Cushing Syndrome
Clinical Snapshot
Cushing syndrome is the clinical syndrome produced by chronic exposure to excess glucocorticoid, from any source. By far the most common cause overall is exogenous (iatrogenic) corticosteroid therapy — an estimated 1% or more of the adult population in high-income countries is on chronic glucocorticoid therapy at any given time, a population many times larger than the pool of patients with a true endogenous hypercortisolism-producing tumor.[1] Endogenous Cushing syndrome is rare and is classified by whether ACTH drives it: ACTH-dependent disease (about 80-85% of endogenous cases) is caused by a pituitary corticotroph adenoma — this specific entity is called Cushing's disease and accounts for roughly three-quarters to four-fifths of ACTH-dependent cases, with most of the remainder from an ectopic ACTH-secreting tumor (most often a bronchial carcinoid); ACTH-independent disease (about 15-20% of endogenous cases) arises directly from the adrenal cortex — a cortisol-producing adenoma, adrenocortical carcinoma, or primary bilateral adrenal hyperplasia. Cushing's disease itself is estimated to occur in only about 1.2-1.8 people per million per year.[2]
Whatever the source, the downstream physiology is the same: sustained glucocorticoid excess drives fat redistribution, catabolism of muscle and skin collagen, insulin resistance, sodium retention and hypertension, bone loss, immunosuppression, and mood disturbance. This chapter treats the endogenous causes and their surgical/medical management in detail, but its central practical message is that the pharmacist's most common encounter with Cushing syndrome is the iatrogenic form — a patient whose chronic prescribed corticosteroid has itself produced the syndrome — and the priorities there are recognizing cumulative exposure across every route of administration, never stopping the causative steroid abruptly, and reinforcing the same metabolic and bone-health monitoring that applies regardless of cause.
Recognize the Condition
Two categories of finding — the physical appearance, and the systemic complications
Physical findings that accumulate regardless of cause
Central/truncal obesity with relatively thin limbs, moon facies (rounded, plethoric facial appearance), a buffalo hump (dorsocervical fat pad), and supraclavicular fat pads. Wide, violaceous (purple-red) striae — typically wider than 1 cm and concentrated on the abdomen, breasts, axillae, or thighs — are considerably more specific to glucocorticoid excess than the narrower pink or white striae of ordinary weight gain or pregnancy. Thin, fragile skin with easy bruising and poor wound healing, proximal muscle weakness (classically noticed as difficulty rising from a chair or climbing stairs without using the arms), facial plethora, acne, and — when there is co-existing adrenal androgen excess (more common with an adrenal or ectopic ACTH source) — hirsutism and menstrual irregularity. Mood and cognitive changes are common and can range from irritability, anxiety, and depression to, less often, mania or psychosis.
Metabolic, cardiovascular, and immune complications — what actually drives morbidity
Hypertension and new-onset or worsened diabetes/hyperglycemia are near-universal with sustained exposure. Glucocorticoid excess is an independent hypercoagulable state with an increased risk of venous thromboembolism, seen in both endogenous and iatrogenic disease. Glucocorticoid-induced osteoporosis causes fracture risk out of proportion to bone mineral density alone — standard fracture-risk tools can underestimate risk in a patient on chronic glucocorticoids, so glucocorticoid exposure must be factored in explicitly.[3] Chronic supraphysiologic glucocorticoid exposure also causes clinically significant immunosuppression, raising the risk of opportunistic and atypical infection while blunting the usual inflammatory signs (fever, localized pain) that would normally flag it early.
Risk Factors
- Exogenous (iatrogenic) corticosteroid therapy at a supraphysiologic dose and/or duration, by any route — oral, high-potency topical, intra-articular or epidural injection, inhaled, or intranasal — is by far the most common cause of Cushing syndrome overall.[1] Risk scales with potency, dose, and duration: a pooled meta-analysis found HPA-axis-suppression prevalence ranging from about 4% with intranasal corticosteroid use up to about 52% with intra-articular/epidural injection, with inhaled-corticosteroid-only asthma patients averaging 6.8% but rising to 21.5% at high inhaled doses and 27.4% after more than 1 year of continuous use.[4]
- A new drug interaction added to an existing, previously well-tolerated corticosteroid — strong CYP3A4 inhibitors (ritonavir and other boosted HIV protease inhibitors, itraconazole, and even moderate inhibitors such as some SSRIs) can precipitate clinical iatrogenic Cushing syndrome without any change in the corticosteroid dose itself, since several commonly used corticosteroids (fluticasone, budesonide) depend heavily on CYP3A4 for clearance.[4]
- Cushing's disease — a pituitary corticotroph adenoma — the most common endogenous cause, typically presenting in adults 25-45 years old and more common in women.
