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NURS 106 Exam 3
Orientation to Pharmacology
Question | Answer |
---|---|
What is pharmacology? | The science of dealing with interactions between living systems and drugs |
Define: Drug | any chemical that can affect living processes |
Define: Pharmacokinetics | the way in which the body handles drugs, it is the study of the movement of drugs throughout the body or what the body does to the drugs. |
Define: pharmacodynamics | the way in which the drug affects the body |
Define: pharmacotherapeutics | the effective use of drugs for treating diseases |
What are nursing responsibilities in regards to pharmacology 1 | anticipate possible reactions, understand the pt and the disorder/condition, know which meds are appropriate, know the contraindications, know probable consequences of the interaction between drug and the pt |
What are nursing responsibilities in regards to pharmacology 2? | pre-administration assessment, dosage and administration timing, evaluating/promoting therapeutic effects, min adverse effects/interactions, making PRN decisions, managing toxicity |
What are nursing responsibilities in regards to pharmacology 3? | To collaborate with prescribers, pharmacists and providers, provide client education, understand physiology of the pt and the pharmacologic properties of the meds |
What are the primary IDEAL drug characteristics | effective, safe and selective |
What are secondary IDEAL drug characteristics? | reversible action, predictable, ease of administration, low cost, freedom from drug interactions, chemical stability, possession of simple generic names |
What factors determine the intensity of a drug's response? | administration, pharmacokinetics, pharmacodynamics, prescribed dose, administered dose, concentration at site of action, intensity of responses |
What are the processes of pharmacokinetics that determine the concentration of a drug at its site of action? | absorption, distribution, metabolism, excretion |
In pharmacokinetics what does absorption mean? | drug going into the blood/blood stream |
In pharmacokinetics what does distribution mean? | drug going through the interstitial space to the cells |
In pharmacokinetics what does metabolism or biotransformation mean? | enzymatic medication alteration of a drug structure |
In pharmacokinetics what does excretion mean? | out of the body |
In pharmacokinetics what does metabolism and excretion mean? | ELIMINATION = out of the body |
What are the three ways that meds can cross the membrane? | channels and pores (sm ions K+, Na+), transport system, direct penetration of membrane |
What is the most common way for a drug to cross the membrane? | direct penetration |
What is required for direct penetration? | lipid solubility |
Explain the transport system? | drugs go into the blood, or into the cell or through renal excretion and which sometimes require the use of energy |
Describe properties of non-lipid soluble polar molecules. | They have no net charge, have uneven distribution of charge, dissolve in polar solvents, don't dissolve in lipid layer of cell membrane |
Describe properties of non-lipid soluble ions | have a net electrical charge, unable to cross membranes unless very small |
What are quaternary ammonium compounds? | ions, that carries a nitrogen atom, + charge, and won't absorb in GI tract nor cross blood brain barrier or placenta |
what are properties of Ph dependent ionization? | may or may not carry a charge, charge is determined by surrounding pH, acid donates and base accepts a proton |
What are properties of ion trapping or pH partioning? | ions accumulate in a media that favors ionization, acids are with alkaline media and basics with acid media |
What determines the intensity of a drug based on absorption? | the amount that was absorbed |
What does the absorption rate determine? | how soon the drug will work |
What does absorption bioavailability determine? | when the drug enters the blood stream |
what does absorption mean? | movement of the drug from the site of administration into the blood |
What factors affect drug absorption? | rate of dissolution, surface area (stomach vs. intestines), blood flow, lipid solubility, and pH partitioning |
How does pH partitioning affect drug absorption? | the greater the pH difference, the faster the absorption |
How does blood flow and affect drug absorption? | the higher the blood flow equates to faster absorption due to the concentration gradient |
what does enteral mean? | site of administration in the gastrointestinal tract |
name the sites of administration of drugs? | parenteral (injection), enteral, topical, transdermal, inhalation, rectal, vaginal, buccal |
Name all the different parenteral administration types | intravenous, subcutaneous, intramuscular, intraarterial, direct injection into site or organ, interosseous |
When is the preferred route of oral administration not preferred? | emergency/demand rapid onset, plasma drug levels need tight control, GI tract won't destroy the drug, compound can't cross membrane, drug will cause local injury, prolonged effect is needed, pt won't or can't take oral meds |
