Renal Function Caveats
Use of increased numbers of medications and age-related decline in renal function make older patients more susceptible to adverse medication effects. Drug pharmacokinetics change, and it’s important to remember that drug metabolism is affected by a number of processes.
Renal elimination of drugs is based on nephron and renal tubule capacity, which decrease with age.1 Older individuals will not metabolize and excrete drugs as efficiently as younger, healthier individuals.
According to the Centers for Disease Control and Prevention (CDC), there are more than 36 million adults in the United States older than 65, and overall U.S. healthcare costs related to them are projected to increase 25% by 2030.2
Preventing health problems, preserving patient function, and preventing patient injury that can lead to or prolong patient hospitalizations will help contain these costs.
Quartarolo, et al., recently reported that although physicians noted the estimated glomerular filtration rate (GFR) in elderly hospitalized patients, they didn’t modify their prescribing.3 They also noted that drug dose changes in these hospitalized patients are important to prevent dosing errors and adverse reactions.
There are four major age-related pharmacokinetic parameters:
- Usually decreased gastrointestinal absorption changes ;
- Increases or decreases of a drug’s volume of distribution leading to increased blood drug levels and/or plasma-protein-binding changes;
- Usually decreased clearance with increased drug half-life effect (hepatic metabolism changes); and/or
- Decreased clearance (and increased half-life) of renally eliminated drugs.4,5
