Patients receiving mifepristone may experience adrenal insufficiency. Because serum cortisol levels remain elevated and may even increase during treatment with Korlym, serum cortisol levels do not provide an accurate assessment of hypoadrenalism in patients receiving Korlym. Patients should be closely monitored for signs and symptoms of adrenal insufficiency, including weakness, nausea, increased fatigue, hypotension, and hypoglycemia. If adrenal insufficiency is suspected, discontinue treatment with Korlym immediately and administer glucocorticoids without delay. High doses of supplemental glucocorticoids may be needed to overcome the glucocorticoid receptor blockade produced by mifepristone. Factors considered in deciding on the duration of glucocorticoid treatment should include the long half-life of mifepristone (85 hours).
Treatment with Korlym at a lower dose can be resumed after resolution of adrenal insufficiency. Patients should also be evaluated for precipitating causes of hypoadrenalism (infection, trauma, etc.).
In a study of patients with Cushing's syndrome, hypokalemia was observed in 44% of subjects during treatment with Korlym. Hypokalemia should be corrected prior to initiating Korlym. During Korlym administration, serum potassium should be measured 1 to 2 weeks after starting or increasing the dose of Korlym and periodically thereafter. Hypokalemia can occur at any time during Korlym treatment. Mifepristone-induced hypokalemia should be treated with intravenous or oral potassium supplementation based on event severity. If hypokalemia persists in spite of potassium supplementation, consider adding mineralocorticoid antagonists.
Vaginal Bleeding And Endometrial Changes
Being an antagonist of the progesterone receptor, mifepristone promotes unopposed endometrial proliferation that may result in endometrium thickening, cystic dilatation of endometrial glands, and vaginal bleeding. Korlym should be used with caution in women who have hemorrhagic disorders or are receiving concurrent anticoagulant therapy. Women who experience vaginal bleeding during Korlym treatment should be referred to a gynecologist for further evaluation.
QT Interval Prolongation
Mifepristone and its metabolites block IKr. Korlym prolongs the QTc interval in a dose-related manner. There is little or no experience with high exposure, concomitant dosing with other QT-prolonging drugs, or potassium channel variants resulting in a long QT interval. [See Use Of Strong CYP3A Inhibitors] To minimize risk, the lowest effective dose should always be used.
Exacerbation/Deterioration Of Conditions Treated With Corticosteroids
Use of Korlym in patients who receive corticosteroids for other conditions (e.g., autoimmune disorders) may lead to exacerbation or deterioration of such conditions, as Korlym antagonizes the desired effects of glucocorticoid in these clinical settings. For medical conditions in which chronic corticosteroid therapy is lifesaving (e.g., immunosuppression in organ transplantation), Korlym is contraindicated. [See CONTRAINDICATIONS]
Use Of Strong CYP3A Inhibitors
Korlym should be used with extreme caution in patients taking ketoconazole and other strong inhibitors of CYP3A, such as itraconazole, nefazodone, ritonavir, nelfinavir, indinavir, atazanavir, amprenavir, fosamprenavir, boceprevir, clarithromycin, conivaptan, lopinavir, posaconazole, saquinavir, telaprevir, telithromycin, or voriconazole, as these could substantially increase the concentration of mifepristone in the blood. The benefit of concomitant use of these agents should be carefully weighed against the potential risks. Mifepristone should be used in combination with strong CYP3A inhibitors only when necessary, and in such cases the dose should be limited to 300 mg per day. [See QT Interval Prolongation, DRUG INTERACTIONS, and CLINICAL PHARMACOLOGY]
Pneumocystis Jiroveci Infection
Patients with endogenous Cushing's syndrome are at risk for opportunistic infections such as Pneumocystis jiroveci pneumonia during Korlym treatment. Patients may present with respiratory distress shortly after initiation of Korlym. Appropriate diagnostic tests should be undertaken and treatment for Pneumocystis jiroveci should be considered.
Potential Effects of Hypercortisolemia
Korlym does not reduce serum cortisol levels. Elevated cortisol levels may activate mineralocorticoid receptors which are also expressed in cardiac tissues. Caution should be used in patients with underlying heart conditions including heart failure and coronary vascular disease.
