1. A poloxamer /chitosanin situ forming gel with prolonged retention time for ocular delivery PRESENTED BY VEERANNA.B DEPARTMRNT OF PHARMACEUTICS NIPER-A

2. Flow of seminar Introduction Research article Objective Materials and methods Results and discussion Conclusion References

3. Anatomy of eye: Eye anatomy Rule of seven in eye anatomy: Volume of eye: ≈7.0 mL Circumference of eye: ≈ 7.0 cm Total protein in eye: ≈0.7% w/v Total sugar present: ≈0.7% w/v Total NaCl present: ≈ 0.7% w/v Total mineral elements(Na+, K+. NH3+): ≈0.7% w/v Volume of lachrymal fluid : ≈7.0 μl Corneal surface epithelial intracellular pore size: ≈0.7 nm Protein in blood: ≈7.0% w/v and pH of lachrymal fluid (tears): ≈ 7.0

4. Conventional dosage forms : The conventional ocular dosage forms for the delivery of drugs are Eye drops Eye ointments Eye lotion

5. Limitations of conventional dosage forms

6. The recent trends in ophthalmic drug delivery : Mucoadhesive dosage forms: Phase Transition systems: In-situ gelling Ocular Inserts or films: SODI, NODS, Minidiscs Collagen shields Drug presoakedhydrogel type contact lens Ocular Iontophoresis (Pulsatile drug delivery) Vesicular systems: Microspheres, microparticles, Nanoparticles, liposomes, niosomes, and PEGylation.

7. Cont… The poor bioavailability and therapeutic response exhibited by conventional ophthalmic solutions due to rapid precorneal elimination of the drug may be overcome by the use of in situ gel-forming systems that are instilled as drops into the eye and undergo a sol–gel transition in the cul-de-sac.

8. IN-SITU SYSTEM : IN-SITU SYSTEM In-situ: at the place Improved local bioavailability, Reduced dose concentration, Less total drug Improved patient acceptability, Reduced dosing frequency. Advantages More comfortable than insoluble or soluble insertion, Less blurred vision as compared to ointment, Increased bioavailability due to Increased precorneal residence time. Decreased nasolacrimal drainage of the drug. Chances of undesirable side effects arising due to systemic absorption of the drug through naso-lacrimal duct is reduced.

9. In-situ gelling system : In-situ forming hydrogels are liquid upon instillation and undergo phase transition in the ocular cul-de-sac to form visco-elastic gel and this provides a response to environmental changes. Such as Change in pH, Change in temperature, Ion activation.

10. Chitosan: Chitosan is a biodegradable polymer. Has excellent ocular compatibility . It posses positively charged amine groups in its chemical structure that could interact with the negatively charged mucous layer, conferring a mucoadhesive property. Chitosan solutions have been successfully used in prolonging contact time with the ocular surface. Therefore, a combination of this polymer with poloxamer would be very promising for ocular administration.

13. AIM To obtain an ophthalmic delivery system with improved mechanical and mucoadhesive properties that could provide prolonged retention time for the treatment of ocular diseases.

14. Materials: Chitosan MMW (190,000–310,000 Da) Mucin type III Poloxamer 407. Deionized water. Acetic acid. Sodium chloride.

15. Methods: Preparation of gels. Measurement of gelation temperature. Texture profile. In vitro mucoadhesive strength. In vivo scintigraphy studies.

16. Preparation of gels All poloxamer solutions used in this study (14–20% w/w) were prepared by mixing the polymer in cold ultrapure water. Solutions were kept in a refrigerator for at least 24 h to ensure complete dissolution. Chitosan dissolved in a solution of acetic acid 0.5% v/w. solution was then refrigerated and used as a solvent for the poloxamer dispersion. Formulations had a pH between 6.0 and 6.5. The osmolality of the final formulation was 295 ± 5.7 mOsm kg1. This value was achieved by the addition of 68 mM of NaCl

17. Measurement of gelation temperature The solid–gel transition temperature (Tsol/gel) of each formulation under examination was measured using a Carri-med CSL-100 rheometer (T.A. Instruments New Castle, DE) with a stainless steel cone and plate. Samples were applied to plate of rheometer and allowed to equilibrate for 5 min prior to analysis. Silicon oil added to surface of sample to prevent evaparation of solvent. The storage modulus (G1) and loss modulus (G11) were then determined using Rheology Advantage software provided by T.A. Instruments.

18. Texture profile(TPA) TPA was performed using a TA-XT2 Texture Analyzer (Stable Micro Systems, Surrey, England) in TPA mode. Formulations (35 g) were transferred into 50-ml bottles, taking care to avoid the introduction of air into the samples. A cylindrical analytical probe (35 mm diameter) was forced down into each sample at a defined rate (1 mm/s) and to a defined depth (10 mm). Five replicate analyses of each sample were performed at temperatures of 25oC and 35oC. From the resulting force–time plots, hardness, compressibility and adhesiveness were derived.

