drug delivery systems for delivering agents capable of reducing the quantity of residual antibiotics reaching the colon following oral or parenteral antibiotic therapy , and for delivering metallo - dependent enzymes , and methods of using the drug delivery systems , are disclosed . the drug delivery systems include pectin beads that encapsulate the active agent , where the pectin is crosslinked with zinc or any divalent cation of interest and the pectin beads are coated with eudragit ®- type polymers . the drug delivery systems are orally administrable , but can deliver the active agents to the colon . in some embodiments , they can administer the agents to various positions in the gastro - intestinal tract , including the colon . one metallo - dependent enzyme is the β - lactamase l1 from stenotrophomonas maltophilia , and agents that inactivate macrolide , quinolone , fluoroquinolone or glycopeptide antibiotics can also be used . the delivery of the active agent can be modulated to occur at various pre - selected sites of delivery within the intestinal tract by gelling / crosslinking a mixture of the active agent , such as a metallo - dependent enzyme , and pectin , with divalent metallic cations such as ca + 2 or zn + 2 . a stable metallo - dependent enzyme formulation can be delivered to the lower intestine or colon . the use of zinc cations to crosslink the pectin is particularly preferred when specific metallo - dependent enzymes , which are zn 2 + dependent , could interact with other cationic species if they were used to gel the pectin beads and thus adversely affect the activity of such metallo - dependent enzymes .