Composite Polysaccharide Hydrogels An Innovative Approach for Sustained Release of Hydrophobic Drugs Dr. Elinor Josef1,2, Keren Delmar2, Havazelet Bianco-Peled2,3 1Inter-Departmental Program for Biotechnology, 2The Russell Berrie Nanotechnology Institute, 3Department of Chemical Engineering. Technion-Israel Institute of Technology 8th International Conference and Exhibition on Pharmaceutics & Novel Drug Delivery Systems March 07-09, 2016 Madrid, Spain

Motivation How to use hydrogels to deliver hydrophobic drugs? Hydrogels have many advantages as drug delivery vehicles: Biocompatible Tunable release patterns Injectable Environmental sensitive systems Can encapsulate proteins and DNA Ideal for oral and mucosal delivery Vashist et al. J. Mater. Chem. B, 2014,2, 147-166 On the down side, hydrogels cannot easily be used as delivery matrices for hydrophobic drugs, that now constitute over 40% of new developed drugs.

Microemulsions Microemulsions are often used to solubilize hydrophobic moieties for transdermal drug delivery. M. J Lawrence et al. , Advanced drug delivery reviews (2000) Microemulsions are thermodynamically stable dispersions of oil and water, stabilized by a surfactant film. Microemulsions can’t be used for oral/mucosal sustained release

Composite Hydrogels Hypothesis: Drug loading will increase due to its higher solubility in the oil droplets, while the cross-linked hydrogel matrix could be readily used as a solid controlled delivery system. 4

System Design Challenges Stable polymer-microemulsion mixture. Empirical formulation only. Use of biocompatible ingredients: Hydrocarbon oils are not acceptable. Limited number of surfactants. Many of the co-surfactants are long chain alcohols which are not biocompatible. Short chain alcohols could cause phase separation upon dilution Incorporation of the drug. Composite hydrogel Stable polymer-microemulsion mixture. Crosslinking of the polymer.

Microemulsion Tween-80 Span-20 IPM (Isopropyl Ketoprofen (KT) C64H124O26 1310 gr/mol Span-20 C18H34O6 346 gr/mol IPM (Isopropyl Myristate) C17H34O2 270 gr/mol Ketoprofen (KT) C16H14O3 254 gr/mol 6

Formation of the Microemulsion Cryo-TEM Dynamic Light Scattering 100nm Diameter [nm] ± stdev ME φ=2.8% 11.6±0.8 ME φ=1.4% 9.8±0.5 ME φ=0.9% 9.9±0.4 ME-KT φ=2.8% 8.9±0.7 ME-KT φ=1.4% 10.3±0.2 ME-KT φ=0.9% 10.5±0.6 φ – Surfactants Concentration ME- Microemulsion ME-KT- Microemulsion with Ketoprofen Josel et al., Acta Biomaterialia, 6(12), 4642-4649 2010

Structure of the Microemulsion Small angle X-ray scattering (SAXS) curves of ME and ME-KT with φ=2.8% (upper curve) and 1.4%. Φ= Surfactants concentration ME- Microemulsion. ME-KT- Microemulsion with ketoprofen. Parameter ME φ=2.8% φ=1.4% ME-KT Rc [nm] 4.4 ± 0.05 4.6 ± 0.07 4.5 ± 0.06 4.3 ± 0.1 Rshell [nm] 5.7 ± 0.04 5.6 ± 0.07 6.0 ± 0.04 Shell density [el/nm3] 53 ±2 81 ± 8 69 ± 4 43 ± 3 σ 0.6 ±0.02 0.6 ± 0.02 0.7 ± 0.02 0.7 ± 0.04 Rc Rshell Drug is located in the shell

Hydrogel Ca Biocomaptable Easy cross-linking Mucoadhesive L-guluronic acid (G) D-mannuronic acid (M) Ca Biocomaptable Easy cross-linking Mucoadhesive

Composite hydrogels Alginate gels crosslinked with Calcium ions Alginate 25 mg/ml Ca-EGTA 15 mM Ketoprofen 1 mg/ml No Drug With Drug With Drug in ME Alginate-ME Calc. Alginate + ME ]nm-3[ SAXS curves of alginate-ME gel with 7.5mM and 15mM Ca-EGTA Alginate ME

Ketoprofen Release Profiles Time to 20% Release Ketoprofen in Alginate Composite Hydrogel Alginate 25 mg/ml, Ca-EGTA 5.5, 7.5, 20 mM Time to 50% Release

Release from Composite Hydrogels Time to 20% Release Time to 50% Release Crosslinker: Calcium 7.5 mM Crosslinker: Calcium 20 mM Release rate can be varied by changing the gel composition (network structure)

Release from Composite Hydrogels Release from composite hydrogels with the same alginate hydrogel 5 “empty” MEs Progesterone in 3 MEs Progesterone , vitamin D, and empty ME Nile Red, different concentrations Release rate does not depend on the exact ME composition, the drug type or its concentration Josel et al., Acta Biomaterialia, 9(11), 8815-8822 2013

Alginate Sponges Self-microemulsifying Drug Delivery Systems Droplets are preserved after a drying – rehydration cycle Josef & Bianco-Peled, Int J Pharm 458(1), 208-217, 2013

Limitations of alginate composite hydrogels Release is completed within few hours Disintegrates in buffer Idea: positively charged hydrogel, anionic microemulsion

Chitosan hydrogels Chitosan has been reported to be non-toxic biocompatible biodegradable antimicrobial and antifungal properties Making it an ideal candidate for controlled release applications

Crosslinking of chitosan 20 hours Before swelling, 20 hour gelation pH=5 pH=4.0 pH=4.5 pH=5.0 pH=5.5 90 hours Swollen chitosan (1% w/v) hydrogels crosslinked with genipin (0.1% w/v) K. Delmar and H. Bianco-Peled, Carbohydrate Polymers 127, 28-37, 2015

Release from chitosan composite hydrogels Release in water Nile Red Curcumin pH=5.5 pH=4.0 Release rate depends on the exact ME composition Faster release from the highly crosslinked hydrogels K. Delmar and H. Bianco-Peled, Carbohydrate Polymers 136, 570-580, 2016.

Release from chitosan composite hydrogels Release in PBS buffer Nile Red Curcumin pH=5.5 pH=4.0 Release rate depends on the exact ME composition Release is faster in PBS

Swelling of chitosan composite hydrogels

Swelling of chitosan composite hydrogels

FTIR analysis

Conclusions Composite hydrogels were successfully designed. Addition of drug resulted in a clear gel with no visible precipitations. Microemulsion droplets exist in the composite hydrogel. The system showed potential as a drug delivery vehicle.

Acknowledgments

Thank you for your attention Haifa, Israel