Pharmacokinetics Flashcards
pharmacokinetics
the study of how a drug moves through the body or how our bodies affect a drug; time course of drug movement thru the body
–> young population not fully metabolically competent (not as able to metabolize certain things)
–> elderly have diminished metabolism and excretion
enteral route of administration
drugs administered orally (mouth or tube), including sublingual (under tongue) and buccal (pill against gum and cheek) routes and rectal admin
–> absorption primarily in small intestine
topical route of administration
type of parenteral route in which drugs are applied to the skin or an orifice (e.g., creams, eye drops, nasal spray, etc.)
–> absorption is slow as drug delivery is highly targeted to site of application – intensity of effect may be less but should last for longer duration of time in body
–> not much gets to other areas of body
–> allows for circulation thru bloodstream once absorbed
parenteral route of administration
more invasive route that bypasses the GI tract. involves injection of drugs with a needle, including IV (drug injected directly into bloodstream –> high levels of drug in bloodstream immediately and then a steady decrease as drug is excreted), intramuscular, subcutaneous, and intradermal; inhalation (drugs inhaled into lungs); and mucosal (drugs placed on mucosal membranes)
absorption
how will a drug get into the bloodstream & into the circulatory system
–> pregnant population:
-progesterone decreases intestinal motility
-increased stomach pH (less acidic)
-increased heart rate and tidal volume of repspiration increases ___ of inhalants
Drugs dissolved in water are absorbed ____ and have a ____ duration of action
rapidly; shorter
Drugs dissolved in oil are absorbed more ____ and have a ____ duration of action.
slowly; longer
Acidic drugs are absorbed in ____; basic drugs are absorbed in ________.
stomach; small intestine
The more lipid _____ a drug is, the ____ it reaches the blood stream and the brain.
soluble; faster
distribution
the way that drugs move through the bloodstream after being absorbed or injected into it to reach target cells and molecules
–> must pass thru several membranes to reach target (drugs that are lipid soluble get to their targets faster than drugs that are not lipid soluble; larger molecules have more difficulty crossing cell membranes)
–> tight binding to plasma proteins prevent delivery (reaching its target cells)
–> pregnancy: increased fluid volume; affects Cmax (highest level of concentration in blood)
metabolism
how a drug is broken down; reactions that inactivate the drug and target for excretion; describes modification by enzymes to render the drug ineffective
–> most drugs are ___ in the liver –> drugs taken orally will enter the hepatic portal system
–> not everyone has the same enzymes in the same concentration so you don’t want to give a drug to someone who doesn’t have the enzymes to metabolize it
–> pregnancy: some enzymes induced by estrogen/progesterone, others are reduced
excretion/elimination
how the drug or its remnants exit the body
–> drugs are most commonly ___ via the kidneys once drug is metabolized but can also be via lungs, bile, skin, sweat, & saliva
–> molecule must be water-soluble and large
–> accomplished thru urination and defecation
–> pregnancy: increase renal blood flow –> increased elimination of drugs that are ___ unchanged
half-life
time required to completely clear system of the drug such that once a drug is in the elimination phase, how long does it take for the concentration in the blood to decrease by half
–> allows us to estimate how long the drug will stay in the body (the longer the ___ the longer it takes t eliminate the drug from the body)
tolerance
a progressive decline in response to repeated usage of a drug, which includes 3 types:
1) metabolic
2) pharmacodynamic
3) behavioral conditioning
dependence
administration of a drug is required to avoid withdrawal symptoms
