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pharm
introduction to pharm
| Question | Answer |
|---|---|
| Therapeutic Drug Monitoring (TDM) 4 characteristics | narrow therapeutic window significant degree of PK variability relationship between plasma concentration and clinical effect established therapeutic concentration range |
| ADME | absorption, distribution, metabolism, elimination |
| absorption | the processes by which unchanged drug proceeds from the site of administration to the sit of measurement (plasma) |
| distrubution | the reversible transfer of a drug to and from the site of measurement and the peripheral tissues (heart, kidney, bone, brain, adipose tissue) |
| metabolism | the conversion of one chemical species to another (unchanged drug to metabolite) |
| elimination | the irreversible loss of drug from the site of measurement. elimination occurs through metabolism and excretion |
| excretion | the irreversible loss of chemically unchanged drug (urinary excretion, fecal excretion |
| where absorption occurs | small intestine |
| two processes of absorption | passive diffusion (thru cell membrane) active transport (something brings it in) |
| when does a drug into go through absorption? | when given intravascularly (IV) |
| factors that affect drug absorption | surface area (larger SA=more drug absorption) nature fo epithelial membrane presence of bile and mucus (thicker mucus, lower absorption) blood perfusion (higher perfusion=higher absorption) differences in luminal pH along the GI tract |
| stomach pH | 1-2 |
| duodenum pH | 5-6 |
| small intestine pH | 7.5 |
| colon pH | 7-8 |
| dosage forms and absorption rate | 1. IV (fastest) 2. sublingually, orally 3. Immediate release tablet 4. extended-release tablet (slowest) |
| bioavailability | -extent to which a drug is absorbed into the systemic circulation -percentage of drug absorbed from extravascular relative to IV administration |
| drugs with good absorption | high bioavailability (>70%) |
| drugs with bag absorption | bad bioavailability (<10%) |
| area under the curve (AUC) | most reliable measurement of a drugs bioavailability represents the amount of drug that has reached the systemic circulation |
| Cmax | maximum concentration of the drug in the body |
| Tmax | time at which the drug concentration is at its maximum |
| volume of distribution | (amount of drug in the body at time t)/(Cplasma at time t) |
| drug distribution | dictated by the physiochemical properties of a drug as well as the physiologic factors of the pation |
| physiochemical properties | molecular weight of the drug binding affinities to plasma proteins (ex albumin) lipophilicity ionization state (ionized drugs cross cell membranes less than nonionized) |
| physiological factors | adipose tissue to skeletal muscle ratio biological sex |
| metabolism | process by which a drug is converted from its origional chemical structure (parent drug) into other forms (metabolites) |
| primary sites for metabolism | gut and liver they contain many drug metabolizing enzymes |
| first pass metabolism | blood from stomach travels to the liver before it reaches the rest of the body |
| first pass in the liver contains | metabolizing enzymes that catalyze major reactions (oxidation, reduction, hydrolysis, conjugation) |
| drugs with extensive first pass | can bypass first pass by giving non-oral routes |
| phase 1 metabolizing enzymes | conversion of parent drug to a polar metabolite |
| phase 1 includes which reactions | oxidation reduction hydrolysis (convert prodrugs to active drugs) |
| phase 1 is catalyzed by | cytochrome P450s, flavin-containing monooxygenases and epoxide hydrolases |
| phase 1 introduces functional groups to | increase water solubility and drastically alter pharmacological activity |
| cytochrome P450 ezymes | -superfamily with families and subfamilies with increasing gene sequence similarities -work together with drug transporters to influence systemic bioavailability -CYP3A4/5 family is involved in the majority of phase 1 metabolism |
| phase 2 metabolism | occurs after phase 1 conjugation reactions catalyzed by |
| phase 2 conjugation reactions are catalyzed by | sulfotransferases (sulfate group) UDP- glucuronosyltransferases (glucuronic acid group) glutathione S transferases (glutathione group) N-acetyltransferases (acetyl group) methyltransferases (methyl group) |
| phase 2: metabolites need to have | oxygen, nitrogen, or sulfur atoms to accept hydrophilic moiety |
| UGT and CYP3A4/5 involved in | the metabolism of more than 75% of drugs |
| elimination | the process of irreversible removal of drugs from the body describes the efficiency of drug removal from the body |
| elimination occurs through | kidneys (urine) gut (feces) skin (sweat) |
| clearance | the rate of drug removal in a certain volume of plasma over a certain time (look at formula) |
| zero-order rate processes | the rate of drug elimination is independent of drug concentration |
| first-order rate processes | the rate of drug elimination is dependent of drug concentration more common |
| pathways of renal clearance | glomerular filtration, tubular secretion, reabsorption |
| glomerular filtration | affects all solutes of appropriate size influences by protein binding passive and unidirectional |
| tubular secretion | occurs mostly in proximal tubules of the nephron requires carrier protein to bring drugs out saturable process not influenced by protein binding |
| reabsorption | occurs all along the nephron passive by nature and active favors lipid soluble, unionized drugs weak acids and weak bases depend on the urine pH and pKa of the drug |
| renal clearance | a net result of filtration, secretion, and reasborption |
| dosing in pediatrics | weight-based dosing |
| dosing in geriatrics | dosing meds based on reduction in clearance secondary to reductions in liver and kidney function |
| pharmacokinetics | what the body does to the drug ADME |
| pharmacoDynamics | what the Drug does to the body |
| tolerance | when the body adapts to repeated drug use, needing higher doses to get the same effect |
| wide therapeutic window | ideally we want a wide window, there is little to no overlap between therapeutic doses and toxic doses safer |
| narrow therapeutic window | small changes in dose result in large increases in the likelihood of toxicities, has to be more precise not as safe |
| therapeutic index | the range of doses at which a medication is effective without unwanted adverse effects |
Created by:
ago24