Digoxin Immune Fab therapy in the management of digitalis intoxication: safety and efficacy results of an observational surveillance study. An observational surveillance study was conducted to monitor the safety and effectiveness of treatment with Digoxin Immune Fab (Ovine) (Digibind) in patients with digitalis intoxication. Before April 1986, a relatively limited number of patients received treatment with digoxin-specific Fab fragments through a multicenter clinical trial. Beginning with commercial availability in July 1986, this study sought additional, voluntarily reported clinical data pertaining to treatment through a 3 week follow-up. The study included 717 adults who received Digoxin Immune Fab (Ovine). Most patients were greater than or equal to 70 years old and developed toxicity during maintenance dosing with digoxin. Fifty percent of patients were reported to have a complete response to treatment, 24% a partial response and 12% no response. The response for 14% of patients was not reported or reported as uncertain. Six patients (0.8%, 95% confidence interval 0.3% to 1.8%) had an allergic reaction to digoxin-specific antibody fragments. Three of the six had a history of allergy to antibiotic drugs. Twenty patients (2.8%, 95% confidence interval 1.7% to 4.3%) developed recrudescent toxicity. Risk of recrudescent toxicity increased sixfold when less than 50% of the estimated dose of antibody was administered. A total of 215 patients experienced posttreatment adverse events. The events for 163 patients (76%) were judged to result from manifestations of underlying disease and thus considered unrelated to Fab treatment. Digoxin-specific antibody fragments were generally well tolerated and clinically effective in patients judged by treating physicians to have potentially life-threatening digitalis intoxication. 