Drug Interactions between moxifloxacin / triamcinolone and vigabatrin

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.

GENERALLY AVOID: Theoretical concerns exist that oculotoxic effects of vigabatrin may be additive with those of other drugs that are associated with serious adverse ophthalmic effects. Vigabatrin causes permanent bilateral concentric visual field constriction in 30% or more of patients, with severity ranging from mild to severe. Vigabatrin can also damage the central retina and decrease visual acuity. The onset of vision loss is unpredictable, occurring within weeks of starting treatment to months or even years later. The risk of vision loss increases with increasing dose and cumulative exposure, although there is no dose or exposure known to be risk-free. It is possible that vision loss can worsen even after discontinuation of vigabatrin.

MANAGEMENT: Vigabatrin should generally not be used with other drugs associated with serious adverse ophthalmic effects such as retinopathy or glaucoma unless the benefits clearly outweigh the risks. These drugs may include amiodarone, deferoxamine, ethambutol, quinine derivatives, tamoxifen, and long-term corticosteroids. Vision testing at baseline (no later than 4 weeks after starting vigabatrin) and at least every 3 months during therapy is required for adults. Vision testing is also required about 3 to 6 months after the discontinuation of vigabatrin therapy. Due to the risk of irreversible vision loss, vigabatrin should be withdrawn from patients who fail to show substantial clinical benefit within 3 months of initiation, or sooner if treatment failure becomes obvious. The patient's response and continued need for vigabatrin should be periodically reassessed. The lowest dosage and shortest duration of treatment consistent with clinical objectives should be employed.