Description on classification of elderly, changes in pharmacokinetic parameters in elderly, and adjust the dose accordingly

1. DOSING IN ELDERLY
Dr. Ramesh Bhandari
Asst. Professor
Department of Pharmacy Practice
KLE College of Pharmacy, Belagavi

2. BACKGROUND
Elderly subjects are considered as specific populations.
Defining “elderly” is difficult.
The geriatric populations often arbitrarily defined as patients who are older than 65
years, and many of these people live active and healthy lives.
In addition, there is an increasing number of people who are living beyond 85 years
old, who are often considered the “older elderly” population.
The aging process is more often associated with physiologic changes during aging
rather than purely chronological age.

3. Classification of Elderly
1. Young Old (Age 65-75 years old)
2. Old (Age 75-85 Years old)
3. Old Old (Age >85 Years old)

4. INTRODUCTION
Performance capacity and the loss of homeostatic reserve decrease with advanced age but
occur to a different degree in each organ and in each patient.
Physiologic and cognitive functions tend to change with the aging process and can affect
compliance, therapeutic safety, and efficacy of a prescribed drug.
The elderly also tend to be on multiple drug therapy due to concomitant illness.
Decreased cognitive function in some geriatric patients, complicated drug dosage schedules,
and/or the high cost of drug therapy may result in poor drug compliance, resulting in lack of
drug efficacy, possible drug interactions, and/or drug intoxication.

5. ABSORPTION
In the elderly, age-dependent alterations in drug absorption may include:
• a decline in the splanchnic blood flow,
• altered gastrointestinal motility,
• increase in gastric pH, and
• alteration in the gastrointestinal absorptive surface.
The incidence of Achlorhydria in the elderly may have an effect on the dissolution of
certain drugs such as weak bases and certain dosage forms that require an acid
environment for disintegration and release.

6. DISTRIBUTION
 Drug–protein binding in the plasma may decrease as a result of
decrease in the albumin concentration:
• Age-related changes in plasma albumin and α1-acid glycoprotein
may also be a factor in the binding of drugs in the body.
The apparent volume of distribution may change due to a
decrease in muscle mass and an increase in body fat.

7. METABOLISM
Decrease in hepatic cells and hepatic blood flow
The activity of the enzymes responsible for drug biotransformation
may decrease with age, leading to a decline in hepatic drug
clearance.

8. EXCRETION
Renal drug excretion generally declines with age as a result of decrease in
the glomerular filtration rate (GFR) and / or active tubular secretion.
Further decrease in plasma flow and active secretion
Co-morbid condition like hypertension, diabetes mellitus will compromise
renal function further.

9. AGE RELATED CHANGES IN TRANSPORTERS
P-glycoprotein, organic anion transporting peptide, organic cation
transporter, and organic anion transporter are the transporters which are
involve in drug absorption, distribution, metabolism and excretion.
Effect of aging on the expression and function of drug transporters are not
much studied however, few data exist which relatively provide impact of
advancing age on P-glycoprotein activity and expression.

10. PHARMACODYNAMICS
Decrease in number of receptors which will change in receptor binding process
Organ specific changes occurs during elderly
Changes in baroreceptor reflex sensitivity
Decrease in response (Eg; β-blockers)
Increase in response (Eg: diazepam, Morphine)

11. EFFECT OF AGE ON DOSING THE OLDER ADULTS
Based on limited knowledge for the impact of aging on pharmacokinetic and
pharmacodynamics properties, it is difficult to make definite dosage
recommendations for older patients.
Dosing recommendation – ‘start low and go slow’

12. CONSIDERATION IN ELDERLY PATIENTS
Elderly patients may have several different pathophysiologic conditions that
require multiple drug therapy that increases the likelihood for a drug
interaction.
Moreover, increased adverse drug reactions and toxicity may result from
poor patient compliance.
Poly pharmacy results in increase drug interaction, ADR and non
compliance.
Non compliance: Taking the wrong dose, forgetting to take medication,
incorrect timing etc.

13. APPROACHES TO AVOID ADE IN OLDER ADULTS
1. The Beers list (Beers Criteria):
 Developed by Mark H Beers for identifying inappropriate use of
medications in older patients.
 Used by physicians and pharmacists.
 Originally developed for older individuals living in nursing homes latter
updated and expanded to generalize to the older population.

14. APPROACHES TO AVOID ADE IN OLDER ADULTS
1. The Beers list (Beers Criteria):
 First edition in 1991 and revised in 1997, 2003, 2012, 2015 and the
latest edition is American geriatrics society 2019 updated AGS Beers
criteria for potentially inappropriate medication use in older adults.
 Limitations:
 Obsolete drugs, drug-drug interactions and prescribing omission
errors.
 STOPP (Screening Tool of Older Persons Prescription) / START
(Screening Tool to Alert doctors to Right Treatment)

15. ROLE OF PHARMACIST IN DOSING ELDERLY PATIENT
Patient counselling and monitoring
Assess the effects of medications and refilling the medication
regularly.
Helps to improve medication adherence.