[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Adrenal steroid synthesis inhibitors](https://durgical.com/en/pharmacology/classes/adrenal-steroid-synthesis-inhibitors/) › Osilodrostat

# Osilodrostat

## Adrenal steroid synthesis inhibitors?

Adrenal steroid synthesis inhibitors

An oral blocker of the last enzyme in cortisol synthesis. It lowers cortisol in Cushing's syndrome when surgery is not possible or has failed.

Updated Nov 1, 2026

## Quick facts

**Group**
[Adrenal steroid synthesis inhibitors](https://durgical.com/en/pharmacology/classes/adrenal-steroid-synthesis-inhibitors/)

**Target**
11-beta-hydroxylase (CYP11B1), and aldosterone synthase (CYP11B2)

**Used for**
Endogenous Cushing's syndrome

**Key effects**
Nausea · Headache and tiredness · Swelling of the legs

**Monitor**
Cortisol levels · ECG before and during treatment

**ATC**
H02CA02

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

✂**11-beta-hydroxylase (CYP11B1), and aldosterone synthase (CYP11B2)**Osilodrostat

ⓘ The figure shows osilodrostat bound to the heme of human aldosterone synthase (CYP11B2), a very similar enzyme that osilodrostat also inhibits; CYP11B1, its main target for cortisol, has the same kind of site.

**Target in 3D:** 11-beta-hydroxylase (CYP11B1), and aldosterone synthase (CYP11B2). PDB structure 7M8V (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/7M8V) · Drag to rotate · pinch to zoom

Osilodrostat is a non-steroidal inhibitor of 11-beta-hydroxylase (CYP11B1), which converts 11-deoxycortisol to cortisol, and of aldosterone synthase (CYP11B2). Cortisol falls. Precursors before the block accumulate: 11-deoxycortisol and deoxycorticosterone (mineralocorticoid effects: low potassium, oedema, high blood pressure) and adrenal androgens (hirsutism, acne). Too much effect causes adrenal insufficiency.

- Osilodrostat binds the heme of CYP11B1 (and CYP11B2)
- 11-deoxycortisol is not converted to cortisol
- Cortisol falls; precursors and androgens accumulate
- Doses are titrated to avoid adrenal insufficiency

## Indications

- Endogenous Cushing's syndrome (including Cushing's disease) when pituitary surgery is not possible or has not cured it [Cushing syndrome →](https://durgical.com/en/conditions/cushing-syndrome/)

## Adverse effects

### Common

- Nausea, vomiting, diarrhoea, abdominal pain and reduced appetite
- Headache and tiredness
- Swelling of the legs (oedema)
- Excess hair growth and acne in women
- Dizziness on standing

### Serious (rare, important)

- Adrenal insufficiency (hypocortisolism)
- QT prolongation and arrhythmias
- Hypokalaemia and high blood pressure from accumulated mineralocorticoid precursors

## Contraindications

- Hypersensitivity to osilodrostat
- Caution: long QT, other heart disease, uncorrected low potassium or magnesium

## Key interactions

**Other drugs that prolong the QT interval**
Additive QT prolongation; ECG monitoring

**Other medicines in general**
Doses may need adjusting or closer monitoring; a full medication list is reviewed

## What is monitored

- Cortisol levels (urine or serum) during dose titration
- ECG before and during treatment
- Potassium and magnesium
- Blood pressure and signs of adrenal insufficiency

## Administration and safety

- Oral tablets on a regular schedule; started low and adjusted gradually
- Low potassium and magnesium are corrected before starting
- Not stopped without the prescriber, who may lower or interrupt it if cortisol falls too far

## Pregnancy and breastfeeding

Data in pregnancy are limited; the prescriber is told about pregnancy plans. Breastfeeding is avoided during treatment and for a week after the last dose.

## Nursing care

- Teach the signs of low cortisol: nausea, vomiting, tiredness, abdominal pain, loss of appetite, dizziness
- Check ECG and electrolyte results
- Advise rising slowly from lying or sitting
- Laboratory staff are told the person takes osilodrostat

## Pharmacokinetics

**Absorption**
Taken by mouth, with or without food

## Memory aid

OSILOdrostat blocks the eLEVENth step (11-beta-hydroxylase): cortisol off, precursors and androgens up.

## Test yourself

Think of the answer, then tap the question to see it.

## Which enzyme does osilodrostat mainly inhibit to lower cortisol?

11-beta-hydroxylase (CYP11B1), the final step from 11-deoxycortisol to cortisol; it also inhibits aldosterone synthase.

## Why can osilodrostat cause hypokalaemia and oedema?

Precursors before the block, such as deoxycorticosterone, accumulate and have mineralocorticoid activity.

## Which cardiac test is done before and during osilodrostat?

An ECG, because the drug can prolong the QT interval.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/osilodrostat/)

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## Connections

## Related drugs 4

- [Metyrapone](https://durgical.com/en/pharmacology/metyrapone/)
- [Mitotane](https://durgical.com/en/pharmacology/mitotane/)
- [Pasireotide](https://durgical.com/en/pharmacology/pasireotide/)
- [Ketoconazole](https://durgical.com/en/pharmacology/ketoconazole/)

## Related conditions 1

- [Cushing syndrome](https://durgical.com/en/conditions/cushing-syndrome/)

[← Back to the class: Adrenal steroid synthesis inhibitors](https://durgical.com/en/pharmacology/classes/adrenal-steroid-synthesis-inhibitors/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Osilodrostat: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a625069.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=H02CA02) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/pharmacology/osilodrostat/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/osilodrostat/