lOMoARcPSD|11700591
Study guide exam one units 1-3 Unit one Week one pharmacology
Pharmacokinetics and Pharmacodynamics Week one notes Pharmacodynamics- what the drug does to the body What effect does the drug have on the person you are giving it to Pharmacokinetics- Pharmaco (drug) kinetics (movement) - What does the body do to the drug Pharmacokinetics has 4 phase
AD-ME – Absorption, distribution, metabolism, excretion A-Absorption Drug moves from site of absorption (small intestine) into the bloodstream Bioavailability – how much of the drug reaches the blood stream Factors affecting absorption 1.Circulation - Poor blood flow to the GI tract and you taking oral med will lead to a decrease in the rate of absorption - Happens in pt. in shock or vasoconstricting drugs 2. Pain, stress, exercise - Blood gets shunted away from the gut.
lOMoARcPSD|11700591
Food / decrease in GI motility - delays absorption PH - most drugs needs a low PH for absorption acids breaks things down into a more absorbable form Route - route of administration affects absorption /bioavailability - iv = 100 percent bioavailability 80 % of drugs are taken orally - in order for drug to be used (absorbed) has to go through a process called disintegration – (broken down into smaller particles.) then it has to dissolve (dissolution) - enteric coated tabs slower disintegration - enteric coated tabs need an alkaline environment for absorption first pass effect - affects absorption /bioavailability of oral medications - example of the 1st pass effect is PO vs IV Tylenol - drug travels to the liver via the portal vein and gets broken down D- distribution - Describes delivery of the blood from the blood stream to the tissue (target cells) Factors affecting distribution
lOMoARcPSD|11700591
1.Protein binding (blood interaction with plasma proteins) - If a drug is tightly bound to proteins it won’t be able to reach target cells. - Tight binding prevents drug delivery (distribution) - Unbound portion = free drug which is what reaches the cell - Conversely- lower plasma protein levels = more free drug, however to much free drug = toxicity Anatomical barriers - Blood brain barrier - Placental barrier - Benadryl 1st generation crosses the blood brain barrier which causes sleepiness - Claritin 2nd generation does not M- metabolism - Describes the process of blood inactivation. Drug being broken down before its eliminated broken down in the liver. Factors affecting 1.Half life - Amt of time it takes for the amt of drug to be reduced by half Ex. Long half lives - Digoxin – half life is 36 hr