Int J Pharm Pharm Sci, Vol 7, Issue 2, 554-559Original Article


FORMULATION AND EVALUATION OF ION-SENSITIVE IN-SITU NASAL GEL OF ZOLMITRIPTAN

P. R. PATIL*, V. K. SALVE, R. U. THORAT, S. R. SHAHI

Government college of Pharmacy, Department of Pharmaceutics, Hotel Vedant Road, Osmanpura, Aurangabad, Maharashtra, India 431005
Email: chitru.p@gmail.com

Received: 10 Jul 2014 Revised and Accepted: 08 Sep 2014


ABSTRACT

In situ gel system is novel drug delivery system in which there is transition of sol to gel on external stimuli like change in pH, temperature or change in ion concentration (sol-gel transition). In the present study various formulations were prepared by using gellan gum as gelling agent and HPMC K100 as controlled or sustained release polymer. All the formulations were evaluated for various parameters like pH, viscosity, drug content, gel strength, mucoadhesive strength and drug release. At minimum concentration of polymer lose their integrity and at maximum concentration stiff gel were formed. At optimized concentration of gelling agent and HPMC K100 showed in situ gelling with all parameter in range. In Vitro release data revealed that the optimized formulation showed controlled and sustained drug release pattern. The optimized formulation also obeyed korsmer Peppas model equation and which showed the release exponent n value 0.765. Thus the ex vivo higher bioavailability can be expected from the optimized formulation.

Keywords: In situ gelling, Nasal delivery, Migraine, Polymers, Sustained release, Higher bioavailability etc.

INTRODUCTION

Migraine headache is one of the most common human ailment and the most common complaints of patients evaluated by neurologist. It is a specific neurological syndrome that has a wide variety of manifestations. In recent years, the Nasal route has received a great deal of attention as a convenient and reliable method for the systemic administration of drugs. The nasal cavity as a site for the systemic absorption of drugs has some advantages which include relative large surface area, porous endothelial basement, highly vascularised epithelial layer, high total blood flow/cm3, avoiding the first pass metabolism and easy access. Zolmitriptan, 4S-4-({3-[2-(dimethylamino) ethyl]-1H-indol-5-yl} methyl)-1, 3-oxazolidin -2- one, is a second –generation triptan prescribed for patients with migraine attacks, with or without an aura, and cluster headaches. It is an effective agent in the treatment of acute migraine attack with or without aura. However, oral bioavailability is poor with only 40 % of the dose reaching systemic circulation.

This is likely due to extensive presystemic clearance on first pass. As migraine sufferers have markedly reduced functional ability, they would be benefited from acute treatment that helps them to resume their functional activities as quickly as possible. In situ gel, or in vivo gel, environment sensitive gel, is a new dosage form which has been applied as nasal drug delivery recently. Compared with liquid nasal formulations, nasal in situ gels are instilled as low viscosity solutions into the nasal cavity and upon contact with the nasal mucosa, or nasal composition the polymer changes conformation producing a gel, so it cannot only prolong the contact time between the drug and the absorptive sites in the nasal cavity, but also release drug slowly and continuously. Hence, it is especially very useful for those drugs used chronically. The phase transition can be induced by the presence of cations as for gellan gum a shift in pH as for cellulose acetate phthalate, a shift in temperature as for the thermo gelling Poloxamer 407.

MATERIALS AND METHODS

Zolmitriptan was obtained as a gift sample from Emcure Pharmaceuticals pune India HPMC K100 From Colorcon Goa, Gellan Gum(kelcogel) From Signet Pharma, Benzalkonium chloride from Merck Pharma. All the ingredient used were of LR Grade.

Preparation of standard curve of Zolmitriptan

Accurately weighed 10 mg of Zolmitriptan was dissolved in 100 ml of distilled water to get stock solution of 100μg/ml. From this stock solution aliquots of 0.1, 0.2, 0.3, 0.4, 0.5 ml were withdrawn and further diluted to 10 ml with distilled water to obtain a concentrations range of 1 to 5 μl/ml. The absorbance of the solutions was measured at 283.5 nm by using UV-Vis spectrophotometer. A graph of concentration vs. Absorbance was plotted. (Table 1)