- Ectopic ACTH-secreting tumor — most often a bronchial carcinoid; also small cell lung cancer, pancreatic neuroendocrine tumor, medullary thyroid carcinoma, or pheochromocytoma. Skews toward an older population and, with an aggressive malignancy, a more rapid and severe presentation.
- Adrenal cortisol-producing adenoma or adrenocortical carcinoma — carcinoma typically presents with a larger mass, faster onset, and more pronounced androgen co-secretion than a benign adenoma.
- Primary bilateral (macronodular or micronodular) adrenal hyperplasia — less common ACTH-independent causes, occasionally with a genetic basis (McCune-Albright syndrome, Carney complex, or a familial isolated micronodular hyperplasia syndrome).
Red Flags & Refer
Refer or escalate urgently for any of the following:
- Signs of adrenal crisis during a corticosteroid taper, or after an unplanned abrupt cessation — hypotension, severe weakness, nausea/vomiting, abdominal pain, or altered mental status. Treat exactly as adrenal crisis in primary adrenal insufficiency: immediate parenteral hydrocortisone and emergency transport, without waiting for confirmatory labs.[1]
- A new venous thromboembolism — a painful, swollen limb, or acute dyspnea/chest pain — given that Cushing syndrome (endogenous or exogenous) is an independent hypercoagulable state.
- Severe or atypical infection in a patient on chronic immunosuppressive glucocorticoid doses — unexplained fever, an infection disproportionate to its apparent trigger, or one that seems to progress unusually fast, since the usual inflammatory warning signs are blunted.
- Hypertensive emergency, or severe/refractory hyperglycemia (including diabetic-ketoacidosis-range or hyperosmolar-range glucose) precipitated or worsened by glucocorticoid excess.
- Acute psychiatric symptoms — severe depression with suicidal ideation, mania, or steroid-induced psychosis — which can occur at any point in therapy, including during a taper, and need urgent psychiatric involvement alongside the endocrine plan.
- Pituitary apoplexy — sudden severe headache, visual loss, or ophthalmoplegia — in a patient with known or suspected Cushing's disease.
- A new vertebral compression fracture (sudden severe back pain) in a patient on chronic glucocorticoids.
Also refer to endocrinology for any newly suspected endogenous Cushing syndrome (confirmatory biochemical testing, localization imaging, and surgical planning should not be managed outside specialist care); any patient whose chronic glucocorticoid therapy genuinely cannot be reduced despite significant Cushingoid complications, to discuss a steroid-sparing strategy with the prescribing specialty; and any patient being considered for medical therapy or bilateral adrenalectomy.
Assessment & Diagnosis
First: rule out an exogenous source before testing for endogenous disease
Before ordering any biochemical workup, take a complete inventory of every corticosteroid-containing product the patient uses — oral, topical, inhaled, intranasal, injected, and any compounded or unregulated product — since patients frequently do not think to mention a topical, inhaled, or injected product as "medication," and ask specifically about any recently added interacting drug (see Risk Factors). If a supraphysiologic exogenous source adequately explains the clinical picture, biochemical testing for endogenous disease is unnecessary and can be actively misleading — proceed directly to the iatrogenic management pathway (Clinical Decision Algorithm, Algorithm D).[1]
First-line screening, if no exogenous source explains the picture
Per the Endocrine Society diagnostic guideline, use at least 2 of the following 3 first-line tests, with abnormal results confirmed by repeat or a second different test before proceeding to localization:[5]
- 24-hour urinary free cortisol (UFC) — at least 2 collections, compared against the assay-specific upper limit of normal provided by the reporting laboratory.
- Late-night salivary cortisol — at least 2 measurements, compared against an assay-specific reference range.
- 1 mg overnight dexamethasone suppression test (DST), or the 2-day low-dose (0.5 mg every 6 hours for 48 hours) DST — a post-dexamethasone cortisol above 1.8 mcg/dL (50 nmol/L) is the standard abnormal threshold.
Discordant results should prompt repeating or adding a different first-line test, not immediately escalating to localization imaging. Also consider a pseudo-Cushing state — severe depression, alcohol use disorder, poorly controlled diabetes, severe obesity, and pregnancy can all produce a mildly abnormal screening result without true autonomous hypercortisolism; a dexamethasone-CRH test can help separate the two when the distinction is unclear.