What are the different oral drugs | tablets, enteric coated preparations, sustained release preparation |
What are the properties of enteric coated preparations | protect drugs from acid and pepsin, protect the stomach from irritating drugs, may never dissolve, increase variability |
What are the properties of sustained release preparations? | spheres that dissolve at dif rates, reduce number of daily doses, provide relatively steady drug levels, are expensive, may provide variable absorption, may be chemically equivalent but have different bio-availability |
drug distribution is determined on what? | blood flow to tissues, exiting the vascular system, entering cells |
What does blood flow to the tissues determine? | rate of drug distribution. Note> perfused tissues receive better blood flow |
When abscesses occur what should a nurse person do? | drain it |
Do solid tumors perfuse well? | Heck no! |
Explain the purpose of medications exiting the vascular system and how it works? | its req for drug action usually, necessary for metabolism and excretion. Drugs pass between capillary cells not through them to the interstitial space. It occurs in the Placental drug transfer, during protein binding and in the blood brain barrier. |
Explain the concept of entering cells? | some drugs must enter cells to work, all drugs must enter cells for metabolism and excretion, some drugs work by binding to cell wall receptor |
What are between the wall of the capillaries in the CNS in regards to the blood brain barrier? | tight junctions |
What kind of drugs can pass the blood brain barrier? | lipid soluble or drugs that have a transport system to pass through the capillary wall |
What stage in life is the blood brain barrier not fully developed? | neonates |
What are advantages and disadvantages of the BBB? | advantages = protects the brain, disadvanatage = hard to treat the brain |
What compounds pass through the placental membrane? | lipid soluble, and nonionized compounds |
what compounds are excluded from the placental membrane? | Ionized, highly polar or protein bound compounds |
What does pregnancy category A mean? | A - controlled studies in humans |
What does pregnancy category B mean? | human data reassuring (animal positive) OR animal studies show no risk |
What does pregnancy category C mean? | human data lacking, animal studies positive OR not done |
What does pregnancy category D mean? | human data show risk, benefit may outweight |
What does pregnancy category X | animal or human data positive |
What is the most abundant and significant protein? | albumin |
is albumin bond reversible? | yes bound or unbound |
What are the consequences of protein binding? | restricts distribution as only free molecules can pass, restricts action, metabolism and excretion, competition with other drugs can alter bioavailability and result in toxicity |
where does metabolism and biotransformation typically occur? | in the LIVER |
Why does metabolism/biotransformation typically occur in the liver? | Because it contains hepatic drug metabolizing enzymes...der |
What preforms most of the metabolism of drugs? | microsomal enzyme system |
What does the microsomal enzyme system do? | metabolizes them by either breaking them down or synthesizing them to larger molecules |
What are the therapeutic consequences of drug metabolism? | accelerated drug excretion, drug inactivation, increased therapeutic action, activation of pro-drugs, increased/decreased toxicity |
what is the most important consequence of metabolism? | kidneys can't excrete highly lipid soluble drugs, conversion of drug metabolizing enzymes speeds excretion |
what does activation of pro drugs do? | activates an inactive drug |
What can activate a pro drug or inactive drug | biotransformation |
What are the special considerations of drug metabolism? | Age, induction of drug metabolizing enzymes, first pass effect, nutritional status, competition between drugs |
What is first pass effect? | rapid hepatic inactivation of certain oral drugs |
what does induction of drug metabolizing enzyme? | drugs that increase liver's metabolizing capacity, which increases the need for more drugs to reach therapeutic levels |
Explain the steps of first pass effect? | drug is taken orally, drug enters GI tract, active drug is absorbed from the stomach and sm. intestines, high blood concentration of drug in hepatic portal vein, low blood levels after passing through the liver |
why is nutritional status important when giving drugs | metabolism requires co factors from dietary intake |
Name the different paths of excretion | urine, bile, sweat, saliva, breast milk, expired air |
what organ accounts for the majority of excretion? | the kidneys |
what occurs in drug excretion if the renal function is impaired? | increase duration and intensity of drug response |
What do healthy kidneys do to duration of action | it limits it |
What are the steps of renal drug excretion? | glomerular filtration, passive tubular re-absorption, active tubular secretion |
What are the characteristics of glomerular filtration? | most drugs pass through glomerular capillaries into tubular urine, protein bound drugs can't pass |
