Pediatric and Geriatric Pharmacology

Pediatric and Geriatric Nursing Pharmacology lecture notes


Pediatric Pharmacology
Pharmacokinetics
Absorption
Gastric pH alkaline at birth and does not reach adult acidity until age 1-3y
Gastric emptying prolonged in neonates
Greater GI surface area can increase absorption in infants and young children
Topicals more readily absorbed due to thinner, more porous skin in infants and young children


Pediatric Pharmacology
Pharmacokinetics
Distribution
Children under 2y require higher doses of water soluble medications and lower doses of lipid soluble medications
Infants have less albumin and need less of highly protein bound drugs

Pediatric Pharmacology
Pharmacokinetics
Metabolism
Infants have slower metabolic rate but then this speeds up in children
First pass effect can be problematic – sometimes resulting in oral route being bypassed in favor of another route (ex. Rectal)
Excretion
Reduced function until about 9m of age
Can be reduced again in adolescence


Pediatric Pharmacology
Pediatric Medication Administration
Dosing based on:
Weight (kg)
Body surface area (BSA)
Consider developmental age when administering medications
Use topical analgesics prior to painful injections

Drug Therapy in Geriatric Patients
Elderly patients constitute 12% of the population but use 31% of the nation’s prescribed drugs


Drug Complications in the Elderly
Contributing factors to drug complications are
Altered pharmacokinetics
Multiple illnesses
Multiple drug therapy/polypharmacy
Poor compliance


Altered Pharmacokinetics

Distribution
Geriatric Pharmacology
Pharmacokinetics
Absorption is slowed
Distribution changes due to loss of water and increase in adipose tissue
Metabolism is slowed due to diminished liver function
Excretion is slowed due to diminished kidney function and decreased cardiac output
Metabolism
Decreased hepatic metabolism
Renal Excretion
In the elderly, the proper index of renal function is creatinine clearance, not serum creatinine
Excretion
Reduced renal excretion

Adverse Drug Reactions
Seven times more likely in elderly
16% of hospital admissions
50% of all medication-related deaths

Polypharmacy – the use of multiple drugs together
Contributes to:
Falls
Incontinence
Confusion
Malnutrition
Renal dysfunction
Liver dysfunction
Nonadherence

Monitoring for Adverse Drug Reactions
Take thorough drug history
Low dosing
Plasma level monitoring
Simplest regimen
Review drug treatment schedule


Promoting Compliance
Simple drug regimen
Verbal and written instructions
Appropriate dosage form
Clear labeling
Daily reminders
Support system
Frequent monitoring


Geriatric Pharmacology
Effects of Selected Drugs in Older Adults
Hypnotics / Sedatives
More sensitive to medication – need lower doses
Diuretics and Anti-hypertensives
More prone to electrolyte disturbances, orthostatic hypotension
Cardiac Glycosides
Lower dose needed due to reduced renal function
Anti-coagulants
Highly-protein bound – bleeding problems can occur as elderly often have less protein reserves


Geriatric Pharmacology
Effects of Selected Drugs in Older Adults
Anti-bacterials
Dose may need to be reduced due to decreased renal function
Gastrointestinal drugs
Laxative use can cause electrolyte disturbances
Cimetidine (Tagamet) – many drug interactions
Anti-depressants
TCAs less useful – strong anticholinergic properties


Patient Education
Medication generic and trade names
Dose
Use
Self-administration
Diet changes
Side Effects
Cultural / Home / Work Considerations

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Drug Interaction: OTC,Drugs of abuse and Herbals

Drug Interaction: OTC ,Drugs of abuse and Herbals Nursing Pharmacology Lecture notes


Drug Interactions
An altered or modified action or effect of a drug as a result of an interaction with one or more other drugs
Example: warfarin and levofloxacin result in an excessive increase in the INR


Drug Interactions
Pharmacokinetics
Absorption
Change gastric pH
↑ or ↓ gastric emptying time
Forming drug complexes
Distribution
Drug concentration in the blood
Protein-binding "power" of the drug
Volume of distribution


Drug Interactions
Pharmacokinetics
Metabolism
Enzyme inducers
Enzyme inhibitors
Excretion
Drugs that alter urine pH
Drugs that alter kidney perfusion