Testing pitfalls
Oral estrogen raises cortisol-binding globulin and can falsely elevate total cortisol on the DST — discontinue for about 6 weeks before testing where feasible. Oral hydrocortisone and prednisone/prednisolone cross-react with most cortisol immunoassays and must be accounted for or temporarily bridged with dexamethasone before testing, since dexamethasone itself does not cross-react on most assays — the same property that makes chronic dexamethasone the highest HPA-suppression-risk oral agent (see Drug Tables) also makes it useful for bridging a patient through diagnostic testing.
Localizing confirmed endogenous disease
Once endogenous Cushing syndrome is confirmed, measure plasma ACTH:
- Suppressed or undetectable ACTH indicates ACTH-independent disease — proceed to adrenal CT to characterize a unilateral adenoma/carcinoma or bilateral hyperplasia.
- Normal-to-elevated ACTH indicates ACTH-dependent disease — proceed to pituitary MRI. A pituitary lesion 6 mm or larger with concordant biochemistry generally confirms Cushing's disease. If the MRI is negative or equivocal, or results are discordant, a high-dose DST, a CRH or desmopressin stimulation test, and inferior petrosal sinus sampling (IPSS) help distinguish a pituitary from an ectopic ACTH source before a body-imaging search for an occult ectopic tumor.[2]
Treatment Targets
- Normalize tissue cortisol exposure — by removing or resecting the endogenous source, or by reducing exogenous glucocorticoid therapy to the lowest dose that still adequately controls the condition it was prescribed for.
- For iatrogenic disease specifically: taper safely toward physiologic replacement (or full discontinuation) without precipitating adrenal insufficiency, while addressing the original indication for the steroid by another means wherever possible (a genuine steroid-sparing strategy, not simply "less of the same drug").
- Reverse or prevent the systemic complications — hypertension, hyperglycemia, dyslipidemia, osteoporosis/fracture, hypercoagulability, myopathy, and infection risk from immunosuppression.
- Preserve or restore HPA axis function, recognizing that biochemical recovery lags weeks to months behind cortisol normalization and needs confirmation before a taper is fully stopped.
- For endogenous disease not cured by surgery: control cortisol medically without over-treating into iatrogenic adrenal insufficiency — the "block and replace" balance.
- Support psychological well-being throughout — both the physical changes of the syndrome itself and the mood effects of glucocorticoid excess or withdrawal.
Choose Initial Treatment
Surgery first, for essentially every localized tumor
1st line, Cushing's disease Transsphenoidal pituitary surgery by an experienced neurosurgeon is first-line treatment, with the highest remission rates for a well-localized microadenoma at an experienced pituitary center.[2]
1st line, adrenal source Unilateral (usually laparoscopic) adrenalectomy for a cortisol-producing adenoma or carcinoma.
Special situation, ectopic ACTH Resection of the identified tumor when localized and resectable; if occult or metastatic at diagnosis, proceed to medical therapy while the search for the source continues.
Reserved, all sources Bilateral adrenalectomy is reserved for Cushing's disease not curable by pituitary surgery, radiotherapy, or medical therapy, or for severe/life-threatening hypercortisolism needing definitive rapid control — it trades a cure of hypercortisolism for lifelong glucocorticoid-plus-mineralocorticoid replacement and, in Cushing's disease specifically, a lifelong risk of Nelson syndrome (pituitary corticotroph tumor progression once cortisol feedback is removed).[6]
Never stop a chronic corticosteroid abruptly — taper
Step 1 Confirm whether the underlying condition the steroid was prescribed for can be controlled another way (a genuine steroid-sparing therapy, a lower-potency formulation, or reduced frequency) before assuming the dose can simply come down.
Step 2 If it can be reduced, taper gradually toward the physiologic replacement range (roughly a hydrocortisone-equivalent of 15-25 mg/day) before any further slow reduction — the exact schedule depends on the starting dose and cumulative duration of therapy rather than a fixed universal calendar.[1]
Step 3 As the dose nears the physiologic range, assess HPA axis recovery with a morning cortisol or ACTH stimulation test before stopping completely, and provide sick-day dosing education and a steroid emergency card throughout the taper — identical to primary adrenal insufficiency — since the HPA axis remains unable to mount its own stress response until it has recovered.
