Prescribing in older patients Flashcards
What are two simple principles in drug absorption?
Acid drugs require an acidic environment for absorption (pH < 7.35) eg phenytoin, aspirin, penicillins
Basic drugs require a basic environment for absorption (pH > 7.35) eg diazepam, morphine pethidine
What environment of pH does it tend to be in an older patient?
Because of reduced production, they tend to have increased gastric pH
What is the change in drug distribution (in blood stream) in elderlies?
- Protein binding
In blood stream, albumin (a basic protein) - Lipid binding
- Body water
Why do elderlies tend to have a higher volume of distribution for drugs and how does that lead to problems?
*a particular form of diet that leads to release of fat tissue (where a lot of lipophilic, hence long-acting, drugs bind)
What is the equation for half-life from volume of distribution and clearance?
When is eGFR not a reliable marker for renal function?
At the extremes of BMI, which can be rather commonly seen in elderlies
Most pharmaceutics achieve same effect in the elderly with lower doses, but what are examples of some where effects are in fact decreased?
Beta-blockers on heart rate
How to calculate therapeutic index? What are ten major drugs with a narrow therapeutic index (ie <2)?
Why does therapeutic window get narrower in older patients?
Why are NSAIDs not ideal in elderlies? What are alternatives?
What are four polypharmacy principles to keep in mind?
What is the STOPP-START tool for prescribing?
