WHO IS ORDERING ALL THOSE CYCLOSPORINE CONCENTRATIONS AND HOW DO THEYUSE THEM - AN AUDIT OF CYCLOSPORINE THERAPEUTIC DRUG-MONITORING

Therapeutic drug monitoring is used for the immunosuppressant drug, cy closporin, even though it is often unclear what concentration should b e targetted. At St. Vincent's Hospital, Sydney, a polyclonal, whole bl ood immunoassay is used to measure cyclosporin and metabolites. The ob jective of the present study was to audit how the concentration result s produced by the laboratory were actually used to adjust dosage. Each transplantation unit was asked about their policy for dosage adjustme nt and which therapeutic range was used. The audit criteria were consi dered to be passed if the action taken based on a concentration result was (a) predictable based solely on the concentration and its relatio nship to the stated therapeutic range (e.g., dosage increased if conce ntration was below therapeutic range) or (b) based on clinical conside rations (e.g., dosage decreased because of increased serum creatinine) . Data were collected for the actions taken following 347 concentratio n results over a 6-week period. Audit criteria were fulfilled for 246 (71%) of the results. The majority of the cyclosporin concentrations ( 75%) were determined for the cardiopulmonary unit; 66% of these fulfil led audit criteria. Approximately two-thirds of all the cyclosporin co ncentrations requested were followed up by appropriate action based on stated therapeutic ranges or documented clinical reasons.