[An approach to the preparation of digestive enzyme-drug for oral administration: complex lactase microcapsules]

Complex microcapsules which could protect enzyme drugs from inactivation in both the stomach and intestine were prepared. In the process, semipermeable microcapsules were first formed by enveloping the enzymes within spherical, ultrathin semipermeable membranes. To resist gastric juice, the semipermeable microcapsules were further encapsulated by enteric-soluble materials to form complex microcapsules. When the preparations were taken into the intestine, the semipermeable microcapsules were released and small molecular substrates could then equilibrate rapidly across the semipermeable membrane to be acted on by the enveloped enzymes, while alimentary proteases remained outside. This complex microcapsulated lactase could retain over 65% of its activity after simulation in gastric juice for 2 h, and over 60% of its activity was retained after 6 h in pancreatin-containing simulated intestinal juice. On the contrary, unencapsulated lactase lost all activities immediately under the same conditions.