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BasicPharm
Basic Pharmacologic Principles& Key Points
Question | Answer |
---|---|
PHARMACOKINETICS... | movement of med molecules in the body; absorption, distribution, metabolism, excretion |
ABSORPTION... | movement of med from admin site to blood stream |
most common routes of admin | enteral (GI tract) and parenteral (inj) |
ABSORPTION: RATE... AMOUNT... ROUTE... | -determines how soon the med will take effect -determines its intensity -affects the rate/amnt of absorption |
ORAL: ABSORPTION PATTERN | varies greatly: stability/solubility of med, gastric intestinal pH/emptying time, presence of food, other meds, forms of med (entericCoated, liquid) |
IM/SC: ABSORPTION PATTERN | rapid or slow: water solubility of med (>soluble absorbed in 10-30min; <soluble slower); inj site (>blood flow=rapid; <blood flow=slower) |
IV: ABSORPTION PATTERN | instantaneous-direct into blood; complete-all reach blood |
ORAL:ADVANTAGES&DISADVANTAGES | -safe, inexpensive, easy/convenient ->variable absorption, inactivation by GI tract/ first pass effect, pt must be cooperative/conscious, contra-NV |
FIRST PASS EFFECT... | . |
IM: ADVANTAGES&DISADVANTAGES | -used for poorly soluble med, appropriate for preapring meds absorbed slowly for extended period of time/depot preparations -inconvenient, >cost, pain with RF infection and local tissue/nerve damage |
DEPOT PREPARATIONS... | . |
IV: ADVANTAGES&DISADVANTAGES | -rapid onset, can control precise amnt, allows admin of large vol of fluid, irritating meds given free-flowing IV, immediate absorption/response -potentially dangerous of admin of wrong med, >>cost/inconvenient, RF infection/embolism |
DISTRIBUTION... | transportation of med to its site of action by body fluids; influenced by circulation, plasma protein binding, barriers |
CIRCULATION... | delayed if pt has peripheral vascular or cardiac disease |
PLASMA PROTEIN BINDING... | meds compete for protein binding sites; one displaces another med from protein binding site=cause free concentration of that med to rise; eg sulfonamide abx displaces warfarin= >free concentration, >RF bleeding |
BARRIERS... | only meds that have transport system or lipid-soluble able to cross the blood-brain barrier; neonates= <dose of med that have actions in brain (immature blood-brain barrier) |
METABOLISM... | occurs primarily in liver; liver dysfunction= <ability to metabolize, RF accumulation/toxicity |
THERAPEUTIC CONSEQUENCES OF METABOLISM | >renal excretion, inactivation of med, >therapeutic action, activation of pro-med into active forms, <toxicity when active forms converted to inactive, >toxicity when inactive converted to active |
FACTORS INFLUENCING RATE OF MED METABOLISM | age, med-metabolizing enzymes, first-pass effect, 2 or more med, nutritional status |
AGE... | very young=hepatic immaturity; very old/aging=declining hepatic med metabolism =prolonged med effects |
MED-METABOLIZING ENZYMES... | . |
FIRST PASS EFFECT... | meds are inactivated on their first pass through the liver *impt to know w/c meds must be given nonenteral route bc of high first pass effect |
METABOLISM OF 2 OR MORE MEDS WHEN GIVEN CONCURRENTLY... | rate of metabolism is affected=med accumulation *impt observe > or < levels of meds when given together |
NUTRITIONAL STATUS... | malnourished pt may be deficient in factors necessary to produce med-metabolism enzymes = impaired med metabolism |
EXCRETION... | elimination of med from body primarily through kidneys *impt monitor pt with renal dysfunction for > duration/intensity of med responses |
half-life (t1/2) | affected by liver/kidney function; takes 4half-lives to achieve steady state of serum concentration (drug intake = drug metabolism/excretion) |
short half-life | med leaves body quickly 4-8hr; short-dosing interval or minimum effective concentration (MEC) will drop between doses |
long half-life | med leaves body more slowly 24+hr, >RF med accumulation/Toxicity; med given at longer intervals w/o loss of therapeutic effects, take longer time to reach steady state |
PHARMACODYNAMICS... | mechanism of action; interaction between meds and target cells, body system, organs to produce effects |
UNCONTROLLED SUBSTANCES... | require monitoring by primary care provider, but no risk of abuse and/or addiction; eg Abx |
CONTROLLED SUBSTANCES... | meds that have potential for abuse and dependence, categorized into schedules; SCHEDULE I-IV |
SCHED? | . |
FDA PREGNANCY RISK CATEGORY... | . |
SEVERAL FACTORS INFLUENCE INDIVIDUAL DIFFERENCES IN MED RESPONSE... | body wt, age, gender, genetics, biorhythmic cycles, tolerance, accumulation, psychological factors, med conditions, allergy? |
PEAK & TROUGH LEVELS... | peak blood draw depends on route of admin, oral take longer to peak than IV trough blood levels done immediately before next dose |
EXTRAPYRAMIDAL SYMPTOMS (EPS) | abnormal body movements; involuntary fine motor tremors, rigidity, uncontrollable restlessness, acute dystonias (spastic movements, muscle rigidity affecting head, neck, eyes, facial area, limbs) |
NURS RESPONSIBILITY WHEN PT REFUSES TO TAKE MED | determine the reason for refusal, provide information risk of refusal, notify MD, document refusal and actions taken |
LACTATION | giving the med immediately after breastfeeding will minimize med concentration in the next feeding |