Mifepristone

INDICATIONS AND USAGE KORLYM (mifepristone) is a cortisol receptor blocker indicated to control hyperglycemia secondary to hypercortisolism in adult patients with endogenous Cushing's syndrome who have type 2 diabetes mellitus or glucose intolerance and have failed surgery or are not candidates for surgery. LIMITATIONS OF USE: KORLYM should not be used in the treatment of patients with type 2 diabetes unless it is secondary to Cushing's syndrome. KORLYM (mifepristone) is a cortisol receptor blocker indicated to control hyperglycemia secondary to hypercortisolism in adult patients with endogenous Cushing's syndrome who have type 2 diabetes mellitus or glucose intolerance and have failed surgery or are not candidates for surgery ( 1 ). Important Limitations of Use: Do not use for the treatment of type 2 diabetes mellitus unrelated to endogenous Cushing's syndrome.

DOSAGE AND ADMINISTRATION 200 mg mifepristone tablet on Day 1, followed 24 to 48 hours after mifepristone tablet dosing by 800 mcg buccal misoprostol. ( 2.1 ) Instruct the patient what to do if significant adverse reactions occur. ( 2.2 ) Follow-up is needed to confirm complete termination of pregnancy. ( 2.3 ) 2.1 Dosing Regimen For purposes of this treatment, pregnancy is dated from the first day of the last menstrual period. The duration of pregnancy may be determined from menstrual history and clinical examination. Assess the pregnancy by ultrasonographic scan if the duration of pregnancy is uncertain or if ectopic pregnancy is suspected. Remove any intrauterine device (“IUD”) before treatment with Mifepristone Tablets, 200 mg begins [see Contraindications (4)] . The dosing regimen for Mifepristone Tablets, 200 mg and misoprostol is: Mifepristone Tablets, 200 mg orally + misoprostol 800 mcg buccally • Day One : Mifepristone Tablets, 200 mg Administration One 200 mg tablets of Mifepristone is taken in a single oral dose. • Day Two or Three : Misoprostol Administration (minimum 24-hour interval between, Mifepristone Tablet, 200 mg and misoprostol) Four 200 mcg tablets (total dose 800 mcg) of misoprostol are taken by the buccal route. Tell the patient to place two 200 mcg misoprostol tablets in each cheek pouch (the area between the cheek and gums) for 30 minutes and then swallow any remnants with water or another liquid (see Figure 1 ). Patients taking Mifepristone Tablets, 200 mg must take misoprostol within 24 to 48 hours after taking Mifepristone Tablets. The effectiveness of the regimen may be lower if misoprostol is administered less than 24 hours or more than 48 hours after mifepristone administration. Because most women will expel the pregnancy within 2 to 24 hours of taking misoprostol [see Clinical Studies ( 14 )], discuss with the patient an appropriate location for them to be when taking the misoprostol, taking into account that expulsion could begin within 2 hours of administration. figure-1 2.2 Patient Management Following Misoprostol Administration During the period immediately following the administration of misoprostol, the patient may need medication for cramps or gastrointestinal symptoms [see Adverse Reactions ( 6 )] . Give the patient: Instructions on what to do if significant discomfort, excessive vaginal bleeding or other adverse reactions occur A phone number to call if the patient has questions following the administration of the misoprostol The name and phone number of the healthcare provider who will be handling emergencies. 2.3 Post-treatment Assessment: Day 7 to 14 Patients should follow-up with their healthcare provider approximately 7 to 14 days after the administration of Mifepristone Tablets, 200 mg. This assessment is very important to confirm that complete termination of pregnancy has occurred and to evaluate the degree of bleeding. Termination can be confirmed by medical history, clinical examination, human Chorionic Gonadotropin (hCG) testing, or ultrasonographic scan. Lack of bleeding following treatment usually indicates failure; however, prolonged or heavy bleeding is not proof of a complete abortion. The existence of debris in the uterus (e.g., if seen on ultrasonography) following the treatment procedure will not necessarily require surgery for its removal. Patients should expect to experience vaginal bleeding or spotting for an average of 9 to 16 days. Women report experiencing heavy bleeding for a median duration of 2 days. Up to 8% of women may experience some type of bleeding for more than 30 days. Persistence of heavy or moderate vaginal bleeding at the time of follow-up, however, could indicate an incomplete abortion. If complete expulsion has not occurred, but the pregnancy is not ongoing, patients may be treated with another dose of misoprostol 800 mcg buccally. There have been rare reports of uterine rupture in women who took Mifepristone Tablets, 200 mg and misoprostol, including women with prior uterine rupture or uterine scar and women who received multiple doses of misoprostol within 24 hours. Patients who choose to use a repeat dose of misoprostol should have a follow-up visit with their healthcare provider in approximately 7 days to assess for complete termination. Surgical evacuation is recommended to manage ongoing pregnancies after medical abortion [see Use in Specific Populations ( 8.1 )] . Advise the patient whether you will provide such care or will refer them to another provider as part of counseling prior to prescribing Mifepristone Tablets, 200 mg. 2.4 Contact for Consultation For consultation 24 hours a day, 7 days a week with an expert in mifepristone, call Evita Solutions LLC at 1-866-718-0098.