Drug Interactions
Pharmacodynamics
Additive effects - 2 or more drugs of similar action are given and is the sum of the effects of the drugs
Synergistic effects – 2 or more drugs are given, one can potentiate effects of others and the sum is greater than expected combined effects
Antagonistic effects – 2 or more drugs are given and one negate the effects of others


Drug-Food Interactions
Food can increase, decrease or delay drug absorption
Example: dairy binds with tetracyclines
Example: food increases metoprolol absorption
Protein intake is important in protein-bound drugs
"Classic" interaction – MAOI and tyramine rich foods (wines, cheeses, beer, yogurt, sour cream, bananas) – results in norepinephrine release resulting in hypertensive crisis


Drug-Laboratory Interactions
Abnormal laboratory values (albumin, electrolytes, etc) can affect drug actions
Example: Hypokalemia with digoxin can result in digoxin toxicity

Drug-Induced Photosensitivity
Photosensitivity – skin reaction that can occur with exposure to sunlight
Examples:
Sulfa drugs
Tetracyclines
Methotrexate
Amiodarone

Over-the-Counter (OTC) Drugs
OTC drugs – those available without a prescription
FDA responsible for monitoring


Over-the-Counter (OTC) Drugs
Concerns with OTCs
Delays in diagnosis of potentially serious illness in those that self-treat
Symptoms may be masked making diagnosis difficult
Labels and instructions not clearly followed
Not consulting a healthcare professional before use
Potential for interactions with prescribed, otc, or herbal medications
Potential for overdose


Drugs of Abuse
Drug Misuse – indiscriminate use of a substance for a purpose other than which it is intended
Drug Abuse – drug use inconsistent with medical or social norms
An overindulgence in a substance that results in physical, psychological or social harm to an individual
Drug Addiction – compulsive, uncontrolled craving for the substance that causes severe physical or psychological reactions


Drugs of Abuse
Tolerance – reduced responsiveness of neurons in the brain leads to tolerance, requiring a larger dose of the substance to obtain the same "high"
Cue-induced craving – craving for the substance after a period of abstinence due to circumstances that prompt an association with the substance


Drugs of Abuse
Intoxication – state of being poisoned by the drug or substance
Detoxification – treatment to diminish or remove the substance or effects from the body
Withdrawal syndrome – s/s that occur in physically dependent persons when the substance is stopped
Alcohol, opioids, benzos cause strong reaction
Cannaboids, amphetamines weak reaction
Hallucinogens little to no reaction


Stimulants - Nicotine
Pharmacodynamics
Stimulates release of dopamine
Pharmacokinetics
Rapidly absorbed into blood from lungs; transfers easily into breast milk
Elimination 1-2h
Side Effects
CNS stimulation
Treatment
Nicotine replacement therapy; bupropion (Zyban), Chantix


Stimulants - Cocaine
Pharmacodynamics
Stimulates dopamine receptors resulting in rapid dependence; increases norepinephrine release
Pharmacokinetics
Peak depends upon route; duration generally lasts 60 – 90 min
Easily crosses placental barrier
Side Effects
CNS stimulation, mood swings, memory loss, paranoia, depression
Treatment
Control sx
Other tx remains investigational


Stimulants - Amphetamines
Pharmacodynamics
Similar to cocaine
Pharmacokinetics
Peak 60 -90 min, duration 2-4h
Side Effects
Increased alertness, anorexia, increased HR and BP, anxiety, paranoia
Treatment
Sx control
No specific medications helpful


Stimulants - Caffeine
Pharmacodynamics
Stimulates cns; diuretic effect
Pharmacokinetics
Peaks 1h
Side Effects
CNS irritability, insomnia, gastric hyperacidity, tachycardia
Treatments
Tx sx
Gradual reduction of caffeine


Depressants - Alcohol
Pharmacodynamics
Binds to dopamine receptors; CNS depressing effects
Pharmacokinetics
Food delays absorption
Metabolized at a constant rate (1drink/hr)
Side Effects
Relaxation, impaired judgment and motor skills, vomiting, coma, seizures, death
Treatments
Benzodiazepines, antipsychotics, disulfuram (Antabuse), naltrexone (ReVia), acamprosate (Campral)