Avoid Abrupt discontinuation of any chronic glucocorticoid course for any reason. This risks precipitating adrenal crisis from unrecognized HPA suppression, and can separately unmask a "steroid withdrawal syndrome" (myalgia, arthralgia, fatigue, low mood) that can occur even when the replacement cortisol dose is technically adequate.
Non-Pharmacologic Treatment
- Steroid emergency card and medical alert identification for any patient actively tapering off, or recently discontinued from, chronic glucocorticoid therapy — identical to primary adrenal insufficiency — until HPA axis recovery is confirmed.[1]
- An individualized, written tapering schedule the patient keeps and can follow themselves, since a safe taper can run for months and adherence commonly slips without one.
- Bone health — weight-bearing exercise, fall-risk reduction, and adequate calcium/vitamin D intake, alongside the pharmacologic bone protection covered in Monitoring & Follow-Up.
- Structured cardiovascular risk-factor management — home blood pressure monitoring and dietary counselling — given the added contribution of glucocorticoid excess to hypertension and dyslipidemia.
- Infection-prevention counselling for a patient on ongoing supraphysiologic glucocorticoid doses — a routine vaccination review (avoiding live vaccines during significant immunosuppression) and prompt reporting of any new fever, since classic inflammatory warning signs are blunted.
- Coordinated, multidisciplinary follow-up — endocrinology, the specialty that originally prescribed the causative corticosteroid (respirology, rheumatology, transplant medicine, dermatology, and others), and neurosurgery when a pituitary or adrenal tumor is identified.
- For confirmed endogenous disease: pre-operative counselling and post-operative expectation-setting, since transient glucocorticoid-withdrawal symptoms are expected even after a technically successful surgical cure, while the normal (previously suppressed) adrenal tissue recovers.
Special Populations
Pregnancy
Cushing syndrome in pregnancy is rare, and diagnosis is genuinely different: normal pregnancy physiologically raises cortisol-binding globulin and free cortisol, so the DST is unreliable — late-night salivary cortisol (with trimester-specific reference ranges) and UFC are preferred, and dexamethasone-based localization testing and CT imaging should be avoided or deferred. Surgery (ideally in the 2nd trimester, if needed) is generally favoured over medical therapy given fetal risk. Mitotane and mifepristone are absolutely contraindicated (teratogenic, and abortifacient at these doses, respectively); ketoconazole and osilodrostat also lack adequate pregnancy safety data and are generally avoided.[6] For a patient who genuinely needs ongoing physiologic glucocorticoid replacement during pregnancy (e.g., while tapering iatrogenic disease), oral hydrocortisone or prednisone is preferred over dexamethasone, which crosses the placenta freely.
Pediatrics
Growth failure or a slowing growth velocity despite ongoing weight gain is the most specific pediatric clue to Cushing syndrome — in simple exogenous (non-glucocorticoid) obesity, height velocity is normal or increased, not reduced. Iatrogenic Cushing syndrome from high-dose or prolonged inhaled, intranasal, or topical corticosteroids is a particular pediatric concern given the added growth-suppression risk on top of adrenal suppression — use the lowest effective pediatric dose and step down as soon as disease control allows.[4]
Older adults
Baseline osteoporosis/fracture risk and cardiovascular risk are already higher in this group, so glucocorticoid-attributable bone loss and hypertension are more consequential, not less — do not defer bone protection while "watching and waiting" in an older patient on chronic corticosteroids.[3] Cognitive and mood effects of both hypercortisolism and glucocorticoid withdrawal can be harder to distinguish from other causes of delirium or dementia in this age group.
Hepatic and renal considerations
Ketoconazole and mitotane both carry meaningful hepatotoxicity risk and need baseline and periodic liver enzyme monitoring; avoid ketoconazole in significant pre-existing hepatic impairment. Mitotane accumulates in adipose tissue with a very long half-life and needs specialist-guided dosing regardless of renal function; other agents in this chapter do not require routine renal dose adjustment, but doses should still be reviewed individually.
