Term
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Definition
| Characterizes relationship of drug concentration at site of action to intensity of biological effect |
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Term
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Definition
Characterizes quantitative aspects of drug absorption, distribution, metabolism and excretion
Describes the time course of drug and metabolite concentrations at their "site of action" |
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Term
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Definition
| Denotes the area or compartment around the "site of action" or receptor site |
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Term
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Definition
| Denotes the rate and extent of absorption of drug administered extravascularly or orally |
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Term
| What is an important point regarding bioavailabilty? |
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Definition
| transport to biophase must be greater than metabolism and excretion |
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Term
| A tablet may not be "bioavailable." Why? |
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Definition
| A tablet may be pressed so tight that it will just not dissolve and will pass through the body unchanged |
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Term
| Testosterone given to an animal via the I.P. route may have no effect. Why? |
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Definition
| Drugs metabolized in the liver and given IP may show a large “first pass effect”, i.e., the fraction of drug removed on the first pass through the gastrointestinal wall and/or liver before it reaches the general circulation |
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Term
| What are the 3 routes of drug administration through alimentary route? |
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Definition
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Term
| What is the advantage of oral route? |
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Definition
| convenient, safe, slow, economical |
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Term
| What is the disadvantage of oral route? |
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Definition
| irritation to GI tract, variable rate of absorption, inactivation of protein, insolubility, non-absorp |
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Term
| What is the advantage of sublingual route? |
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Definition
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Term
| What is the disadvantage of sublingual route? |
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Definition
| irritation, unpleasant taste |
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Term
| What is the advantage of rectal route? |
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Definition
| unconscious pt., vomiting pt |
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Term
| What is the disadvantage of rectal route? |
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Definition
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Term
| What are the different parenteral routes? |
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Definition
intravenous, intramuscular, subcutaneous, intraperitoneal,
and intraarterial injections |
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Term
| What are the advantages of parenteral route? |
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Definition
| rapid response, accurate dose, unconscious or vomiting pts |
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Term
| What are the disadvantages of parenteral route? |
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Definition
| toxicity, sterile form, painful, expensive |
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Term
| What is the advantage of skin route? |
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Definition
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Term
| What is the disadvantage of skin route? |
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Definition
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Term
| What is the advantage of respiratory route? |
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Definition
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Term
| What is the disadvantage of respiratory route? |
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Definition
| Limited by particle size and volatility |
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Term
| What is the advantage of intrathecal route? |
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Definition
spinal anesthesia to treat CNS when drug doesn't pass
blood-brain barrier |
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Term
| What is the disadvantage of intrathecal injection? |
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Definition
| Limited use, inconvenient |
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Term
| What determines the drug's potential danger from toxicity? |
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Definition
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Term
| What are the factors that determine the dissolution rate of tablet and capsule |
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Definition
| Dispersion Rate, Particle Size & compression, Solubility, Patient Compliance |
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Term
| What are the factors that affecting membrane transport? |
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Definition
| Cell membrane structure and Pores in membrane |
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Term
| How does the bimolecular lipid layer affect drug? |
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Definition
| It acts as lipid solvent and is highly permeable to lipid soluble drugs |
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Term
| What is the most important passive transport for drugs? |
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Definition
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Term
| What does simple diffusion depend on? |
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Definition
| Fick’s Law, lipid solubility and ionization |
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Term
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Definition
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Term
| What is the formula for Fick's Law? |
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Definition
Drug flux = - (Dose; directly proportional to temperature and inversely proportional to the
molecular weight) * membrane area * concentration gradient
dQ/dt = - D A dC/dX |
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Term
| What is activity of drug determined as? |
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Definition
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Term
| What is Lipid:Water partition coefficient? |
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Definition
| measure of solubility of a drug |
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Term
| What is the Henderson-Hasselbach equation used for? |
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Definition
| Characterizes the effects of pH and ionization of drugs on passive transport of drugs |
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Term
| What is Lipid solubility is proportional to? |
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Definition
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Term
| What is lipid solubility dependent on? |
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Definition
| dependent on the pKa of the drug and the pH of the medium |
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Term
| What is the H-H equation? |
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Definition
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Term
| What does buffering do to aspirin |
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Definition
Buffering (sodium bicarbonate) causes the acidic drug tablet to effervesce, thus physically breaking
up the tablet, causing the tablet to dissolve and be absorbed more rapidly |
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Term
| If the pH in the stomach increase, what effect does it have on the drug? |
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Definition
| drug would be mostly in the ionized state and therefore the drug would not be absorbed as readily |
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Term
| The H-H equation explains which clinically important facts? |
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Definition
| Weak acid drugs are best absorbed in low pH, which includes re-absorption from kidney tubules back into the blood |
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Term
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Definition
| desired steady-state blood level |
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Term
| What are the special transport system for drugs in membrane? |
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Definition
| Carrier Mediated (Active and Facilitated), Pinocytosis |
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Term
| What are the forces binding drug to plasma protein? |
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Definition
| VAN DER WAALS, HYDROGEN, IONIC BONDING |
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Term
| What are the factors that determine drug binding to plasma protein? |
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Definition
| BLOOD LEVEL OF DRUG, AMOUNT OF PLASMA PROTEIN, AMOUNT BOUND TO PLASMA PROTEIN, UNBOUND DRUG CAUSES EFFECT |
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Term
| What is free:bound drug ration dependent on? |
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Definition
1. Amount of tissue protein, i.e., albumin, and
2. K, the binding constant |
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Term
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Definition
| K = [Drug][Protein] / [Drug-Protein] |
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Term
| What explain drug-drug interactions? |
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Definition
| Competition for plasma protein |
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Term
| What are the fundamental pharmacokinetic principles based upon? |
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Definition
| body is considered a SINGLE compartment - the most elementary kinetic model |
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Term
| What factors is unequal distribution of drug depended on? |
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Definition
| Tissue Affinity, Body Fat, BBB, Blood Supply |
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Term
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Definition
| Metabolism, Biotransformation, Excretion |
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Term
| Where do Metabolism or Biotransformation take place? |
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Definition
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Term
| Where do excretion of drug take place? |
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Definition
1. Kidney
2. Liver Biliary Tract
3. Lungs
4. Skin |
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Term
| What factors determine drug decay? |
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Definition
Franction Absorbed [F]
Dose [D]
Fractional Rate Constants (absorption [Ka] and elimination [Ke])
Volume of Distribution [Vd] |
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Term
| What is the value F define? |
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Definition
F=1 - Drug completely absorbed.
