How the drug is broken down - Chemical structure of drug is converted to metabolite more easily used and excreted. - Liver is primary site for metabolism, although many other organs have metabolizing enzymes. - Genetic differences in drug metabolism can affect serum drug levels and rate of excretion. - Greater understanding of the human genome can lead to "personalized medicine" tailored to individual metabolism for maximum therapeutic effect.

How the drug leaves the body - Drugs and their metabolites are excreted in sweat, saliva, and other secretions but primarily through kidneys. - Renal drug excretion occurs when drug is passed through kidney and involves glomerular filtration, active tubular secretion, and passive tubular reabsorption. - Assessment of creatinine clearance rate an important consideration in older adults to prevent drug toxicity.

- philic = like - phobic = dislike

- Lipoproteins, globulins, and albumin - Some drugs are bound to proteins for distribution

Chapter 9 Geropharmacology Flashcards by Rebecca Pierce

Absorption

How the drug is taken into the body
-Bioavailability
-Amount of drug that passes through absorbing surfaces in body
•Some medications are directly absorbed through the stomach
•Most are absorbed in the duodenum

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Pharmacokinetics

Study of the movement and actions of a drug in the body

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Distribution

Where the drug goes in the body

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Metabolism

How the drug is broken down

Chemical structure of drug is converted to metabolite more easily used and excreted.
Liver is primary site for metabolism, although many other organs have metabolizing enzymes.
Genetic differences in drug metabolism can affect serum drug levels and rate of excretion.
Greater understanding of the human genome can lead to “personalized medicine” tailored to individual metabolism for maximum therapeutic effect.

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Excretion

How the drug leaves the body

Drugs and their metabolites are excreted in sweat, saliva, and other secretions but primarily through kidneys.
Renal drug excretion occurs when drug is passed through kidney and involves glomerular filtration, active tubular secretion, and passive tubular reabsorption.
Assessment of creatinine clearance rate an important consideration in older adults to prevent drug toxicity.

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Where are most meds absorbed?

Duodenum

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Absorption changes with aging: GI motility

Decreased GI motility

Increased absorption time
Can lead to increased levels of the medication in the patients system
NO CONCLUSIVE EVIDENCE TO SUPPORT THIS
Least effected by the aging process

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Absorption changes with aging: Skin

Skin changes with aging

Underweight and overweight: unreliable dosing
Thinning, dryness, and roughness of the skin effects absorption
Allergic reaction risk is increase
Must be placed on intact skin
Need to see the clint do it (return demonstration)

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Distribution: Lipophilic drugs

Pass through the capillaries easily
More rapid and greater volume of distribution
Stored in fatty tissue
Older adults have a higher ration of adipose tissue to body mass

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Hydrophilic drugs

-Decreased body water: increased serum plasma concentrations

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-philic vs -phobic

philic = like

- phobic = dislike

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Plasma Proteins

Lipoproteins, globulins, and albumin

- Some drugs are bound to proteins for distribution

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Problems with protein bound medications

Meds not bound to protein are free in the plasma and wiill have their therapeutic effect.
Decreased protein = decreased med-protein binding = higher plasma concentrations.
Some meds compete with others for protein binding (whichever loses is displaced and their serum concentrations are increased)
Ill elderly: Decreased serum albumin (malnutrition, acute illness, long-standing chronic condition) = unpredictable amounts of free-drug available.

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Decreased protein binding, increased drug effect:

Warfarin

Phenytoin

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Increased protein binding, and less drug effect

ASA
Lorazepam
Diazepam
Chlorpromazine
Phenobarbitol
Haloperidol
Lidocain
Propanolol

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Changes with aging: Metabolism

First Pass metabolism

Decreased liver mass
Decreased liver blood flow
Decreased liver function
Decreased hepatic exposure

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Every single vein in the digestive system joins with what vein in the liver?

Portal vein

Drugs that are typically not affected by First-Pass metabolism, and therefore not typically affected by the aging process, include:

antibiotics

Baroreceptor reflex decreases with aging

Anticholinergic drugs: risk with position changes, and risk with volume changes

Increase in Sympathetic Nervous System

Decreased response to Beta blockers

Increased response to diuretic

Polypharmacy

Taking multiple medications at same time
Increased risk for drug interactions: Drug-supplement interactions, Drug-food interactions, Drug-drug interactions.
20% of older adults take 10 or more drugs (even higher in long term care settings.
The main problem is lack of communication between healthcare providers.

