TDM Flashcards
The term PHARMACOKINETICS refers to the:
-Relationship between drug dose and the drug blood level
-Concentration of drug at its sites of action
-Relationship between blood concentration and therapeutic response
-The relationship between blood and tissue drug levels
Relationship between drug dose and the drug blood level
Pharmacokinetics is the mathematical expression of the relationship between drug dose and drug blood level. When the appropriate formula is applied to quantitative measures of drug dose, absorption, distribution, and elimination, the blood concentration can be accurately determined.
The term PHARMACODYNAMICS is an expression of the relationship between:
-Dose and physiological effect
-Drug concentration at target sites and physiological effect
-Time and serum drug concentration
-Blood and tissue drug levels
Drug concentration at target sites and physiological effect
Pharmacodynamics is the relationship between the drug concentration at the receptor site (tissue concentration) and the response of the tissue to that drug. For example, the relationship between lidocaine concentration in the heart muscle and the duration of the action potential of Purkinje fibers.
The study of PHARMACOGENOMICS involves which type of testing?
-Family studies to determine the inheritance of drug resistance
-Testing drugs with cell cultures to determine the minimum toxic dosage
-Testing for single nucleotide polymorphisms known to affect drug metabolism
-Comparison of dose-response curves between family members
Testing for single nucleotide polymorphisms known to affect drug metabolism
Pharmacogenomics refers to the study of genes that affect the performance of a drug in an individual. One method is to test for single nucleotide polymorphisms (SNPs) using DNA microarrays in genes such as those that code for the cytochrome P450 enzymes involved in the metabolism of many drugs. Genetic variations of one such enzyme may account for individual pharmacokinetic differences and can be used to predict the efficacy of the drug.
Select the five pharmacological parameters that determine serum drug concentration.
-Absorption, anabolism, perfusion, bioactivation, excretion
-Liberation, equilibration, biotransformation, reabsorption, elimination
-Liberation, absorption, distribution, metabolism, excretion
-Ingestion, conjugation, integration, metabolism, elimination
Liberation, absorption, distribution, metabolism, excretion
Liberation is the release of the drug and absorption is the transport of drug from the site of administration to the blood.
Distribution refers to the delivery of the drug to the tissues. It involves dilution and equilibration of the drug in various fluid compartments including the blood, and is influenced by binding to proteins and blood cells.
Metabolism is the process of chemical modification of the drug by cells. This results in production of metabolites with altered activity and solubility.
Excretion is the process by which the drug and its metabolites are removed from the body.
Most common route of drug delivery:
Intravenous
Oral
Rectal
Transcutaneous
Oral
Oral administration is the most common route of delivery.
Drug administration which offers the most direct route with effective delivery to their sites of action:
Intramuscular
Intravenous
Oral
Rectal
Subcutaneous
Intravenous
Intravenous (IV) administration into the circulatory system offers the most direct route with effective delivery to their sites of action.
Drug delivery commonly used in INFANTS and in situations in which oral delivery is unavailable:
Intramuscular
Intravenous
Rectal
Subcutaneous
Rectal
Rectal delivery (suppository) is commonly used in infants and in situations in which oral delivery is unavailable.
Which route of administration is associated with 100% bioavailability?
Sublingual
Intramuscular
Oral
Intravenous
Intravenous
When a drug is administered intravenously, all the drug enters the bloodstream, and therefore, the bioavailable fraction is 1.0.
In pharmacokinetics, serum concentrations ______ when the rate of absorption exceeds distribution and elimination.
Decline
Spuriously decline
Rise
Spuriously rise
Rise
Serum concentrations rise when the rate of absorption exceeds distribution and elimination.
The concentration declines as the rate of elimination and distribution exceeds absorption.
The rate of elimination can only be determined after absorption and distribution are complete.
In pharmacokinetics, the concentration of the drug _____ as the rate of elimination and distribution exceeds absorption.
Declines
Spuriously declines
Rises
Spuriously rises
Declines
Serum concentrations rise when the rate of absorption exceeds distribution and elimination.
The concentration declines as the rate of elimination and distribution exceeds absorption.
The rate of elimination can only be determined after absorption and distribution are complete.
Single most important factor in therapeutic drug monitoring (TDM):
Amount of WBCs in the specimen
Presence of glucose in the specimen
Timing of specimen collection
Volume of specimen
Timing of specimen collection
Timing of specimen collection is the single most important factor in TDM.
In general, trough concentrations for most drugs are drawn right before the next dose; peak concentrations are drawn 1 hour after an orally administered dose.
Specimen of choice for the determination of circulating concentrations of most drugs:
Expectorated sputum
Gastric fluid
Serum or plasma
Urine
Serum or plasma
Serum or plasma is the specimen of choice for the determination of circulating concentrations of most drugs.
Heparinized plasma is suitable for most drug analysis. The calcium-binding anticoagulants add a variety of anions and cations that may interfere with analysis or cause a drug to distribute differently between cells and plasma. As a result, ethylenediaminetetracetic acid (EDTA), citrated and oxalated plasma are not usually acceptable specimens.
Blood sample collection time for peak drug levels:
Varies with the drug, depending on its rate of absorption
Is independent of drug formulation
Is independent of the route of administration
Is 30 minutes after a bolus intravenous injection is completed
Varies with the drug, depending on its rate of absorption
The peak concentration of a drug is the highest concentration obtained in the dosing interval.
For oral drugs, the time of peak concentration is dependent upon their rates of absorption and elimination and is determined by serial blood measurements.
Peak levels for oral drugs are usually drawn 1–2 hours after administration of the dose.
For drugs given intravenously, peak levels are measured immediately after the infusion is completed.
When should blood samples for trough drug levels be collected?
30 minutes after peak levels
45 minutes before the next dose
1–2 hours after the last dose
Immediately before the next dose is given
Immediately before the next dose is given
Trough levels are usually collected just before the next dose is given.
A urine sample is received in the laboratory with the appropriate custody control form, and a request for drug of abuse screening. Which test result would be cause for rejecting the sample?
Temperature after collection 95°F
pH 5.0
Specific gravity 1.005
Creatinine 5 mg/dL
Creatinine 5 mg/dL
Approximately 5 per 1,000 urine samples received for DAU testing have been adulterated by either dilution, substitution, or addition of substances such as glutaraldehyde that interfere with testing.
The majority of these situations can be detected by determining temperature (90°F–100°F) pH (4.5–8.0), specific gravity (1.003–1.019), and creatinine (≥20 mg/dL).
All of the values listed are within the limits of an acceptable sample with the exception of creatinine.