What factors modify renal drug excretion? | pH dependent ionization, competition for active tubular transport, age |
what does pH dependent ionization do? | accelerates renal excretion of drugs |
what occurs in pH dependent ionization when urine pH changes? | increases ionization |
What does competition for active tubular transport do? | can delay excretion and prolong effects |
What occurs to renal function as we age? | the diminish |
at what age do infant's kidneys don't function to full capacity? | 3-4 months |
What are some non-renal routes of drug excretion? | breast milk, bile, lungs |
What should nursing mothers avoid? | medications |
Are infants liver and kidneys fully function-able? | no |
what kind of drugs pass via breast milk? | lipid soluble |
what kind of drugs are restricted via breast milk | polar and ionized |
What does enterohepatic recirculation do? | prolong drugs activity |
what are excreted via the lungs? | volatile anesthetics |
What occurs in bile excretion? | drugs from the liver excreted in bile to intestines |
what is the clinical significance of plasma drug levels? | it can alter the drug by adjusting the dose or timing of administration, the site of action is most drugs is not plasma, there is a direct CORRELATION between therapeutic and toxic responses and drug plasma level |
MEC? | min effective concentration |
What should the plasma level of drugs be at? | greater than the min effective concentration and less than the toxic concentration |
What is the goal of drug therapy? | to maintain plasma drug levels in the therapeutic range |
what do pt on drugs with narrow therapeutic range require? | close monitoring |
What determines the length of time it takes to achieve a therapeutic level? | rate of absorption |
what determines how long the therapeutic level is maintained? | excretion and metabolism |
when do drug concentrations rise? | during absorption |
when do drug concentrations decline? | during metabolism and excretion |
Define drug half life? | time req for the amt of drug in the body to decrease by 50% |
what determines dosing intervals | half life |
what is the plateau drug level process | the amt of drug eliminated between doses equals the dose administered = plateau |
what is the time to plateau | drug administered at the same dose will achieve plateau in approx 4 half lives |
if the dosage remains constant the time req to reach plateau is _________________ of dosage size | independent |
what does continuous infusion do? | keeps a constant drug level |
how can you reduce fluctuations in drug levels with repeated doses | reduce dose and increase frequency |
if the therapeutic range is narrow what should fluctuation be kept at? | min |
What is an loading dose? | large initial dose to achieve the plateau level desired quickly |
what is the % of drugs that are eliminated over 4 half lives? | 94% |
What is an maintenance dose? | smaller doses in order to maintain the plateau level |
Define: maximal efficacy | the largest therapeutic effect a drug can produce |
Define: relative potency | the amount of drug needed to elicit an effect |
what are the basic features of dose response relationships | the response is graded, as the dose increases the response is larger, provides for tailoring the dose to the patient |
Receptor? | any functional macro-molecule in a cell with which a drug binds to produce an effect |
what is a super cool attribute of receptors? | they are almost always reversible |
what is an drug receptor interaction? | chemicals interacting with other chemicals to produce an effect, drugs that mimic or block the body's own chemicals |
what are the primary receptor families? | cell membrane embedded enzymes, ligand gated ion channels, G protein coupled receptor systems, transcription factors, |
does selectivity guarantee safety? | Hell no |
what is receptor selectivity? | drugs act through specific receptors (lock and key) |
when a drug acts on one receptor site can it still produce non-selective effects? | yes just like the body |
affinity? | strength of attraction |
intrinsic activity? | ability to activate the site |
what is the theory of simple occupancy of drug receptor interactions? | number of sites occupied = max response, however does not explain potency and efficacy |
agonists? | endogenous or drug activate receptors |
antagnoists: | endogenous or drug that block receptors. Affinity but no intrinsic activity |
What are competitive antagonists? | reversible antagonists |
What are noncompetitive antagonists? | irreversible antagonists |
What is 2nd to agonists? | desensitization or refractory from continual exposure to the agonist |
what is 2nd to antagonists? | hypersensitivity, due to lack of exposure to the agonist and continual exposure to the antagonist |
what drugs are receptor less? | antacids, antiseptics |
what drugs do not involve drugs? | simple physical or chem reactions (chelating agents) |
LD | LETHAL DOSE - to 50% of animals treated |
if the therapeutic index is higher what does that indicate? | that its safer |
The highest dose req to produce therapeutic effects must be what in the therapeutic index? | must be substantially lower than the lowest dose capable of causing death. |