Most common errors of medication administration via enteral feeding tubes

Incompatible route
Improper preparation
Improper administration
Always have pharmacist provide liquid form when available

Issues and Trends in Medicine Use: Self-Prescribing of Medicinal Products

-People of all ages frequently medicate themselves with former prescriptions, prescriptions borrowed from friends, or over-the-counter (OTC) drugs
-Self-treatment includes purchasing herbal and nutritional supplements, which may be recommended by acquaintances and are thought to be harmless because they are “natural.”
-Problem is with under-reporting, and patient education

Adverse Drug Events (ADR’s): Most common categories associated with ADR’s

Cardiovascular agents
Psychotropics
Anticoagulants
Diuretics
Hypoglycemics
Non-opioid analgesics

Antidepressants

- SSRI's most effective - Most older adults are sensitive to these, and lower doses need to be considered - Side effects are manageable and usually resolve with time (dry mouth, sedation, sexual dysfunction) - SNRI's have less sexual side effects.

Anxiolytic agents

-Bezodiazepines, and Buspirone -Many people self-medicate with antihistamines. Side effects: drowsiness, dizziness, ataxia, mild cognitive impairment, and memory impairment

Signs of Toxicity:

``` Excessive sedation Unsteady gait Confusion Disorientation Agitation Wandering Cognitive and Memory Impairment ```

Mood stabilizers

- Lithium, Valporic Acid, Lamictal - Low salt diet: elevated serum Lithium levels - Thiazide Diuretics and NSAIDS: elevated serum Lithium levels (ibuprofen) - Valporic acid: liver functions must be monitored as well as therapeutic levels.

Antipsychotics

- Work by blocking Dopamine receptor pathways in the brain | - Sedation, Hypotension, and Extrapyramidal Side Effects (EPS), and altered thermoregulation

Neuroleptic malignant syndrome

- Altered thermoregulation - Even slightly higher environmental temperature will raise core body temp and damage liver. - Cool environment, hydration, avoid direct sunlight.

Acute dystonia

- Slows continuous muscular contractions/spasms - Starts hours to days after start of treatment or increase in dose. - Mouth, jaw, face, and neck. - Eyes may lock up (oculogyric crises), jaw may lock (Trismus), tongue may roll back and block throat, neck may arch backwards. - Painful and frightening

Akathisia

- Compulsion to be in motion - Feel restless, and unable to stay still - "Crawling out of skin" - May be mistaken for worsening psychosis

Parkinsonian symptoms

- Bilateral Tremor, bradykinesia, rigidity, akinesia, inflexible facial expression - Often misdiagnosed as depression - Occur within weeks to months of start of treatment

Tardive dyskinesia

- WILL NEVER GO AWAY - Tongue thrusting, and twitches or spasms of the face - Involuntary twisting of limbs, trunk, neck and face

Treatment for Acute Dystonia (not life-threatening

–Anticholinergic Medications: benztropine (Cogentin), trihexiphenidyl (Artane), diphenhydramine (Benadryl) •IM or PO –Amantadine (Symatrel) •Longer onset of action (not used in acute): Used for prevention •Not very safe for use in elderly

Treatment for Parkinsonian and Akathisia

–Same meds, but effect is less predicible | –Propanolol and Clonidine: Akathisia •Hypotension and sedation can be unsafe in elderly

Treatment for Tardive Dyskinesia

NO TREATMENT | PERMANENT

Issues and Trends in Medication Use: Misuse of Drugs

- Overuse, underuse, erratic use, and contraindicated use - May occur due to inadequate skills of the nurse or the prescriber, misunderstanding of instructions, or inadequate funds to purchase prescribed medications.

What is the most important factor to include in safe medication use?

EDUCATION

Pearls for gerontological nurses

``` –Key persons •Who manages the medications •Make sure they are present when teaching is done –Environment •Minimize distractions •Make sure patient is comnfortable (Toileting, Hunger, thirst, etc…) –Timing –Communication •Simple and direct language –Reinforce teaching ```