Toxicology/ TDM

study of biochemical and physiological effects of drugs. relationship between the concentration at the receptor site and the response of the tissue to that drug. EX: liodcaine on heart muscle and the duration of the action potential of fibers.
> receptor binding, post receptor effects, chemical interactions.
look at drug movement throughout body. Relationship between drug dose and drug blood level. Drug absorption, bioavailability, distribution, metabolsim, elimination.
Five pharmacological parameters for serum drug concentration
Drug liberation, absorption, distribution, metabolism, excretion.
First pass metabolism
SOME drugs is metabolized from the portal circulation reducing bio availability. fraction of drug that is absorbed and actually reaches the blood. Low bioavailability: quickly metabolized by liver, imeediately after being absorbed in the small intestine.
Steady state
point at which the concentration of the drug is in equilibrium with the rate of dose adminstration and the rate of elimiation.
Oral vs intravenous
Oral dosing intervals give peaks and troughs in the dose response curve, while intravenous is constant.
Trough collected when?
Right before next dosage
Intravenous drugs model of elimination..
biphasic/ two compartment with serum level rapidly falling in the first phase. Tissue vs blood/good tissues (profused). Ex: digixon. Lots can be accumulated in the tissues while target is fine. Oral route is uniformly distribution. One compartment.
Aminoglycoside antibiotics… why pay attention to it?
Highly toxic, must perform peak and trough measurements. Concentrates at the kidneys bro! Toxic can damage kidneys and hearing.
TLC and drugs screen.
Rf values match with standards. Comparison to see what drugs it can contain.
Lead specimen type
whole blood (trace element tube blue) with AAS.It intereferes with heme synthesis by binding to ALA’s sulhydrl group. Navy blue top for others.

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