Category: Introduction to Nursing Pharmacology

Drug Therapy in the 21st Century

Post author By Mark Anthony Sabandal
Post date February 14, 2011
1 Comment on Drug Therapy in the 21st Century

Drug Therapy in the 21st Century

Changes in Health Care in the 21st Century

Access to medical and pharmacologic information is available from many sources
Consumers are taking steps to demand specific treatments and considerations
Alternative therapies are being offered and advertised
Financial pressures are leading to early discharge
Patient teaching and home care provisions are vital

Federal Guidelines—Drug Advertising

When the advertisement states the indication, it must also include:
- Contraindications
- Adverse effects
- Precautions

Internet Sources for Drug Information

Pharmaceutical company information sites
Chat rooms with other people who are taking the drug
Online pharmacies
Lists of government regulations
Research reports about the drug and its effectiveness

Internet Site Evaluation

Navigation
- Is the site easy to access and navigate or confusing?
Contributor
- Who prepared the site and what are his qualifications? Is it reviewed, or is it purely commercial?
Dates
- Is the site updated frequently?
Accuracy/reliability
- Is the information supported by other sites, accurate, and in agreement with other sources you have reviewed? Are other links listed?

Problems Associated With OTC Medications

Can mask the signs and symptoms of disease
Can interact with prescription drugs
Can be taken in greater than the recommended dose, leading to toxicity

Over-the-Counter Drugs

Drugs that were “grandfathered” in
Former prescription drugs that have been tested and found to be safe for the general public if used as directed

Alternative Therapy Drawbacks

The active ingredient has not been tested by the FDA
Incidental ingredients are unknown
Patients do not always mention these therapies to their health care providers
Drug–alternative therapy interactions may occur

Controls for Alternative Therapy

Herbal medications and alternative therapies are not controlled or tested by the FDA
Advertisement for these drugs is not restricted because they are considered dietary supplements
No regulation by any industry

Off-Label Medications

Definition
- The use of a drug for an indication that is not approved by the FDA
Occurrence
- Commonly takes place in groups of patients for whom there is little premarketing testing
- Used with pediatric and geriatric populations

Health Care in Crisis

Skyrocketing cost of medical care and drugs
Huge research and equipment requirements to meet consumer demands
Rising cost of health insurance
Earlier discharge from hospitals

Measures to Protect the Public From Bioterrorism

Emergency preparedness at all levels of the government

Treatments for Exposure to Biological/Chemical Weapons

Recommended Treatments for Biological/Chemical Weapons Exposure

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Dosage Calculation

Dosage Calculations

Dosing Considerations

Sex
Weight
Age
Physical condition
Other drugs that the patient is taking

Accurate Dosing

Dependent on:
- The prescriber who orders the drug
- The pharmacist who dispenses the drug
- The nurse who administers the drug

Measuring Systems

Metric system
Apothecary system
Household system
Avoirdupois system

Metric System

Solids: gram (g)
- 1 milligram (mg) = 0.001 g
- 1 microgram (mcg) = 0.000001 g
- 1 kilogram (kg) = 1000 g
Liquids: liter (L)
- 1 milliliter (mL) = 0.001 L
- 1 mL = 1 cubic centimeter = 1 cc

Apothecary System

Solids: grain (gr)
- 60 gr = 1 dram (dr)
- 8 dr = 1 ounce (oz)
Liquids: minim (min)
- 60 minim = 1 fluidram (f dr)
- 8 f dr = 1 fluidounce (f oz)

Household System

Solids: pound (lb)
- 1 lb = 16 ounces (oz)
Liquids: pint (pt)
- 2 pt = 1 quart (qt)
- 4 qt = 1 gallon (gal)
- 16 oz = 1 pt = 2 cups (c)
- 32 tablespoons (tbsp) = 1 pt
- 3 teaspoons (tsp) = 1 tbsp
- 60 drops (gtt) = 1 tsp

Conversion Table

Conversion Between Systems

amount of drug available = amount of drug prescribed
one tablet or capsule # of tablets or capsules to give

amount of drug available = amount of drug prescribed
volume available volume to administer

Solving for X

amount of drug available = amount of drug prescribed
one tablet or capsule # of tablets or capsules to give