F < 1 - Drug poorly absorbed |
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Term
| How is dose related to blood concentration? |
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Definition
| Blood concentration of a drug at any time is directly proportional to the dose |
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Term
| How is Ka and Ke quantitatively? |
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Definition
Ka, is much greater than Ke.
Absorption is more rapid than elimination |
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Term
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Definition
apparent or "virtual" volume into which a drug distributes
Unit: volume/body weight |
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Term
| What is the formula for Vd? |
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Definition
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Term
| What is clearance in terms of Vd? |
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Definition
| Clearance = Vd Ke [Unit: volume/time] |
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Term
| Can Vd be larger than the total plasma volume in the body? |
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Definition
| Yes because some drugs can be highly lipid soluble |
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Term
| What does drug decay curve show? |
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Definition
| final net effect of absorption, distribution, metabolism and excretion |
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Term
| What is the formula for drug decay in terms of Ke? |
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Definition
| Half-life = t1/2 = ln 2/Ke = 0.693/Ke |
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Term
| After how many half lives is drug eliminated (94%) in terms of 1st order elimination? |
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Definition
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Term
| What is the formula for first order decay? |
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Definition
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Term
| What is the formula for the rate of decline in 1st order elimination? |
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Definition
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Term
| What is the formula zero-order elimination? |
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Definition
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Term
| What is the formula for the rate of decline in zero-order elimination? |
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Definition
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Term
| What does zero order elimination mean? |
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Definition
| elimination processes ARE saturated; rate remains constant no matter what |
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Term
| What is the formula for drug decay when using multiple IV injections? |
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Definition
Cmax = Co (1/1-f)
Cmax = maximum plasma concentration
C0 = starting concentration
f = fraction remaining at the end of the dosing interval |
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Term
| What is the effect of a drug given repeatedly? |
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Definition
| When a drug is given repeatedly, the total body store increases exponentially to a plateau, with a half-time of increase that is equal to the elimination half-time |
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Term
| What would happen if the dosing interval is less than 4 half-lives? |
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Definition
| There will be drug accumulation |
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Term
| What is the effect of giving dose after every half-life time? |
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Definition
Since 4 half-lives are required to virtually eliminate the drug, subsequent doses will never reach peak levels greater than with one dose
Thus there will be no accumulation |
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Term
| If the dosing interval equals the half-life of the drug, what would be the final concentration? |
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Definition
| Twice that seen after the initial dose |
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Term
| If the dosing interval is such that there is a large fraction remaining, what would be the final concentration? |
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Definition
| Accumulation over multiple doses may reach toxic levels |
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Term
| What does the half-life of a drug determine? |
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Definition
| Half-life of drug determines the dose interval necessary to obtain desired level of drug |
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Term
| How is drug action prolonged? |
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Definition
1. Frequent doses
2. Slow absorption
3. Slow excretion
4. Inhibit metabolism |
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Term
| Will giving TWICE the dose of a drug with short half-life double the duration? |
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Definition
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Term
| How are drugs with larger half-life given? |
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Definition
| Give large LOADING dose followed by smaller MAINTENANCE doses |
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Term
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Definition
| Reduces time to reach steady state concentration (drug accumulation) during a multi-dose regimen |
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Term
| What is the formula for loading dose? |
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Definition
D* = Vd Css
D* = D (1/1-f) |
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Term
| For a drug with a half-life of 4 hours, 30 mg is taken once every 8 hours to maintain a therapeutic level. What is the proper loading dose? |
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Definition
| After 2 half-lives, 25% remains, so D* = 30 (1/1-0.25) mg = 30 (1/0.75) mg = 40 mg |
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Term
| How does disease alter pharmacokinetic? |
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Definition
| changing elimination rate constants and clearance through excretory organs and tissues |
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Term
| What is the loading dose for a drug with a Vd of 50 liters and a desired Css of 20 micrograms/ml? |
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Definition
| D* = 50 liters x 20 micrograms/ml = 1000 liters x micrograms/ml = 106 ml x 10-6 grams/ml = 1 gram |
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Term
| What can alter pharmacokinetic? |
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Definition
1. Kidney
2. Liver
3. Drug Interactions
4. Altered Kinetics |
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