Drug interactions
Ketoconazole, osilodrostat, and etomidate all carry QT-prolongation risk — review the full medication list for other QT-prolonging drugs before starting any of them. Ketoconazole is itself a potent CYP3A4 inhibitor and raises levels of many co-administered drugs, including some inhaled/intranasal corticosteroids — the same interaction mechanism responsible for the case illustrated in Recognize the Condition. More broadly, any strong CYP3A4 inhibitor (ritonavir and other boosted protease inhibitors, itraconazole, and some SSRIs) added to an existing corticosteroid is a well-documented precipitant of iatrogenic Cushing syndrome at an otherwise unremarkable steroid dose.[4]
Monitoring & Follow-Up
- Confirmed endogenous disease, post-treatment: cortisol/UFC per specialist protocol to confirm surgical remission, then periodically thereafter to screen for recurrence, since recurrence can occur years after an apparently successful cure.[6]
- Iatrogenic disease, during and after a taper: track progress against the written taper schedule at every visit; check a morning cortisol or ACTH stimulation test as the dose approaches the physiologic range to judge HPA axis recovery before full discontinuation, and continue sick-day/emergency-injection education until recovery is confirmed.[1]
- Any patient on medical therapy for endogenous disease (except mifepristone — see Common Errors): periodic UFC/cortisol to titrate dose and avoid over-treating into iatrogenic adrenal insufficiency.
- Bone: baseline DXA at diagnosis or at the start of chronic glucocorticoid therapy, with periodic follow-up per the ACR glucocorticoid-induced-osteoporosis guideline, and a fracture-risk assessment that explicitly accounts for glucocorticoid exposure rather than bone density alone.[3]
- Cardiometabolic: blood pressure at every visit; fasting glucose/HbA1c and a lipid panel at baseline and periodically, more frequently during pasireotide therapy or a high-dose steroidogenesis inhibitor.
- Liver enzymes at baseline and periodically for a patient on ketoconazole or mitotane.
- Electrolytes (potassium) for a patient on metyrapone, osilodrostat, or mifepristone, given their mineralocorticoid-related effects.
- ECG/QTc at baseline and with dose changes for ketoconazole, osilodrostat, or etomidate, and whenever another QT-prolonging drug is added.
- Ongoing screening for infection, mood/psychiatric symptoms, and — in a patient with Cushing's disease treated by bilateral adrenalectomy — pituitary MRI surveillance for Nelson syndrome.
Common Errors to Avoid
- Stopping a chronic glucocorticoid abruptly for any reason, including running out of medication between refills or a patient self-discontinuing once they feel better.
- Ordering an endogenous Cushing syndrome workup without first taking a complete inventory of every corticosteroid-containing product the patient uses — an unrecognized exogenous source makes biochemical testing uninterpretable and the workup unnecessary.
- Missing a new drug interaction (a CYP3A4 inhibitor added to an existing corticosteroid) as the actual cause of new Cushingoid features, rather than assuming the steroid dose itself must have changed.
- Diagnosing Cushing syndrome from a single abnormal screening test without a second confirmatory test, or without considering a pseudo-Cushing state (depression, alcohol use disorder, poorly controlled diabetes, severe obesity).
- Using UFC or serum cortisol to titrate mifepristone — it blocks the glucocorticoid receptor rather than lowering cortisol, so cortisol levels do not fall and are not interpretable; dose only on the clinical picture.
- Not recognizing that a patient can have symptoms of adrenal insufficiency on mifepristone despite a normal or elevated cortisol level, because of receptor blockade rather than true cortisol deficiency.
- Assuming HPA axis recovery is complete as soon as the glucocorticoid dose reaches the physiologic range — recovery can lag weeks to months and needs confirmation before full discontinuation.
- Skipping bone-protective and cardiometabolic monitoring in a patient who "only" needs a short course of high-dose steroids, when such courses are often extended or renewed in practice.
- Missing the hypercoagulable state of Cushing syndrome (endogenous or exogenous) as a contributor to a new venous thromboembolism.
- Forgetting that dexamethasone does not cross-react on most cortisol immunoassays (useful for bridging testing) while hydrocortisone and prednisone/prednisolone do — using the wrong bridging agent invalidates the test.
- Treating iatrogenic Cushing syndrome as a reason to stop the causative steroid outright, rather than first addressing whether the condition it treats can be controlled another way.
Clinical Decision Algorithm
Drug Tables
How to use this table: Doses are adult doses and require patient-specific confirmation. Select any linked drug name to open its complete Pharmasist Drug Database page.