Depressants – Sedatives/Hypnotics
Pharmacodynamics
CNS depressing effects
Pharmacokinetics
Effects can vary depending on route of administration
Side Effects
Respiratory depression, death, little cross-tolerance with opioids
Withdrawal peaks 2-3d short-acting, 7d for long-acting
Treatments
Flumazenil (Romazicon) – antidote for benzo OD
Sx control


Depressants - Opioids
Pharmacodynamics
CNS depressing effects
Pharmacokinetics
Vary depending upon route of administration
Side Effects
Drowsiness, slurred speech, flushed feeling, feeling of euphoria, respiratory depression, death
Treatments
Naloxone (Narcan) – antidote for OD
Methadone, Naltrexone (ReVia), Suboxone


Other Drugs of Abuse
Cannabis
Psychedelic Agents
Inhalants


Herbal Therapy
Herbal therapy – plant or plant part used for its medicinal properties
NOT approved by the FDA
Some oversight by the FDA and National Center for Complimentary and Alternative Medicine (Branch of NIH)


Herbal Therapy
Fresh herbs
Dried herbs
Extracts
Oils
Salves
Teas
Tinctures
Syrups


Common Herbal Remedies
Aloe
Used to tx burns, insect bites, psoriasis
Can be toxic if ingested in large quantities
Chamomile
Used for GI complaints, mild sedating effects
Careful with ragweed allergy
Echinacea
Used as immune booster
Uninterrupted use not recommended
Garlic
Used to lower cholesterol, blood pressure and anti-platelet activity, anti-infective properties
Can cause bleeding


Common Herbal Remedies
Ginger
Used for GI complaints, migraines, joint pain
Highly protein bound
Milk Thistle
Used to protect the liver
St John’s Wart
Used to treat depression and anxiety
Concerns with increased suicide risk
Valerian
Used to treat anxiety and insomnia


Concerns About Herbals
Little is known about many herbs
Some forms of administration safe, others toxic
Variability in purity and active ingredients
Patients consider these "natural" remedies and may not report their use unless specifically asked


Patient Education Related to Herbals
Avoid if pregnant (or attempting to conceive) or nursing
Avoid in young children
Treat the herb just like any other medicine
Store in a safe place
Use products from reputable companies and buy products from the same companies
Discuss herb use with your health care provider

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Culture,Ethics &and Drugs of abuse in Nursing Pharmacology

Culture,Ethics &and Drugs of abuse in Nursing Pharmacology lecture notes

Controlled Substances

Schedule I
Drugs with high potential for abuse – heroin, cocaine
Schedule II
Drugs with highs potential for abuse but have medical potential – oxycodone, morphine, etc
Schedule III
Less potential for abuse – codeine, propoxyphene
Schedule IV
May cause dependence – lorazepam, diazepam, etc
Schedule V
Limited potential for abuse – codeine in cough preps


Nursing Responsibilities
Double-lock and key
Account for all use and verify counts
Witness and account for all wasting
Limit access to those authorized to administer, prepare, stock narcotics

Know state regulations and state Nurse Practice Act!


Drug Names

Chemical Name – chemical structure
Generic Name – official name
Trade (Brand) Name – company name
Example: furosemide (Lasix)


Pregnancy Categories
A – No risk to fetus. Studies show no fetal harm.
B – No risk in animal studies and well-controlled studies in pregnant women are not available. It is assumed there is little or no risk in pregnant women.
C – Animal studies indicate a risk to the fetus. Controlled studies on women are not available. Risk vs benefit must be weighed. It could be used in life threatening events.
D – A risk to human fetus has been proved. Risk vs benefit must outweigh benefit. It could be used in life threatening conditions.
X – A risk to the human fetus has been proved. Risk outweighs benefit and the drug should be avoided during pregnancy.


