DRUG ACTIVITY Flashcards
is any drug or substance with specific affinity to a receptor.
Receptors are molecules to which a drug has specific affinity.
LIGAND
Not all drugs require receptors to produce an effect.
True
2 requirements for drug activity
affinity & effficacy
drug with affinity but without intrinsic activity may produce a
physiological change.
is a drug that does not have intrinsic activity but binds with
specific receptors.
antagonist
Some drugs have both agonistic and antagonistic properties.
true
– a drug having both agonistic and antagonistic properties
Dualist
cannot produce an effect except in the presence of
an agonist.
Competitive antagonist
– inhibits the action of an agonist by binding at a site
other than the receptor.
Non competitive agonist
Features of the dose response curve
Potency
Slope
Variability
a function of the drug’s affinity for the receptor, absorption, excretion, degradation rates.
potency
indicates the range of dosage over which the drug acts, from minimally detectable to maximally effective.
slope
in the same patient can be due to circadian changes, age, state of health, drug – indeed.
variability
The body reservoir that holds the greatest amount of the barbiturate thiopental is
fat
Body fat may contain up to_______of an administered dose of lipid soluble thiopental 3 hours after injection.
70%
Drugs are usually released much
more slowly from fat because fat has a relatively limited blood supply.
True
Yohembine injection to reverse the sedative effect of?
xylazine,
xylazine is a ?
commonly use in veterinary medicine a sedative, muscle relaxant, and analgesic (painkiller).
a drug that belongs to a class of compounds called alpha-2 adrenergic agonists.
It blocks the effects of alpha-2 adrenergic agonists.
yohimbine
when one of the two drugs has zero intrinsic activity.
potentiation
The drug with zero intrinsic activity is considered a
potentiator.
– effect of a drug combination is greater than the separate effects of the individual drugs.
Synergism
the combined effect of the drugs is equal to the sum of their individual effect.
Additive effect
results from coulombic forces ( electrostatic attraction ) between oppositely charged ions.
Ionic bond
A covalent bond can be broken at very high temperature or
intervention of catalytic enzymes.
two atoms share a pair of electrons. It has high binding
energy.
Covalent bond
arises from the ability of a proton ( H ) to accept
an electron pair. It is stronger than a covelant bond.
Hydrogen bond
from very weak bond between
depoles or induced dipoles, often between similar atoms.
intermolecular forces or ( van der Waals Forces)
The most dangerous route of drug administration is IV. Although it has many advantages, it is potentially the most dangerous route of drug administration. Care must be used in computing the total dose and rare of
injection.
IV injection
injection of the drug into rumen.
Enteral
oral administration of drugs, absorption occurs mostly
duodenum
by mouth, per os, per orem, p.o ) and rectal route.
Enteral route
but in some cases oral administration it may also occur in the
mouth, stomach & colon
the study of the rate of change from the initial state to the final state of a substance.
Kinetics
a constant percentage of the drug remaining in the site of
administration is absorbed (or disappears from the site with time )
First order kinetics
the actual amount of drug absorbed per unit time is the
same regardless of how much of the drug remains in the site.
Zero order kinetics
the time it takes for a drug concentration to be reduced to 50% its initial concentration.
Half-life
the total quantity of drug absorbed intact.
bioavailability
Micromized particles readily disintegrate and absorption is increased.
true
Salts are more soluble than their corresponding organic is increased.
true
Higly lipid soluble drugs are almost completely absorbed from the skin.
true
Absorption from the skin is usually insignificant for most drugs except when the skin is extensively damage.
true
when injected into the circulation stays confined to
the cardiovascular system. Its volume of distribution therefore is equal to the
plasma volume.
Evan’s blue or l-albumin
– freely diffuses out of blood vessels but does not enter the
cells. It therefore measures the ECF.The difference between ECF and plasma
volume is the interstitial fluid volume.
Inulin or EDTA
readily crosses all epithelial barriers. It is used to
measure total body fluid volume.
Isotopic water or antipyrine
are extracellular fluids but enclosed within
epithelial tissues. They include synovial, intraocular, cerebrospinal, peritoneal,
pericardial, and pleural fluids.
Transcellular fluid volume
removal of drug and drug metabolities from the body.
excretion
inactivation of most drugs.
Biotransformation
terminated drug activity by removing
the drug from its site of action into other sites within the body.
Redistribution of sequestration
reduction of drug activity.
Detoxification
normal anabolic and metabolic reactions ex. Hormones
metabolism
is the most important site of drug biotransformation in the body, but biotransformation also occurs in other organs including the intestinal mucosa,
lungs, and kidneys.
liver
are generally less active than the parent compound if not totally
inactive.
Metabolities
Metabolities or by products are almost always more polar and less soluble than the parent compound.
true
the process of transforming and inactive or less active
compound to a more active metabolite but the resulting does not always
cause death.
Lethal synthesis
The microsomal enzymes also known___________
oxidases, are a complex of proteins and heme which are located in the SER wherein pieces of which are called
microsomes.
cytochrome P-40
the most important means of eliminating drugs from body
URIN & BILE
