TDM Flashcards
TDM ensures that a given drug dosage produce —
- maximal therapeutic effect
- minimal toxic adverse effects
TDM involves the — (3)
- analysis
- assessment
- evaluation of circulating concentrations of drugs in serum, plasma, or whole blood
main highway in the body in order for one product or drug to proceed from point A to point B
circulation
TDM is a — procedure performed for?
quantitative procedure
performed for DRUGS WITH A NARROW THERAPEUTIC INDEX
only — can interact with the site of action and result in a biological response
free fraction of the drugs
drugs that are able to travel to the site where it is needed
when it is needed and when its concentration is elevated?
“free drug”
drugs that are circulating freely in the blood
elevated concentration is considered as TOXIC
it is able to do more harm than good such as destroying the environment of the target site
those drugs that are bound to — should be unbound first
carrier proteins
enumerate the causes of drug toxicity
- elevated concentrations of free drug
- abnormal response to drug after administration
- presence of active metabolites
enumerate the factor of TDM (6)
- route of administration
- rate of absorption
- protein binding
- drug administration
- drug distribution
- drug elimination
enumerate the therapeutic failure (5)
- non-compliance
- sub-therapeutic dose
- bioavailability
- malabsorption
- drug interaction
enumerate the types of assays required (3)
- total drug
- free drug
- metabolites
true or false
in TDM, we usually check for metabolites and the total drug while free drug is tested seldomly.
FALSE!
we usually check for total drug and free drug
metabolites are usually check in toxicology.
common specimen of metabolites
urine
enumerate the routes of administration for drugs
what is the most common method?
- INJECTION (intravenous, intramuscular, subcutaneous, epidermal)
- INHALED
- ABSORBED IN THE SKIN
- RECTAL (suppository)
- ORAL
ORAL ADMINISTRATION
intravenous is with — bioavailability
what is the bioavailable fraction?
100% bioavailability
1.0 bioavailable fraction
for intravenous, drugs is administered directly in circulation and it will not pass the?
GIT and liver
bioavailability of oral administration
0.7
if oral administration, drug travels —
(enumerate the whole journey hahaha)
- mouth
- GIT
- liver
- circulation
- target site
not the complete drug will reach to the target organ since it has already processed first in the liver.
the distribution is through?
blood flow via capillary permerability
location/s where the drugs are effective
it can either be?
BODY TISSUES
not generally in the blood
binding to proteins or free fractions
differentiate the distribution for binding to proteins or free fractions
binding to proteins: still need to undergo a process of unbinding
free fractions: can immediately reach the target site
this will matter in some drug distribution
- lipid solubility of the drug
- pH gradient
the drugs can be broken down into metabolites, such as —
- water soluble
- pharmacologically active or inactive
- easily excreted
absorption is via?
also, absorption can depend on?
passive diffusion or active transport
formulation of drug
a pill requires — while liquids are —
pill requires dissolution
liquids are rapidly absorbed
indications and counterindications that we need to observe (5)
- intestine motility
- pH
- inflammation
- food, age, pregnancy
- concurrent pathologic conditions
for eliminations, the route of drug is via?
but most commonly, elimination is through?
hepatic metabolism or renal filtrations
renal filtration
other modes of elimination (enumerate)
skin is done through?
- skin
- lungs
- breast
- saliva
- skin is done through?
- breast is through?
skin = sweating
breat = breastmilk
the rate at which a particular drug is cleared from the cirulation is dependent not only on the type of drug itself, but?
also on a patient’s capacity to metabolize and excrete it
refers to the time required to reduce the blood level drug concentration to half after equilibrium is obtained.
steady state
what is the most important factor to consider in specimen collection?
timing
trough is?
peak is?
trough is 30 mins BEFORE the next dose
peak is 1 hr AFTER administration
true or false.
there are some drugs that we can check randomly
TRUE
specimen of choice
anticoagulants that can interfere in analysis.
WHOLE BLOOD
but serum and plasma can still be used.
EDTA, citrate, oxalate
- if serum will be used, what should be noted/avoided?
- if plasma?
for yellow top, what should be avoided?
- if serum, avoid the GEL
- if plasma, use heparinized samples
THIXOTROPIC GEL is not allowed.
the measurement of serum concentration should be done only?
after steady state has been achieved
true or false
URINE cannot be used for testing TDM.
FALSE.
URINE can still be used but only rare
enumerate the methods of TDM
- enzyme multiplied immunoassay technique
- enzyme link immunosorbent assay
- radioimmunoassay
- high performance liquid chromatography
- fluorescence polarization immunoassay
true or false
the amount of enzyme activity is inversely proportional to the amount of drugs present in the sample.
FALSE
directly proportional
this method has moderate sensitivity, automated, and has rapid turn-around time
enzyme link immunosorbent assay
this method has high sesnitibity but long turnaround time.
what is the disadvantage of this method?
radioimmunoassay
poses health risk due to radiation involved in the process.
this is with highest sensitivity, least expensive, but long turnaround time. the measurement depends on the type of column used, the solvent and detector systems.
high performance liquid chromatography
this method is automated, with rapid turn-around time and moderate sensitivity.
fluorescence polarization immunoassay
which method has highest sensitivity?
high performance liquid chromatography
which method has rapid turn-around time?
fluoresence polarization immunoassay