Pregnancy Category: Examples of Drugs
A – ?
B – acetaminophen (Tylenol)
C – nifedipine (Procardia)
D – paroxetine (Paxil)
X – atorvastatin (Lipitor)


Culture and Medicine
Family organization
Spirituality
Nutrition
Health care practices
Complimentary practices
Self-medicating practices
Sick role
Pain
Mental illness
Health care practitioners
Gender and health care

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Pharmacodynamics

Pharmacodynamic Phase of drug action nursing lecture notes

Pharmacodynamics
What the drug does to the body
Primary effects – desired effects
Secondary effects – may be desirable or undesirable
Dose Response – dose needed to produce desired response
Maximal efficacy – maximum drug effect


Onset, Peak, Duration


Receptors
Drugs act at receptors to produce or block a response
Agonists – drugs that produce a response
Antagonists – drugs that block a response

Cholinergic Receptors

Alpha and Beta Receptors


4 Categories of Drug Action
Stimulation or Depression
Replacement
Inhibition or Killing of Organisms
Irritation

Therapeutic Index
Safety margin of the drug
Low or narrow = greater danger of toxicity
Example: Digoxin (0.5 – 2.0ng/ml)


Peak & Trough Levels, Loading Dose
Peak level – highest plasma concentration of a drug
Trough level – lowest plasma concentration of a drug
Loading Dose – large initial administration to achieve minimum effective concentration of a drug


Effects
Side effects – effects not related to desired effects of the drug
Adverse reaction – more severe than side effects
Toxic effects – adverse effects - depends upon drug

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Pharmacokinetics Lecture notes

Pharmacokinetics Lecture notes

Four basic pharmacokinetic processes are

¬Drug movement throughout the body
¬Absorption – movement of drug from its site of administration into blood
¬Dissolve – must dissolve before being absorbed
¬Surface area – the larger the faster
¬Blood flow – most rapid where blood flow is high
¬Lipid solubility - the higher the faster
¬pH partitioning

Absorption - Routes
IV – no barriers to absorption
Intramuscular – good for poorly soluble drugs, "time released"
Subcutaneous – again no significant barriers
Oral – must pass through cells of epithelium, enteric coating
Safer but highly variable absorption – enteric, sustained-release, tablets

Factors Affecting Drug Absorption
Rate of dissolution
Surface area
Blood flow
Lipid solubility
pH partitioning

Distribution
Blood flow to tissues
Exiting the vascular system once it has been delivered – pass through pores in capillary wall
Protein - binding
Drugs can bind with proteins
Parts of drugs will be bound during any given time period
Impedes drug’s ability to reach sites of action, metabolism, or excretion

Drug Distribution
Factors influencing distribution are
Blood flow to tissue
– Exiting the vascular system
– The blood-brain barrier
– Placental drug transfer

Metabolism
LIVER
Enzymatic alteration of drug structure
Consequences of metabolism
Accelerated renal excretion – kidney cannot excrete highly lipid soluable
Drug inactivation
Increased therapeutic action
Activation of prodrugs
Increased or decreased toxicity



Drug Metabolism
Biotransformation
Liver—primary site of drug metabolism
P450 system (cytochrome P450)

Drug Metabolism—Implications
Therapeutic consequences are
Accelerated drug excretion
Drug inactivation
Increased therapeutic action
Activation of prodrugs
Toxicity variations

Routes of Administration
Two major groups
Enteral
Via gastrointestinal tract
Parenteral
Outside the gastrointestinal tract
Usually referred to as "by injection"
Common routes—intravenous, subcutaneous, intramuscular

Special Considerations in Drug Metabolism
Age
Induction of drug-metabolizing enzymes
First-pass effect
Nutritional status
Competition between drugs

Drug Excretion
Removal of drug from the body
Kidney—via three processes
Glomerular filtration
Passive tubular reabsorption
Active tubular secretion

Time Course of Drug Responses
Plasma drug levels
Minimum effective concentration (MEC)
Toxic concentration
Therapeutic range
Drug half-life
Loading dose
Maintenance dose


Achieving and Maintaining Therapeutic Concentrations

•Repeated dose scheduling
•Drug accumulates in blood stream
•Plateau reached
•Amount administered = amount excreted


Differentiate between Loading Dose and Maintenance Dose

•Loading Dose
–Higher amount of given drug

•Maintenance Dose
–Doses administered at intermittent (scheduled) times

Drug Half-life
The time for the amount of drug in the body to decrease by 50%

Excretion
KIDNEY
Glomerular filtration – blood to tubular urine
Tubular reabsorption
Active tubular secretion – pumps for organic acids and organic bases – to urine

Monitoring drug levels
Plasma drug levels
Therapeutic range

Drug Half-life
Time requires for the amount of drug in the body to decrease by 50%
Will determine dosing requirements

