Pharmacology Ch. 3

study of how drug moves into, through, and out of the body

study of how the drug produces its effect on the body

ideal range of drug concentrations within the body

top end of the therapeutic range and represents the border between those concentrations that are beneficial and those at which signs of toxicology develop

bottom end of the normal therapeutic range

below therapeutic range, insufficient drug, will not achieve benefical effect

larger than the drug's maintenance dose and is designed to raise the drug concentration to the therapeutic range in a short time

smaller amount of drug given more frequently; used to maintain the therapeutic concentrations established by the loading dose

the time between administration of separate drug doses

the combined amount of drug administered in a given day

dosage interval of 24 hours

Intravenous; drug injected into vein, drug is carried from the tissues toward the heart where it is diluted by the venous blood returning to the heart from the body

single injection, large volume at one time

slowly injected or "dripped" into a vein over a period of several seconds, minutes, or hrs

when drug concentration plateaus and remain there until infusion is stopped

accidental injection of an IV administered drug outside the blood vessel; some can cause extreme tissue inflammation and tissue necrosis (tissue death)

places the drug directly into the blood vessel; injected into artery and thus carries the injected drug away from the heart and toward a specific tissue or organ; produces local toxicosis

within the muscle

beneath the skin

administered within the skin with very small needles, reserved for skin testing

administered into the abdominal body cavity and frequency used when IV or IM are not practical or when volumes of solution must be administered for rapid absorption

PO, by mouth

drugs applied to the surface of the skin such as lotions and liniments

meaning "air or gas solution", indicates that the drug is administered in an inhaled mist or gas and absorbed at different speed and efficiency

majority of drug movement through tissue fluid or membrane barriers; random movement of drug molecules from high to low concentration

movement of drug molecules from area of high concentration to an area of low concentration or vice versa

passive transport mechanism across cell membrane that involves a special "carrier molecule" located in the cell membrane

involves a specialize carrier molecule and energy expended to either move the drug across the membrane or to "reset" the carrier molecule after transport so that it can transport again

meaning cell drinking; involves a small invagination forming in the cell membrane that surrounds the drug molecule and brings it into the cell; require energy

meaning cell eating, a process in which most or the entire cell surrounds the drug molecule; require energy

when more drug molecules are available for transport than available carrier molecules; all carrier molecules are continuously occupied with drug molecules

rate at which drug molecules move across the membrane, cannot be increased

fat loving, nature of the molecule- reflecting the molecule's ability to dissolve in phospholipids of the cell membrane

water loving; molecules that do not readily dissolve in fat or oil

liquid medium

• 1. Absorption
• 2. Distribution
• 3. Metabolism
• 4. Excretion

of a drug is defined as the movement of drug molecules from the site of administration to the system circulation

the degree to which an administered drug is absorbed

blood concentrations of drug because mostly occupy only fluid or water component of blood and not within the blood cells

drug whose chemical structure causes it to release a hydrogen ion or proton into the liquid as the drug is placed in increasingly alkaline environments; becomes more hydrophilic as it is placed in a more basic environment

becomes more hydrophilic when placed in an increasing acidic environment and more lipophilic when placed in a more alkaline environment

• -pH 1-3
• -pH 6-7
• -pH 7.4

when lipophilic drug passes through a cell membrane and enters a body compartment whose pH results in a significant shift to hydrophilic form which leads to the drug molecule not being able to exit the compartment

dissolving of the drug, critical step in absorption for PO drugs

refers to stomach contractions that mix mix stomach contents and move the contents from the stomach to the small intestine

defined as the mixing and propulsive contractions of the intestine

conducts the blood from the intestine to the liver, where the materials from the intestine can be acted on

foreign substances

the phenomenon by which the liver removes so much of the drug that little reaches the systemic circulation; those with extensive FPE are not recommended PO administration

the extent to which a tissue is supplied with blood

dilation of blood vessels; enhances perfusion of tissues and therefore increases drug absorption in SC tissue and muscle

can be caused by the sympathetic nervous system, contrict blood vessels, decreases perfusion of tissue and drug absorption

movement of a drug from the systemic circulation into the tissues

small gaps, "windows," parts of the body capillary walls between adjacent cells; allows water and small drug molecules to pass through; not in brain

made up from astrocytes and glial cells around the capillaries to provide for additional barrier

when concentrations between the blood and perfused tissues (brain) are equal

movement of drug from the blood, to the tissue (brain), back to the blood, and then to a second tissue (fat), continues until equilibrium is reached

small enough to distribute through the capillary fenestrations; in equilibrium with protein-bound molecules

acts as a storage pool and component of the drug dose that is largely inactive

pharmacokinetic value that provides an approximation of the extent to which a drug is distributed throughout the body; larger Vd= more tissues the drug appears to be able to penetrate = lower drug concentration in the blood

specifically shaped protein located on the cell's surface or within the cell that drug molecules combine with for cells to respond

bind to receptor to exert a certain effect

block effect of other drugs, ex. antidotes

when 2 drugs have an equal opportunity to exert their own effect on the cell; determined by which drug is present in greater quantity

