ATI RN Pharmacology for Nursing (8th Ed) - Chapter 1-2

Absorption - the transmission of meds from the location of administration to the bloodstream (7 ways meds can be absorbed) -rate of med absorption determines how soon the med will take effect -amount of med body absorbs determines intensity of its effects - route of administration affects rate & amount of absorption Agonists - meds that bind to or mimic the receptor activity that endogenous compounds regulate. Ex: Morphine is an agonist bc it activates the receptors (the meds target sites on or within the cell) that produce analgesia, sedation, constipation & other effects Antagonists - meds that can block the usual receptor activity that endogenous compounds regulate or the receptor activity of other meds. Ex: Losartan, an angiotensin II receptor blocker, is an antagonist. It works by blocking angiotensin II receptors on blood vessels, which prevents vasoconstriction Chemical name - name of med that reflects its chemical compositions & molecular structure (isobutylphenyl propanoic acid) Common med errors - - wrong med or IV fluid - incorrect dose or IV rate - wrong pt, route or time - admin of an allergy-inducing med -omission of a dose or admin of extra doses - incorrect discontinuation of a med or IV fluid - inaccurate prescribing - inadvertently giving med that has similar name Components of a medication prescription - - Pts full name - Date and time of the prescription - Name of med (generic/brand) - Strength & dose of med - Route of admin - Times & frequency of admin (exact times/# of times per day) - Quantity to dispense & # of refills - Signature of the prescribing provider Distribution - the transportation of meds to sites of action by bodily fluids Factors that influence distribution: - Circulation: conditions that inhibit blood flow/perfusion, such as peripheral vascular/cardiac disease, can delay med distribution - Permeability of cell membrane: the med must be able to pass through tissues & membranes to reach its target area. Meds that are lipid-soluble or have a transport system can cross the blood-brain barrier & the placenta - Plasma protein binding: Meds compete for protein binding sites within the bloodstream, primarily albumin. The ability of a med to bind to a protein can affect how much of the med will leave & travel to target tissues. 2 meds can compete for the same binding sites, resulting in toxicity Excretion - the elimination of meds from the body primarily through the kidneys. Elimination can take place in liver, lungs, intestines & exocrine glands (such as breast milk). Kidney dysfunction can lead to an increase in duration & intensity of med response, so its impo to monitor BUN & creatinine levels Generic name - official or nonproprietary name the US Adopted Names Council gives a med. Each med has only 1 generic name (Ibuprofen) Half-life (t1/2) - refers to the time for the med in the body to drop by 50%, liver & kidney function affect half-life. Usually takes 4 half-lives to achieve a steady blood concentration (med intake=med metabolism & excretion) -SHORT HALF-LIFE: Meds leave the body quickly (4-8 hr). Short-dosing interval or minimum effective concentration (MEC) drops b/w doses -LONG HALF-LIFE: Meds leave body more slowly: over more than 24 hr, w greater risk for med accumulation & toxicity. Meds can be given at longer intervals w/out loss of therapeutic effects. Meds take a longer time to reach steady state. Inhalation via mouth, nose - Barriers to absorption: inspiratory Absorption pattern: rapid absorption through alveolar capillary networks Intradermal, topical - Barriers to absorption: close proximity of epidermal cells Absorption pattern: -slow, gradual absorption - effects primarily local, but systemic as well, especially w/ lipid-soluble meds passing through subcutaneous fatty tissue Intravenous (IV) - Barriers to absorption: no barriers Absorption patter: - immediate -- enters directly into the blood - complete -- reaches the blood in its entirety Med reconciliation - The Joint Commission requires policies & procedures for med reconciliation. Nurses compile a list of each pts current meds, including all meds w their dosages & frequency. They compare the life w new med prescriptions & reconcile it w provider to resolve any discrepancies. This process usually takes place at admission, when transferring pts b/w facilities & at discharge Metabolism (biotransformation) - changes meds into less active/inactive forms by the the action of enzymes. Occurs primarily in the liver, can also take place in kidneys, lungs, intestines & blood Factors influencing rate of med metabolism: - AGE: infants have a limited med-metabolizing capacity. Aging process also can influence med. metabolism, but varies w the individual. In general, hepatic meds metabolism tends to decline w age. Older adults require smaller doses of meds due to the possibility of accumulation in the body - INCREASE IN SOME MED-METABOLIZING ENZYMES: this can metabolize a particular med sooner, requiring an increase in dosage of that med to maintain a therapeutic level. It can also cause an increase in the metabolism of other concurrentuse meds - FIRST-PASS EFFECT: the liver inactivates some meds on their 1st pass through the liver & thus they require a non enteral route (SL, IV) bc of their high 1st pass effect -SIMILAR METABOLIC PATHWAYS: when the same pathway metabolizes 2 meds, it can alter the metabolism of 1 or both of them. In this way, the rate of metabolism can decrease for 1 or both of the meds; leading to med accumulation - NUTRITIONAL STATUS: clients who are malnourished can be deficient in the factors that are necessary to produce specific med-metabolizing enzymes, thus impairing med metabolism