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Trilostane (Systemic)

Primary: HS900
Secondary: AN500

Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).

*Not commercially available in the U.S.

Not commercially available in Canada.




Note: Bracketed information in the Indications section refers to uses that are not included in U.S. product labeling.


Cushing's syndrome (treatment)—Trilostane is indicated for temporary treatment of Cushing's syndrome associated with adrenal cortical hyperfunction, [adrenal carcinoma, and ectopic ACTH–producing tumors] , in cases where definitive therapy is not appropriate or until definitive measures such as surgery or pituitary radiation can be undertaken.


Physicochemical characteristics:
Molecular weight—

Mechanism of action/Effect:

Trilostane produces suppression of the adrenal cortex by inhibiting enzymatic conversion of steroids by 3-beta-hydroxysteroid dehydrogenase/delta 5,4 ketosteroid isomerase, thus blocking synthesis of adrenal steroids.




Elimination—8 hours.

Precautions to Consider


Studies for 18 months in rats given doses of 250 mg per kg of body weight (mg/kg) per day found an increased incidence of adrenal adenomas. These were shown to be related to compensatory adrenocorticotropic hormone (ACTH) stimulation rather than to a direct action of trilostane.


Standard tests found no evidence of mutagenicity.

Gonadal function may be depressed during trilostane therapy. This is reversible upon cessation of therapy.

Trilostane is not recommended during pregnancy because it has been reported to reduce circulating progesterone, produce cervical dilation, and terminate pregnancy in some women. Studies in rats have shown that trilostane is teratogenic (skeletal abnormalities) in doses approximately 13 times the recommended human dose; teratogenicity seems to be related to the reduction in circulating progesterone.

FDA Pregnancy Category X.


It is not known whether trilostane is excreted in breast milk. However, problems in humans have not been documented.


Appropriate studies have not been performed in the pediatric population.


No geriatrics-specific information is available on the use of trilostane in geriatric patients. However, elderly patients are more likely to have age-related renal function impairment, which may require caution in patients receiving trilostane {02}.

Drug interactions and/or related problems
The following drug interactions and/or related problems have been selected on the basis of their potential clinical significance (possible mechanism in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):

Aminoglutethimide or
Mitotane    (concurrent use with trilostane may result in severe adrenocortical hypofunction)

Laboratory value alterations
The following have been selected on the basis of their potential clinical significance (possible effect in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):

With physiology/laboratory test values
Plasma cortisol concentrations    (expected to decrease as a result of adrenocortical inhibition)

Serum potassium concentrations    (may be increased)

Urinary 17-hydroxycorticosteroid concentrations    (expected to increase as a result of adrenocortical inhibition)

Medical considerations/Contraindications
The medical considerations/contraindications included have been selected on the basis of their potential clinical significance (reasons given in parentheses where appropriate)— not necessarily inclusive (» = major clinical significance).

Risk-benefit should be considered when the following medical problems exist
Hepatic function impairment
» Infection or
» Shock or
» Surgery or
» Trauma, severe    (additional steroids may be required because adrenal suppression may prevent the normal response to stress; it is recommended that trilostane be temporarily withdrawn immediately following shock or severe trauma)

Renal function impairment
Sensitivity to trilostane{03}

Patient monitoring
The following may be especially important in patient monitoring (other tests may be warranted in some patients, depending on condition; » = major clinical significance):

» 8 a.m. plasma cortisol or
24-hour urinary 17-hydroxycorticosteroid    (determinations recommended at periodic intervals to aid in assessing clinical response; steroid supplement therapy may be necessary)

Serum electrolyte concentrations    (recommended at regular intervals to detect electrolyte imbalance)

Side/Adverse Effects
The following side/adverse effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:

Those indicating need for medical attention
Incidence rare
Adrenocortical insufficiency (darkening of skin; drowsiness or tiredness; loss of appetite; mental depression; skin rash; vomiting)

Those indicating need for medical attention only if they continue or are bothersome
Incidence more frequent
stomach pain or cramps

Incidence less frequent
Aching muscles
belching or bloating
burning mouth or nose
dizziness or lightheadedness
increase in salivation
watery eyes

Patient Consultation
As an aid to patient consultation, refer to Advice for the Patient, Trilostane (Systemic).

Consider advising the patient on the following (» = major clinical significance):

Before using this medication
  Conditions affecting use, especially:

See Precautions to Consider.

Proper use of this medication
» Importance of not taking more or less medication than the amount prescribed

» Proper dosing
Missed dose: Taking as soon as possible; not taking if almost time for next dose; not doubling doses

» Proper storage

Precautions while using this medication
» Importance of close monitoring by physician

» Checking with physician immediately if injury, infection, or other illness occurs, because of the risk of adrenal insufficiency

» Caution if any kind of surgery (including dental surgery) or emergency treatment is required

Carrying medical identification card or wearing bracelet stating that medication is being used

Side/adverse effects
Signs of potential side effects, especially adrenocortical insufficiency

General Dosing Information
Patients receiving trilostane should be under the supervision of a clinical endocrinologist.

Initial treatment usually occurs in the hospital until dosage is stabilized, although it may occur on an outpatient basis with frequent monitoring.

Dosage must be adjusted to produce the desired level of adrenal suppression.

Patients should be monitored carefully during periods of stress such as surgery, trauma, or acute illness. Additional steroids may be required because adrenal suppression may prevent the normal response to stress. It is recommended that trilostane be temporarily withdrawn immediately following shock or severe trauma.

Oral Dosage Forms


Note: Trilostane capsules are not commercially available in the U.S. or Canada.

Usual adult dose
Cushing's syndrome
Initial: Oral, 30 mg four times a day, the dosage being gradually increased at intervals of three to four days until the desired response is achieved.

Maintenance: Oral, usually less than 360 mg per day in four divided doses.

Usual adult prescribing limits
Up to 480 mg per day.

Usual pediatric dose
Dosage has not been established.

Strength(s) usually available

Note: Withdrawn from the U.S. market in April 1994.

Not commercially available.

Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), in a well-closed container, unless otherwise specified by manufacturer.

Revised: 10/16/2000


Note: All references used in the development and earlier revisions of this monograph have not yet been incorporated into the computer database and, therefore, are not listed below. Citations for information not yet referenced in the monograph will be provided upon request.

  1. General concept per Geriatrics Advisory Panel (1985–1990), 1990 revision.
  1. General precaution per DID policy, 1990 revision.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.