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intro to pharm 1
exam 1
| Question | Answer |
|---|---|
| pharmacokinetics | what the body does to the drug (A,D,M,E) |
| pharmacodynamics | what the drug does to the body |
| four characteristics for therapeutic drug monitoring (TDM) | narrow therapeutic window, a significant degree of PK variability, a relationship between the plasma concentration and clinical effect, an established therapeutic concentration range |
| therapeutic drug monitoring | measuring drug concentrations in a patient's blood to ensure the dose is effective and safe |
| ADME | absorption, distribution, metabolism, elimination |
| absorption examples | systemic absorption, intestinal absorption |
| absorption | the processes by which unchanged drug (i.e., non metabolized) proceeds from the site of measurement (i.e., the plasma) |
| distribution | the reversible transfer of a drug to and from the site of measurement and the peripheral tissues (heart, kidney, bone, brain, adipose tissue, etc.) |
| metabolism | the conversion of one chemical species to another (ex. unchanged drug to metabolite) |
| elimination | the irreversible loss of drug from the site of measurement. elimination occurs by two processes, excretion and metabolism |
| excretion | the irreversible loss of chemically unchanged drug (ex. urinary excretion, biliary excretion, fecal excretion) |
| where does the drug usually exit in elimination? | through the kidney or liver |
| 4 processes of pharmacokinetics | absorption, distribution, metabolism, elimination |
| where does most oral drug absorption occur? | in the small intestine |
| two primary processes of absorption | passive diffusion, active transport |
| when is absorption not required? | when a drug is given intravascularly |
| factors that affect drug absorption | surface area, nature of epithelial membranes, presence of bile and mucus, blood perfusion, differences in luminal pH along the GI tract |
| how does surface area affect drug absorption? | larger surface area, higher drug absorption |
| example of how nature of epithelial membranes affects drug absorption | infection in the GI tract can affect absorption |
| how does presence of bile and mucus affect drug absorption? | thicker mucus, lower drug absorption (usually due to infection) |
| how does blood perfusion affect drug absorption? | higher blood perfusion, higher drug absorption |
| how do differences in luminal pH along the GI tract affect drug absorption? | affects location of drug absorption |
| stomach pH | 1-2 |
| duodenum pH | 5-6 |
| small intestine pH | about 7.5 |
| colon pH | 7-8 |
| major site of drug absorption | small intestine |
| dosage forms and absorption rate (fastest to slowest) | intravenous, sublingual/oral dissolving tablet, immediate release tablet, extended-release tablet |
| bioavailability | extent to which a drug is absorbed into the systemic circulation |
| bioavailability is the percentage of what? | drug absorbed from extravascular relative to intravascular administration (IV) |
| drugs with good absorption= | high bioavailability (>70%) |
| drugs with poor absorption= | low bioavailability (<10%) |
| area under the curve (AUC) | represents the amount of the drug that has reached the systemic circulation |
| what is the most reliable measurement of a drug's bioavailability? | area under the curve (AUC) |
| Cmax | maximum concentration of drug in the body |
| Tmax | time at which the drug concentration is at its maximum |
| volume of distribution | a proportionality constant that relates: vd= amount of drug in the body at a time t (At)/ Cplasma at a time t |
| example of volume of distribution | in the body about 5L of vasculature, if drug is higher than that amount it does not stay in vasculature |
| drug rapidly distributes out of _____, and into ____ | plasma, well perfused tissues (liver and kidney) |
| what is drug distribution dictated by? | the physiochemical properties of a drug as well as the physiologic factors of the patient |
| physiochemical properties of a drug that determine drug distribution | molecular weight of drugs, binding affinities to plasma proteins, lipophilicity, ionization state |
| ionization state | ionized drugs traverse cellular membranes to a lesser extent compared to their nonionized counterparts |
| physiologic factors that determinate drug distribution | adipose tissue to skeletal muscle ratio, biological sex |
| metabolism | process by which a drug is converted from its original chemical structure (parent drug) into other forms (metabolites) |
| primary sites of metabolism | gut and liver |
| why are the gut and liver the primary sites of metabolism? | they contain many drug-metabolizing enzymes |
| first pass metabolism | blood from the stomach travels to the liver before it reaches the rest of the body (before drugs reach systemic circulation, liver takes a cut) |
| what does the liver contain to make drug absorption easier on the body during first pass metabolism? | transporters and metabolizing enzymes that catalyze major reaction (oxidation, reduction, hydrolysis, conjugation) |
| certain drugs with extensive first pass metabolism can? | bypass by giving non-oral routes |
| phase I metabolizing enzymes | conversion of parent drug to a more polar metabolite (body can handle polar compounds easily) |
| reactions that help parent drug become more polar | oxidation, reduction, hydrolysis |
| what does hydrolysis convert? | prodrugs to active drugs |
| phase I metabolizing enzymes are catalyzed by? | cytochrome P450s, flavin-containing monooxygenases, and epoxide hydrolases |
| what do phase I metabolizing enzymes introduce? | functional groups to increase water solubility and drastically alter pharmacological activity |
| cytochrome (CYP) 450 enzymes | superfamily with families and subfamilies with increasing gene sequence similarities |
| cytochrome (CYP) 450 enzymes work together with? | drug transporters to influence systemic bioavailability |
| what family is involved in the majority of Phase I metabolism? | CYP3A4/5 |
| When do phase II metabolizing enzymes usually occur? | after phase I metabolism |
| what are conjugation reactions catalyzed by in phase II metabolism? | sulfotransferases (sulfate group), UDP- glucouronosyltransferases- glucouronic acid group, glutathionine-S-transferases- glutathione group, N-acetyltransferases- acetyl group, methyl group |
| what do the metabolites in phase II metabolism need to have to accept hydrophilic moiety? | oxygen, nitrogen, or sulfur atoms |
| UGT and CYP3A4/5 are involved in the metabolism of? | more than 75% of drugs |
| elimination | process of irreversible removal of drugs from the body |
| what does elimination describe? | the efficiency of drug removal from the body |
| what does elimination occur through? | kidneys-> urine, gut-> feces, skin-> sweat |
| clearance | rate of drug removal in a certain volume of plasma over a certain amount of time |
| clearance= | elimination rate/concentration= dose/ area under the curve |
Created by:
camrynfoster