Indications for ISTURISA:
Treatment of patients with Cushing’s disease for whom pituitary surgery is not an option or has not been curative.
Initially 2mg twice daily. Based on rate of cortisol changes, tolerability, improvement in signs/symptoms, titrate by 1–2mg twice daily at least every 2 weeks; if 10mg twice daily is tolerated and continues with elevated 24hr urine free cortisol (UFC) levels above ULN, then titrate by 5mg twice daily every 2 weeks. Maintenance dose: individualized, usually 2–7mg twice daily; max 30mg twice daily. Initially monitor cortisol levels every 1–2 weeks from at least two 24hr UFC collections until adequate response, then at least every 1–2 months after maintenance dose is achieved or as indicated. Hepatic impairment (moderate): initially 1mg twice daily; (severe): initially 1mg once daily in the evening.
Risk of hypocortisolism, adrenal insufficiency. Monitor 24hr UFC, serum/plasma cortisol, and patient's signs/symptoms during therapy. Discontinue temporarily or reduce dose if UFC levels fall below the target range, rapid decrease in cortisol levels, and/or hypocortisolism symptoms. If serum/plasma cortisol levels are below target range with adrenal insufficiency symptoms, discontinue and treat with glucocorticoid replacement; re-initiate at lower dose when resolved. Risk of QTc prolongation. Obtain baseline ECG, repeat within 1 week after initiation, then as clinically indicated; withhold dose if QTc interval >480ms. Correct electrolyte abnormalities, hypokalemia and/or hypomagnesemia prior to initiation; monitor periodically. Congenital long QT syndrome. CHF. Bradyarrythmias. Moderate to severe hepatic impairment: monitor (see Adult). Moderate to severe renal impairment. Pregnancy. Nursing mothers: not recommended (during and for 1 week after the last dose).
Cortisol synthesis inhibitor.
May be potentiated by strong CYP3A4 inhibitors (eg, itraconazole, clarithromycin); reduce dose by ½. May be antagonized by strong CYP3A4 and/or CYP2B6 inducers (eg, carbamazepine, rifampin, phenobarbital): monitor cortisol levels; consider Isturisa dose adjustments. Caution with CYP1A2 and CYP2C19 substrates with a narrow therapeutic index (eg, theophylline, tizanidine, S-mephenytoin). Caution with concomitant drugs known to prolong the QT interval; monitor ECG more frequently.
Adrenal insufficiency, fatigue, nausea, headache, edema; elevated adrenal hormone precursors and androgens.
Generic Drug Availability:
Tabs—60 (3x20 blisters)