Drug Interactions between aspirin / butalbital / caffeine and osilodrostat

MONITOR: Coadministration with osilodrostat may increase the plasma concentrations of drugs that are metabolized by CYP450 1A2, 2C19, 2D6, and/or 3A4. Osilodrostat has been shown to be a moderate inhibitor of CYP450 1A2, a mild to borderline moderate inhibitor of CYP450 2C19, and a weak inhibitor of CYP450 2D6 and 3A4. In a pharmacokinetic study with 20 healthy volunteers using a single 50 mg dose of osilodrostat and a probe drug cocktail, osilodrostat increased the exposures to caffeine (CYP450 1A2 substrate), omeprazole (CYP450 2C19 substrate), dextromethorphan (CYP450 2D6 substrate), and midazolam (CYP450 3A4/5 substrate) by 2.5-, 1.9-, 1.5- and 1.5-fold, respectively.

MANAGEMENT: Caution is advised when osilodrostat is used concurrently with drugs that are substrates of CYP450 1A2, 2C19, 2D6 and/or 3A4, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever osilodrostat is added to or withdrawn from therapy.

MONITOR: Coadministration with inducers of CYP450 3A4 and/or 2B6 may decrease the plasma concentrations of osilodrostat, which is partially metabolized by these isoenzymes. According to the product labeling, multiple CYP450 isoenzymes (CYP450 3A4, 2B6, and 2D6) and UDP-glucuronosyltransferases contribute to osilodrostat metabolism, and no single pathway contributes greater than 25% to the total clearance. Some of the known CYP450 3A4 and 2B6 inducers also induce UDP-glucuronosyltransferases. Pharmacokinetic data for osilodrostat in combination with an inducer of one or more of these pathways have not been reported. Reduced therapeutic efficacy of osilodrostat may occur during coadministration. On the other hand, discontinuation of a CYP450 3A4 and/or 2B6 inducer during treatment with osilodrostat may result in increased osilodrostat plasma concentrations and increased risk of adverse effects such as hypocortisolism (which may lead to life-threatening adrenal insufficiency), QT prolongation (which may increase the risk of ventricular arrhythmias including torsade de pointes and sudden death), and elevated androgen and 11-deoxycorticosterone levels (the latter of which may activate mineralocorticoid receptors and cause hypokalemia, edema, and hypertension).

MANAGEMENT: The potential for diminished pharmacologic effects of osilodrostat should be considered during concomitant use of a CYP450 3A4 and/or 2B6 inducer. An increase in the dosage of osilodrostat may be required. Dosage adjustments should be based on clinical response and tolerance. Patients should have regular monitoring of 24-hour urine free cortisol and serum or plasma cortisol during treatment, as well as regular evaluations of their signs and symptoms. A reduction in dosage of osilodrostat may be required if the CYP450 3A4 and/or 2B6 inducer is discontinued during treatment with osilodrostat.

One study has reported that coadministration of caffeine and aspirin lead to a 25% increase in the rate of appearance and 17% increase in maximum concentration of salicylate in the plasma. A significantly higher area under the plasma concentration time curve of salicylate was also reported when both drugs were administered together. The exact mechanism of this interaction has not been specified. Physicians and patients should be aware that coadministration of aspirin and caffeine may lead to higher salicylate levels faster.