Corticosteroid formulations most associated with iatrogenic Cushing syndrome and HPA-axis suppression
Not a treatment table — a quick reference for the routes and formulations most often implicated, to support the exposure inventory in Assessment & Diagnosis and the tapering plan in Choose Initial Treatment. Risk scales with potency, dose, duration, and any interacting CYP3A4 inhibitor.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Prednisone (oral) | Any chronic course: The exposure to quantify is cumulative dose x duration, not a single "typical" dose | Same Cushingoid/HPA-suppression risk as any oral corticosteroid, scaling with dose and duration. | Levels raised by strong CYP3A4 inhibitors; has its own enzyme-interaction profile at higher doses. | No published Drug Database oral-tablet entry currently exists (the same caveat as in the Addison's Disease chapter) — named here as text only. |
| Dexamethasone | Any chronic course: Risk is cumulative — assess total exposure, not a single dose | Long half-life and lack of a physiologic peak/trough pattern give it a materially higher HPA-suppression risk than hydrocortisone or prednisone at an equivalent anti-inflammatory dose. | Levels raised by strong CYP3A4 inhibitors. | Does not cross-react on most cortisol immunoassays — useful for bridging a patient through diagnostic testing, but the same property makes chronic dexamethasone the highest-risk oral agent for a missed cumulative exposure. |
| Clobetasol propionate (high-potency topical) | Extensive/prolonged use: Risk rises with treated body-surface area, occlusion, and duration | Systemic absorption and HPA suppression can occur with extensive-area, occlusive, or prolonged use — the topical route is not risk-free. | None specific to topical use at recommended areas/durations. | The highest-potency topical corticosteroid class in routine use; counsel on treated area, duration, and occlusion limits at every dispense. |
| Fluticasone propionate (inhaled) | Standard use: Risk scales with dose and duration even without an interacting drug | Adrenal suppression prevalence in asthma patients on inhaled corticosteroid alone was about 6.8% in a pooled meta-analysis, rising to 21.5% at high inhaled doses and 27.4% after more than 1 year of use. | Clearance depends heavily on cytochrome P450 3A4 — a concurrent strong or moderate CYP3A4 inhibitor (ritonavir and other boosted protease inhibitors, itraconazole, some SSRIs) can precipitate clinical iatrogenic Cushing syndrome without any change in the inhaled dose. | The most potent and lipophilic inhaled corticosteroid, with the longest tissue half-life — the agent most often implicated in reported iatrogenic Cushing syndrome cases from a drug interaction (see Recognize the Condition). |
| Budesonide (intranasal) | Standard use: Lowest-risk route, still cumulative with any other corticosteroid exposure | Intranasal corticosteroids carry the lowest reported adrenal-suppression risk of any route (about 4% pooled prevalence), but it is not zero with prolonged high-dose use or an interacting drug. | Same CYP3A4-interaction risk as other corticosteroids, though systemic exposure is inherently lower with the intranasal route. | Often mistakenly considered risk-free by patients since some formulations are available without a prescription — worth asking about specifically at medication reconciliation. |
| Methylprednisolone acetate (intra-articular/epidural injection) | Per injection: Repeated injections over a short interval compound the cumulative systemic exposure | Highest reported pooled adrenal-suppression prevalence of any route in a meta-analysis of corticosteroid use (about 52%), reflecting the large local depot dose and slow, sustained systemic absorption. | Same CYP3A4-interaction considerations as other corticosteroids. | Easy to overlook as a systemic exposure since it is often given by a different clinician than the patient's usual prescriber — ask specifically about recent joint or epidural injections at medication reconciliation. |
Steroidogenesis inhibitors (adrenal-directed medical therapy)
1st-line medical option for endogenous hypercortisolism not cured by surgery, or as a bridge before surgery.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Ketoconazole | Adults: 200-400 mg PO 2-3 times daily initially; titrate by UFC/response to a usual maximum of 1200-1600 mg/day | Hepatotoxicity (routine LFT monitoring required, the main safety concern), adrenal insufficiency if over-titrated, QT prolongation, testosterone suppression and gynecomastia in men. | Potent CYP3A4 inhibitor — raises levels of numerous co-administered drugs, including some inhaled/intranasal corticosteroids; additive QT-prolongation risk with other QT-prolonging drugs; requires an acidic gastric environment for absorption, so avoid concurrent acid-suppressing therapy where possible. | Blocks several steroidogenic enzymes (11β-hydroxylase, 17,20-lyase, cholesterol side-chain cleavage). A newer stereoisomer, levoketoconazole, is FDA-approved specifically for this indication but is not currently a published Drug Database entry. |
