Isturisa (osilodrostat)
An approved treatment for Cushing Disease.
The same compound appears under different names depending on the context. Here is how to identify Osilodrostat wherever you encounter it, plus the key facts at a glance.
- Generic name
- Osilodrostat
- Brand name
- Isturisa
- Development code
- LCI699
- Drug class
- Cortisol synthesis inhibitor
- Manufacturer
- Recordati
- How it's taken
- Taken by mouth twice daily.
An oral medication that reduces cortisol production by blocking the enzyme responsible for the final step in cortisol synthesis. Approved for adults with endogenous Cushing's syndrome, including Cushing's disease, for whom surgery is not an option or has not been curative.
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Where Osilodrostat fits
First-line medical therapy option for Cushing's disease when surgery is not possible or has not been curative. Targets cortisol production directly at the adrenal gland level.
How Osilodrostat works
In Cushing's disease, an ACTH-secreting pituitary tumor drives the adrenal glands to overproduce cortisol. Osilodrostat blocks 11-beta-hydroxylase, the enzyme in the adrenal glands that converts 11-deoxycortisol into cortisol. By shutting down this final production step, cortisol levels drop even though the pituitary tumor is still sending signals to make more.
Mechanism: Cortisol synthesis inhibitor that blocks 11-beta-hydroxylase, the final step in cortisol production
Side effects and safety
The most common side effects include adrenal insufficiency (too-low cortisol), headache, nausea, vomiting, fatigue, and fluid retention. QTc prolongation (a heart rhythm concern) can occur and requires monitoring with ECGs. Elevated adrenal hormone precursors and increased androgen levels may cause acne or excess hair growth in women.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Osilodrostat
Taken by mouth twice daily. Starting dose is typically 2 mg twice daily, titrated up every 2 weeks based on cortisol levels and tolerability. Maintenance doses in clinical trials ranged from 2-7 mg twice daily. Maximum dose is 30 mg twice daily.
Availability and cost
Only available as the brand-name product.
Oral cortisol synthesis inhibitor for a rare endocrine disorder. Requires ongoing monitoring of cortisol levels, ECGs, and adrenal function during dose titration.
Help paying for Isturisa
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Copay help
Qualified patients with commercial insurance pay a $20 co-pay. Eligibility requirements, restrictions and limitations apply.
For: private insurance · source - Insurance and case manager help
Reimbursement team helps with prior authorization, appeals and benefit checks; nurse educators and 24/7 pharmacists support treatment.
The official page does not say who qualifies. Ask the program. · source - Free medicine program
For uninsured or underinsured patients, R.A.R.E. can coordinate support from the Recordati Rare Diseases Patient Assistance Program.
For: no insurance, underinsured · source
Good to know: Patients prescribed Isturisa are automatically eligible for R.A.R.E. services; enrollment is processed with the prescription. Phone 1-888-855-RARE (7273), Mon-Fri 8AM-8PM ET. Uninsured patients who meet certain financial requirements may qualify for the Patient Assistance Program; exact income limits are not published.
- From a charity · HealthWell FoundationCushing's Disease or Cushing's Syndrome fundOpen
Pays for: Copays, premiums or other treatment costs.
- From a charity · NORD RareCareCushing's Syndrome Medical Assistance fundOpen
Pays for: Medical and medication costs.
The foundation says: “Accepting new applications and re-enrollments for current year” - From a charity · NORD RareCareCushing's Syndrome Premium Copay Assistance fundOpen
Pays for: Insurance premiums and copays.
The foundation says: “Accepting new applications and re-enrollments for current year” - From a charity · TotalAssist (formerly PAN Foundation)Cushing's Disease or Syndrome fundOpen
Pays for: Out-of-pocket costs for approved medications, up to $9,500 per year. Requires health insurance (any kind).
How Cushing disease treatments compare
Four FDA-approved medical therapies are available for Cushing's disease. Your endocrinologist will recommend a treatment based on the source of your excess cortisol, your blood sugar levels, surgical history, and how you respond to initial therapy. This chart summarizes the key practical differences between options.
4 FDA-approved cushing disease treatments are available: Isturisa (osilodrostat, approved 2020); Korlym (mifepristone, approved 2012); Recorlev (levoketoconazole, approved 2021); Signifor LAR (pasireotide, approved 2012). Isturisa is typically used as first-line medical therapy when surgery is not possible or has not been curative.
