DRUGS IN GERIATRICS
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Transcript of DRUGS IN GERIATRICS
DRUGS IN GERIATRICS
Dr AZZA ELSHERBINYAssistant professor of pharmacology
By the end of this lecture the student should be able to describe:
1-The changes in physiological functions in elderly
2-The changes in pharmacokinetics in elderly3-Pharmacodynamics changes in elderly4-Drug interactions in elderly5-Changes in drug effects in elderly6-Adverse drug reactions in the elderly7-Practical aspects of geriatric pharmacology
GENERAL CONSIDRATIONS1-An increasing number of adults ≥65 years are living with
multiple health problems2-There are more women than men among older
population.3-Among all persons ≥65 years of age, the five leading
causes of death are heart diseases, cancer, stroke, chronic obstructive pulmonary diseases,
influenza and diabetes4-There is high incidence of adverse effects in elderly due
to polypharmacy, reduced drug elimination, multiple disease states and ↑ drug sensitivity
5-Other problems in elderly are patient compliance, memory changes, hear loss and ↓ vision
PHARMACOKINETIC CHANGES IN THE ELDERLY
-Physiological changes associated with aging, diseases and pharmacological factors can affect pharmacokinetic parameters.
These changes can alter drug response
Absorption:
Can be affected due to physiological changes:-
1-Delayed gastric emptying rate2-↑ Gastric pH 3-↓ splanchnic blood flow4-↓ absorptive surface5-Impaired intestinal motility
Disease states:- e.g.
1-Achlorhydria2-Diarrhea3-Gastrectomy4-Malabsorptive syndromes5-Pancreatitis
Pharmacological factors:- e.g.
1-Drug interactions2-Antacids3-Anticholinergics4-Cholstyramine5-Food
DistributionPhysiological changesWhat is the effect of the changes in serum albumin and
in body fats on drug distribution?1-↓ cardiac output2-↓ total body water3-↓Lean body mass4-↓ Serum albumin5-↑ α1-acid glycoprotein6-↑ body fatQUIZE:-What is the effect of the changes in serum albumin on
drug distribution?
Disease states
1-CHf2-Dehydration3-Edema4-Ascites5-Hepatic failure6-Malnutrition7-Renal failure
Pharmacological Factors
1-Drug-drug interactions2-Protein binding(displacement) can you
provide examples?
Metabolism
1-↓ Hepatic mass2-↓ Enzyme activity 3-↓ Hepatic blood flowExplain the following, ↓ enzyme activity at
old age?
Disease states
1-CHF2-Hepatic failure3-Malignancy4-Malnutrition5-Thyroid disease6-Viral infection
Pharmacological Factors
1-Alcohol2-Smoking3-Induction of metabolism4-Inhibition of metabolismExplain the effects of both enzyme induction
and inhibition on drug response?
ExcretionPhysiological changes1-↓ Renal blood flow2-↓ GFR3-↓ Tubular secretion4-↓ Renal mass↓renal elimination↑adverse effects of drugs (drugs
eliminated by kidney)Drugs highly dependent on renal function for
elimination(Aminoglycosides, acetazolamide, allopurinol, amantadine,
amiloride, atenolo, cephalosporines,Clonidine, fluconazole, H2 antagonists,
enalapril……………………………etc…)
PHARMACODYNAMICS CHANGES IN THE ELDERLY
These changes due to inefficient homeostatic adjustments or
receptors sensitivity
HomeostasisOrthostatic or postural hypotension occurs as a result of
impaired baroreceptor functionAnd a failure of cerebral blood flow auto regulation. Can be
aggravated by1-Sympatholytics2-Volume-depleting drugs and vasodilating agentsThese can contribute to falls in blood pressure.Most common drugs which are used and produce interfere
with homeostasis1-TCAS:- hypotension,and has other side effects such as
tremors, cardiac arrhythmias, sedation2-Antihypertensive;- most of them causes postural
hypotension
Impaired in coordination in old age-Benzodiazepines and sedative hypnotics:-
sedation, weakness, ↓ coordination, confusion
-Narcotic analgesics:- sedation, ↓ coordination, confusion
-Antipsychotics:- sedation, extra pyramidal effects
Receptor sensitivity changes can lead to exaggerated response (e.g.
nitrazepam, heparin, warfarin)1-A decline in the dopamine system ↑
sensitivity to dopamine blocking agents(e.g. neuroleptics, metoclopramide)
2-Cholinergic deficits in the central nervous can ↑ susceptibility to confusion caused by ant-cholinergic
AgentsWhat are the drugs that can induce
confusion in older patients?
ADVERSE DRUG REACTIONS IN THE ELDERLY1-Studies have shown that the percentage of
patients with adverse reactions↑ from about 10%
When a single drug is being taken nearly 100% when ten drugs are taken
2-What are the other reasons for high incidence of errors in prescribed drugs?.
DRUG-DRUG INTERACTIONS
-Enzyme inhibitors:-e.g.Cimetidine(H2 blocker) inhibits the hepatic
metabolism of many drugs including phenytion
Mention other drugs are affected by liver enzyme activity?
-Enzyme inducersWhat are the enzyme inducers, explain
their effect on other drugs?
PRACTICAL ASPECTS OF GERIATRIC PHARMACOLOGY
Drug therapy has considerable potential for both helpful and harmful effects in elderly
This balance may be tipped in the right direction by adherence to a few principles
1-Take a careful drug history, why? (Drug-drug interaction, drug induce disease, drug
Treating disease)2-Prescribe only for a specific indication and real
need of the drugs
PRACTICAL ASPECTS OF GERIATRIC PHARMACOLOGY
3-Define the goal of drug therapy, start small dose and increase gradually
Wait at least 3 half-lives of the drug, until reach the expected response (why),
If no improvement↑ dose if no response shift to a different drug
4-Maintain a high index of suspicion regarding drug reactions and interactions in elderly
5-Simplify the regimen as much as possible (↓ number of drugs being taken,
Collect the drugs that can be taken at same time of the day)