Table 1: Absorbance of Standard solutions at 283.5 nm

S. No.
Conc.(μg/ml)
Absorbance
1 10 0.202
2 20 0.367
3 30 0.567
4 40 0.756
5 50 0.933



Fig. 1: Calibration curve of Zolmitriptan

Preparation of nasal formulations

Gellan gum solutions of various concentrations were prepared by adding the gum to deionised water and heating up to 90°C continuing stirring remi- stirrer. After cooling to below 40°C, HPMC K100, Zolmitriptan (25% w/v), mannitol (5%, w/v), and Benzalkonium chloride (0.01%, w/v) were added and mixed well. Three various kinds of Zolmitriptan in situ gels were prepared at the concentrations of Gellan gum which were 0.3%, 0.6%, 0.9% and with combination of HPMC K100 concentrations0.10%, 0.13% and 0.0.15% (w/v) respectively.(table 2)

Characterization and evaluation of nasal in situ gel

Appearance

The developed formulations were inspected visually for clarity, colour in sol and gel form against white background and for particulate matter any if present.

pH of gel

Each formulated batch pH was measured using pH meter which was previously calibrated using standard buffers of pH 4 & pH 7.26

Determination of mucoadhesive strength

The mucoadhesive strength of each formulation was determined by measuring a force required to detach the formulation from nasal mucosal tissue. A section of sheep nasal mucosal was fixed on each of two glass slides using thread. 50mg of gel was placed on first slide and this slide placed below the height adjustable pan. While another slide with mucosal section was fixed in an inverted position to the underside of the same pan. Both the slides with mucosal section were fixed in inverted position to the underside of the same pan. Both the slides with gel formulation between them held in contact with each other, for 2 min to ensure intimate contact between them.

Then weight was kept rising in the second pan until slides get detached from each other. The mucoadhesive force expressed as the detachment stress in dynes/cm2 was determined from the minimal weight that detached the mucosal tissue from the surface of each formulation.

Where, m = weight required for detachment in grams, g = Acceleration due to gravity (980 cm/s2). A = Area of mucosa exposed.

Table 2: Composition of nasal in situ gel formulation of zolmitriptan

Ingredients (%w/v) Formulation
F1 F2 F3 F4 F5 F6 F7 F8 F9
Zolmitriptan 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5
Gellan gum 0.3 0.3 0.3 0.6 0.6 0.6 0.9 0.9 0.9
Hpmc(100) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1
BK CL%(v\v) 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01
Mannitol% 5 5 5 5 5 5 5 5 5
Dis. water q. s q. s q. s q. s q. s q. s q. s q. s q. s

Table 3: Appearance pH gelling capacity and drug content estimation of various formulations

Form. code Appearance Gelling capacity pH Drug content
Z-1 Transparent Solution --- 5.7 ± 0.265 96.05
Z-2 Transparent and less viscous solution + 6.1 ± 0.153 97.03
Z-3 Transparent Solution +++ 6.2 ± 0.265 97.32
Z-4 Transparent Solution +++ 6.5 ± 0.200 96.02
Z-5

Transparent and less

viscous solution

 + 5.8 ± 0.210 96.00
Z-6 Transparent and viscous solution +++ 6.1 ± 0.251 95.00
Z-7 Transparent Solution +++ 6.2 ± 0.265 96.05
Z-8 Transparent and viscous solution ++++ 5.7 ± 0.252 96.10
Z-9 Transparent Solution +++ 6.2 ± 0.132 95.02

- No gelation, + Gelation occurred in few min and remained for few h, ++ Gelation immediate, remained for few h +++ Gelation immediate, and for extended period, ++++ Very stiff gel.

Rheological studies

Viscosity of the prepared formulations was measured by using Brookfield Cone and Plate Viscometer. The suitable spindle was lowered perpendicularly into the fixed volume of gel which was to be measured. The spindle was rotated at varying speeds and the suitable speed was selected. The temperature was maintained at 25°C and then the viscosity was measured as the system was allowed to cool gradually (fig. 6, 7).

Gelation study

It is the proportion of cations at which the liquid phase makes a transition to gel. Gelation point was considered as the proportion where formulations would not flow when test tubes were tilted to 90° angle, as the cations ions concentration was gradually increased.

In vitro release studies

In Vitro release study of the formulated in situ gel was carried out in two chamber diffusion cells through dialysis membrane-70 with molecular weight cut off 1200-1400 KDa. Diffusion of diameter 1.5 cm and 20 ml capacity consisted of upper cylindrical compartment open from above and diffusion membrane at its base. To prepare artificial membrane, pieces of dialysis membrane were soaked in PBS pH6.6 for hrs before mounting on diffusion cell. Dialysis experimental and the content of the receiver compartment was stirred using magnetic stirrer. The position of the donor compartment was adjusted so that dialysis membrane just touches the diffusion medium. An aliquot of 3 ml was withdrawn from receiver compartment initially after 15 and 30 min and then 1 hr interval and replaced with the same amount of fresh medium. Aliquots withdrawn were suitably diluted and analysed using UV spectrophotometer at 283.50 nm for drug.