| Drug | How it works | How it’s given | How often | Where you get it | Typical use | FDA approved |
|---|---|---|---|---|---|---|
Isturisa osilodrostat You are here | Cortisol synthesis inhibitor — blocks 11-beta-hydroxylase, the final enzyme step in cortisol production | Oral tablet | Twice daily | Home (self-administered) | First-line medical therapy when surgery is not possible or has not been curative | 2020 |
Korlym mifepristone | Glucocorticoid receptor blocker — blocks cortisol from binding to its receptor (does not lower cortisol levels) | Oral tablet | Once daily with a meal | Home (self-administered) | For Cushing's patients with type 2 diabetes or glucose intolerance when surgery is not an option or has failed | 2012 |
Recorlev levoketoconazole | Cortisol synthesis inhibitor — blocks multiple steroidogenic enzymes including 11-beta-hydroxylase | Oral capsule | Twice daily with food | Home (self-administered) | For adults with Cushing's syndrome when surgery is not possible or has not been curative | 2021 |
Signifor LAR pasireotide | Pituitary-targeted somatostatin analog — suppresses ACTH secretion from the tumor, reducing the signal that drives cortisol production | Intramuscular injection (monthly) or subcutaneous injection (twice daily) | Monthly (LAR) or twice daily (subcutaneous) | LAR: doctor's office or infusion center; Subcutaneous: self-administered at home | For Cushing's disease (pituitary-dependent) when surgery is not an option or has failed; only drug that targets the tumor itself | 2012 |
This comparison is for FDA-approved medical therapies only and does not include surgical or radiation treatments, which are typically first-line for Cushing's disease. Always discuss treatment selection with your endocrinologist, who can factor in tumor size, cortisol severity, metabolic complications, and your individual response.
Clinical trial results
Phase 3 LINC 3 trial enrolled 137 adults with Cushing's disease. At week 24, 53% of patients had normal urinary free cortisol without needing a dose increase after week 12. In the 8-week withdrawal phase, 86% of patients who stayed on osilodrostat kept normal cortisol, against 29% of those switched to placebo. LINC 4 trial confirmed durability of response. FDA approved March 2020.
Development history
Originally developed by Novartis, transferred to Recordati Rare Diseases. FDA approved in March 2020 for Cushing's disease. In April 2025, the FDA expanded the indication to adults with endogenous Cushing's syndrome for whom surgery is not an option or has not been curative, not just pituitary-driven Cushing's disease.
Explore Cushing Disease trials
Other Cushing Disease treatments
Common questions about Osilodrostat
▸What is Osilodrostat (Isturisa)?
An oral medication that reduces cortisol production by blocking the enzyme responsible for the final step in cortisol synthesis. Approved for adults with endogenous Cushing's syndrome, including Cushing's disease, for whom surgery is not an option or has not been curative.
▸How does Osilodrostat work?
In Cushing's disease, an ACTH-secreting pituitary tumor drives the adrenal glands to overproduce cortisol. Osilodrostat blocks 11-beta-hydroxylase, the enzyme in the adrenal glands that converts 11-deoxycortisol into cortisol. By shutting down this final production step, cortisol levels drop even though the pituitary tumor is still sending signals to make more.
▸What are the side effects of Osilodrostat?
The most common side effects include adrenal insufficiency (too-low cortisol), headache, nausea, vomiting, fatigue, and fluid retention. QTc prolongation (a heart rhythm concern) can occur and requires monitoring with ECGs. Elevated adrenal hormone precursors and increased androgen levels may cause acne or excess hair growth in women.
▸How is Osilodrostat taken?
Taken by mouth twice daily. Starting dose is typically 2 mg twice daily, titrated up every 2 weeks based on cortisol levels and tolerability. Maintenance doses in clinical trials ranged from 2-7 mg twice daily. Maximum dose is 30 mg twice daily.
▸Is Osilodrostat FDA approved?
Yes, Osilodrostat (Isturisa) is FDA approved (2020) for the treatment of Cushing Disease.
▸How does osilodrostat lower cortisol?
Osilodrostat blocks 11-beta-hydroxylase, the enzyme responsible for the final step in cortisol production in the adrenal glands. By inhibiting this last step, it rapidly and effectively reduces cortisol levels in patients with Cushing disease.
▸How does osilodrostat compare to other cortisol-lowering drugs?
Osilodrostat targets the final step of cortisol synthesis, providing potent cortisol reduction. Levoketoconazole blocks multiple steroidogenic enzymes, while mifepristone blocks the cortisol receptor rather than reducing cortisol production. Each has different advantages depending on the patient.
▸What monitoring is needed with osilodrostat?
Regular cortisol level monitoring is essential to avoid adrenal insufficiency (too-low cortisol). Liver function, electrolytes, and heart rhythm (QT interval) should also be monitored during treatment.
▸How is Isturisa taken?
Isturisa is taken orally as tablets, typically starting at a low dose and titrated upward based on cortisol levels. The dose is individualized to achieve normal cortisol without over-suppression.
▸When was osilodrostat approved?
Osilodrostat (Isturisa) was approved by the FDA in 2020 for Cushing disease, manufactured by Recordati. It provided a new option for cortisol control when surgery is not possible or has not been curative.
▸Can osilodrostat cause adrenal insufficiency?
Yes. Because osilodrostat potently blocks cortisol production, over-suppression can lead to adrenal insufficiency (hypocortisolism). Symptoms include fatigue, weakness, and low blood pressure. Dose adjustments and cortisol monitoring help prevent this.