Adhesive material from the fimbriae (esp. Type 1) of bacteria or synthetic analogues or fragments thereof is combined with a drug to provide for attachment to the gut of a mammal, thereby prolonging the transit time of the drug through the gut. The 28 kDa polypeptide from E. coli Type 1 fimbriae is the preferred adhesive material (“adhesin”). The drug is presented in a carrier such as albumin, a polylactide/glycolide copolymer or alginate microcapsules. The adhesin may be incorporated in the carrier during preparation thereof, adsorbed onto the carrier after preparation, or covalently linked thereto, for example with carbodiimide.