WARNINGS AND PRECAUTIONS Adrenal insufficiency : Patients should be closely monitored for signs and symptoms of adrenal insufficiency ( 5.1 ). Hypokalemia : Hypokalemia should be corrected prior to treatment and monitored for during treatment ( 5.2 ). Vaginal bleeding and endometrial changes : Women may experience endometrial thickening or unexpected vaginal bleeding. Use with caution if patient also has a hemorrhagic disorder or is on anti-coagulant therapy ( 5.3 ). QT interval prolongation : Avoid use with QT interval-prolonging drugs, or in patients with potassium channel variants resulting in a long QT interval ( 5.4 ). Use of Strong CYP3A Inhibitors : Concomitant use can increase mifepristone plasma levels. Use only when necessary and limit mifepristone dose to 900 mg ( 5.6 ). 5.1 Adrenal Insufficiency Patients receiving mifepristone may experience adrenal insufficiency. Because serum cortisol levels remain elevated and may even increase during treatment with mifepristone, serum cortisol levels do not provide an accurate assessment of hypoadrenalism in patients receiving mifepristone. 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 mifepristone 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 mifepristone 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.). 5.2 Hypokalemia In a study of patients with Cushing’s syndrome, hypokalemia was observed in 44% of subjects during treatment with mifepristone. Hypokalemia should be corrected prior to initiating mifepristone. During mifepristone administration, serum potassium should be measured 1 to 2 weeks after starting or increasing the dose of mifepristone and periodically thereafter. Hypokalemia can occur at any time during mifepristone 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. 5.3 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. Mifepristone should be used with caution in women who have hemorrhagic disorders or are receiving concurrent anticoagulant therapy. Women who experience vaginal bleeding during mifepristone treatment should be referred to a gynecologist for further evaluation. 5.4 QT Interval Prolongation Mifepristone and its metabolites block IKr. Mifepristone 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 Warnings & Precautions ( 5.6 )] . To minimize risk, the lowest effective dose should always be used. 5.5 Exacerbation/Deterioration of Conditions Treated with Corticosteroids Use of mifepristone in patients who receive corticosteroids for other conditions (e.g., autoimmune disorders) may lead to exacerbation or deterioration of such conditions, as mifepristone 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), mifepristone is contraindicated [see Contraindications ( 4.3 )] . 5.6 Use of Strong CYP3A Inhibitors Mifepristone should be used with caution in patients taking ketoconazole and other strong inhibitors of CYP3A, such as itraconazole, nefazodone, ritonavir, nelfinavir, indinavir, atazanavir, amprenavir, fosamprenavir, clarithromycin, conivaptan, lopinavir/ritonavir, posaconazole, saquinavir, telithromycin, or voriconazole, as these could 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 900 mg per day [see Warnings & Precautions ( 5.4 ), Drug Interactions (7.2), and Clinical Pharmacology ( 12.3 )] . 5.7 Pneumocystis jiroveci Infection Patients with endogenous Cushing’s syndrome are at risk for opportunistic infections such as Pneumocystis jiroveci pneumonia during mifepristone treatment. Patients may present with respiratory distress shortly after initiation of mifepristone. Appropriate diagnostic tests should be undertaken and treatment for Pneumocystis jiroveci should be considered. 5.8 Potential Effects of Hypercortisolemia Mifepristone 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. 5.9 Risk of Allergic Reactions due to Tartrazine This product contains FD&C Yellow No. 5 (tartrazine) which may cause allergic-type reactions (including bronchial asthma) in certain susceptible persons. Although the overall incidence of FD&C Yellow No. 5 (tartrazine) sensitivity in the general population is low, it is frequently seen in patients who also have aspirin hypersensitivity.

