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75 Cards in this Set
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study of how drugs move into, through and out of the body |
Pharmacokinetics |
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study of how drugs produce their effects in the body |
Pharmacodynamics |
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Ideal range of a drug concentration within the body. Too much can be toxic, too little has no beneficial effects and can cause antibiotic resistance. |
Therapeutic range |
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top end of normal therapeutic range |
Maximum Effective Concentration |
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bottom end of normal therapeutic range before hitting the sub therapeutic range. |
Minimum Effective Concentration |
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Amount of drug administered at one time.Units of mass such as grams, milligrams, or litres, millilitres. |
Drug Dose |
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amount administered to animal at one time. |
dose |
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amount to be given over entire treatment period |
dosage |
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Time between administrations of separate drug dosages. e.g., BID, TID q4h |
dosage interval |
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Random movement of drug molecules from high concentration to low. e.g, iso into the brain Movement continues down the concentration gradient until equilibrium is reachedNo energy required |
Passive diffusion |
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Passive movement that requires a carrier molecule e.g., glucose moving into cellsNo energy required |
Facilitated Diffusion |
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Movement that uses a special carrier molecule.Requires energyDrug can move against concentration gradient |
Active Transport |
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small invagination in cell wall will surround particles and bring them into the cellDrug molecules engulfed by cell membrane- requires energy |
Pinocytosis |
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Large invagination that brings larger molecules into cellalso requires energy |
phagocytosis |
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4 steps of pharmacokinetics |
absorption distribution metabolism/biotransformation excretion/elimination |
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dosages designed to result in therapeutic concentrations based on ___ of the drug |
ADME |
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movement from site to systemic circulation |
Absorption |
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degree to which a drug is absorbed and enters the general circulation |
Bioavailability |
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Rate of drug absorbed amount of drug absorbed distribution of drug throughout the body drug metabolism or biotransformation rate and route of excretion |
factors influencing the blood concentration levels of a drug |
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Cells and cell membranes are phospholipids Move quickly into extracellular fluid absorb slowly if given SQ or IM |
Lipophilic |
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Cells and cell membranes are phospholipids Extracellular fluid is water and solutes Move quickly into cells absorbed quicker when given SQ or IM. |
Hydrophilic |
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oral drugs should be |
lipophilic |
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greater absorption(slower absorption) |
hypomotile |
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less absorption(faster absorption) |
hypermotile |
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blood circulating in the intestines must travel through the liver before returning to the system circulation through the hepatic portal system |
first pass effect |
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liver recognizes some drugs as foreign substances |
xenobiotics |
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movement of drug from the systemic circulation into tissues |
distribution |
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math value that gives an estimate of the extent to which a drug is distributed throughout the body |
Vd |
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the ______ Vd of a drug, the more tissues drug will penetrate. Because the drug gets distributed to many compartments in the body, the drug concentration in the blood will be lower |
larger |
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______deliver the blood to the tissues from the bloodstream _____ are lined by cells with fenestrations in between them |
capillaries |
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lipophilic drugs are highly_______, dosage is based on this |
protein bound |
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if animal has ____ protein level, the amount of free drug reaching tissue quickly will increase and could be toxic |
low |
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drugs reach well perfused tissues easier- tissues with high blood flow or vasodilation |
perfusion of tissues |
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Blood-brain barriervery tight junctions between capillary cellsno fenestration |
barriers |
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drugs must be small or ___ to enter the brain |
lipophilic |
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Brain has _____pumps that pump out drugs that enter. also found in testis and GIT |
P-glycoprotein |
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drug molecules combine with parts of a cell to alter cell functioneffect on the cell could be depression, stimulation, irritation or death |
Receptors |
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degree to which a drug produces desired response |
Efficacy |
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tendency of a drug to combine with a receptor |
affinity |
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high level of affinity and efficacy causes a specific action |
agonist |
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less affinity and efficacy |
partial agonist |
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drug that blocks another drug from a receptor |
Antagonist |
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when drugs can be eliminated by the body |
metabolism/biotransformation |
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altered drug molecule is called a ___ |
metabolite |
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Biotransformation results in a metabolite that is more ___ so it can be eliminated by kidney or liver |
Hydrophilic |
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when lipophilic drugs diffuse back into circulation from ingest and return to liver it is called the |
enterohepatic |
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drugs that require biotransformation to become activeprednisone to its active form prednisolone |
Prodrugs |
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is a liver enzyme. It changes bilirubin into a form that can be removed from the body through the bile. It also changes some hormones, medicines, and toxins into non-harmful products. |
Glucoronyl Transferase |
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Movement of drug molecules out of the body |
elimination |
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most common routeoccurs via renal artery and the glomeruli through processes called filtration (passive) and active secretion |
renal elimination |
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Passive process as blood flows through glomeruliSmall drugs not bound to proteins filter into bowman capsule and get removed in urine |
glomerular filtration |
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Drugs that are actively secreted into urine results in drug being removed quicker which is beneficial if treating a UTI |
active secretion |
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from the proximal convoluted tubule the filtrate moves into the loop of henlein the loop drugs can move passively from filtrate back into circulation through ______ |
reabsorption |
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passive process so drug must be in ____ form. |
lipophilic |
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decreases blood flow into glomerulus- slower eliminationcould cause toxic levels and increases WTdehydration, blood loss, shock |
Hypotension |
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decreased blood flow to kidney and liver- slower rate of elimination |
Congestive heart failure |
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result in hypoalbuminemia or hypoproteinemia which results in less drugs being protein bound so these drugs are eliminated rapidly |
Liver disease |
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Elimination of drugs by the liver. Drugs removed this way go into the bile |
Biliary excretion |
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If drugs arrives in duodenum in a lipophilic form, it can be reabsorbed into the hepatic portal circulation back to the liver to be excreted by the liver again or reabsorbed back into systemic circulation |
Enterohepatic Cycle |
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May result in drug having an effect on the body for a longer period of timeIf _____ is compromised by disease or old age, rate of elimination is reduced |
Liver Compromise |
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Rate at which drugs leave the body is expressed as the drugs clearance or _____ |
half-life eliminatiion |
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The point at which drug accumulation and elimination are balanced Peak and trough concentration should all be the same |
Steady State |
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The point at which drug accumulation and elimination are balancedPeak and trough concentration should all be the same |
Withdrawal Time |
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A measure of how safe a drug is |
Therapeutic Index |
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The delay between the administration of a drug and when the effects of the drug are seen |
Latent Period |
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unusual or unsuspected reaction is called an _________ |
idiosyncratic drug reaction |
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Severe and life threatening Fluid in lungs- severe dyspnea Swelling of respiratory tract |
Anaphylaxis |
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less severe swelling, hives, itchiness Usually occurs within 2 hours of giving the drug but could take longer |
Urticaria |
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Damage to DNA of a cell In antibiotics or antifungals that work on bacterial cell DNA Should be a warning on the label |
Carinogens |
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Cause birth defects in pregnant animals Fulvicin- anitfungal- missing limbs Tetracycline- discolor teeth, bones May not always state “dont use on pregnant animals” |
Teratogens |
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TDM |
Therapeutic Drug Monitoring |
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Periodically measure blood levels for certain drugs |
TDM |
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Drugs may precipitate when mixed togetherValium and anything other than Diazepam |
Chemical/Physical |
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Altered Absorption Calcium will bind to many drugs and interfere with absorption Altered Metabolism and Elimination Dewormers and tranquilizers, anesthetics Use the same enzymes to be metabolized |
Pharmacokinetic |
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Interaction at the site of a drug actionAgonist and antagonists |
Pharmacodynamic |