Last reviewed · How we verify

Cysteamine Bitartrate Delayed-release Capsules

Amgen · Phase 3 active Small molecule

Cysteamine bitartrate reduces cystine accumulation in lysosomes by converting cystine to cysteine and cysteamine, thereby decreasing intracellular cystine levels.

Cysteamine bitartrate reduces cystine accumulation in lysosomes by converting cystine to cysteine and cysteamine, thereby decreasing intracellular cystine levels. Used for Cystinosis (nephropathic cystinosis).

At a glance

Generic nameCysteamine Bitartrate Delayed-release Capsules
Also known asRP103, PROCYSBI®
SponsorAmgen
Drug classCystine-depleting agent
TargetLysosomal cystine
ModalitySmall molecule
Therapeutic areaRare Genetic Disorder
PhasePhase 3

Mechanism of action

Cystinosis is a lysosomal storage disorder caused by mutations in the CTNS gene, leading to cystine accumulation in lysosomes and cellular damage. Cysteamine acts as a reducing agent that converts the disulfide cystine into two molecules of cysteine and cysteamine, which can then exit the lysosome via alternative transporters. This mechanism reduces toxic cystine levels and slows progression of organ damage, particularly in the kidneys.

Approved indications

Common side effects

Key clinical trials

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

SourceUsed for
ClinicalTrials.govTrial enrolment, design, endpoints, results