What are the three phases of Drug Action?

pharmaceutic

pharmacokinetic

pharmacodynamic

What two things happen during

pharmaceutic phase?

Disintegration

&

Dissolution

Disintegration

breakdown of tablet

into smaller particles

Dissolution

dissolving of smaller particles

in GI fluid before

absorption

rate limiting

time for drug to disintegrate

and dissolve to become

available for absorption

pharmacokinetics

four processes of drug movement to achieve drug action -

Absorption, Distribution,

Metabolism, Excretion

Absorption

movement of drug particles from GI Tract to body fluids

- Passive Absorption,

Active Absorption, pinocytosis

Passive Absorption

by diffusion, from high concentration to low concentration, requires no energy

Active Absorption

carrier is needed like an enzyme or protein; goes against a conentration gradient; energy is required

Pinocytosis

cells carry drugs across a membrane by engulfing them

Protein-bound drug

causes inactive drug action/

response

unbound drug

(free drug)

free active drug causing

a pharmacologic response;

not bound to protein

nonselective receptors

drugs that affect various receptors

first pass effect

or

hepatic first pass

process in which a drug passes to the liver first

(directly from intestine to liver)

bioavailability

percentage of administered drug dose that reaches systemic circulation;  for oral, always less than 100%; for IV, usually 100%

Highly Protein-Bound Drugs

Moderately High Protein-Bound

Moderately Protein-Bound

Low Protien-Bound

> 89%

61-89%

30-60%

<30%

Metabolism

happens in GI tract and primarily in the Liver; liver converts most drugs to inactive

Half-Life

time required after absorption for half of the drug to be eliminated

short: 4-8hrs   long: 24hrs+

excretion

main route of elimination in through the kidneys (urine)

biological activity

of drug

is determined by the fit of the drug at the receptor site

Creatinine Clearance

most accurate test to determine renal function;  varies with age and gender;  lower levels in elderly and women - normal is 85-135 ml/min; elderly is 60ml/min

Pharmacodynamic

effect of drug action on cells;  causes primary (desired) and secondary effects (desired/undesired)

dose response

relationship between the minimal versus maximum amount of drug dose needed to produce desired drug effect

onset of action

the time it takes to reach the minimum effective concentration (MEC) after drug is administered

peak action

when drug reaches its highest blood or plasma concentration

duration action

length of time the drug has pharmacological effect

time response curve

evaluates three parameters of drug action:  onset, peak, and duration

agonists

drugs that produces a response

antagonists

drugs that block a response

cholinergic receptors

located in the bladder, heart, blood vessels, lungs, eyes

nonspecific drugs

drugs that affect various sites; receptor is located in different parts of the body and initiate a variety of responses

nonselective drugs

drugs that act at different receptors

therapeutic index (TI)

estimates the margin of safety of a drug; ratio of effective dose (ED) and lethal dose (ED); the closer to 1 the greater the toxicity

low therapeutic index

narrow margin of safety

(dangerous)

high therapeutic index

wide margin of safety,

less dangerous

therapeutic range (window)

in plasma, is between min. effective concetration of desired drug action and min. toxic effect

peak drug level

after drug administration, indicates the highest plasma concentration of drug at a specific time

trough drug level

after drug administration, indicates the lowest plasma concentration of drug at a specific time

loading dose

for immediate drug reponse, this large initial dose is given

side effects

physiological effects not related to desires drug efects (desireable or undesirable) are expected

pharmacogenetic

effects of a drug action that varies form predicted drug response because of genetic factors or hereditary influence

adverse reactions

more severe than side effects and undesirable; identified through plasma

toxicity

toxic effect as a result of drug dose/therapy;  identified through plasma; first adverse symptom occurs at particular dose

tolerance

decreased responsiveness over the course of therapy

tachyphylaxis

rapid decrease in reponse to a drug; "acute tolerance"; drug tolerance to repeated admin. of a drug

placebo effect

psychological benefit from a compound that may not have the chemical structure of a drug effect

Nursing Process

Assessment, Planning, Implementation, Evaluation

Assessment

includes Nursing Diagnosis, current health histories, lab results, DATA

subjective data

perspectives, feelings, opinions, (Verbal), mental status

objective data

truth in the details;  lab tests and physical assessments

Planning

goal setting, expected outcomes; develop Nursing Interventions

implementation

the action to accomplish the goals;  use of training aids, Client Teaching

Evaluation

effectiveness of health teaching and drug therapy; attainment of final goal;  adresses effectiveness of health teaching

Client Teaching

General, Skill, Diet, Side Effects

pharmacology

the study of the effects of chemical substances on living tissues

United States Pharmacopeia National Formulary

(USP-NF)

current authoritative source for drug standards; revised every  years; high standards

International Pharmacopeia

first published by World Health Organization (WHO), provides basis for standards of drugs in world

Food and Drug Administration

(FDA)

monitors and regulates the manufactoring and marketing of drugs; tests for harmful effects and labels adverse effects (1938)

Durham-Humphrey Amendment

(1952) distinguishes between drugs that can be sold with or without a prescription

Kefauver-Harris Amendment

(1962)  required adverse reactions and contraindications must be labeled and included in litarature; re-evaluation of testing process

Controlled Substances Act

(1970)  to remedy drug abuse; promotion of drug education, enforcement, treatment/rehab

controlled substances

Five Schedules

I.   high abuse potential - no medial use

II.  high abuse potential - limited medical use

III.  potential abuse - medically accepted

IV.  some dependence - medically accepted

V.  very limited dependence - medically accepted

Drug Enforcement Administration

(DEA)

Nation's sole legal drug enforcement agency

misfeasance

negligence; giving the wrong drug or dose that results in the client's death

nonfeasance

omission; omitting a drug dose that results in the client's death

malfeasance

giving the correct drug but by the wrong route that results in the client's death

chemical name

describes the drug's chemical structure

generic name

official and nonproprietary name; not owned by pharmaceutical company and universally accepted; usually ordered this way

brand (trade) name

aka proprietary name

chosen by drug company and trademarked

American Hospital Formulary Service (AHFS) Drug Information

published yearly by the American Society of Health-System Pharmacists;  accurate and complete drug info on nearly all US prescription drugs

Physicians' Desk Reference

(PDR)

lists several thousands drugs with complete information given by pharmacuetical companies; yearly

Drug Facts and Comparisons

(D & C)

contains info on almost all marketed drugs in US

United States Pharmacopeia -

Drug Information

(USP-DI)

three-volume set available in most hospitals and pharmacies