Lisdexamfetamine vs Dextroamphetamine: what is the difference?

How they differ

Lisdexamfetamine is dextroamphetamine with the amino acid lysine attached, and it does nothing at all until enzymes in the blood cut that lysine off. That conversion is the entire design: it happens at a rate the body sets rather than one a formulation sets, which gives a smoother rise and makes the molecule far less useful if crushed or injected. Once cleaved, what circulates is dextroamphetamine, so the two are the same drug arriving by different routes. Lisdexamfetamine is the much heavier molecule at 263.38 against 135.21 because of the attached lysine, and only part of that weight is the active portion. Both are controlled substances in the US.

Side by side

Structural similarity 0.40 of 1, computed as a Morgan fingerprint Tanimoto coefficient. It measures shape, not effect.

Common questions

What is the difference between Lisdexamfetamine and Dextroamphetamine?

Lisdexamfetamine is dextroamphetamine with the amino acid lysine attached, and it does nothing at all until enzymes in the blood cut that lysine off. That conversion is the entire design: it happens at a rate the body sets rather than one a formulation sets, which gives a smoother rise and makes the molecule far less useful if crushed or injected. Once cleaved, what circulates is dextroamphetamine, so the two are the same drug arriving by different routes.

Is Lisdexamfetamine bigger than Dextroamphetamine?

Lisdexamfetamine is the heavier molecule, 263.38 g/mol against 135.21 g/mol for Dextroamphetamine. Lisdexamfetamine is C15H25N3O and Dextroamphetamine is C9H13N.