A. Bernkopschnurch et Nc. Gockel, DEVELOPMENT AND ANALYSIS OF A POLYMER PROTECTING FROM LUMINAL ENZYMATIC DEGRADATION CAUSED BY ALPHA-CHYMOTRYPSIN, Drug development and industrial pharmacy, 23(8), 1997, pp. 733-740
We have been developing a modified polymer which protects inserted pep
tide and protein drugs from chymotrypsinic degradation. A trypsin-chym
otrypsin-inhibitor was covalently bound to a bioadhesive polymer (poly
(acrylic acid)) by a condensation reaction of the available amino grou
ps of the inhibitor with the carboxyl groups of the polymer. The inhib
ition of or-chymotrypsin by the isolated conjugate was determined by a
n enzyme assay using N-benzoyl-L-tyrosine ethyl ester as substrate. It
had an inhibitory effect of 2.4 CIU (= chymotrypsin inhibiting units)
per mg. The protective effect was also evaluated in a drug delivery s
ystem containing 5% of this modified polymer. Under physiological a-ch
ymotrypsin concentrations it demonstrated, in lateral parts of the car
rier matrix, the remaining of 71.4% +/- 14.3% (means of three experime
nts; +/- S.D.) of undigested inserted test-protein (beta-galactosidase
) after 7 hr of incubation at 37 +/- 0.5 degrees C. Samples from the c
enter of the matrix did not show any digestion of the protein. On the
other hand a complete digestion in lateral parts and the remaining of
only 67% +/- 14.4% of undigested test-protein in the center, could be
observed by the same delivery system without the conjugate. Because of
this verified protective effect and the possibility to exclude toxic
side effects of the inhibitor by immobilization, the system described
here seems to be an important step towards a successful peroral (poly)
peptide drug administration.