Drug Interactions between dexamethasone / moxifloxacin and trospium

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: Theoretically, coadministration of trospium chloride with other drugs that are eliminated by active tubular secretion may result in increased plasma concentrations of trospium and/or the coadministered drug(s). The mechanism is competitive inhibition of renal excretion. Drugs that are thought to undergo active tubular secretion include acyclovir/valacyclovir, cidofovir, cimetidine, digoxin, flecainide, ganciclovir/valganciclovir, metformin, midodrine, morphine, pancuronium, procainamide, quinidine, ranitidine, tenofovir, triamterene, and vancomycin.

MANAGEMENT: Patients receiving trospium chloride in combination with other drugs that undergo active tubular secretion should be monitored for excessive pharmacologic effects of one or both drugs, and the dosages of the drugs adjusted if necessary.