Pharmacology Basics Part 2 Flashcards
(115 cards)
Pharmacokinetics
All about What the/our body does to the drug
How body processes med
Pharmacokinetics: 4 processes that are part of it
Absorption: getting drug to blood - most in SI, into bloodstream, into portal vein, processed and metabolized by the liver, put out into systemic circ and there distributed to tissues, excreted by kidneys and happens over and over again until all drug been broken down and excreted from body
Distribution: getting drug to tissues
Metabolism: breaking drug down
Excretion: getting drug out of body
Absorption
Getting drug from outside into the bloodstream to be distributed to tissues - lot talking about absorption and pertinent is route
Many factors influence drug absorption:
Many factors influence drug absorption: (Absorption)
Route - big one; how getting into body
Drug properties
Patient properties
Drug properties (Many factors influence drug absorption: (Absorption)
Molecular size, lipid solubility, pH
Patient properties (Many factors influence drug absorption: (Absorption)
Surface area of absorptive surface, blood flow to site of absorption
Oral route
Majority meds given via this route; easier route to do; not invasive and cheaper to make oral drugs than other preps
Some medications are absorbed in the stomach, but most drugs are absorbed in the small intestine and into portal vein - because of this metabolic process happens immediately after absorbed get through liver and get metabolized before sent out to systemic circ (first pass effect) - onset slightly delayed for oral drugs relative to other routes for that reason; whole process takes place before gets into systemic bloodstream where exerts its effects
Due to first-pass metabolism, the onset of action for most oral drugs is 30-60 minutes - lot things that impact absorption so not exact science
Many diff factors affect drug absorption via oral route (next slide)
Some medications are absorbed in the stomach, but most drugs are absorbed in the small intestine and into portal vein - because of this metabolic process happens immediately after absorbed get through liver and get metabolized before sent out to systemic circ (first pass effect) - onset slightly delayed for oral drugs relative to other routes for that reason; whole process takes place before gets into systemic bloodstream where exerts its effects (Oral route)
Must pass through lipoid cell membranes to get to blood stream
Due to first-pass metabolism, the onset of action for most oral drugs is 30-60 minutes - lot things that impact absorption so not exact science (Oral route)
See metabolism slides
Factors affecting absorption via oral route (Oral route)
Each impact absorption
Molecular weight:
Lipid solubility:
Surface area of gastrointestinal mucosa
Blood flow to gastrointestinal system
Rate of gastric emptying
Oral preparation:
Administration of multiple drugs simultaneously (interaction)
Foods and fluids administered with drugs (binding)
Molecular weight: (Factors affecting absorption via oral route (Oral route)
Too big, can’t pass membrane (alt route)
Composition of some drugs is just too big to pass through lipid membrane that drugs need to do to be absorbed via the oral route - get from GI tract into bloodstrea and pass through lipid bilayer membrane and some too big and cannot get into bloodstream and not distributed anymore are worthless; stay in GI tract and leave body so most circumstances need be given alternate route
Lipid solubility: (Factors affecting absorption via oral route (Oral route)
Small and highly lipid soluble drugs rapidly through membrane (passive diffusion) - highly lipid soluble pass through membrane
Low lipid-soluble drugs: facilitated diffusion, active transport, pinocytosis
Highly water soluble - dissolves before absorbed correctly - use alternate route
Surface area of gastrointestinal mucosa (Factors affecting absorption via oral route (Oral route)
That is available for absorption
Certain GI probs - atrophic gastritis, gastric bypass surgery affects way absorb meds
Oral preparation: (Factors affecting absorption via oral route (Oral route)
Liquid»_space;»> enteric coated tablet (see next slide)
Way prep effects how fast absorbed
Administration of multiple drugs simultaneously (interaction) (Factors affecting absorption via oral route (Oral route)
2 drugs together at same time impacts absorption of one drugs for some reason - some drug-drug interactions
Foods and fluids administered with drugs (binding) (Factors affecting absorption via oral route (Oral route)
Ca - bind with lot drugs; not take drugs with milk products because have lot Ca; may be absorbed, not absorbed, stays in GI, not do thing, not do therapeutic effect
Gen rules for oral drugs
Administer oral drugs 1 hour before or 2 hours after a meal with full glass (about 8 oz.) water; best taken on empty stomach - taking out any probability drug-food interaction; allow for best absorption; take with full glass of water - help dilute med and help decrease gastric irritation that pat might have
Assess for drug effects 30-60 minutes after administration/given; wait 60 min so enough time to work and on safe side
Sublingual
Absorbed into highly vascular tissue under tongue; really rapid action
Put underneath tongue and dissolves
Underneath tongue - very vascular: dissolves and into bloodstream quickly
Want rapid that do at home and want take effect quickly
Fast action
Topical
Delivers drug directly to affected area (skin, eye, ear, inhaler lungs, etc.)
Typ have minimal systemic absorption - once systemic absorption more likely have more adverse effects
For local effects
Transdermal
Provides constant rate of drug absorption
More rare route
Always apply to intact skin (broken skin increases absorption)
Intravenous (IV)
Full strength; immediate onset and fully absorbed; more likely to cause toxic effects
If administering more than 1 drug at same site, must be compatible; talk how to give multiple meds through 1 IV line but make sure can give together - need compatible - mix well - if not clog and precipitate in line; when mix in same line make sure are compatible
Giving full effect of the drug
Straight into bloodstream; no first pass effect; most potent form of med can give; be esp diligent when giving something IV
Pretty immediate circ because in vein and pumped out to systemic circ
Vein - drops to heart and pumps out to systemic circ and distributed everywhere in body; Lot drugs can be caustic - meaning can cause damage - arteries seem to get damaged easier - going away from heart less overall volume and not diluted blood when traveling from heart when more volume
Intramuscular (IM)
Absorbed directly into capillaries in muscle and sent into circulation
Men more vascular muscles than women; men reach a peak level faster than women
Slowly absorbed; timing of absorption varies depending on fat content and state of local circulation
Increased adipose tissue = decreased absorption (less capillaries)
Good for certain things but less predictable due to pat variation - one variations is amount of adipose tissue; more adipose tissue someone has less absorption get from med because not as much blood flow to tissue and need really good blood flow to area for drug be absorbed into bloodstream
Excess adipose tissue not allow good absorption; hard know when becomes issue - means people have sig amounts adipose tissue need higher dose SQ meds because not absorb as effectively
Subcutaneous (SQ)
Means Amount of drug that reaches systemic circ through distribution; able get distributed to tissues and cause an effect
IV: 100% absorption - going right into the bloodstream: 100% bioavailable
IM/SQ: 100% absorption: <100% bioavailable
Oral: <100% absorption: 0-70% bioavailable for distribution so not all of it - all factors impact absorption so not ever have 100% and varies depending on pat and on factors present in pat for oral route; also have consider first pass effect; when factors and first pass effect not all available reaching tissues
IV and oral dose not same for pat for any drug; IV dose would be less because getting full strength and not having all factors affecting absorption and no first pass effect that happens before put into circ
If figure out not very bioavailable move to diff route where more effective and more bioavailable in drug phases when developing a drug
Bioavailability