| Osilodrostat | Adults: 2 mg PO twice daily initially; titrate by UFC/response about every 2 weeks to a usual maximum of 30 mg twice daily | Adrenal insufficiency if over-titrated, hypokalemia and hypertension from mineralocorticoid-precursor accumulation, QT prolongation, hirsutism/acne from adrenal-androgen-precursor accumulation. | Additive QT-prolongation risk with other QT-prolonging drugs; CYP3A4 interactions are less pronounced than with ketoconazole but should still be reviewed. | More potent, more selective, and better tolerated hepatically than ketoconazole; specifically approved for Cushing's disease not cured by pituitary surgery. |
| Metyrapone | Adults: 500 mg PO every 4-6 hours initially; titrate to a usual maximum of 6 g/day | Same mineralocorticoid-precursor effects as osilodrostat (hypokalemia, hypertension, edema), hirsutism/acne, GI upset, adrenal insufficiency if over-titrated. | Levels affected by concurrent CYP3A4 inducers/inhibitors; additive hypokalemia risk with other agents that lower potassium. | Fast onset makes it useful for rapid pre-operative control; often combined with a second steroidogenesis inhibitor for severe disease. Not currently a published Drug Database entry. |
| Mitotane | Adults: Usually 1-2 g/day PO initially, titrated slowly to therapeutic levels over weeks to months per specialist protocol | GI intolerance (very common, often dose-limiting), neurologic toxicity (ataxia, lethargy) at higher drug levels, hepatotoxicity, hypercholesterolemia. | Potent hepatic enzyme inducer — reduces levels of numerous co-administered drugs including warfarin (higher dose usually needed) and many other CYP3A4 substrates. | Adrenolytic rather than a reversible enzyme blocker — slow onset (weeks to months) and a very long half-life; requires therapeutic drug level monitoring under specialist supervision. Absolutely contraindicated in pregnancy (teratogenic). |
Glucocorticoid receptor antagonist
Blocks the glucocorticoid receptor rather than lowering cortisol production — cortisol/UFC cannot be used to monitor or titrate this drug; dose only on the clinical picture.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Mifepristone | Adults: 300 mg PO once daily initially; titrate by clinical response to a usual maximum of 1200 mg/day | Adrenal-insufficiency symptoms (fatigue, nausea, hypotension) despite a normal-to-high cortisol level, hypokalemia, endometrial thickening and vaginal bleeding, QT prolongation. | CYP3A4 substrate — levels raised by strong CYP3A4 inhibitors and lowered by strong inducers; additive hypokalemia risk with potassium-lowering drugs; caution with other QT-prolonging drugs. | Approved specifically for hyperglycemia/diabetes in Cushing syndrome of any source when surgery is not curative or not an option. Absolutely contraindicated in pregnancy. Not currently a published Drug Database entry — the Database's only "mifepristone" formulation is the misoprostol combination product used for medical abortion, a different product and indication. |
Pituitary-directed medical therapy — Cushing's disease specifically
Targets the corticotroph tumor itself rather than blocking cortisol synthesis or action; reserved for Cushing's disease not cured by, or awaiting, pituitary surgery.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Pasireotide | Short-acting, subcutaneous: 0.3-0.9 mg SC twice daily initially Long-acting depot: May transition to the monthly intramuscular depot once tolerated and effective | Hyperglycemia/new diabetes is common and often the dose-limiting effect, GI upset, cholelithiasis, bradycardia, QT prolongation. | Additive bradycardia with beta-blockers or other bradycardia-inducing drugs; can materially alter insulin/oral hypoglycemic requirements. | A somatostatin analog acting on the corticotroph tumor's somatostatin receptor subtype 5. Check HbA1c before starting and monitor glucose closely; anticipate needing diabetes therapy. |
| Cabergoline | Adults: 0.5-1 mg PO 1-2 times weekly initially; titrate up to 3-7 mg/week based on response | Nausea, orthostatic hypotension, impulse control disorders (compulsive gambling, hypersexuality) with long-term use, cardiac valvulopathy at higher cumulative doses. | Avoid combining with other ergot-derived drugs; efficacy reduced by concurrent dopamine-antagonist drugs (e.g., some antipsychotics, metoclopramide). | Off-label for this indication — corticotroph tumors express dopamine D2 receptors. Least effective option used alone; most useful for mild residual disease or as an add-on. Baseline and periodic echocardiogram given the doses used. |
