Process for the preparation of azo-and /or disulfide polymer matrix drug delivery system for the site specific delivery of an active agent in the colon

A process for the preparation of a drug delivery system for the site specific delivery of an active agent in the colon comprising the steps of:

• (a) preparing a colon specific reduction sensitive polymer selected from the group consisting of (i) azo-containing polymers, (ii) disulfide-containing polymers and (iii) azo- and disulfide-containing polymers, by copolymerizing an azo- and/or disulfide-containing .alpha.,.omega.-difunctional reagent by polycondensation or polyaddition with a suitable .alpha.,.omega.-difunctional comonomer according to the general reaction sheme illustrated below:
• n Y-R.sub.1 -R-XX-R-R.sub.2 Y+n HX-R.sub.3 -XH.fwdarw.Y-R.sub.1 -R-XX-R-R.sub.2 -[-Z-X-R.sub.3 -X-Z-R.sub.1 -R-XX-R-R.sub.2 -].sub.n-1 -Z-X-R.sub.3 -XH
• with
• -XH=-NH.sub.2, -OH
• -Y=-COOH, CO-Hal, COOAlkyl, -N.dbd.C.dbd.O, ##STR15## -SO.sub.2 Hal, -COOSuccinimide -XX-=-N.dbd.N-, -S-S-
• and
• R=alkyl, ##STR16## R.sub.1, R.sub.2 =alkyl, aryl, alkylaryl groups all or not substituted R.sub.3 =alkylidene, arylidene, alkylarylidene all or not substituted polyether, polyester
• hal=halogen radical, e.g. Cl, Br
• with:
• -Y+H-X-.fwdarw.-Z-X
• and Z=C.dbd.O, NH-C.dbd.O, CH.sub.2 -CH-OH, SO.sub.2
• and whereby X and Y are interchangeable in the above formulas;
• and (b) compounding or coating said active agent with said polymer to form said drug delivery system capable of providing a site specific delivery of said active agent in the colon.