The binding of thio-TEPA in human serum and to isolated serum protein fractions.

Binding of triethylenethiophosphoramide (thio-TEPA) in serum from healthy individuals and from cancer patients and its binding to isolated serum protein fractions were studied by equilibrium dialysis. A drug-protein binding in the order of 10% was demonstrated in serum, with little interindividual variation. The protein binding of thio-TEPA seemed to be restricted to albumin and lipoproteins, with the greatest affinity to albumin. The previously reported selective binding of thio-TEPA to gamma globulin was contrary to our findings. The almost insignificant degree of serum protein binding of thio-TEPA indicates that the drug is well suited for use in cancer drug combinations.