Basic of Geriatrics and Internal Medicine for Physiotherapist by Rasheedy D - HTML preview

Pharmacotherapy in elderly

Many older patients are prescribed multiple drugs, take over-the-counter drugs, and are then prescribed additional drugs to treat the side effects of medications they are already taking resulting in polypharmacy (usually defined as consuming ≥ 5 medications). The elderly are the biggest consumer of the drug industry, Elderly account for 1/3 of prescription drug use, while only 13% of the population.

The Effects of Aging on pharmacokinetics:

Several age-related biological and physiological changes are relevant to pharmacology. Except for changes in renal function, however, the effects of these age-related changes on dosages of specific drugs for individual patients are variable and difficult to predict

The Effects of Aging on pharmacodynamics:

1. Generally, lower drug doses are required to achieve the same effect with advancing age.
2. Change in receptor numbers, affinity can increase or decrease drug sensitivity: HR response to beta-blockers
3. Changes in homeostatic mechanisms can increase or decrease drug sensitivity. sensitivity to warfarin due to a greater decrease in clotting factor synthesis

Other factors affecting drug prescription in elderly:

1. Multiple morbidities: e.g. NSAIDs may cause acute decompensation in patients with chronic heart failure.(drug- disease interaction)
2. Multiple medications leading to drug-drug interactions: ACEIs and aldactone causes hyperkalemia
3. Psychological factors: depressed patients may have their stable conditions exacerbated due to non-adherence to treatment
4. Social factors: economic problems and Problems with transportation may interfere with obtaining the medications.
5. Diminished hearing, impaired vision, poor literacy, and poor short-term memory can interfere with patient education and adherence to treatment regimens.

POTENTIALLY INAPPROPRIATE MEDICATIONS FOR OLDER PERSONS:

Multiple tools are available to clinicians that can assist in making information readily available to avoid adverse drug reactions and interactions.

1. The Beers Criteria: developed to assist healthcare providers in improving medication safety in older adults. The criteria were originally published in the Archives of Internal Medicine in 1991 and were updated in 1997 and again in 2003,2012,2015. Last edition on 2019 https://onlinelibrary.wiley.com/doi/full/10.1111/jgs.15767
2. STOPP criteria (Screening Tool of Older Persons’ Potentially Inappropriate Prescriptions)

Principles of Prescribing in the Elderly:

• Consider non-pharmacologic agents
• Start with a low dose and titrate slowly
• Avoid starting 2 agents at the same time
• Reach therapeutic dose before switching or adding agents
• Review meds regularly (at least q3 months)
• Avoid prescribing to treat side effect of another drug
• Use 1 medication to treat 2 conditions, Use simplest regimen possible
• Adjust doses for renal and hepatic impairment
• Use least expensive alternative.
• Monitor for adverse drug reactions, drug-disease, drug-drug, and nutrients-drug interaction.
• Avoid inappropriate drug prescription for old age using The Beers Criteria or similar tools.

NB: example of nutrients drug interactions:

1. Tyramine, a component of cheese and a potent vasoconstrictor, can cause hypertensive crisis in some patients who take monoamine oxidase inhibitors and eat cheese.

2. Foods with vitamin K (arugula, avocado, green beans, Cucumber), produce blood-clotting substances that reduce the effectiveness of oral anticoagulants (Warfarin).

Safe analgesic prescription