intro to pharmacology

what is pharmacology

interaction of chemical substances with living organisms

what is pharmacodynamics

study of drug action at the biochemical or physiological level

what is pharmacokinetics

study of how drugs enter the body, reach the site of action, and are eliminated from the body

what dod rugs that selectively bind to receptors on cell membranes do

alter cellular physiology

what is an agonist

a drug that bonds to a specific receptor and produces physiologic effect by stimulating receptor

what does norepinephrine stimulate

beta-1 receptors on SA node

what does norepinephrine do

increases HR and BP

what is an antagonist

a drug that binds to a specific recpetor and blocks pther substances from stimulating the receptor

what does propranolol do

decrease HR and BP

what does propanol block

beta-1 receptors on SA node

what does naloxone block

mu-opiod receptors in the respiratory center of the medulla oblangata

what does naloxone do

reverse respiratory depression in opioid overdoes

what does diphenhydramine bind to

histamine receptors and induce a conformational change in the receptor

what does diphenhydramine do

prevent histamine from binding to H-1 receptors

prevent allergic reactions and symptoms

what is affinity

drugs ability to bind to its receptor

what is efficacy

drugs ability to stimulate its receptor

what is morphine classified as

agonist

what is naloxone classified as

antagonist

what is diazapam classified as

agonist

what is flumazenil classified as

antagonist

what is acetylcholine classified as

agonist

what is atropine classified as

antagonist

what are the 4 phases of pharmacokinetics

absorption

distribution

metabolism

elimination

what happens after a drug is ingested orally

absorbed from stomach/intestine

enters hepatic system

liver

drug enters general circulation

what are the benefits of oral ingestion

convenient and economical

what is meant by sublingual drug administration

drug dissolved under the tongue

what is transdermal drug administration

drug path provides continous drug dose

drug enters circulation before passing through liver

what are the advantages/when would a drug be administered rectally

when pt is unconscious or vomiting

when oral administration is not possible

what are the disadvantages of rectal drug administration

erratic or incomplete absorption

what happens during inhalational drug adminstration

drug inhaled as a gas aresol into lungs

exerts local effect on lungs

rapid onset of drug effects as it enters through lungs

what are the advantages to a parenteral route of drug administration

avoid unpredictable absorption

useful in unconscious or uncooperative patients

what are the disadvantages to parenteral drug adminstration

need sterile conditions to prevent infection

more costly than other routes of administration

once injected drug cannot be retrieved

pain at injection site

what is the general rule for drug distribution

small and highly lipophilic drug molecules penetrate cell membranes capillaries and physiological barriers more readily than larger, polar drug molecules

what is another way to say a drug is polar

non-lipophilic

what are the characteristics of drug absorption

drugs must be relatively lipid soluble to pass through GI tract membranes

drugs exist in either a lipid soluble or non lipid soluble form depending on pH

what decides if a drug is lipid solulble or non-lipid soluble

pH

is the stomach acidic or basic (alkaline)

highly acidic

is the small intestine acidic or basic (alkaline)

basic (alkaline)

what does bioavailability describe

what proportion of the administered drug is available to produce a pharmacologic response

what factors influence bioavailability

drug dissolution

inert ingredients

presence of food

what is achlorhydria

deficiency in pancreatic and intestinal secretions

what does achlorohydria prevent

dissolution of enteric coated tablets

what does the degree of drug dissolution depend on

physical and chemical properties of a drug and its ability to penetrate cell membranes, capillaries, blood brain barrier, placenta

what kinds of drugs are able to pass the blood brain barrier

only lipid soluble drugs and very small molecules

why does heroin corss the BBB more readily than morphine

greater lipid solubility factor

what doe many drugs reversibly bind to in the blood

plasma

what are only unbound or free drugs allowed to do

diffuse through capillary walls

produce pharmacological effect

be metabolized

be excreted

what does a free drug turn into

a protein bound drug

what happens after a drug becomes bound to a protein

goes to the circulating drug reservoir which prolongs drug action

what is tissue trapping

certain tissues store drugs temporarily or permanently converting them to an inactive form

when these drugs leave the storing tissues they become active again

what organ is largely responsible for metabolizing drugs

liver

what does the liver do to lipid soluble drugs

converts them to water soluble drugs to be excreted by the kidneys

what is the first pass effect of the liver

inactivation of potentially harmful chemicals and drugs before being distributed throughout the body

what does nicotine induce

metabolism of theophylline

what does a decreased level of theophylline in the blood cause

wheezing

what does tagamet do

inhibit metabolism of theophylline, increasing theophylline blood levels causing toxicity

what percent does kidney function decrease per every 20 years

10% per decade after age 20

what happens to metabolized drugs

goes into the bile and is eliminated via defecation

what is enterohepatic recirculation

metabolized drug secreted in bile then enters the small intestine

drug reabsorbed and returns to liver

drug secreted in bile

what age considerations should we take for infants in regard to drug elimination

their underdeveloped ability to metabolize and excrete drugs

what age considerations should we take for the elderly in regards to drug elimination

their impaired ability to metabolize and excrete drugs

what happens if there is liver/kidney disease present

decreased ability to metabolize and excrete drugs leading to prolonged toxic drug effects

what is the “lifecycle” of a drug in the body following administration

absorbed by plasma

turns into a free drug

moves to storage in tissue, site of action, is metabolized, or excreted