1. DRUG TARGETING STRATEGY
FOR THE TREATMENT OF IBD: A NOVEL PRODRUG APPROACH
Shimon Ben-Shabat
Department of Clinical Biochemistry and Pharmacology,
Faculty of Health Sciences,
Ben Gurion University of the Negev

2. IBD
Inflammatory bowel disease (IBD) is a group of inflammatory conditions of the colon and small intestine. The major types of IBD are Crohn's disease and ulcerative colitis

3. Signs and Symptoms

4. Treatment
There are several methods dealing with Gastrointestinal (GI) symptoms of the disease:
Systemic treatment (Aminosalicylates, steroids).
Immunosupresants – (Azathioprine, mercaptopurine, cyclosporine….)
Local treatment by suppositories (especially for colitis) or targeted drugs delivery.
I.V or I.M dosage (for Immunosupresants)
Biological Therapy: Infliximab, a high-affinity chimeric anti-TNF-a monoclonal antibody. Infliximab neutralizes and effectively clears TNF-α following intravenous infusion.

5. Existing delivery systems
Time dependent
pH dependent
Microbial dependent
All the existing strategies
enable targeting only to
a particular region of
the intestine

6. catalyze the hydrolysis
Phospholipase A2 (PLA2)
Group of enzymes that mediate multiple functions
eicosanoid signaling, microbial control, and integren binding
Phospholipid-hydrolyzing enzymes that generate bioactive lipid mediators
Secreted form overexpressed in inflammation, athrosclerosis, cancer
catalyze the hydrolysis
of the sn-2 acyl bond

7. DRUG TARGETING STRATEGY FOR THE TREATMENT OF IBD: A NOVEL PRODRUG APPROACH
Synthesis of phospholipid-based prodrugs with diverse linker length.
In-vitro and in vivo evaluation of drug absorption into inflamed cells and PLA2-mediated activation, as function of linker length.
Significantly improve drug therapy in IBD patients, enabling higher efficacy and lower toxicity profiles.

8. Our delivery system: PL-diclofenac conjugates with different linker length
PLA2

9. PL-cyclosporine conjugates with different linker length

10. PL-tacrolimus conjugates

11. PLA2: Overexpresion in Inflammation
PLA2 activity elevates in caco-2 culture media, 24h after treatment with 10ng/ml TNF-α + 100U/ml IL1-α.

12. In vitro PLA2-mediated activation (left) of the four novel PL-diclofenac conjugates, and the corresponding appearance of free drug (right).

13. Enzymatic Degradation
secreted amidase/peptidase

14. In vitro PLA2-mediated activation of PL-indomethacin conjugates

15. Indomethacin plasma concentration versus time profiles (mean±S. D
Indomethacin plasma concentration versus time profiles (mean±S.D., n=5)
The phospholipid–indomethacin conjugate as the whole
complex was not detected in the plasma

16. Stability of PL-diclofenac conjugates
Enteric coating to pass the stomach

17. Determining Optimal Linker Length by Computational Approach
Thermodynamical alchemical cycle
The rate of PLA2 cleavage reaction is determined by the free energy of prodrug binding.
The free energy changes associated with increasing/decreasing linker length were calculated.
PLA2/PL-indomethacin prodrug complexes with 2 and 8 carbon linker.

18. Determining Optimal Linker Length by Computational Approach
The optimal linker length for indomethacin prodrug is 5 CH2 units:

19. Optimal Linker Length: Calculated Results Correlate Well with Experimental Data
Binding free energies of prodrug in PLA2 transition state compared to previously published experimental results:

20. The overall work plan is presented in the following illustration:

21. Acknowledgments Ben Gurion University
Prof. Arik Dahan
Sveta Epstein
Noa Cohen
Milica Markovic
Cloud Pharmaceuticals, North Carolina
Dr. Shahar Keinan
University of Florida
Prof. Ellen Zimmermann
Prof. Aaron Aponick
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