Emergency parenteral therapy — severe or life-threatening hypercortisolism
ICU-level therapy for florid, rapidly progressive hypercortisolism (severe psychosis, uncontrolled infection, severe hypokalemia/hypertension) where oral steroidogenesis inhibitors cannot act fast enough.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Etomidate | Severe hypercortisolism: Sub-hypnotic continuous IV infusion, titrated to a target cortisol under frequent monitoring, in an ICU/monitored setting | Over-suppression causing adrenal insufficiency if not carefully titrated, sedation at higher infusion rates, injection-site discomfort. | Additive sedation with other CNS depressants at higher infusion rates; no major pharmacokinetic interactions at the sub-hypnotic doses used for this indication. | Inhibits 11β-hydroxylase at doses well below those used for anesthesia induction. Requires a continuous ICU-monitored infusion with frequent cortisol checks and a "block and replace" hydrocortisone plan as cortisol falls into the target range. |
Physiologic glucocorticoid replacement — iatrogenic-Cushing tapering and HPA-axis recovery
Used once a chronic corticosteroid taper approaches the physiologic range, and for any patient with confirmed or presumed ongoing HPA-axis suppression — identical in principle to chronic replacement in primary adrenal insufficiency.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Hydrocortisone (oral) | Typical bridging dose: 15-25 mg/day PO in 2-3 divided doses, largest dose on waking, tapered further as HPA recovery is confirmed | Cushingoid signs if excessive (weight gain, striae, hyperglycemia); fatigue and recurrence of Cushingoid-withdrawal symptoms if insufficient. | Strong CYP3A4/hepatic enzyme inducers (rifampin, phenytoin, carbamazepine) accelerate clearance and can raise the dose requirement. | No published Drug Database oral-tablet entry currently exists (the same caveat as in the Addison's Disease chapter) — named here as text only. Dosed and tapered to mimic normal cortisol physiology, largest dose on waking. |
| Hydrocortisone sodium succinate (Solu-Cortef) | Adrenal crisis / severe illness: 100 mg IM or IV immediately, then per institutional adrenal-crisis protocol until stable | Same effects as oral hydrocortisone at supraphysiologic doses — expected and accepted in a genuine emergency. | None significant that should delay emergency administration. | For any patient with confirmed or presumed HPA-axis suppression from prior chronic glucocorticoid therapy who develops symptoms of adrenal crisis — treat exactly as primary adrenal insufficiency; issue an emergency injection kit and train the patient/a household member. |
References
- European Society of Endocrinology and Endocrine Society Joint Clinical Guideline: Diagnosis and Therapy of Glucocorticoid-induced Adrenal Insufficiency — The Journal of Clinical Endocrinology & Metabolism, European Society of Endocrinology and Endocrine Society (Beuschlein F, Else T, Bancos I, et al.). J Clin Endocrinol Metab 2024;109(7):1657-1683
- Consensus on Diagnosis and Management of Cushing's Disease: A Guideline Update — The Lancet Diabetes & Endocrinology, Pituitary Society (Fleseriu M, Auchus R, Bancos I, et al.). Lancet Diabetes Endocrinol 2021;9(12):847-875
- 2017 American College of Rheumatology Guideline for the Prevention and Treatment of Glucocorticoid-Induced Osteoporosis — Arthritis Care & Research, American College of Rheumatology (Buckley L, Guyatt G, Fink HA, et al.). Arthritis Care Res (Hoboken) 2017;69(8):1095-1110
- Adrenal Insufficiency in Corticosteroids Use: Systematic Review and Meta-Analysis — The Journal of Clinical Endocrinology & Metabolism (Broersen LHA, Pereira AM, Jørgensen JOL, Dekkers OM). J Clin Endocrinol Metab 2015;100(6):2171-2180
- The Diagnosis of Cushing's Syndrome: An Endocrine Society Clinical Practice Guideline — The Journal of Clinical Endocrinology & Metabolism, Endocrine Society (Nieman LK, Biller BMK, Findling JW, Newell-Price J, Savage MO, Stewart PM, Montori VM). J Clin Endocrinol Metab 2008;93(5):1526-1540
- Treatment of Cushing's Syndrome: An Endocrine Society Clinical Practice Guideline — The Journal of Clinical Endocrinology & Metabolism, Endocrine Society (Nieman LK, Biller BMK, Findling JW, Murad MH, Newell-Price J, Savage MO, Tabarin A). J Clin Endocrinol Metab 2015;100(8):2807-2831
Professional reference only. Apply clinical judgment and verify patient-specific decisions against current authoritative guidance and product information.