Relacorilant
Relacorilant is an investigational selective glucocorticoid receptor modulator (antagonist) in late-stage development for Cushing's syndrome. Unlike mifepristone it does not bind the progesterone receptor, avoiding antiprogestin effects, and does not raise cortisol-driven mineralocorticoid activity the same way, aiming for fewer of mifepristone's downsides. Human data come from Cushing's trials; it is not approved and has no physique application.
01 Overview
Relacorilant selectively antagonises the glucocorticoid receptor to counter the peripheral effects of excess cortisol (hyperglycaemia, hypertension) in Cushing's syndrome, while sparing the progesterone and mineralocorticoid receptors. This selectivity is intended to avoid the endometrial and hypokalaemia problems seen with mifepristone. Phase 2 and phase 3 (GRACE) programmes have reported improvements in glucose and blood pressure control.
As an investigational drug its long-term safety profile is still being established, and it is not available outside trials or regulatory pathways. It illustrates the therapeutic direction of selective cortisol-receptor blockade, but there is no evidence base for any athletic or recovery use.
02 Mechanism
Selective glucocorticoid receptor antagonist that blocks cortisol action without meaningful progesterone or mineralocorticoid receptor activity.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Cushing's (trial) | 100–400 mg/day | Oral | Investigational trial dosing; not an approved regimen. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Blockade of cortisol actionReduces hyperglycaemia and hypertension of cortisol excess via selective GR antagonism. | improved glucose/BP in trials | Clinical | |
| Fewer off-target effects vs mifepristoneSparing of progesterone and mineralocorticoid receptors avoids antiprogestin effects and hypokalaemia. | receptor selectivity | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Functional cortisol withdrawalFatigue, nausea and arthralgia consistent with reduced glucocorticoid signalling. | Moderate | Reported in trials | Clinical | |
| Gastrointestinal upsetNausea and related GI symptoms reported during treatment. | Mild | Common in trials | Clinical | |
| Uncharacterised long-term safetyAs an unapproved agent, long-term and rare risks are not yet established. | Moderate | Investigational | Unconfirmed |