Drug Interactions between dexamethasone / moxifloxacin and riociguat

MONITOR CLOSELY: Concomitant administration of corticosteroids may potentiate the risk of tendinitis and tendon rupture associated with fluoroquinolone treatment. The mechanism is unknown. Tendinitis and tendon rupture have most frequently involved the Achilles tendon, although cases involving the rotator cuff (the shoulder), the hand, the biceps, and the thumb have also been reported. Some have required surgical repair or resulted in prolonged disability. Tendon rupture can occur during or up to several months after completion of fluoroquinolone therapy.

MANAGEMENT: Caution is recommended if fluoroquinolones are prescribed in combination with corticosteroids, particularly in patients with other concomitant risk factors (e.g., age over 60 years; recipient of kidney, heart, and/or lung transplant). Patients should be advised to stop taking the fluoroquinolone, avoid exercise and use of the affected area, and promptly contact their physician if they experience pain, swelling, or inflammation of a tendon. In general, fluoroquinolones should only be used to treat conditions that are proven or strongly suspected to be caused by bacteria and only if the benefits outweigh the risks.

MONITOR: Coadministration with inducers of CYP450 3A4 may decrease the plasma concentrations of riociguat, which is partially metabolized by the isoenzyme. According to the product labeling, administration of riociguat with the moderate CYP450 3A4 inducer bosentan resulted in an approximately 30% decrease in riociguat systemic exposure (AUC). The magnitude of interaction is expected to be greater with more potent inducers.

MANAGEMENT: The potential for diminished therapeutic effects of riociguat should be considered when prescribed in combination with CYP450 3A4 inducers. No dose adjustment is necessary for concomitant use with moderate CYP450 3A4 inducers. Data are not available to guide dosing of riociguat when coadministered with potent CYP450 3A4 inducers such as carbamazepine, enzalutamide, phenobarbital, phenytoin, rifamycins, and St. John's wort. Patients should be closely monitored and alternative agents with no or minimal CYP450 3A4-inducing activity should be considered whenever possible.