A COMMUNITY PHARMACY-BASED SURVEY OF ANTIHYPERTENSIVE AND ANTIDIABETIC DRUG DOSAGES IN NORTHERN IRELAND

Abstract

International drug utilization data comparisons for antihypertensive and antidiabetic agents based on standard daily dosage units, Defined Daily Doses (DDD), show that less of these drugs are prescribed per head of population in Northern Ireland than in Norway or Sweden. A study was designed to investigate whether actual prescribing practices in Northern Ireland might account for some of these apparent differences by comparing the average prescribed daily dose, (PDD) with the DDD for antihypertensive and antidiabetic drugs. Daily dosage information was collected on the antihypertensive and antidiabetic drugs dispensed at 47 Northern Ireland pharmacies during Oct. 1981. A high proportion (73%) of the community pharmacies randomly chosen, to take part in the survey were able to record daily dosage instructions. Thirty percent of the prescriptions monitored were as directed, but in over 1/3 (42%) of these cases, pharmacy staff ascertained how the drug was to be taken by questioning the recipient. For each antihypertensive and antidiabetic drug, the PDD was calculated from the aggregated data. In general, the Northern Ireland PDD were close to the DDD units of international comparisons assigned to each drug. Most .beta. -blocking agents and other hypotensives had average prescribed daily doses that were only slightly lower than the DDD assigned. The PDD of all hypoglycemic agents and insulin were marginally less than the corresponding DDD. The apparent low prescribing of these drugs in Northern Ireland is evidently not due to marked differences between assumed and actual prescribing practices.