Pharmacology week 1 quick facts

Pharmacology

Scientific study of origin, nature, chemistry, and effects of drugs

Pharmacokinetics

What the body does to the drug (ADME)

Pharmacodynamics

What the drug does to the body; biochemical and physical effects

ADME

Absorption, Distribution, Metabolism, Excretion

Additive effect

Two drugs of the same action given together; positive; allows lower doses and better pain control

Synergistic effect

Potentiation; one drug enhances the effect of another; positive

Antagonistic effect

Two drugs combined are not better than each alone; negative

Altering absorption

One drug changes absorption of another (ex: stomach acidity); can wait 2 hours

Allergic reaction

Unintended immune response

Secondary effects

Can be beneficial or adverse

Morphine secondary effects

Constipation, respiratory depression

Hypersusceptibility

Excessive response to usual therapeutic dose

Overdose

Toxic reaction from excessive dose (intentional or accidental)

Iatrogenic effect

Adverse drug reaction mimicking a pathological disorder (ex: asthma from propranolol)

Absorption routes

Oral, injection, inhalation, topical/transdermal, enteral

Primary absorption site

Small intestine

First-pass effect

Liver or intestinal inactivation before systemic circulation

Cytochrome 450

Liver enzyme system involved in metabolism

Bioavailability

Amount of drug available for use

Distribution

Spread of drug via bloodstream

Free drug

Active; can cross membranes and BBB

Protein-bound drug

Inactive while bound

Albumin

Major plasma protein for drug binding

Organs with highest blood flow

Liver and heart (drugs may act faster)

Only free drugs can

Cross cell membranes and blood brain barrier

Metabolism

Drug breakdown (mostly liver)

Metabolites

Products formed during metabolism

Prodrug

Inactive until metabolized into active form

Grapefruit

Can cause severe side effects with some drugs

Excretion

Removal of parent drugs and metabolites

Kidney excretion

Most common; filtered; some reabsorbed; excreted in urine

Kidney function tests

Creatinine, creatinine clearance, GFR

Liver excretion

Bile into intestines; eliminated in stool

Liver function tests

AST (cell injury), ALT (liver injury)

Lung excretion

Anesthesia, alcohol

Other excretion

Sweat, tears, reproductive fluid, breast milk

Special populations

Peds, babies, older adults

Start low and go slow

Due to decreased body water, muscle mass, kidney/liver function, and blood flow

MOA

mechanisms of action

Agonist

Binds tightly to receptor and activates it

Antagonist

Competes and blocks receptor activation

Prescription medication

Specific person, specific use, prescribed by licensed person

OTC drugs

Available without prescription; often lower doses

Herbals/supplements

Not regulated; no checks and balances

Generic vs brand

Same drug (ex: aspirin vs Bayer)

Therapeutic Window

Therapeutic index/window

Low therapeutic index

Narrow window; higher risk

Peak

Highest concentration

Peak times

Oral 60 min; IM 30-60 min; IV 15-30 min

Trough

Lowest concentration; measured before next dose

Nursing Responsibilities

Right drug

Minimize interactions

Know drug history; avoid OTC interference

Managing toxicity

Early identification and intervention

Right dose

Correct calculation and administration

Extravasation risk

Certain IV drugs cause severe tissue damage

Rule

Never give drug if unsure what it's for

Right patient

Ensuring the medication is given to the correct individual.

Right time

the time the prescribed dose is ordered to be administered

Right assessment

Confirm that the medication is appropriate for the client's condition.

Right documentation

Right evaluation

Pre-administration assessment

Check contraindications and interactions

Collect baseline data

Evaluate therapeutic response and adverse effects

Identify high-risk patients

Liver/kidney impairment, genetics, pregnancy, elderly, pediatrics

PRN decisions

Know reason; assess medical need

New trials use

Controls, randomization, blinding

OTC statistics

Americans use 20 billion; 60% doses; 40% take every 2 days

IR

Immediate Release

ER

Extended Release

SR

Sustained Release

XL

Extra Long

XR

Extended Release

NCLEX Rule

Do NOT crush, chew, or split ER/SR/XL/XR meds