Patient Counseling Information
As a part of patient counseling, doctors must review the Korlym Medication Guide with every patient. [See FDA-Approved Medication Guide]
Importance Of Preventing Pregnancy
- Advise patients that Korlym will cause termination of pregnancy. Korlym is contraindicated in pregnant patients.
- Counsel females of reproductive potential regarding pregnancy prevention and planning with a non-hormonal contraceptive prior to use of Korlym and up to one month after the end of treatment.
- Instruct patients to contact their physician immediately if they suspect or confirm they are pregnant.
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Mifepristone was evaluated for carcinogenicity potential in rats and mice. Rats were dosed for up to two years at doses of 5, 25, and 125 mg/kg of mifepristone. The high dose was the maximum tolerated dose, but exposure at all doses was below exposure at the maximum clinical dose based on AUC comparison. Female rats had a statistically significant increase in follicular cell adenomas/ carcinomas and liver adenomas. It is plausible that these tumors are due to drug-induced enzyme metabolism, a mechanism not considered clinically relevant, but studies confirming this mechanism were not conducted with mifepristone. Mice were also tested for up to 2 years at mifepristone doses up to the maximum tolerated dose of 125 mg/kg, which provided exposure below the maximum clinical dose based on AUC. No drug-related tumors were seen in mice.
Mifepristone was not genotoxic in a battery of bacterial, yeast, and mammalian in vitro assays, and an in vivo micronucleus study in mice.
The pharmacological activity of mifepristone disrupts the estrus cycle of adult rats at a dose of 0.3 mg/kg (less than human exposure at the maximum clinical dose, based on body surface area). However, following withdrawal of treatment and subsequent resumption of the estrus cycle, there was no effect on reproductive function when mated.
A single subcutaneous dose of mifepristone (up to 100 mg/kg) to rats on the first day after birth did not adversely affect future reproductive function in males or females, although the onset of puberty was slightly premature in dosed females. Repeated doses of mifepristone (1 mg every other day) to neonatal rats resulted in potentially adverse fertility effects, including oviduct and ovary malformations in females, delayed male puberty, deficient male sexual behavior, reduced testicular size, and lowered ejaculation frequency.
Use In Specific Populations
Korlym is contraindicated in pregnancy. Korlym can cause fetal harm when administered to a pregnant woman because the use of Korlym results in pregnancy loss. The inhibition of both endogenous and exogenous progesterone by mifepristone at the progesterone receptor results in pregnancy loss. If Korlym is used during pregnancy or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to a fetus. [See CONTRAINDICATIONS]
In a report of thirteen live births after single dose mifepristone exposure, no fetal abnormalities were noted.
Teratology studies in mice, rats and rabbits at doses of 0.25 to 4.0 mg/kg (less than human exposure at the maximum clinical dose, based on body surface area) were carried out. Because of the anti-progestational activity of mifepristone, fetal losses were much higher than in control animals. Skull deformities were detected in rabbit studies at less than human exposure, although no teratogenic effects of mifepristone have been observed to date in rats or mice. These deformities were most likely due to the mechanical effects of uterine contractions resulting from antagonism of the progesterone receptor.
Mifepristone is present in human milk of women taking the drug. Because of the potential for serious adverse reactions in nursing infants from Korlym, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Safety and effectiveness of Korlym in pediatric patients have not been established.
Clinical studies with Korlym did not include sufficient numbers of patients aged 65 and over to determine whether they respond differently than younger people.
The maximum dose should not exceed 600 mg per day in renally impaired patients. [See CLINICAL PHARMACOLOGY]
In patients with mild to moderate hepatic impairment, the maximum dose should not exceed 600 mg per day. The pharmacokinetics of mifepristone in patients with severe hepatic impairment has not been studied, and Korlym should not be used in these patients. [See CLINICAL PHARMACOLOGY]
Females Of Reproductive Potential
Due to its anti-progestational activity, Korlym causes pregnancy loss. Exclude pregnancy before the initiation of treatment with Korlym or if treatment is interrupted for more than 14 days in females of reproductive potential. Recommend contraception for the duration of treatment and for one month after stopping treatment using a non-hormonal medically acceptable method of contraception. If the patient has had surgical sterilization, no additional contraception is needed.This monograph has been modified to include the generic and brand name in many instances.
Last reviewed on RxList: 11/24/2014
Additional Korlym Information
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