10 mg = 40 mg
1 x

Examples

1 oz = 6 oz
30 mL X

1 oz x X = 6 oz x 30 mL
1(oz)X = 180 (oz) (mL)

X = 180 (oz) (mL)
1 oz
X = 180 mL

Calculating IV Drip Rate

drops/min = mL of solution prescribed per hr x drops delivered per mL
60 min/hr

Difference Between Children and Adults

Children absorb, distribute, metabolize, and excrete drugs differently than adults
Children’s organs are not as developed as adults’ organs

Pediatric Dosage Calculation

Fried’s rule
Young’s rule
Clark’s rule
Surface area calculation

Fried’s Rule

This rule assumes that an adult dose would be appropriate for a child who is 12.5 years (150 months) of age

child’s dose (age <1 year) = infant’s age (in months)
150 months x average adult dose

Young’s Rule

child’s dose (age 1 to 12 years) =

child’s age in years
child’s age in years + 12 x average adult dose

Clark’s Rule

Uses the child’s weight to calculate the appropriate dose and assumes the adult dose is based on a 150-lb person

child’s dose = weight of child in pounds
150 pounds x average adult dose

Surface Area Calculation

Determine the child’s surface area with the use of a nomogram (the height and weight of the child are taken into consideration in this chart)

child’s dose = surface area in square meters
1.73 x average adult dose

Nomogram

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Toxic Effects of Drugs

Adverse Drug Reaction

Definition
- Adverse effects are undesired effects that may be unpleasant or even dangerous
Reasons adverse drug reactions occur:
- The drug may have other effects on the body besides the therapeutic effect
- The patient is sensitive to the drug given
- The drug’s action on the body causes other responses
- The patient is taking too much or too little of the drug

Types of Adverse Reactions

Primary actions
- Overdose: extension of the desired effect
Secondary actions
- Undesired effects produced in addition to the pharmacologic effect
Hypersensitivity reactions
- Excessive response to the primary or secondary effect of the drug

Types of Drug Allergies

Anaphylactic reaction
Cytotoxic reaction
Serum sickness reaction
Delayed allergic reaction

Variety of Adverse Effects Associated With Drug Use

Drug-Induced Tissue & Organ Damage

Dermatologic Reactions

Rash/hives
- Assessment
  - Abnormalities in the skin, red areas, blisters
- Interventions
  - May need to discontinue the medication
Stomatitis
- Assessment
  - Inflammation of the mucous membranes
- Interventions
  - Frequent mouth care

Drug-Induced Tissue and Organ Damage

Superinfections: destruction of the body’s normal flora
- Assessment
  - Fever, diarrhea, and vaginal discharge
- Interventions
  - Supportive care (mouth/skin care), give antifungal medications, stop drug responsible for the infection
Blood dyscrasia: bone marrow suppression
- Assessment
  - Fever, chills, and weakness
- Interventions
  - Monitor blood counts and protective isolation

Toxicity

Liver
- Assessment
  - Fever, nausea, jaundice, change in color of urine or stool, and elevated liver enzymes
- Interventions
  - Discontinue medication
Kidney
- Assessment
  - Change in urinary pattern or elevated BUN and creatinine
- Interventions
  - Notify physician, stop medication, or decrease dosage

Poisoning

Poisoning occurs when an overdose of a drug damages multiple body systems
Damage to multiple systems can lead to a fatal reaction

Altered Glucose Metabolism

Hypoglycemia
- Assessment finding: low serum blood glucose level
- Intervention: restore glucose to the body (D50)
Hyperglycemia
- Assessment finding: high serum glucose level
- Intervention: administer medications to decrease glucose level (insulin)

Electrolyte Imbalances

Hypokalemia
- Assessment finding: decrease in serum potassium level
- Interventions: replace serum potassium (IV or oral supplement) and monitor serum level of potassium
Hyperkalemia
- Assessment finding: increase in serum potassium level
- Interventions: decrease the serum potassium concentration (using sodium polystyrene sulfonate), monitor serum level of potassium, and monitor cardiac rhythm

