Drug assay services and management of epilepsy in Barbados a one year review - abstract

ABSTRACT

Therapeutic drug monitoring with a clinical pharmacology consultative service has been available in Barbados for one year. Its use is reiewed in 143 epileptic patients, from whom 239 blood samples were drawn. Three hundred and eleven assays were performed by Enzyme Mediated Immunoassay [EMIT] (phenytoin 179, phenobarbitone 85 and carbamzepine 47). Efficiency of prescribing was assessed by comparing plasma levels with Recomended Therapeutic Ranges (RTR). Sixty-eight per cent of all assays were outside the RTR (47 percent below and 21 percent above). Only 24 percent of phenytoin levels were in the RTR, compared with 39 percent for carbamzepine and 49 percent for phenobarbitone. Ten per cent of all assays showed insignificant drug concentrations, indicating severe non-compliance. Assay reports included suggestions for dose adjustments were made in 38 percent. Non-compliance or"on-off" compliance was the major therapeutic problem and was identified in 48 percent, but the clinician recorded compliance counselling in only 27 percent. Reports were frequently not noted, drugs changed instead of doses, or inappropriate dose blood test and tests and (ii) different doctors reviewing. These results demonstrate unsatifactory mangement of epilepsy. Mean annual drug cost for these patients was 10 time the cost of one assay. Improved fit control and projected savings from reduced doses and reduced drug wastage more than justify costs of therapeutic drug monitoring in the Caribbean, when linked with consultative services and education in drug use (AU)