Which hypoglycemic agent is contraindicated in the elderly due to a long half-life of approximately 32 hours?

• A. Tolbutamide
• B. Chlorpropamide
• C. Tolazamide
• D. Glipizide

Answer: (B)

The important idea is how long a drug stays active in the body affects safety in older adults. Chlorpropamide has a very long half-life—around 32 hours—so it remains active for a prolonged period. In the elderly, decreased liver and kidney function slows clearance, allowing the drug to accumulate and continue stimulating insulin release. That combination raises the risk of prolonged and potentially severe hypoglycemia. Because of this, chlorpropamide is avoided in older patients. Other options have much shorter durations of action, which means they’re less likely to cause prolonged hypoglycemia in this population, though all sulfonylureas require careful monitoring.