Question | Answer |
pharmaceutic phase | the first phase of drug action, also known as dissolution |
disintegration | the breakdown of a tablet into smaller particles |
dissolution | the dissolving of smaller particles into the GI fluid before absorption |
Rate limiting | the time it takes the drug to disintegrate and dissolve to become avaliable to the body to absorb it |
pharmacokinetic phase | the process of drug movement to achieve drug action. The 4 processes are absorption, distribution, metabolism (or biotransformation) and excretion (or elimination). |
absorption | the movement of drug particles from the GI tract to body fluids by passive absorption, active absorption or pinocytosis |
passive absorption | occurs mostly by diffusion (movement from higher concentration to lower concentration); energy is not required |
active absorption | requires a carrier such as an enzyme or protein to move the drug against a concentration gradient; energy is required |
pinocytosis | is a process by which cells carry a drug accros their memebrane by engulfing the drug particles |
*Remember* | drugs that are lipid soluble and nonionized are absorbed faster than water-soluble ad ionized drugs |
first-pass effect | the process in which the drug passes to the liver first, ex: wafrarin and morphine |
Bioavailibility | a subcategory of absorption; it is the % of the administered drug dose that reaches the systemic circulation. |
Factors that affect Bioavailibility | Bioavailibility the drug form, the route, GI mucosa and motility, food and other drugs and changes in liver metabolism |
distribution | the process by which the drug becomes avaliable to the body fluids and body tissues |
half-life | the time it takes for one half of the drug concentration to be eliminated |
elimination | main route is through the kidneys |
creatinine clearance | most accurate test to determine renal function |
pharmacodynamic | is the study of drug concentration and its effects on the body |
onset of action | the time it takes to reach the minimum effective concentration (MEC) after a drug is administered |
peak action | occurs when the druge reaches its highest blood or plasma concentration |
duration of action | is the length of time the drug as a pharmacologic effect |
time-response curve | evaluates 3 parameters of drug action; the onset of drug action, peak action and duration of action |
receptor families | 4 families; kinase-linked receptor, ligand-gated ion channels, G protein-coupled receptor systems and nuclear receptors |
ligand-binding domain | the site on the receptor in which drugs bind |
kinase-linked receptors | the ligand-binding domain for drug binding is on the cell surface, the drug activates the enzyme (inside the cell) and a response is initiated |
ligand-gated ion channels | the drug spans the cell memebrane and with this type of repetor,the channel opens, allowing for the flow of ions into and out of the cell. The ions are primarily sodium and calcium |
G protein-coupled receptor systems | there are 3 components to this receptor response; the receptor, G protein that binds with guanosine triphosphate and the effector that is either an enzyme or an ion channel |
nuclear receptors | cell nucleus and not on the surface of the cell membrane, activation of receptors through the transcription factor is prolonged |
agonists | drugs that produce a response |
antagonists | drugs that block a response |
nonspecific drugs | drugs that affect various sites, have properties of nonspecificity |
nonselective drugs | drugs that affect various receptors; have properties of nonselectivity |
Categories of drug action | stimulation or depression, replacement, inhibition or killing of organisms, irritation |
theraputic index | estimates the margin of safety of a drug through the use of a ratio that measres the effective dose (ED) in 50% of persons/animals and the lethal dose (LD) in 50% of people/animals; the close the ratio is to 1, the greater danger of toxicity |
low theraputic index | drugs that have a narrow margin of safety; small safety range between the ED and LD |
high theraputic index | drugs that have a wide margin of safety and less danger of producing toxic effects |
theraputic range (window) | the drug concentration that is between the minimum effective concentration in the plasma for obtaining desired drug action and the minimum toxic concentration |
peak drug level | the highest plasma concentration of drug at a specific time; indicates rate of absorption |
trough drug level | the lowest plasma concentration of a drug and it measures the rate at whichthe drug has been eliminated |
loading dose | a large initial dose of drug to achieve a rapid minimum effective concentration in the plasma |
side effects | physiologic effects not related to desired drug effects |
pharmacogenetics | the effect of a drug action that varies from a predicted drug response because of genetic factors or hereditary influence |
tolerance | refers to a decreased responsiveness over the course of therapy |
tachyphylaxis | refers to a rapid decrease in response to the drug; think "acute tolerance" |
placebo effect | a psychologic benefit from a compound that may not hav the chemincal structure of a drug effect |