Drug Interactions between gold sodium thiomalate and moexipril

MONITOR: Concomitant ACE inhibitor therapy may potentiate the risk of nitritoid (vasomotor) reactions associated with injectable gold therapy. The mechanism of interaction is unknown, although investigators suggest that ACE inhibitors may unmask drug hypersensitivity reactions by preventing the breakdown of bradykinins. In one published case report, two patients with rheumatoid arthritis who had been treated with intramuscular sodium aurothiomalate for over 20 years without incident developed nitritoid reactions after they were started on ACE inhibitor therapy within the previous 15 months. The interaction was also suspected in several other reported cases. One patient experienced anaphylaxis and cardiac arrest after a gold injection. She had been on gold therapy for 16 months and lisinopril for 12 months. Two other cases occurred 1 to 4 weeks after starting ACE inhibitor therapy. The patients were switched to gold sodium aurothioglucose with no further problems. In general, nitritoid reactions can occur in approximately 5% of patients treated with gold. Most are transient and occur within a few minutes of drug administration within the first year of treatment. Serious sequelae including myocardial infarction have been reported.

MANAGEMENT: Patients on injectable gold therapy in combination with an ACE inhibitor should be monitored for symptoms of nitritoid reactions such as facial flushing, nausea, vomiting, and hypotension following an injection. Elderly patients in particular should be observed following treatment. Oxygen, intravenous fluids, epinephrine, steroids, and other supportive therapy may be necessary for treatment.