unbound drug

unbound drug

Free drug Therapeutics The fraction of drug in serum that is not bound to a carrier protein or other molecule, which generally is pharmacologically active
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This is important because only unbound drug molecules can exert a therapeutic effect in the body or undergo metabolism and excretion.
The immediate onset of inhibition and slow dissociation observed with ITMN-191 suggest that liver concentrations may underestimate its antiviral activity, since ITMN-191 will likely remain bound to the protease target after unbound drug is cleared from the liver.
Because only unbound drug is pharmacologically active, it is useful to measure the free concentration when any of the above conditions are present.
The common laboratory practice is to measure total phenytoin concentrations, which assumes that phenytoin protein binding is relatively constant, so that the concentration of the active unbound drug can be predicted from the total drug plasma concentration (2,3).
Disopyramide Monitor unbound drug concentrations in renal failure patients.
1, 1990 CANCER RESEARCH that two LDL-bound injected drugs -- methotrexate and floxuridine -- successfully dodged the body's natural clearance mechanisms to circulate at least six times longer in the blood of rats than did unbound drugs.