Drug Interactions between moxifloxacin / triamcinolone and sodium phenylbutyrate

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: Drugs that can increase plasma ammonia levels such as corticosteroids, haloperidol, or the anticonvulsants carbamazepine, topiramate, and phenobarbital may interfere with the therapeutic effects of phenylbutyrate therapy in the management of urea cycle disorders. Corticosteroids can cause the breakdown of body protein, which may lead to increased ammonia levels. The use of haloperidol has been associated with hyperammonemia in a young child with citrullinemia, an inherited disorder of ammonia excretion. The mechanism for haloperidol, carbamazepine, topiramate, and phenobarbital has not been established.

MANAGEMENT: Plasma ammonia levels should be closely monitored when corticosteroids, haloperidol, carbamazepine, topiramate, or phenobarbital are used in patients with urea cycle disorders receiving phenylbutyrate therapy.