BASIC PHARMACOLOGIC PRINCIPLES NUR 106
Objectives
Identify the agencies and legislations that help to ensure drug quality and safety.
Distinguish between drug names and drug classifications.
Identify the four processes of pharmacokinetics.
Describe the influence of protein binding on drug bioavailability.
Differentiate the four types of drug interactions.
Identify the factors that affect drug absorption.
Identify the primary site of drug metabolism in the body.
Discuss how drug excretion occurs in the body.
Define onset, peak and duration of drug action; therapeutic level, peak and trough level and biological half-life.
Compare and contrast the different types of medication effects and reactions.
Describe the “Six Rights” of medication administration.
Demonstrate proper usage of the 24-hour clock.
Identify “Do Not Use” abbreviations.
Identify the different routes of drug administration.
The "Six Rights" of medication administration include:
Right Patient: Ensure that the medication is given to the correct person.
Right Medication: Verify that the medication being administered is the correct one prescribed.
Right Dose: Double-check that the dosage is accurate as per prescription guidelines.
Right Time: Administer the medication at the correct time and frequency.
Right Route: Use the correct method of administration as indicated (e.g., oral, intravenous).
Right Documentation: Properly document the medication administration after giving it to the patient.
Medication Legislation and Safety
Drug Legislation – Regulates quality and safety.
Food and Drug Administration (FDA).
Controlled Substances Act.
Nurse Practice Acts.
State and Federal Regulations.
Special Regulations for Controlled Substances
Narcotics are stored in a locked, secure area.
Narcotic counts.
RN witness for disposal of narcotics.
Proper disposal of unused narcotics.
Documentation.
Nontherapeutic Medication Use
Definition: Use of medication for reasons other than their intended effect.
Use of prescription drugs without prescription.
Commonly abused prescription medications:
Opioids – hydrocodone, oxycodone, etc.
Stimulants – Adderall, Ritalin, etc.
Benzodiazepines – Valium, Xanax, etc.
Medication Names
Chemical name: Rarely used in clinical practice.
Generic name: Also referred to as the “official” name (e.g., Acetaminophen); Each drug has only one.
Trade name: Also referred to as the “brand” name (e.g., Tylenol); Name in which manufacturer markets the medication; May have more than one.
Look alike/sound alike names: Examples include lorazepam vs. clonazepam and Inderal vs Adderall.
Medication Classification
Method of grouping medications.
Medications can be classified by:
Usage.
Body systems.
Symptoms.
Chemical class.
Important note: Drugs can have more than one use and work for more than one body system.
Medication Forms
The form (how it comes) of medication determines the route(how you give it).
Different medication forms have different rates of absorption and metabolism:
Liquid
Tablet
Capsule
Powder
Aerosol
Ointment
Suppositories
Drops
IV infusions
IM injections
SQ injections
Gel
ID injections
Patches
Implants
Inhalers
Routes of Administration
Oral(Always swallowed)
Rectal
Inhalation
Enteral (stomach)
Sublingual
Buccal/transmucosal
Subcutaneous
Intraspinal
Topical
Instillations
Intravenous
Intramuscular
Intradermal
Intrathecal
Epidural
Therapeutic Window and Safety
Not enough (sub-therapeutic) -> harmful
Therapeutic -> beneficial
Too much (toxicity) -> harmful
Goal: Give a dose that will benefit (not harm) the patient
Note: Therapeutic window concepts include balancing efficacy with safety.
Pharmacokinetics
Four processes: Absorption, Distribution, Metabolism, Excretion.
Absorption: Movement of medication into the bloodstream from the site of administration.
Distribution: Delivery of medication to specific body sites.
Metabolism: Biochemical modification of drugs, often to enhance excretion.
Excretion: Elimination of drugs from the body.
Absorption
Movement of medication into the bloodstream from the site of administration.
Factors affecting absorption:
Route.
Form.
Blood flow to site of administration.
Body surface area.
Lipid solubility.
Absorption routes by form:
Topical, oral, Sublingual/buccal/inhalation, SQ, IM, IV.
