Thiolated Polymers as Potential Novel systems for Oral Delivery of Peptides and Proteins

Transcription

1 Thiolated Polymers as Potential Novel systems for ral Delivery of Peptides and Proteins Krum Kafedjiiski, A. Bernkop-Schnürch, University of Innsbruck

2 Thiolated Polymers / Thiomers S S S S S S S S Background

3 Chemical Structure of Anionic Thiomers CN C C S C Polycarbophil-cysteine CN C C S Polycarbophil-cysteamine Chitosan-4-thiobutylamidine [12] C 2 N N R2 R1 C 2 C Carboxymethylcellulose-cysteine S S N C C Alginate-cysteine (R 1 =, R 2 =C or R 1 =C, R 2 =) S Poly(acrylic acid)-homocysteine Background

4 Chemical Structure of Cationic Thiomers S 2 N C 2 N Chitosan-cysteine S C 2 N Chitosan-4-thiobutylamidine [12] Chitosan-thioglycolic acid S C 2 N + 2 C l - N S C 2 N 2+ Cl - N Chitosan-thioethylamidine Chitosan-4-thio-butylamidine Background

5 Advantages of Thiomers Improved mucoadhesive properties Improved cohesive properties Inhibitory effect towards proteases Controlled drug release Permeation enhancing effect Background

6 Advantages of Thiomers Improved mucoadhesive properties Improved cohesive properties Inhibitory effect towards proteases Controlled drug release Permeation enhancing effect Background

7 The idea behind Polymer C C C N C s s s s s s C s s s s s s s s s Mucus layer s s Mucoadhesion

8 Tensile Studies 0.0 g Mucoadhesion

9 TWA (µj) Mucoadhesive Properties Control Chitosan-TBA M. Roldo et al. Eur. J. Pharm. Biopharm. 57 (2004) Mucoadhesion

10 Rotating Cylinder Mucoadhesion

11 Polymer Degree of modification (µmol/g) Adhesion time (h) Improvement ratio Chitosan-4- thiobutylamidine 682 >160 >94 Poly(acrylic cysteine Chitosan-thioglycolic acid acid)- Chitosanthioethylamidine Polycarbophilcysteine Sodium Carboxymethyl cellulose-cysteine > Table. Comparison of the mucoadhesive properties of various polymeric excipients. Mucoadhesion studies were performed via rotating cylinder method; Improvement ratio = adhesion time of thiomer/adhesion time of corresponding unmodified polymer. Mucoadhesion

12 xidation and/or Thiol/Disulfide Exchange Reactions Polymer S + Mucin S-S Mucin Polymer S + S x. Polymer S-S Polymer Polymer S-S Mucin + S Mucin Polymer S + S Mucin x. Mucin S + S x. Mucin Polymer S-S Mucin Mucin S-S Mucin rientating Studies

13 Advantages of Thiomers Improved mucoadhesive properties Improved cohesive properties Inhibitory effect towards proteases Controlled drug release Permeation enhancing effect Background

14 S S S S S S S S S S Cohesion

15 Disintegration Studies Disintegration time [h] PCP PCP-Cys CMC CMC-Cys Bernkop-Schnürch, A. et al. (2000) J. Control. Release, 66, Cohesion

16 Advantages of Thiomers Improved mucoadhesive properties Improved cohesive properties Inhibitory effect towards proteases Controlled drug release Permeation enhancing effect Background

17 Zn 2+ Enzyme - - S S Thiomer Zn S S Enzyme Thiomer Enzyme Inhibition

18 1.0 Inhibitory Effect towards Carboxypeptidase B A / (A + A) Time [min] PAA-Cys PAA Control Bernkop-Schnürch, A. and Thaler, S. (2000). J. Pharm. Sci., 89, Enzyme Inhibition

19 Inhibitory Effect towards Aminopeptidase N 0,15 control p -nitroaniline ( mol) 0,1 0, Time (min) 0.25% PAA 0.25% PAA-Cys Bernkop-Schnürch et al. (2001) J. Pharm. Sci., 90, Enzyme Inhibition

20 Advantages of Thiomers Improved mucoadhesive properties Improved cohesive properties Inhibitory effect towards proteases Controlled drug release Permeation enhancing effect Background

21 Controlled Drug Release 100 % insulin released time (h) Marschütz, et al. Pharm. Res, 17 (2000) Controlled Release

22 Advantages of Thiomers Improved mucoadhesive properties Improved cohesive properties Inhibitory effect towards proteases Controlled drug release Permeation enhancing effect Background

23 Thight Junctions Permeation Enhancement

24 Responsible Mechanism: systemic circulation Model drug ccludin ccludin ccludin Model drug P T P S Model drug PAA-S P T P S GSSG GSSG GS GS GS GS P T P S S G Model drug PAA-S-S-PAA P T P S mucosal surface PAA-S-SG Clausen, A.E., et al. (2002). Pharm. Res., 19, Permeation Enhancement

25 Na-Fluorescein cumulative transport (% of total dose) time (min) Clausen et al. Pharm. Res., 19 (2002) Permeation Enhancement

26 Permeation Enhancing Properties 0.25 permeated rhodamine [%] % chitosan-tba 0.5% chitosan time (min) Permeation Enhancement

27 In vivo... Proof of concept

28 ral Insulin glucose level [%] time (hours) Marschütz, et al. Pharm. Res, 17 (2000) Proof of Concept

29 ral administration of a thiomer formulation containing insulin-1peg glucose level (%) Time [h] Caliceti et al. Eur. J. Pharm. Sci. 22 (2004) Proof of Concept

30 ral eparin heparin [IU/ml] * ** ** ** * thiomer/gs system 0.1 control time [hours] Kast et al. Pharm. Res. 20 (2003) Proof of Concept

31 Conclusions By the covalent immobilization of thiol groups to well-established polymeric excipients features such as mucoadhesive, cohesive, controlled drug release and permeation enhancing properties can be strongly improved. The efficacy of these novel polymers could be verified for numerous drugs on various mucosal membranes in various species. Conclusion