19. In vitro mucoadhesive strength Evaluated in vitro by measuring the force required to detach the formulation from a mucin disc using an Instron universal testing machine. Mucin disc is attached to cylindrical probe by double sided adhesive tape. Analytical probe lowered into vessel such that disc was in contact with sample surface. After 30 sec. probe was moved upward at constant speed of 1 mm/sec. All measurment were performed at 350c

21. RESULTS AND DISCUSSION

22. Influence of chitosan on the gelation temperature and dynamic properties Tsol/gel is dependent on polymer concentration. The Tsol/gel obtained for different poloxamer concentrations (14%, 16%, 18% and 20% w/w). 16% of poloxamer has adequate Tsol/gel i.e. 32 ± 1.20C. The effect of different chitosan concentrations (0.5–1.5% w/w) on the gelation temperature of the in situ gel containing 16% poloxamer was evaluated. The results indicated that chitosan did not significantly interfere with the formulation Tsol/gel.

24. Cont… Rheological analyses were performed in two extreme conditions: a) Without dilution, presuming immediate gelation in the eyes after administration b) After complete dilution with available tear fluid The results of the rheological analyses confirm the viscoelastic characteristics of the formulation at 25o C, where G11 > G1 and a frequency dependence is observed. At this temperature, the loss modulus is predominant. Without dilution at 35o C , the rapid increase in the storage modulus reflects the formation of a strong gel network with G1 > G11

25. Cont… Elastic (G1) and viscous (G11) modulus as a function of frequency (Hz) of a formulation comprised of poloxamer/chitosan (16% and 1.0% w/w, respectively) at (A) 25o C and (B) 35o C.

26. Cont… After a 50:7 dilution with simulated tear fluid, the formulation contained 14% w/w of poloxamer. As a result, there was a shift on the Tsol/gel, and the formulation was still a viscoelastic solution at350C and decreased frequencies. With frequency increase, gelation (G1 > G11) occurred. With an increase in the chitosan content, the elastic characteristic was higher; therefore, the frequency needed for gelation was lower.

27. Cont… Elastic (G1) and viscous (G11) modulus as a function of frequency of formulations comprised of poloxamer (16% w/w) and chitosan in the following concentrations: (A) 0%, (B) 0.5%, (C) 1.0% and (D) 1.5% w/w at 35o C. Samples were previously diluted with simulated tear fluid in a ratio of 50:7.

28. Texture profile The mechanical properties (hardness, compressibility and adhesiveness) of poloxamer (P) and chitosan (Chi) formulations, separately or together, determined using texture profile analysis at (A) 25o C and (B) 35o C. Data represent mean ± SD (n = 5). The numbers following polymer abbreviations P and Chi represent the amount of polymer expressed in % w/w.

29. In vivo scintigraphy studies Gamma scintigraphy is a well-established technique for in vivo evaluation of ophthalmic retention time. Although the rabbit is the traditional animal model for ophthalmic formulations evaluation, human volunteers are preferred for this study due to physiological differences between rabbits and humans, especially the blinking rate. No adverse or irritant effects (blinking, conjunctival redness or discharge) in the short or long term were observed. They notice that the gel formulation remained on the cornea surface (ROI) longer than did the saline solution.

30. Cont… Dynamic scintigraphic images of volunteers’ eyes up to 10 min after administration of labeledpoloxamer/chitosan in situ forming gel (Chi1.0P16) and saline control (control).

31. PRE-CORNIAL CLEARANCE For both gel and control, the activity remaining as a function of time consisted of a rapid initial clearance phase followed by a slowerbasal drainage phase. After 2 min, approximately 65% of the gel formulation was still in contact with the cornea versus only 27% of the saline solution. At the end of the experiment, these values were 50–60% for the gel and 15% for the saline formulation. The saline solution clearance is also evidenced by the high amount of radioactive tracer in the lacrimal ducts after the first few minutes.

32. Cont… Pre-corneal clearance of the poloxamer/chitosan in situ forming gel (Chi1.0P16) containing 99mTc. Labeled saline solution was used as control. Data show mean ± SD (n = 4).

33. conclusion In this study, an in situ forming gel with improved mechanical and mucoadhesive properties, as well as improved retention time, was obtained by the combination of poloxamer and chitosan. Poloxamer/chitosan formulation in a concentration of 16/1.0% w/w showed an optimal gelation temperature (320C) and was able to withstand low shearing forces at 350C. The mechanical properties indicated that the formulation has a high hardness value (especially at 350C) and a high adhesiveness that may contribute to the retainment of the formulation at the administered site.

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35. Thank you