Pharmacotherapy in Elderly
Patients older than 65 years represent approximately 14% of the population in the Czech republic.[1] Aging brings with it quite a few changes, some of which have implications for treatment.
- polymorbidity - greater number of diseases requiring greater number of drugs
- polypharmacy - the use of large quantities of drugs (4 or more), incorrect combinations of drugs or prescription non indicated drugs
- underprescription - nonprescription drugs that have a demonstrable effect on the disease and survival (typically statins, β-blockers after AMI, cholinesterase inhibitors in Alzheimer's dementia, sufficient analgoterapie in cancer patients, antidepressants)
- decreased compliance - due to dementia or just due to excessive amounts of drugs
Changes in Pharmacokinetics[edit | edit source]
Absorption Decrease[edit | edit source]
There is pH increase in stomach, atrophy of villi and mucous in gut (decrease resorptive area), decrease in blood flow and motility in the GI tract. Overall, this leads to a slower onset of action of drugs administered orally. Muscle atrophy and reduced blood flow to the periphery is involved in the delayed onset of action of medications given intramuscularly.
Distribution[edit | edit source]
There is physiological decrease of total body water, it can be enhanced by dehydration (typical for the elderly). Dehydration affects the drugs that are water-soluble. Their concentration in plasma is increased and toxic.
On the contrary, the concentration of drug fat-soluble increases due to higher total body fat (drugs are stored in adipose tissue) → benzodiazepines.
Malnutrition contributes to decrease in serum albumin - by increasing the plasma free fraction of drugs that bind to albumin → PAD, antidepressants, beta blockers.
Decreased Metabolization and Excretion[edit | edit source]
- Due to the decrease in total liver weight and liver perfusion, reduced function of some enzymes (CYP, glucuronyltranspherase → benzodiazepines).
- Decreased glomerular filtration, renal clearance, tubular secretion, renal hypoperfusion → aminoglycosides, lithium, digoxin, cimetidine, allopurinol, a contrast agent.
Changes in Pharmacodynamics[edit | edit source]
- increased number of receptors or sensitivity to drugs (warfarin, heparin).[1]
- increased sensitivity to adverse effects of digoxin.[1]
- increased CNS sensitivity to benzodiazepines, morphine, which cause sedation, delirium, depression, or even at therapeutic doses.[1]
- numbness receptor beta - reduced effectiveness of β-blockers.[1]
Adverse Effects and Drug Interactions[edit | edit source]
Side effects of drugs occur up to 20% of deaths in the elderly.
Typical side effects in the elderly are:
- orthostatic hypotension (syncope, falls)
- diarrhea, constipation
- sedation, delirium, confusion
Often drug interactions:
- warfarin + sulfonamides → displacement of drug from binding to binding protein → higher free fraction of warfarin and the risk of bleeding
Unsuitable/less Suitable Drugs in the Elderly[edit | edit source]
- tricyclic antidepressants - anticholinergic effect
- antispasmodics - the risk of urinary retention, delirium
- barbiturates, benzodiazepines - the risk of sedation, addiction
- methyldopa - depression, sedation, bradycardia
- digoxin - possible high risk of adverse effects
Medical drugs which need smaller doses (evidence based)[1]:
- atorvastatin (standard 10 mg/day, in elderly 5 mg/day)
- ibuprofen (standard 400-800 mg/3-4x day, in elderly 200 mg/3-4x day)
- metoprolol (standard 100 mg/day, in elderly 50 mg/day)
- omeprazole (standard 20 mg/day, in elderly 10 mg/day)
- and more ...
Links[edit | edit source]
Related Articles[edit | edit source]
- Special problems in the geriatric patients
- Principal Geriatric Syndromes
- Psychiatric Disorders in Geriatric Patients
Sources[edit | edit source]
- WikiSkripta.eu. Zvláštnosti farmakoterapie ve stáří [online]. The last revision 2012-02-14, [cit. 2012-02-16]. <http://www.wikiskripta.eu/index.php/Farmakoterapie_ve_stář%C3%AD>.
