pharmacology definitions

pharmacology
the study of drugs and their interactions

drug
any chemical agent that affects living protoplasm

adverse drug reaction (ADR)
any response to a drug which is harmful and unintended

pharmacokinetics
action of the BODY on the DRUG

Processes of Pharmacokinetics
ADME- absorption, distribution, metabolism, and elimination of drugs

Absorption
is the movement of a drug from its site of administration into the central compartment and the extent to which this occurs

Passive absorption
diffusion for higher to lower concentration

active absorption
against a concentration gradient, requires energy

distribution
drug is transported to site where it reacts with various bodily tissues and or receptors

Metabolism
to convert active lipid soluble compounds to inactive water-soluble substances able to be primarily excreted by the kidney

Enzyme inhibitors
decrease the rate of metabolism of object drug by obstructing metabolizing enzymes

enzyme inhibition leads to a (________) in drug concentration?
increase

enzyme induction leads to a (______) in drug concentration and a (______) in clearance of the drug
1. decrease
2. increase

excretion/elimination
process that removes the drug and its metabolites from the body.

pharmacodynamics
the study of the biochemical and physiological effects of DRUGS on the body and their mechanisms of action

Four most important parameters governing drug disposition are
1. bio-availability
2. volume of distribution
3. clearance
4. elimination

bioavailability
the fractional extent to which a dose of drug reaches its site of action

volume of distribution
relates the amount of drug in the body to the concentration of drug in the blood or plasma

half life
the time it takes for the plasma concentration to be reduced by 50%

steady state
amount of drug administered in a given period (maintenance dose) is equal to the amount eliminated in that same period
rate in=rate out

potentiation/synergism
interaction between two or more drugs or agents resulting in a pharmacologic response greater than the sum of individual responses to each drug or agent
1+1=5

antagonism
opposition in action or smaller combined effect than individual agents
2+2=1

receptor
a molecule to which a drug binds to bring about a change in function of the biologic system

receptor site
specific region of the receptor molecule to which the drug binds (more than one drug could bind to specific sites)

inert binding molecule or site
a molecule to which a drug may bind without changing any function

spare receptor
receptor that does not bind drug when the drug concentration is sufficient to produce maximal effect

effector
component that accomplishes the biologic effect after the receptor is activated by an agonist (examples: channel or enzyme molecule)

efficacy, maximal efficacy (Emax)
the maximum effect that can be achieved with a particular drug, regardless of dose

potency
the amount of drug needed to produce a given effect, determined mainly by the affinity of the receptor for the drug and the number of receptors available

graded dose-response curve
a graph of increasing response to increasing drug concentration or dose

quantal dose-response curve
a graph of the fraction of a population that shows a specified response at progressively increasing doses

EC50
the CONCENTRATION that causes 50% of the maximum effect or toxicity

ED50
the DOSE that causes 50% of the maximum effect or toxicity

TD50 (TC50)
the median toxic Dose (concentration), the dose at which toxicity occurs in 50% of cases

LD50 (LC50)
the median lethal Dose (Concentration), the dose required to kill HALF the members of a tested population after a specified test duration

Kd
the concentration of drug that binds 50% of the receptors in the system

Bmax
maximal number of receptors bound

agonist
a drug that activates its receptor upon binding

partial agonist
a drug that binds to its receptor but produces a smaller effect at full dosage than a full agonist

antagonist
binds without activating its receptor and thereby prevents activation by an agonist

competitive antagonist
a pharmacologic antagonist that can be overcome by increasing the concentration of agonist

irreversible antagonist
a pharmacologic antagonist that cannot be overcome by increasing agonist concentration

physiologic antagonist
a drug that counters effects of another by binding to a different receptor and causing opposing effects

chemical antagonist
a drug that counters effects of another by binding the agonist drug (not the receptor)

allosteric antagonist
a drug that binds to a receptor molecule without interfering with normal antagonist binding but alters the response to the normal antagonist

therapeutic index (TI)
-TD50: ED50 dose or concentration were toxicity will happen in 50%

tachyphylaxis
an acute (sudden) decrease in the response to a drug after its administration

downregulation
long-term reductions in receptor number which occur in response to continuous exposure to agonists

upregulation
increases in receptor number which occur when receptor activation is blocked for prolonged periods (usually several days) by pharmacologic antagonists or be denervation

EC50 the drug concentration giving 50% maximal effect (not binding affinity – the magnitude of a drug effect is not proportional to the proportion of receptors occupied by that drug) a drug with a lower EC50 is more potent (half …

systemic dose relationship has two components: Dose – Plasma concentration relationship -Determined by pharmacokinetics parameters of drug (half life, clearance, volume of distribution) Plasma Concentration – Response relationship -Can be studied using in vitro studies How to Determine a Dose- …

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agonist a drug that activates a receptor by binding to that receptor antagonist a drug that binds to the receptor without activating the receptor WE WILL WRITE A CUSTOM ESSAY SAMPLE ON ANY TOPIC SPECIFICALLY FOR YOU FOR ONLY $13.90/PAGE …

Dose response curve shows the relationship between the drug response and the dose Free drug compared to drugs that are protein bound, molecules that can produce a pharmacologic effect WE WILL WRITE A CUSTOM ESSAY SAMPLE ON ANY TOPIC SPECIFICALLY …

What does it mean that DR interactions are concentration dependent? It means that as the concentration of the drug increases the % of receptors bound increases What does it mean the DR interactions are saturable? At a certain concentration 100% …

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