CONTRAINDICATIONS Administration of Mifepristone Tablets, 200 mg and misoprostol for the termination of pregnancy (the “treatment procedure”) is contraindicated in patients with any of the following conditions: Confirmed or suspected ectopic pregnancy or undiagnosed adnexal mass (the treatment procedure will not be effective to terminate an ectopic pregnancy) [ see Warnings and Precautions ( 5.4 )] Chronic adrenal failure (risk of acute adrenal insufficiency) Concurrent long-term corticosteroid therapy (risk of acute adrenal insufficiency) History of allergy to mifepristone, misoprostol, or other prostaglandins (allergic reactions including anaphylaxis, angioedema, rash, hives, and itching have been reported [ see Adverse Reactions ( 6.2 )]) Hemorrhagic disorders or concurrent anticoagulant therapy (risk of heavy bleeding) Inherited porphyrias (risk of worsening or of precipitation of attacks) Use of Mifepristone Tablets, 200 mg and misoprostol for termination of intrauterine pregnancy is contraindicated in patients with an intrauterine device (“IUD”) in place (the IUD might interfere with pregnancy termination). If the IUD is removed, Mifepristone Tablets, 200 mg may be used. Confirmed/suspected ectopic pregnancy or undiagnosed adnexal mass ( 4 ) Chronic adrenal failure ( 4 ) Concurrent long-term corticosteroid therapy ( 4 ) History of allergy to mifepristone, misoprostol, or other prostaglandins ( 4 ) Hemorrhagic disorders or concurrent anticoagulant therapy ( 4 ) Inherited porphyria ( 4 ) Intrauterine device (IUD) in place ( 4 )

DRUG INTERACTIONS Based on the long terminal half-life of mifepristone after reaching steady state, at least 2 weeks should elapse after cessation of mifepristone before initiating or increasing the dose of any interacting concomitant medication. Drugs metabolized by CYP3A: Administer drugs that are metabolized by CYP3A at the lowest dose when used with mifepristone ( 7.1 ). CYP3A inhibitors: Caution should be used when mifepristone is used with strong CYP3A inhibitors. Limit mifepristone dose to 900 mg per day when used with strong CYP3A inhibitors ( 7.2 ). CYP3A inducers: Do not use mifepristone with CYP3A inducers ( 7.3 ). Drugs metabolized by CYP2C8/2C9: Use the lowest dose of CYP2C8/2C9 substrates when used with mifepristone ( 7.4 ). Drugs metabolized by CYP2B6: Use of mifepristone should be done with caution with bupropion and efavirenz ( 7.5 ). Hormonal contraceptives: Do not use with mifepristone ( 7.6 ). 7.1 Drugs Metabolized by CYP3A Because mifepristone is an inhibitor of CYP3A, concurrent use of mifepristone with a drug whose metabolism is largely or solely mediated by CYP3A is likely to result in increased plasma concentrations of the drug. Discontinuation or dose reduction of such medications may be necessary with mifepristone coadministration. Mifepristone increased the exposure to simvastatin and simvastatin acid significantly in healthy subjects. Concomitant use of simvastatin or lovastatin is contraindicated because of the increased risk of myopathy and rhabdomyolysis [see Contraindications ( 4.2 ), Clinical Pharmacology 12.3 ] . The exposure of other substrates of CYP3A with narrow therapeutic ranges, such as cyclosporine, dihydroergotamine, ergotamine, fentanyl, pimozide, quinidine, sirolimus, and tacrolimus, may be increased by concomitant administration with