Trends in oral antihyperglycemic and insulin use in the Nova Scotia senior population (1993-1999).

Trends in prescribing patterns of insulin and oral antihyperglycemic drugs for Nova Scotia seniors pharmacare beneficiaries were examined from April 1, 1993 to March 31, 2000 and evaluated relative to published guidelines. The number of patients, prescriptions, and drug costs for oral antihyperglycemic drugs and insulins were calculated. The source of insulin was examined subsequent to the marketing of human insulin in 1993. The percentage of patients using human insulin increased from 66% in 1993 to 96% in 1995, and beef and pork insulin use decreased from 38% in 1993 to 19% in 1995. First generation sulfonylureas decreased between 1993 and 1999; chlorpropamide decreased from 23% to 7% of antihyperglycemic users, and tolbutamide decreased from 4% to 1%. Among second-generation sulfonyl-ureas, glyburide remained frequently used with 59% of antihyperglycemic users in 1999, while gliclazide increased in use from 2% to 22% between 1993 and 1999. Metformin, a biguanide, increased in use from 29% to 37% of antihyperglycemic users. Acarabose having been introduced to the market later, increased in use from 1% to 5% between 1996 and 1999. Once human insulin became available, patients were rapidly transferred from animal to human insulin. Chlorpropamide remained widely used despite safety concerns for use in the elderly. Glyburide was the most frequently prescribed oral antihyperglycemic agent. Recently raised concerns about its safety in patients with renal disease require follow-up. Further work is needed to determine the reasons for slow uptake of recommendations related to chlorpropamide and the effect of switches to human insulin and newer oral antihyperglycemics on patient outcomes and health care costs.