Goal - plateau

Dosing
Loading doses – when plateau must be achieved quickly
Routine smaller doses – maintenance doses
Peak and trough levels

Maximal efficacy – largest effect a drug can produce

Potency – one that produces its effects at lower dosages

Receptors
Drugs bind to receptors to produce effects
Reversible

All that drugs can do is mimic the physiological activity of the body’s own molecules
Block the physiological activity of the body’s own molecules

Agonists
Mimic the body’s own regulatory molecules

Antagonists
Drugs that block the actions of endogenous regulators

Partial agonists
Mimic the actions but with reduced intensity

Drug Interactions
Can have varying effects
Direct chemical or physical – IV preparation
Drug – Food Interactions
Frequently decreased rate of absorption
Grapefruit juice can inhibit metabolism
"with food" – with or shortly after meal
"empty stomach" – one hour prior to meal or two hours after

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Drug Regulation, Development, Names, and Information

Drug Regulation, Development, Names, and Information Lecture notes

Federal Pure Food and Drug Act—1906
Food, Drug and Cosmetic Act—1938
Kefauver-Harris Amendments—1962
Controlled Substances Act—1970
Food and Drug Administration Modernization Act—1997


Drug Research
Identification of potentially useful chemical → Preclinical testing → development of research study → phase I → phase II → phase III / IV → Submission of New Drug Application (NDA) to FDA → Drug to market

New Drug Development
Stages of drug development
Preclinical testing
Clinical testing
Preclinical Testing
Required before a new drug may be tested in humans
Drug evaluated for
Toxicities
Pharmacokinetic properties
Potentially useful biologic effect
– May take 1 to 5 years
May be tested on humans after sufficient preclinical data are collected

Clinical Testing
There are four phases
Phase I
Normal volunteers
Evaluation of drug metabolism
Effects on humans

Clinical Testing (cont.)
Phase II and Phase III
– Tested in patients
Determine therapeutic effects
Dosage ranges
Patient safety
Total number of subjects—500 to 5000
Duration of phases—3 to 6 months
After Phase III, application for conditionalapproval is made

Clinical Testing (cont.)
Phase IV: Postmarketing Surveillance
With conditional approval from the FDA, Phase IV begins
Usage is for the general population
New side effects may be discovered
Voluntary reporting by health professions is essential

Limitations to Testing Procedure
Women
– FDA 1990s
Children

Drug Names
Chemical name
Chemical description of the drug
Generic name
Assigned by the United States Adopted Names Council
Trade name
Proprietary or brand name

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Pharmacology and the Nursing Process

Pharmacology and the Nursing Process Lecture notes

Steps in the nursing process are
Preadministration
Analysis and Nursing Diagnoses
Planning
Implementation
Evaluation

Application of Pharmacology in Patient Care
Preadministration assessment
Identify high-risk patients
Assess the patient’s capacity for self-care
Evaluate and Promote Therapeutic Effects
Evaluate therapeutic response
Promote compliance
Implement nondrug measures



Capacity for Self-Care Factors
Visual acuity
Manual dexterity
Intellectual ability
Memory
Finances
Cultural attitudes

Analysis
When analyzing drug therapy, one must
Judge the appropriateness of therapy
Identify potential health problems
Analyze patient’s self-care ability

Evaluation—Drug Therapy
The patient is evaluated for
Therapeutic response
Adverse drug reactions/interactions
Compliance with drug therapy
Satisfaction with the drug regimen

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Intro to Pharmacology

Intro to Pharmacology lecture notes

Define the following terms
Drug
Pharmacology
Clinical pharmacology
Pharmacotherapeutics

Properties of an Ideal Drug
Effectiveness
Safety
Selectivity
Reversible action
Predictability
Ease of administration
Minimal drug interactions
Low cost
Chemical stability
Possession of a simple generic name

Intensity of Drug Responses

Multiple factors influencing drug response are
Administration
Pharmacokinetics
Pharmacodynamics
Individual variations

Pharmacokinetics

The four major pharmacokinetic processes are
Drug absorption
Drug distribution
Drug metabolism
Drug excretion

Pharmacodynamics
The impact of drugs on the body once a day has
reached its site of action

Therapeutic Objective
Drug therapy should provide maximal benefitwith minimal harm

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