mifepristone. Therefore, the concomitant use of such CYP3A substrates with mifepristone is contraindicated [see Contraindications ( 4.2 )] . Other drugs with similar high first pass metabolism in which CYP3A is the primary route of metabolism should be used with extreme caution if coadministered with mifepristone. The lowest possible dose and/or a decreased frequency of dosing must be used with therapeutic drug monitoring when possible. Use of alternative drugs without these metabolic characteristics is advised when possible with concomitant mifepristone. If drugs that undergo low first pass metabolism by CYP3A or drugs in which CYP3A is not the major metabolic route are coadministered with mifepristone, use the lowest dose of concomitant medication necessary, with appropriate monitoring and follow-up [see Clinical Pharmacology ( 12.3 )] . 7.2 CYP3A Inhibitors Medications that inhibit CYP3A could increase plasma mifepristone concentrations and dose reduction of mifepristone may be required. Ketoconazole and other strong inhibitors of CYP3A, such as itraconazole, nefazodone, ritonavir, nelfinavir, indinavir, atazanavir, amprenavir and fosamprenavir, clarithromycin, conivaptan, lopinavir/ritonavir, posaconazole, saquinavir, telithromycin, or voriconazole may increase exposure to mifepristone. Caution should be used when strong CYP3A inhibitors are prescribed in combination with mifepristone. The benefit of concomitant use of these agents should be carefully weighed against the potential risks. The dose of mifepristone should be limited to 900 mg, and strong inhibitors of CYP3A should be used only when necessary [see Dosage and Administration ( 2.4 ), Warnings & Precautions ( 5.6 ), and Clinical Pharmacology ( 12.3 )] . 7.3 CYP3A Inducers No medications that induce CYP3A have been studied when coadministered with mifepristone. Avoid coadministration of mifepristone and CYP3A inducers such as rifampin, rifabutin, rifapentin, phenobarbital, phenytoin, carbamazepine, and St. John’s wort. 7.4 Drugs Metabolized by CYP2C8/2C9 Because mifepristone is an inhibitor of CYP2C8/2C9, concurrent use of mifepristone with a drug whose metabolism is largely or solely mediated by CYP2C8/2C9 is likely to result in increased plasma concentrations of the drug. Mifepristone significantly increased exposure of fluvastatin, a typical CYP2C8/2C9 substrate, in healthy subjects. When given concomitantly with mifepristone, drugs that are substrates of CYP2C8/2C9 (including non-steroidal anti-inflammatory drugs, warfarin, and repaglinide) should be used at the smallest recommended doses, and patients should be closely monitored for adverse effects [see Clinical Pharmacology ( 12.3 )] . 7.5 Drugs Metabolized by CYP2B6 Mifepristone is an inhibitor of CYP2B6 and may cause significant increases in exposure of drugs that are metabolized by CYP2B6 such as bupropion and efavirenz. Since no study has been conducted to evaluate the effect of mifepristone on substrates of CYP2B6, the concomitant use of bupropion and efavirenz should be undertaken with caution [see Clinical Pharmacology ( 12.3 )] . 7.6 Use of Hormonal Contraceptives Mifepristone is a progesterone-receptor antagonist and will interfere with the effectiveness of hormonal contraceptives. Therefore, non-hormonal contraceptive methods should be used [See Use In Specific Populations (8.3)] .