In Vitro drug release was carried out for 8 hrs. membrane was in a two chamber cells. In situ gels of gellan gum with drug were placed in the donor compartment. 16 ml of PBS 6.6 was placed in the receptor compartment. The temperature of receiver compartment was maintained at the 37∘0 C ±1.00C during experimental and the content of the receiver compartment was stirred using magnetic stirrer. The position of the donor compartment was adjusted so that dialysis membrane just touches the diffusion medium. An aliquot of 3 ml was withdrawn from receiver compartment initially after 15 and 30 min and then 1 hr interval and replaced with same amount of fresh medium. Aliquots withdrawn were suitably diluted and analysed using UV spectrophotometer at 283.50 nm for drug. In Vitro drug release was carried out for 8 hrs.

In vitro permeation study

Fresh nasal tissues were carefully removed from the nasal cavity of goat obtained from the local slaughterhouse. Tissue sample were inserted in Franz diffusion cell displaying a permeation area of 1.76 cm2 7 ml of 6.6 pH phosphate buffer saline was added to the acceptor chamber and agitated with magnetic stirrer at 370 C. After pre incubation time of 20 min, pure drug solution and formulation equivalent to 0.25%w/v of Zolmitriptan was placed in the donor chamber. From the acceptor compartment 0.2 ml sample aliquots were withdrawn at predetermined time interval up to 6 hrs replacing the sample volume with 6.6 pH PBS after each sampling, filtered and analysed by UV spectrometer at 283.50 nm

RESULTS AND DISCUSSION

Determination of λ max of Zolmitriptan

A stock solution of 100µg/ml of Zolmitriptan was prepared by dissolving 10 mg in 100 ml of de ionised distilled water. The resulting solution was scanned between 200 nm to 800 nm using the double beam UV-visible spectrophotometer (2700-Shimadzu, India). (fig. 1)

Fourier transforms infrared spectral studies

Fourier transform infrared (FTIR) spectra were taken on FTIR (model-200, Thermo Electron, Shimadzu) to investigate any possible chemical reactions between the drug and the polymer. FTIR spectra of the pure drug and physical mixture of drug with polymers were obtained. Pure drug (Zolmitriptan) and polymers were subjected to FTIR studies alone and in Combinations.(1:1) The mixtures were placed in the sample holder and were analyzed by FTIR to study the interference of polymers with the drug.(fig. 2 and 3).

Fig. 2: FTIR spectra of physical mixture of drug and Polymers

Fig. 3: FTIR spectra of plane of drug Zolmitriptan

Differential scanning calorimetry

Differential scanning calorimetry (DSC) was used to evaluate the thermal behaviour of pure drug and physical mixture of the drug and excipients using a DSC-60 (Shimadzu Corporation, Japan.). Samples were weighed and sealed in standard aluminium pans and then scanned over a temperature range from 50 to 300C at a heating rate of 10.00 0C / min. (fig. 4, 5).

Fig. 4: DSC graph for drug sample

Fig. 5: DSC graph for mixture of polymer and drug

Viscosity of optimised formulation

Solution viscosity and gel viscosity were studied on Brookfield Cone and Plate viscometer using various spindle likeC-25 and C-75. and there viscosities were determind. before and after viscosity are given in below(table 4).

Table 4: Viscosity

Viscosity at

(sol)

Viscosity at

(Gel)
10 30
12 35
15 38
20 60
22 68
25 75
28 86
30 92
32 105

Fig. 6: Rheological studies of formulation after gelation

Fig. 7: Rheological comparative studies of formulation

Fig. 8: Thixotropy analysis study of optimised formulation (F3)

Drug content estimation

Acceptable range for all the formulations. % drug content was in the range 95- 97 % indicating uniform distribution of drug. (Table 5) shows the result of percentage drug for all the formulations. The drug content of optimised formulation was found to be in 97.32%.

In vitro release studies

In Vitro release study of the formulated in situ gel was carried out in two chamber diffusion cells through dialysis membrane-70 with molecular weight cut off 1200-1400 KDa.

