definitions Flashcards
Pharmacodynamics
mechanism of action of a drug on an organism
Pharmacokinetics
the process by which a drug is absorbed, distributed, metabolized (biotransformed) and eliminated by the body.
drug
a chemical agent that is used in the diagnosis, the treatment or the prevention of a disease.
Enteral routes
PO
SL
PR
gastric access via tube
Parenteral routes
IV IM SQ Sl drug depots
Drug metabolism
GI–> portal circulation–Liver first
Kidneys cannot filter lipid soluble drugs–agents reabsorbed back into systemic circulaiton
A charged molecule cannot easily diffuse out of the kidney lumen and therefore a charged drug molecule is returned into the systemic circulation.
phase 1 liver metbolism of drugs
convert lipid soluble molecules into water soluble molecules by introducing or unmasking a polar group such as –OH or –NH2.
a drug bound to cytochrome P450 can be oxidized or reduced via NADPH
Phase 2 liver drug metabolism
conjugation, wherein an endogenous polar group is added to a drug molecule—glucuronic acid, sulfuric acid, acetic acid or an amino acid.
This makes the molecule POLAR so kidney can excrete it
Bioavailability
the fraction of administered drug that reaches the systemic circulation in an unchanged form.
influenced by:
Solubility of the agent
Hepatic metabolism of the agent
Chemical binders
Half life
is the amount of time required for the plasma concentration of a drug to decrease by 50% after discontinuation of a drug.
loading dose
an initial dose of drug that is higher then subsequent doses for the purpose of rapidly achieving therapeutic drug concentrations in the serum.
Efficacy
refers to the degree to which a drug is able to induce maximal therapeutic effects. Efficacy is a term often used to compare drugs of different classes.
Potency
the amount of drug required to produce 50% of the maximal response that the drug is capable of inducing. Potency is a term more frequently used to compare drugs of a similar class.
EC50
Effective Concentration in 50% of subjects tested
LD50
Lethal Dose in 50% of subjects tested
Therapeutic index (T.I.)
a ratio of the dose of a drug that produces toxicity relative to the dose of the same drug that produces a clinically desired response.
T.I. = LD50 / EC50
Physiologic antagonism
refers to two agonists in unrelated reactions which cause opposite effects.
Neutralization antagonism
refers to a process in which two drugs bind to one another which serves to inactivate or partial inactivate each of the drugs.
FDA/ DEA classification
CI – No approved medical use CII – High potential for abuse CIII – Moderate potential for abuse CIV – Low potential for abuse OTC – Available over the counter