ADVERSE REACTIONS Most common adverse reactions in Cushing's syndrome (≥ 20%): nausea, fatigue, headache, decreased blood potassium, arthralgia, vomiting, peripheral edema, hypertension, dizziness, decreased appetite, endometrial hypertrophy ( 6 ). To report suspected adverse reactions, contact Corcept Therapeutics at 1-855-844-3270 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, the adverse reaction rates observed cannot be directly compared to rates in other clinical trials and may not reflect the rates observed in clinical practice. Safety data on the use of mifepristone are available from 50 patients with Cushing's syndrome enrolled in an uncontrolled, open-label, multi-center trial (Study 400). Forty-three patients had Cushing's disease and all except one had previously undergone pituitary surgery. Four patients had ectopic ACTH secretion, and three had adrenal carcinoma. Patients were treated for up to 24 weeks. A dose of 300 mg per day was administered for the initial 14 days; thereafter, the dose could be escalated in increments of 300 mg per day based on assessments of tolerability and clinical response. Doses were escalated up to 900 mg per day for patients <60 kg, or 1200 mg per day for patients >60 kg. The most frequently reported adverse reactions (reported in ≥20% of patients, regardless of relationship to mifepristone) were nausea, fatigue, headache, decreased blood potassium, arthralgia, vomiting, peripheral edema, hypertension, dizziness, decreased appetite, and endometrial hypertrophy. Drug-related adverse events resulted in dose interruption or reduction in study drug in 40% of patients. The adverse reactions that occurred in ≥10% of the Cushing's syndrome patients receiving mifepristone, regardless of relationship to mifepristone, are shown in Table 2 . Table 2. Treatment Emergent Adverse Events Occurring in ≥10% of Cushing's Syndrome Patients Receiving mifepristone Body System/Adverse Reaction Percent (%) of Patients Reporting Event (n = 50) *The denominator was 26 females who had baseline and end-of-trial transvaginal ultrasound Gastrointestinal disorders Nausea 48 Vomiting 26 Dry mouth 18 Diarrhea 12 Constipation 10 General disorders and administration/site conditions Fatigue 48 Edema peripheral 26 Pain 14 Nervous system disorders Headache 44 Dizziness 22 Somnolence 10 Musculoskeletal and connective tissue disorders Arthralgia 30 Back pain 16 Myalgia 14 Pain in extremity 12 Investigations Blood potassium decreased 34 Thyroid function test abnormal 18 Infections and infestations Sinusitis 14 Nasopharyngitis 12 Metabolism and nutrition disorders Decreased appetite 20 Anorexia 10 Vascular disorders Hypertension 24 Reproductive system and breast disorders Endometrial hypertrophy 38* Respiratory, thoracic, and mediastinal disorders Dyspnea 16 Psychiatric disorders Anxiety 10 Laboratory Tests Reductions in high density lipoprotein-cholesterol (HDL-C) levels have been observed following treatment with mifepristone. In study subjects that experienced declines in HDL-C, levels returned to baseline following discontinuation of drug. The clinical significance of the treatment-related reduction in HDL-C levels in patients with Cushing's syndrome is not known. In a study of patients with Cushing's syndrome, hypokalemia was observed in 44% of subjects during treatment with mifepristone. In these cases, hypokalemia responded to treatment with potassium supplementation and/or mineralocorticoid antagonist therapy (e.g., spironolactone or eplerenone). Hypokalemia should be corrected prior to initiating mifepristone. [See Warnings and Precautions ( 5.2 )] Elevations of thyroid-stimulating hormone (TSH) were seen in subjects treated with mifepristone. Of the 42 subjects with detectable TSH at baseline, eight (19%) had increases in TSH above the normal range, while remaining asymptomatic. The TSH levels returned to normal in most patients without intervention when mifepristone was discontinued at the end of the study. Vaginal Bleeding and Endometrial Changes In Study 400, the thickness of the endometrium increased from a mean of 6.14 mm at baseline (n=23) to 15.7 mm at end-of-trial (n=18) in premenopausal women; in postmenopausal women the increase was from 2.75 mm (n=6) to 7.35 mm (n=8). Endometrial thickness above the upper limit of normal was reported in 10/26 females who had baseline and end-of-trial transvaginal ultrasound (38%). The endometrial thickness returned to the normal range in 3 out of 10 patients 6 weeks after treatment cessation at the end of the study. Vaginal bleeding occurred in 5 out of 35 females (14%). Two of five subjects with vaginal bleeding had normal endometrial thickness. Endometrial biopsies were performed in six patients; five of these patients had endometrial thickening. No endometrial carcinoma was detected in the sampled cases. Additional Data from Clinical Trials The following are adverse events that were reported