Drug Interactions between Co-trimoxazole and verteporfin

MONITOR: Concomitant use of verteporfin with other known photosensitizing agents may increase the risk of photosensitivity reactions. Examples of medicinal products with known phototoxic or photoallergic potential include fluoroquinolones, phenothiazines, retinoids, sulfonamides, sulfonylureas, tetracyclines, thiazide diuretics, griseofulvin, and hypericin extracts (e.g., St John's Wort).

MANAGEMENT: Caution is advised and pharmacologic response to photodynamic therapy should be carefully monitored if concomitant use of other photosensitizing agents cannot be avoided. Patients will become photosensitive, so they should avoid exposure of unprotected skin, eyes, or other body organs to direct sunlight, bright indoor lights (e.g., tanning salons, bright halogen lights, high power lighting in a surgery operating room), and even prolonged exposure from light-emitting medical devices (e.g., pulse oximeter) for 5 days following the infusion of verteporfin. Patients should be counseled to protect their skin and eyes by wearing protective clothing and dark sunglasses if they must go outdoors in daylight during this time, as UV sunscreens are not effective in protecting against photosensitivity reactions. If emergency surgery is necessary within 48 hours of the verteporfin infusion, as much of the patient's internal tissue as possible should be protected from intense light. Patients should be encouraged to expose their skin to ambient indoor light as it is safe and will help eliminate verteporfin through the skin by a process called "photobleaching."