Fichas
Pharmacokinetics
Fichas del conjunto (53)
- 1What relationship does PK have?Dose-Concentration
- 2What relationship does PD have?Concentration-Effect
- 3What are the four steps of Pharmacokinetics?1. Absorption
2. Distribution
3. Metabolism
4. Elimination - 4What are the characteristics of drugs that allow them to transfer across the cell membrane?1. Molecular size and structure (small)
2. Degree of ionization (non-ionized)
3. Lipid Solubility (HIGH)
4. Protein binding (unbound) - 5What can change ionization?pH
- 6Definition of AbsorptionTransfer of drug from site of admin to Bloodstream
- 7What must oral drugs do to be absorbed? Where? Where do most absorb?Dissolve
Most dissolve in the stomach and absorb in small intestines - 8Why use Enteric-coated (EC) and Delayed-release (DR) drugs*Dissolve in Small Intestine*
1. Protect the stomach from drug
2. Vice versa
3. Release drug after stomach, target - 9What can you not do with EC or DR drugs?Cut, chew, crush, or dissolve
- 10How and where are most drugs absorbed?Via passive transport in the small intestine
- 11Relating to the body- Rate and Extent of drug absorption are determined by...Gastric mobility
Intestinal transit time
pH
Surface area
Food
Blood flow to absoption site - 12Relating to the drug- Rate and Extent of drug absorption are determined by...Molecular weight
Degree of ionization
Lipid/water solubility
Particle size
Dosage form
Concentration - 13Why take a drug with food?May be required for absortion (high fat needed)
Protection
Efficacy
Nausea/vomiting - 14Why take a drug without food?Cation binding, may need to avoid dairy and multivitamins
- 15Two ways body tries to get rid of a drug during absorptionP-glycoprotein
CYP3A4 - 16P-glycoproteinEfflux pump - pumps drugs back into gastrointestinal lumen
- 17CYP3A4An enzyme in enterocytes of small intestine that breaks down drugs
- 18First Pass EffectDrug concentration greatly reduced before systemic circulation
*AKA First Pass Metabolism*
Greatly REDUCE Bioavailability (F) - 19Bioavailability (F)Fraction of drug absorbed into systemic circulation after admin
- 20Route vs First Pass EffectIntravenous (F=100%)
Oral (FPE significant)
Sublingual and Transdermal (Bypass FPE)
Rectal (Less FPE) - 21Area under curve (AUC)Total drug exposure over time
- 22CmaxMaximum concentration of drug in blood
- 23Brand name vs genericNeed bioequivalence
*Can have different excipients (inactive ingredients) - 24BioequivalenceSame rate/extent of absorption
Also need to show same active ingredient, strength, dosage form, route - 25Define DistributionReversible transfer of a drug between compartments
(ex. plasma, intersitial fluid, intracellular fluid) - 26Volume of distribution (Vd)Total amnt of drug in body
___________________________
[Drug] in plasma - 27Protein binding - which can act?Unbound (free) drug is available for action
Bound drug is not available - 28Drug-drug interaction with protein bindingDrugs may compete for plasma protein binding, and may displace one another
- 29Blood brain barrierPrevents distribution of many drugs to brain
*VERY lipophilic can enter - 30Drugs can be store in tissue. T/FTrue
- 31Metabolism definitionBiotransformation - chemical alteration of drug in the body
*think liver* - 32What is the goal of metabolism ?Make drugs easier to excrete
- 33During metabolism, how does the body change the drugINCREASES hydophilicity
Hydrophilic compounds are excreted easier by kidneys - 34What are the two phases of metabolism ?Phase 1 - Oxidation, reduction, hydrolysis
Phase 2 - Conjugation (addition of molecules to drug) - 35Phase 1 metabolism enzymesCytochrome P-450 enzymes
(CYP) - 36ProdrugsAre inactive and require biotransformation to active metabolite
- 37Drugs may be ______ of CYP enzymes.1. Inducers
2. Inhibitors - 38Inducers of CYPSlow
Increase activity by increasing enzyme synthesis - 39Inhibitors of CYPQuick
Block metabolic activity of CYP enzymes - 40OTC and herbal medicationsIMPORTANT - May cause drug-drug interactions
- 41Phase 2 MetabolismConjugation with endogenous substance
*Usually LARGE and/or POLAR - 42Rate and extent of metabolism determined by...D-D interactions, D-food interactions, Diseases, Age, Environment, Genetics
- 43Excretion definitionRemoval of the drug and/or metabolites from the body
- 44Principal organ responsible for excretionKidney
- 45NephronBasic structural and functional unit of the kidney
- 46Four main processes of the nephron.1. Glomerular filtration
2.. Reabsorption
3. Secretion
4. Elimination - 47Glomerular filtration depends on...Plasma protein binding and renal blood flow
- 48Glomerular capillariesAre porous.
Both hydrophilic and lipophilic fall through via gravity.
Protein bound drugs are too large and will remain in circulation. - 49Clearance (Cl)Volume of plasma that is cleared of drug per unit time
- 50Glomerular filtration rate (GFR)-Measure of clearance through kidney, used to make clinical decesions
-Estimated by calculating Creatinine clearance
-Normal rate = ~ 120 mL/min - 51Tubular reabsorptionDepends on urine pH and lipid solubility
*more lipophilic are reabsorbed - 52Half-life (t1/2)Time required for for plasma concentration of drug to decrease by 50%
*If decrease clearance, INCREASE t1/2* - 53Steady state plasma concentration (Css)Attained after 4-5 half lives
Información
- Descripción
- Masters in Physician Assistant Pharmacology I Fichas sobre Pharmacokinetics , creado por Eric Rogers el 29/09/2018.
- Creado por
- Eric Rogers
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