in Study 400 at frequencies of ≥ 5% to 10%, and may be related to mifepristone's mechanism of action: Gastrointestinal disorders: gastroesophageal reflux, abdominal pain General disorders and administration site conditions: asthenia, malaise, edema, pitting edema, thirst Investigations: blood triglycerides increased Metabolism and nutrition disorders: hypoglycemia Musculoskeletal and connective tissue disorders: muscular weakness, flank pain, musculoskeletal chest pain Psychiatric disorders: insomnia Reproductive system and breast disorders: vaginal hemorrhage, metrorrhagia [See Warnings and Precautions ( 5.3 )] Adrenal Insufficiency Adrenal insufficiency was reported in two subjects (4%) in Study 400. The most typical symptoms of adrenal insufficiency were nausea and decreased appetite. No hypotension or hypoglycemia was reported during the events. Adrenal insufficiency resolved in both cases with mifepristone interruption and /or dexamethasone administration. Rash Generalized, maculo-papular rash was reported in 2 subjects (4%) in Study 400. Two additional subjects developed pruritus (4%). None resulted in discontinuation of mifepristone, and all the events resolved by the end of the study. 6.2 Postmarketing Experience The following adverse reaction has been identified during post approval use of mifepristone. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. - Angioedema

CLINICAL PHARMACOLOGY 12.1 Mechanism of Action The anti-progestational activity of mifepristone results from competitive interaction with progesterone at progesterone-receptor sites. Based on studies with various oral doses in several animal species (mouse, rat, rabbit, and monkey), the compound inhibits the activity of endogenous or exogenous progesterone, resulting in effects on the uterus and cervix that, when combined with misoprostol, result in termination of an intrauterine pregnancy. During pregnancy, the compound sensitizes the myometrium to the contraction-inducing activity of prostaglandins. 12.2 Pharmacodynamics Use of Mifepristone Tablets, 200 mg in a regimen with misoprostol disrupts pregnancy by causing decidual necrosis, myometrial contractions, and cervical softening, leading to the expulsion of the products of conception. Doses of 1 mg/kg or greater of mifepristone have been shown to antagonize the endometrial and myometrial effects of progesterone in women. Antiglucocorticoid and antiandrogenic activity: Mifepristone also exhibits antiglucocorticoid and weak antiandrogenic activity. The activity of the glucocorticoid dexamethasone in rats was inhibited following doses of 10 to 25 mg/kg of mifepristone. Doses of 4.5 mg/kg or greater in human beings resulted in a compensatory elevation of adrenocorticotropic hormone (ACTH) and cortisol. Antiandrogenic activity was observed in rats following repeated administration of doses from 10 to 100 mg/kg. 12.3 Pharmacokinetics Mifepristone is rapidly absorbed after oral ingestion with non-linear pharmacokinetics for C max after single oral doses of 200 mg and 600 mg in healthy subjects. Absorption The absolute bioavailability of a 200 mg mifepristone oral dose in females of childbearing age is 69%. Following oral administration of a single dose of 600 mg, mifepristone is rapidly absorbed, with a peak plasma concentration of 1.98 ± 1.0 mg/L occurring approximately 90 minutes after ingestion. Following oral administration of a single dose of 200 mg in healthy men (n=8), mean C max was 1.77 ± 0.7 mg/L occurring approximately 45 minutes after ingestion. Mean AUC 0-∞ was 25.8 ± 6.2 mg*hr/L. Distribution Mifepristone is 98% bound to plasma proteins, albumin, and α 1 -acid glycoprotein. Binding to the latter protein is saturable, and the drug displays nonlinear kinetics with respect to plasma concentration and clearance. Elimination Following a distribution phase, elimination of mifepristone is slow at first (50% eliminated between 12 and 72 hours) and then becomes more rapid with a terminal elimination half-life of 18 hours. Metabolism Metabolism of mifepristone is primarily via pathways involving N-demethylation and terminal hydroxylation of the 17-propynyl chain. In vitro studies have shown that CYP450 3A4 is primarily responsible for the metabolism. The three major metabolites identified in humans are: (1) RU 42 633, the most widely found in plasma, is the N-monodemethylated metabolite; (2) RU 42 848, which results from the loss of two methyl groups from the 4-dimethylaminophenyl in position 11ß; and (3) RU 42 698, which results from terminal hydroxylation of the 17-propynyl chain. Excretion By 11 days after a 600 mg dose of tritiated compound, 83% of the drug has been accounted for by the feces and 9% by the urine. Serum concentrations are undetectable by 11 days. Specific Populations The effects of age, hepatic disease and renal disease on the safety, efficacy and pharmacokinetics of mifepristone have not been investigated.