An amino group containing cyclosporin A (CsA) derivative has been synthesiz
ed and conjugated to N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer via
an aromatic azo bond, which can be specifically cleaved by azoreductase ac
tivity in colon to release the drug for the treatment of colon diseases. Le
ctins, peanut (Arachis hypogea) agglutinin (PNA) and wheat germ agglutinin
(WC;A), have been conjugated to HPMA copolymer-CsA derivative conjugates (P
CsA), respectively, to give bioadhesive conjugates. The PNA and WGA are the
targeting proteins that can bind to diseased colon tissue and healthy tiss
ue, respectively. There were on average four P(CsA) copolymer chains attach
ed on one WGA molecule with a drug content of 16.0 wt % and five P(CsA) cop
olymer chains attached on one PNA molecule with a drug content of 11.5 wt %
. The incubation of a P(CsA) copolymer with the rat cecal contents resulted
in the cleavage of the azo bond and release of the cyclosporin derivative.
The biological evaluation of the conjugates is under way.