Download More Foundations (not in your book

More Foundations (not in your book!) and Drug Therapy Across the Lifespan
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Lecture 2
Transcultural Considerations
Racial, hereditary, and genetic factors affect the way clients metabolize drugs and
experience and tolerate medications and their side effects
Age, gender, dietary practices, living conditions, socio-economic status and high risk
behaviors also affect drug metabolism, efficacy, and client compliance
Client’s religious practices may prescribe what is acceptable in terms of diet (i.e. Jews
& kashrut, Muslims & Ramadan)
Ethnocultural perceptions and beliefs of illness and disease also affect the client’s
compliance with medical treatment and drug therapy
Drug Interaction
An altered or modified action or effect of a drug as a result of interaction with one or
more other drugs
 Do not confuse with:
– Adverse drug reaction - an undesirable drug effect from mild to severe
– Drug incompatibility - chemical or physical reaction that occurs among two or
more drugs outside the body
Pharmacokinetic Interaction
Absorption
 When a person takes two drugs at the same time, the rate of absorption of one or both
drugs can change - one drug can decrease, increase or block the absorption rate of
another drug. It does this in 3 ways, by:
– Decreasing or increasing GI emptying time
– Changing the gastric pH
– Forming drug complexes (such as antacids & tetracyline (which makes the
tetracycline ineffective)
(These are discussed on next slides)
Pharmacokinetic Interaction
Absorption-Cont.
 Drugs that increase the speed of gastric emptying - increase GI motility  what
happens? (decrease in drug absorption in turn lessens the pharmacological reaction)
 Drugs that decrease gastric emptying & decrease GI motility  an increase in
absorption rate  inc. in amount of drug absorption (for those drugs absorbed in the
stomach) What is result?
 Remember the longer the drug stays in the GI system the greater the absorption.
Pharmacokinetic Interaction
Distribution
 Drug distribution to tissues can be affected by its binding to plasma/serum protein
 Remember only drugs unbound are free and can enter body tissues
 Two highly bound protein drugs compete for protein in plasma  a decrease in
binding of one or both drugs  more free drug in circulation leads to drug toxicity
Pharmacokinetic Interaction
Excretion
 Most drugs are excreted in the urine, some through the bile which passes into GI tract
 Drugs can increase or decrease renal excretion of other drugs
-Drugs that decrease Cardiac output decrease renal blood flow and delay excretion
(Result?)
-Diuretics decrease reabsorption of water in the kidneys, and can lead to hypokalemia
and Digoxin toxicity
Pharmacodynamic Interactions
 Reactions that result in additive, synergistic (potentiation), or antagonistic drug effects
 Additive Drug Effect - when two drugs with similar action from the same “category”
(NOT THE SAME CLASS) are administered together
* Result is the sum of the effects of the two drugs
* Desirable: diuretic and Beta Blocker to decrease B/P or
 Undesirable: alcohol & aspirin > GI bleeding
Pharmacodynamic Interactions
 Two more examples:
 Desirable = Two analgesics (pain medications) Tylenol and codeine - together increase
pain relief
 Undesirable = Apresoline for HTN & nitroglycerine for angina > hypotension.
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Pharmacodynamic Interactions
Synergistic Drug Effect - When one drug potentiates or enhances the effect of the
other drug
* Greater than the effect of each alone
* Can be desirable or undesirable
Desirable: Demerol (a narcotic) + Phenergan (an antihistamine) = Phenergan
potentiates the effect of Demerol – Desirable  less Demerol is needed
Undesirable: Alcohol + a sedative-hypnotic (valium)  an increase in CNS
depression
Some antibacterials have an enzyme inhibitor added to potentiate the effect of the drug
(Desirable!)
Pharmacodynamic Interactions
 Antagonistic Drug Effect - Two drugs in opposing drug categories given to the same
patient; they have opposite effects and cancel each other out – Usually undesirable
Desirable example: naloxone (Narcan) is an antagonist given after a morphine
overdose to reverse the narcotic
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Drug – Food Interactions
Food can increase, decrease, or delay drug absorption
Decrease - with food binding ex. tetracycline and dairy products = less plasma
concentration of tetracycline
* Take 1h before or 2 h after meals & no dairy
The classic interaction is when an antidepressant of the MAO (monoamine oxidase)
inhibitor class is taken with tyramine rich foods - Cheese, wine, beer, yogurt, bananas.
- May result in hypertensive crisis
- Clients must be educated to avoid these foods when taking MAO inhibitors
OTC Drugs
 Cold and Cough Remedies - Most stimulate the sympathetic nervous system. Clients
with heart disease, HTN, thyroid disease should not take these without approval
 Sleep Aids - Most contain antihistamine to cause drowsiness. Should not be taken
with a CNS depressant due to additive effects.
*Can cause CNS stimulation in small children and elderly
OTC Drugs
 Weight-Control Drugs - Many on the market. Contraindicated for clients with heart
disease, Hypertension, diabetes mellitus, thyroid disease
 Drug Abuse is the excessive self-administration of a drug that could result in addiction
(physical dependence) and could be detrimental to one’s health.
Pediatrics: What You Need to Know!
 Infants: Newborn – 1 year old
– Drugs generally remain active longer
• Drug levels decline more slowly
• Drug effects are prolonged
• Drug effects may even be more intense
– Increased drug sensitivity due to immaturity of body systems
Pediatrics
 Children 1-12 years
– Most pharmacokinetic parameters similar to those of adults
• Except  they metabolize drugs faster than adults (especially age 1-2)
• May need increased dose / more frequent dosing interval for drugs eliminated
by liver
– Adverse Reactions
• Some drugs cause unique adverse reactions in children –should avoid if possible
Pediatrics
 Dose Determination for Children
– Established dosing
• Somewhat according to age (for metabolism)
• According to weight (mg / kg)
– No established dosing
• Extrapolated from adult dosing
Geriatrics: What You Need to Know!
Drug Therapy
Geriatrics
 Geriatric population
– Use more medications than any other age group
• Elderly (65 or older) represent 13% of US population
• They use 30% of all prescribed drugs
• They also use 40% of the OTC drugs
• Need for more medications related to
– More diseases, and increased severity of disease
– Excessive prescribing
Geriatrics
 Problems with drug therapy
– Elderly are more sensitive to drugs
• Pharmacokinetic changes – especially decreased metabolism
– Decline of hepatic metabolism
– Half life of drugs may increase
– Decline in “first pass effect”
– Degree of decline varies among individuals
– What is net result?:
• Elderly experience more adverse drug reactions
– Elderly experience more drug-drug interactions
• Often related to compliance issues
• Related to polypharmacy
Geriatrics
 Adverse Drug Reactions (ADR)
– Seven times more common in the elderly than in younger adults
• Accounts for 16% of hospital admissions
• Accounts for 50% of medication-related deaths
• Most ADR are dose related
Geriatrics
 Compliance
– 40% of elderly do not take medications as prescribed
• May never fill or refill prescriptions
• Drugs may be cost prohibitive
– Would rather put food on the table
• May not have received good teaching about drugs
– May take them erratically
– May not understand complex regimens
• May be forgetful / confused
Geriatrics
 Compliance
– Steps to improve medication adherence
• Make the regimen simple
• Explain treatment plan clearly and write it down
• Ask about cost concerns; arrange for help
• Inquire about whether patient can get to a pharmacy – are there friends / family
to help
• Use of labels, calendars, diary, pill box