pharmacologically active 2
Inactive Ingredients (Excipients)
The capsule formulation contains the following inactive ingredients 2:
Core ingredients: colloidal silicon dioxide, croscarmellose sodium, magnesium stearate, and microcrystalline cellulose 2
Capsule shell: gelatin, titanium dioxide, and various colorants including D&C Red #28, FD&C Blue #1, FD&C Red #3, FD&C Red #40, FD&C Yellow #6, Iron Oxide Black, Iron Oxide Red, and Iron Oxide Yellow 2
Imprint ink: shellac, black iron oxide, and potassium hydroxide 2
Available Strengths
Vyvanse capsules are available in seven strengths containing 10 mg, 20 mg, 30 mg, 40 mg, 50 mg, 60 mg, and 70 mg of lisdexamfetamine dimesylate (equivalent to 5.8 mg, 11.6 mg, 17.3 mg, 23.1 mg, 28.9 mg, 34.7 mg, and 40.5 mg of lisdexamfetamine base, respectively) 2
Mechanism of Action
Once converted to d-amphetamine, the active drug competitively inhibits the dopamine transporter (DAT) and noradrenaline transporter (NAT), increasing dopamine and norepinephrine concentrations in the synaptic cleft 3
D-amphetamine also promotes the release of these neurotransmitters by being taken up into neuronal cells and acting on the vesicular monoamine transporter 3
Amphetamines are classified as non-catecholamine sympathomimetic amines with CNS stimulant activity 2