Pharmacologic Principles

Chapter 1, 2, 3

Understanding

• Nurses must understand both + and – effects of drugs

• Pharmacotherapeutics– use of drugs and the clinical indications

for drugs to prevent and treat diseases • Pharmacodynamics

– study of what the drug does to the body • Pharmacognosy

– natural drug sources

Drug Names

• Chemical• Trade

– Patented– Belongs to a company

• Generic– Commonly known– Less expensive

Phases of Activity

• Pharmaceutical– Administered– Dissolves or disintegrates

• Pharmacokinetic– Absorbed– Sent to tissues– Metabolized (used)– Excreted (disposed of)

• Pharmacodynamic– Ways drug affects the body

First-Pass Effect

• metabolism of a drug by the liver before its systemic availability

• AKA Bioavailability

• Amount of the drug that makes it into circulation

Drug Transport

• How does the drug get from point A to point B?

• Parenteral Liver Circulation• OR• Gastric Liver Circulation

Action Curve

• Time from delivery to start of therapeutic effect = Onset of Action

• From delivery to maximum therapeutic effect = Peak Effect

• Total amount of time therapeutic effect is notable = Duration of Action

Mechanism of Action

• Receptor– Designated site accepts drug

• Enzyme– Chemical reaction “glues” drug to site

• Nonspecific– Drug stimulates changes in cell to allow

it in

Chemical Bonds

• Agonists

• Antagonists

• Partial-agonist or Agonist-Antagonist

Drug Excretion

Organs: liver, kidneys, intestinesKidneys have primary responsibilityBreakdown by liver makes kidney’s job

easierSome drugs are eliminated through

bowels

Considerations

• Therapeutic Index – difference between good & dangerous effects

• Amount of drug circulating = concentration

• Patient condition – liver & kidney health, age, GI function

• Tolerance or Dependence• Interactions

Drug Misadventures

• Adverse Drug Event (ADE)– Adverse Drug Reaction (ADR)

• Caused by factors inside patient’s body• Allergy, unknown, kidney or liver disease• Not able to be controlled

– Medication Error• Most common type of event• Related to administration, dispensing,

prescribing

Life Span

• Pediatrics– Very young have immature livers - can’t

process drugs as well– Adult drugs may be passed through

breastmilk – check safety if mother is breastfeeding

– Dosage based on mg/kg for safety

Life Span, con’t.

• Adult– Careful of interactions with

• Other drugs• Herbal substances

– Risk for noncompliance d/t ‘undesirable’ effects

Life Span, con’t.

• Elderly– Be aware of possible diminished:

• liver or kidney function – monitor lab tests• Cardiac function – be aware of test results• Digestive changes

– Assess ability to read labels & open containers

– Assess for potential safety issues – meds may cause drowsiness or diminished response

Nursing Process

• Assess– Patient needs– Patient & family understanding– Patient (and family) physical abilities

• Plan (Goal)– Include patient & family– Tailor to patient/family needs– Include social services, prn

Nursing Process, con’t.

• Implement– Regular re-assessments– Monitor for changes– Observe for therapeutic affects

• Evaluate– Is plan working?– Does it need modifying?– What can change?

5 Rights

• Basic to medication administration– Right Drug– Right Dose– Right Time– Right Route – Right Patient

Errors

• IF a med error occurs– Admit the error – don’t try to cover it up– Notify physician– Take emergency/first aid measures, prn– Complete proper reporting form

• NEVER record terms “by mistake”, “on error”, “unintentionally”

• DO NOT record error in patient chart