Drug Interactions between dexamethasone / moxifloxacin and Mytelase Chloride

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.

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ADJUST DOSE: Corticosteroids and adrenocorticotropic agents may diminish the therapeutic effects of acetylcholinesterase inhibitors in myasthenia gravis. The mechanism of interaction is unknown. Marked deterioration in muscle strength has been reported in patients with myasthenia gravis shortly after the initiation of corticosteroid therapy, particularly when high dosages were used. In most cases, the decline in muscular function was relatively refractory to acetylcholinesterase inhibitors. However, clinical improvement generally occurs during prolonged corticosteroid therapy when administered properly.

MANAGEMENT: Corticosteroid therapy should be instituted at relatively low dosages (15 to 25 mg/day of prednisone or equivalent) and in a controlled setting in patients with myasthenia gravis. Respiratory support should be available, and the dosage should be increased stepwise as tolerated (approximately 5 mg/day of prednisone or equivalent at 2- to 3-day intervals until marked clinical improvement or a dosage of 50 mg/day is reached). Dose reductions of the acetylcholinesterase inhibitor may be required as symptoms improve, which often may be delayed and gradual.

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