Distribution
Delivery of medication to specific body compartments.
Affected by:
Physical and chemical properties of the drug.
Physiology of the patient.
Circulation.
Membrane permeability.
Protein binding.
Low albumin levels = more unbound medication in system and less going to target organ.
Clinical note: Low albumin increases the free (unbound) fraction of drug, potentially increasing effects and toxicity.
Metabolism
Occurs after medication reaches its site of action (distribution).
Drugs are metabolized into a less active or inactive form for easier excretion.
Most drugs are metabolized by the liver.
Risk of medication toxicity if the liver is not functioning properly.
Other metabolism sites include kidney, blood, and intestines.
Excretion
Kidneys are the main organ that excrete medications.
Patients with declining renal function are at risk for medication toxicity.
Other excretion sites include liver, bowels, lungs, exocrine glands.
Types of Medication Actions
Therapeutic Effect – what we expect.
Side effect – do they outweigh the benefits of the med? Predictable and expected
Toxic effect – know the antidotes.
Idiosyncratic reaction – unpredictable effect.
Cumulative/Synergistic effect – two or more combined is greater than individual effects.
Allergic reaction – always ask about allergies.
Anaphylactic Reaction (severe allergic reaction)
Severe reaction with sudden constriction of bronchiolar muscles, edema of pharynx and larynx, severe wheezing and shortness of breath.
Medical emergency: Airway management is critical.
Medication Tolerance and Dependence
Medication Tolerance: patient requires higher dose over time to achieve the same therapeutic effect.
Medication Dependence (Addiction): occurs over time.
Physical dependence: body becomes adapted; stopping can be harmful.
Psychological dependence: patient desires the medication for benefits beyond intended effect.
Factors Influencing Medication Actions
Influencing factors can be physiological, environmental, psychological or pathological:
Genetics
Age
Weight
Gender
Pregnancy
Time of administration
Diet
Fluid consumption
Route of administration
Weather
Attitude
Stress
Setting
Nurse behavior
Alcohol use
Medication Interactions
Drug-to-drug interactions.
Food-to-drug interactions.
Environment-to-drug interactions.
Cumulative/synergist interactions.
Contraindications.
Dose Responses
Therapeutic range.
Peak (maximum concentration).
Trough (minimum concentration).
Biological half-life, denoted as .
Onset (time to effect).
Duration (length of effect).
Therapeutic plateau.
Note: In pharmacokinetics, a common relation for elimination half-life is , where $V_d$ is the volume of distribution and $Cl$ is clearance.
Common Administration Schedules
Before meals – AC (ante cibum).
After meals – PC (post cibum).
Twice per day – BID.
As needed – PRN.
Every day – daily.
3 times per day – TID.
Give immediately – STAT.
4 times per day – QID.
Medication Distribution Systems
Stock supplies.
Dispensing automated unit dose systems: PYXIS and Omnicell.
Self-administration.
Administering Medications: Nurse’s Role
Administration of medications.
Monitoring effects/assessment.
Timing of administration.
Patient teaching.
Special Age Considerations
Infants and Children.
Older Adults.
Polypharmacy.
Medication Orders
Written.
Verbal (no longer acceptable in some institutions).
Telephone (emergency situations).
Medication Orders Details
Patient’s name.
Provider/prescriber’s name and state ID number.
Date.
Time.
Drug name.
Dosage.
Route.
Time of administration.
Prescriber’s signature.
Rights of Medication Administration
RIGHT patient.
RIGHT drug.
RIGHT dose.
RIGHT route.
RIGHT time.
RIGHT documentation.
RIGHT reason.
RIGHT to know.
RIGHT to refuse.
Drug Cards
Medication.
Classification.
Indications/actions/effects.
Major adverse reactions/side effects.
Recommended dose.
Nursing implications/considerations.
Teaching.
Evaluation.
Closing note
"I'M NOT TELLING YOU IT'S GOING TO BE EASY, I'M TELLING YOU IT'S GOING TO BE WORTH IT."