Plasmapheresis: a rational treatment for fulminant acute pancreatitis?

erythematous rashes, though dermatographism, nausea, vertigo, and malaise have also been reported. The reactions commonly develop several hours after administration of the radiopharmaceutical and may last up to 48 hours. These localised reactions are considered to be minor, and only one other severe systemic reaction has been described; in that case rechallenge by skin testing proved a causal relation.' We thought that rechallenge was unwise in our case given the severity of the reaction. Diphosphonates are present in several radiopharmaceuticals other than those used for bone scanning; examples are agents for labelling red cells (Amerscan Stannous Agent, Amersham International) and imaging the liver (Microlite, Du Pont (United Kingdom)). Alternative agents should thus be used for patients known or suspected to be sensitive to diphosphonates; bone scanning may be done with pyrophosphates. In addition, hypersensitivity reactions may occur in patients with Paget's disease being treated with therapeutic concentrations of diphosphonates. The radiopharmaceutical that we injected contained only 0 5 mg diphosphonate, whereas single therapeutic doses are in the range 15-30 mg34 and are administered by intravenous infusion over less than two hours. We therefore suggest that skin testing for sensitivity be considered when pharmaceuticals containing diphosphonates are used therapeutically and it would not compromise management of the patient.