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Pharmaceutical Research

, Volume 17, Issue 12, pp 1468–1474 | Cite as

Design and In Vivo Evaluation of An Oral Delivery System for Insulin

  • Michaela K. Marschütz
  • Paolo Caliceti
  • Andreas Bernkop-Schnürch
Article

Abstract

Purpose. To develop an oral controlled release system for insulin.

Methods. The polymer-inhibitor conjugates carboxymethylcellulose (CMC)-Bowman-Birk inhibitor and CMC-elastatinal were homo- genized with polycarbophil-cysteine conjugate, insulin, and mannitol, compressed to 2 mg microtablets and enteric coated with a polymethacrylate. The protective effect of this delivery system for insulin towards enzymatic degradation, as well as the release profile, was evaluated in vitro. In addition, the effect of the dosage form on glucose levels of diabetic mice was determined.

Results. Tablets containing the CMC-inhibitor conjugates showed a strong protective effect for insulin. Whereas 91.6 ± 7.4% (mean ± SD, n = 3) of insulin in the dosage form without the inhibitor conjugates has been degraded within 3 h of incubation in an artificial intestinal fluid containing physiological concentrations of trypsin, chymotrypsin, and elastase, 49.7 ± 5.5% (mean ± SD, n = 3) of insulin remained stable in the delivery system containing the polymer-inhibitor conjugates. Additionally, polycarbophil-cysteine (PCP-Cys) provides high cohesiveness of the dosage form, due to the formation of inter- as well as intramolecular disulfide bonds within the polymer matrix. According to this, a controlled release of insulin could be achieved over a time period of 10 h. Furthermore, in vivo studies in diabetic mice showed a decrease in basal glucose levels of 20% to 40% during a time period of 80 h.

Conclusions. Mucoadhesive polymer-inhibitor conjugates might represent a promising excipient in delivery systems for oral (poly)peptide delivery.

controlled release enzyme inhibitors insulin degradation mucoadhesive polymers oral insulin delivery protective effect serine proteases thiolated polymers 

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Copyright information

© Plenum Publishing Corporation 2000

Authors and Affiliations

  • Michaela K. Marschütz
    • 1
  • Paolo Caliceti
    • 2
  • Andreas Bernkop-Schnürch
    • 3
  1. 1.Center of Pharmacy, Institute of Pharmaceutical Technology and BiopharmaceuticsUniversity of ViennaViennaAustria
  2. 2.Department of Pharmaceutical SciencesUniversity of PaduaPadovaItaly
  3. 3.Center of Pharmacy, Institute of Pharmaceutical Technology and BiopharmaceuticsUniversity of ViennaViennaAustria

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