Sensory Effects

Ocular toxicity
- Assessment finding: visual changes
- Interventions: monitor for visual changes when giving medication known to cause ocular damage; discontinue medication after notifying physician
Auditory damage
- Assessment finding: damage to the eighth cranial nerve
- Interventions: monitor for hearing loss; discontinue medication after notifying physician

Neurologic Effects

General central nervous system (CNS) effects
- Assessment: altered level of consciousness
- Intervention: prevent injury
Atropine-like (anticholinergic) effects
- Assessment: dry mouth, urinary retention, and blurred vision
- Interventions: sugarless lozenges to keep mouth moist; advise the patient to void before administration of the medication
Parkinson-like syndrome
- Assessment: muscle tremors and changes in gait
- Intervention: discontinue medication
Neuroleptic malignant syndrome
- Assessment: extrapyramidal symptoms
- Intervention: discontinue medication

Teratogenicity

Drugs may harm the developing fetus or embryo
Prevent teratogenicity through teaching
- Advise pregnant women that any medication may adversely affect the baby
- Weigh the actual benefits against the potential risks
- Advise pregnant women that they should not take medications without checking with their health care provider first

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Drugs and The Body

Drugs and the Body

Pharmacodynamics

Pharmacodynamics is the science of dealing with interactions between living organisms and foreign chemicals
Chemical reactions occur continuously in the body of each living system
When other chemicals (drugs) are added to the body, additional effects occur

Drug Actions

To replace or act as substitutes for missing chemicals
To increase or stimulate certain cellular activities
To depress or slow certain cellular activities
To interfere with the functioning of foreign cells

Receptor Cells

Receptor site reacts to certain chemicals
The better the fit between receptor site and chemical, the more pronounced the reaction
Enzymes within the body are needed to break down the chemicals to open up the receptor site

Lock & Key

Enzymes

Drugs can interfere with the enzymes that may be catalysts for chemical reactions
Enzymes produce a cascade effect

Pharmacokinetics

Onset of drug action
Drug half-life
Timing of the peak effect
Duration of drug effects
Metabolism or biotransformation of the drug
Site of excretion

The Processes by Which Drugs Are Handled in the Body

Pharmacokinetics

Critical concentration
- The amount of a drug that is needed to cause a therapeutic effect
Loading dose
- A higher dose than that usually used for treatment
Dynamic equilibrium
- The actual concentration that a drug reaches in the body

Dynamic Equilibrium

The actual amount of drug that reaches the body results in a dynamic equilibrium
Dynamic equilibrium is affected by:
- Absorption
- Distribution
- Biotransformation
- Excretion

Absorption

Administration
- Affected by route of administration
- Oral medications affected by presence of food in the stomach
First-pass effect
- Medications are extensively metabolized by the liver

Factors Affecting Absorption

Distribution

Protein binding
Blood–brain barrier
Placenta/breast milk

Biotransformation

The liver is the single most important site for biotransformation (metabolism)
This process breaks down medications
It helps to prevent medications from causing adverse effects on the body

Excretion

Removal of drugs from the body
Kidneys play the most important role in the excretion of medication

Half-Life

Half-life is the time it takes for the amount of drug in the body to decrease to one-half the peak level
Half-life is affected by the absorption, distribution, metabolism, and excretion

Pharmacokinetics

Half-life

Calculating Half-Life

Factors Influencing Drug Effects

Weight
Age
Gender
Physiologic factors
Pathologic factors
Genetic factors
Immunologic factors
Psychological factors
Environmental factors
Drug tolerance
Cumulative effect

Drug-to-Drug Interactions

Can occur any time two or more drugs are taken together
Can occur at:
- Site of absorption
- During distribution
- During biotransformation
- During excretion
- At the site of action

Drug–Food Interaction

Certain foods interact with drugs
Drugs are best taken on an empty stomach

Drug–Laboratory Test Interaction

Drugs may alter the results of lab testing
Laboratory tests may be used to monitor the effects of other medications

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Introduction to Drugs

Nurses’ Responsibility

Administering drug
Assessing for adverse drug effects
Intervening to make the drug regimen more tolerable
Providing patient teaching about drugs and the drug regimen
Monitoring and prevention of medication errors

Pharmacology

Pharmacology is the study of the biological effects of chemicals
Health care providers focus on how chemicals act on living organisms

