New carriers for representative peptides and peptide drugs.

3,5-Disubstituted tetrahydro-2H-1,3,5-thiadiazine-2-thione (THTT) derivatives; 4a-g were prepared and found to be a promising prodrug approach for peptide drugs. The pH profile for their degradation in aqueous buffer solutions was determined using HPLC technique and accounted for, in terms of specific base-catalyzed reactions. All of the compounds however, showed high acid-stability. Enzymatic (human serum) hydrolysis of the different derivatives offered an advantageous range of t1/2's, the property that permits controlling onset and duration of actions of drugs.