a drug has a greater affinity for the receptor than another or it may alter the shape so that the other drug will not fit into receptor

two drugs attaching to a receptor may have different levels of intrinsic activity

one drug is more powerful than another but produces same effect

when drug combines with its receptor to produce a specific effect on the cell

some drugs produce an effect without combining to receptors; mannitol: osmotic diuretic

types of compounds used as drugs that physically combine with ions or other specific compounds in the environment to produce thier effects

process by which many drugs are altered by the enzymes and chemical reactions in the body before they are eliminated

altered drug molecule

enzymatic process where the metabolite is combined with another molecule

most common biotransformation enzyme system in the liver

the effect of repeated exposure to a drug resulting in an increase rate of biotransformation for the drugs

kidney (urine) and liver (bile to feces)

circulating drugs are cleared from the blood through filtration and active secretion

passive process that occurs as the blood flows from renal arteriole through the glomerulus

specialized tuft of capillaries in the kidney

first part of renal nephron; its wall structure prevents blood cells and larger protein molecules from leaving the blood

not filtered through unless in free form

active segment of the nephron that contains many active transport mechanisms for moving electrolytes, glucose and drug molecules back and forth among the urine, renal tubular cells, and the surrounding capillaries

process where some drug molecules are actively transported from the peritubular capillaries into the urine; not dependent on concentration gradient

where some of the drug molecules may move from the filtrate back into circulation, which is called reabsorption (passive diffusion; reabsorbed molecules must be in lipophilic form)

• - distal convoluted tubule
• - collecting ducts
• - renal pelvis
• - ureter

elimination of drugs by the liver

movement of drug from the liver to the intestinal tract and back to the liver

measure of how fast a volume of blood is cleared of the drug and is typically expressed as a volume of blood cleared over time

time value that describes how long the drug concentration takes to decrease by 50%

time (usually in days) after drug administration during which the animal cannot be sent to market for slaugher and the eggs or milk must be discarded

pH greater than 7

pH less than 7

removal from body

SIGNA: to write or label

desired effect wanting to achieve

when administering drugs long-term and they may pass therapeutic effect

dose of drug that is effective for 50 % of the population

individual reactions to a particular drug from an individual animal (not expected, rare)

biological source

vomiting; may be induced to help during toxicity of certain substances; not for corrosive substances or when patient is semiconscious or unconscious; certain species do not vomit (ruminants)

flush out stomach contents with pump

lethal in cats, dogs tolerate it, toxicity signs: depression, weakness, ICTERUS (jaundice), hepatic failure; antidote: acetylcysteine

fatal for cats, may cause liver disease; usually given to dogs for arthritic pain but if given over a period of days may cause gastric ulcers (sign may vomit)

anti cancer cream, interferes with DNA/RNA transcription; dogs love it; sloughs off lining of intestinal tract; lead to gastric and intestinal lavage

in high concentration can kill a dog, active ingredient is thiobromine, causes nervous system stimulation, heart rate increases, seizures; induce emesis and give activated charcoal

• 1. solubility
• 2. route of administration
• 3. chemical properties

determines how much of a dose to be given; if they have the same mechanism of actions you are able to determine the potency by looking at the curve

administer less concentration to produce effect; Effective dose

to determine at which interval to give drug

dose that will kill 50% of the population

LD₅₀/ED₅₀ : gives estimate of relative safety of drug

the study of harmful effects of chemical compounds on biologic systems, including their properties, actions, and effects

toxicant or poison

the disease produced by a toxicant

amount of a toxicant necessary to produce a detrimental effect

describes the likelihood of poisoning under conditions of use

• -hydrogen peroxide 3%
• -apomorphine (dogs): can be given subconjuctively
• -dexdomitor (dogs)
• -xylazine (cats)
• -syrup of ipecac- only if directed

artifical sweetener, highly toxic to dogs, behaves as glucose in the body and increases insulin causing severe hypoglycemia leading to coma, respiratory depression, or death

• treat with IV dextrose
• in some gum

Rat baits; Vitamin K can be an antidote for one type

lilies, onions and garlic, grapes and raisins, not pointsettas

• Acids- burn mucosa or intestinal lining (usually dogs)
• Alkalines- worse burns
• Detergents
• Ant baits- dogs will usually just vomit
• Silica gel- low toxicity
• Toilet bowl tablets- if dilute not has harmful as if they chew the tablet
• Glow necklaces
• Liquid potpourri- very toxic
• batteries- acids will cause ulcers
• nicotine- highly toxic, stimulant
• pennies- 99.7% zinc, starts to dissolve quickly- highly toxic, cause liver failure
• mothballs- all are toxic
• moldy foods- common, fungi release cause tremors and neurologic disorder, worse case: seizures

antifreeze is the active ingredient, worse toxicans seen routinely ingested, cause renal failure, crystal clogs renal tubules, death within 18-24 hours; paladin (antidote, enzyme competitor, must be given before crystals form or before 12 hours pass)