Pharmacotherapeutics

A branch of pharmacology that uses drugs to treat, prevent, and diagnose disease
Pharmacotherapeutics focuses on:
- The drug’s effect on the body
- The body’s response to the drugs
Drug effects
- Therapeutic
- Adverse

Sources of Drugs

Plants
Animal products
Inorganic compounds
Synthetic sources

Plants

Animal Products

Animal products are used to replace human chemicals
Used less frequently due to genetic engineering
Synthetic preparations are considered safer

Inorganic Compounds

Focus on Elements Used for Their Therapeutic Effects

Synthetic Sources

Genetic engineering is used to alter bacteria to produce chemicals that are therapeutic and effective
Changes in chemical structure can make drugs more potent, more stable, and less toxic

Drug Evaluation

Preclinical trials
- Chemicals tested on laboratory animals
Phase I studies
- Chemicals tested on human volunteers
Phase II studies
- Drug tried on informed patients
Phase III studies
- Drug used in vast clinical market
Phase IV studies
- Continual evaluation of the drug

Legislation

Pregnancy Category

Controlled Substances

Drug Names

Chemical name
Generic name
Trade name

Drug Name

Chemical name
- (+/-)-2-(p-isobutylphenyl) propionic acid
Generic name
- Ibuprofen
Trade name
- Motrin®, Advil®

Types of Drugs

Over-the-counter drugs
Prescription drugs

Over-the-Counter Drugs

Drugs considered very safe and useful to patients without a prescription
Drugs may previously have been prescription medications (eg, loratadine)

Concerns With OTC Medications

OTC drugs can mask the signs and symptoms of underlying disease
Taking OTC drugs with prescription medications can result in drug interaction
Taking prescription medication incorrectly with OTC drugs could result in serious overdose

Sources of Drug Information

Reference books
Journals
Internet

•Chapter 1

•Introduction to Drugs

•Nurses’ Responsibility

•Administering drug

•Assessing for adverse drug effects

•Intervening to make the drug regimen more tolerable

•Providing patient teaching about drugs and the drug regimen

•Monitoring and prevention of medication errors

•Pharmacology

•Pharmacology is the study of the biological effects of chemicals

•Health care providers focus on how chemicals act on living organisms

•Pharmacotherapeutics

•A branch of pharmacology that uses drugs to treat, prevent, and diagnose disease

•Pharmacotherapeutics focuses on:

–The drug’s effect on the body

–The body’s response to the drugs

•Drug effects

–Therapeutic

–Adverse

•Sources of Drugs

•Plants

•Animal products

•Inorganic compounds

•Synthetic sources

•Plants

•Animal Products

•Animal products are used to replace human chemicals

•Used less frequently due to genetic engineering

•Synthetic preparations are considered safer

•Inorganic Compounds

•Synthetic Sources

•Genetic engineering is used to alter bacteria to produce chemicals that are therapeutic and effective

•Changes in chemical structure can make drugs more potent, more stable, and less toxic

•Drug Evaluation

•Preclinical trials

–Chemicals tested on laboratory animals

•Phase I studies

–Chemicals tested on human volunteers

•Phase II studies

–Drug tried on informed patients

•Phase III studies

–Drug used in vast clinical market

•Phase IV studies

–Continual evaluation of the drug

•Legislation

•Pregnancy Categories

•Controlled Substances

•Drug Names

•Chemical name

•Generic name

•Trade name

•Drug Name

•Chemical name

–(+/-)-2-(p-isobutylphenyl) propionic acid

•Generic name

–Ibuprofen

•Trade name

–Motrin®, Advil®

•Types of Drugs

•Over-the-counter drugs

•Prescription drugs

•Over-the-Counter Drugs

•Drugs considered very safe and useful to patients without a prescription

•Drugs may previously have been prescription medications (eg, loratadine)

•Concerns With OTC Medications

•OTC drugs can mask the signs and symptoms of underlying disease

•Taking OTC drugs with prescription medications can result in drug interaction

•Taking prescription medication incorrectly with OTC drugs could result in serious overdose

•Sources of Drug Information

•Package insert

•Reference books

•Journals

•Internet

•