Diffusion of diameter 1.5 cm and 16 ml capacity consisted of upper cylindrical compartment open from above and diffusion membrane at its base. To prepare artificial membrane, pieces of dialysis membrane were soaked in PBS pH 6.6 for hrs before mounting on diffusion cell.

Dialysis membrane was in a two chamber cells. In situ gels of Zolmitriptan loaded with drug were placed in the donor compartment. 16 ml of PBS 6.6 was placed in the receptor compartment. The temperature of receiver compartment was maintained at the 37°C ±1.0°C during experimental and the content of the receiver compartment was stirred using magnetic stirrer. The position of the donor compartment was adjusted so that dialysis membrane just touches the diffusion medium. An aliquot of 3 ml was withdrawn from receiver compartment initially after 0 and 30 min and then 1 hr interval and replaced with same amount of fresh medium. Aliquots withdrawn were suitably diluted and analysed using UV spectrophotometer at 283.50 nm for drug. In Vitro drug release was carried out for 8 hrs.

In vitro release studies

Diffusion studies were carried out using Franz diffusion cell, F3 showed the sustained drug release. F7 showed drug release 79.76% at 8 hrs. Concentration of HPMC increases leads to decrease the drug release. Gellan gum concentration affect on drug release.(Table 6)

In vitro permeation study

Fresh nasal tissues were carefully removed from the nasal cavity of goat obtained from the local slaughterhouse. Tissue sample were inserted in Franz diffusion cell displaying a permeation area of 1.76 cm2 7 ml of 6.6 pH phosphate buffer saline was added to the acceptor chamber and agitated with magnetic stirrer at 37°0 C.

After pre incubation time of 20 min, pure drug solution and formulation equivalent to 2.5%w/v of Zolmitriptan was placed in the donor chamber. From the acceptor compartment 0.2 ml sample aliquots were withdrawn at predetermined time interval up to 8 hrs replacing the sample volume with 6.6 pH PBS after each sampling, filtered and analysed by UV spectrometer at 283.50 nm.

Table 5: Evaluation parameter of formulation

Formulation code

pH

(mean ± S. D)

Drug content

(mean ± S. D)

Muco adhesive strength

(Dynes/cm2)

Gel strength(seconds)

(mean ± S. D)

 Viscosity (cps)
F1 4.7 96.05 2032 +0.32 18+0.01 30
F2 4.9 97.03 2205+0.22 20+0.5 35
F3 5.1 97.32 2403+0.45 21+0.6 38
F4 5.2 96.02 2606+0.15 25+0.2 60
F5 5.4 96.00 2801+0.10 28+0.3 68
F6 5.5 95.00 2907+0.20 32+0.2 75
F7 6.1 96.00 3005+0.25 38+0.3 86
F8 6.2 96.05 3215+0.35 45+.01 92
F9 6.0 95.02 3510+0.45 48+.05 105

Table 6: percent drug release from respective formulation

Time in Min F1 F2 F3 F4 F5 F6 F7 F8 F9
0 0 0 0 0 0 0 0 0 0
30 14.00 15.02 12.60 12.65 13.60 14.06 13.08 12.56 13.06
60 20.97 24.06 25.07 28.09 22.02 22.86 24.09 22.09 20.26
120 30.00 32.07 35.04 35.06 30.12 35.06 33.06 31.00 28.08
180 45.05 46.00 45.07 48.00 44.00 47.70 45.00 42.56 41.86
240 55.07 52.07 53.07 56.02 52.86 50.76 56.00 49.06 48.05
300 68.08 62.83 64.05 62.02 60.72 61.02 62.00 60.05 58.08
360 77.08 70.65 74.02 71.00 70.00 68.02 69.00 68.05 66.08
420 82.06 81.05 84.95 82.05 83.26 74.01 73.05 72.10 73.08
480 97.02 95.00 92.02 86.00 85.36 82.06 80.06 78.86 75.08

Fig. 9: In- vitro drug release

Table 7: permeation drug release of selected batch with compare to drug solution

Time min F3 Drug solution
0 0 0
30 12.60 19.56
60 25.07 25.26
120 35.04 30.85
180 45.07 38.01
240 53.07 40.72
300 64.06 51.86
360 74.02 66.96
420 84.95 85.94
480 92.02 97.94

Fig. 10: Ex vivo permeation of selected batch (F3) compare to drug solution

Drug release mechanism

The drug release mechanism was studied by using DD solver software in which various kinetic modelling were studied and it was found that the optimised formulation obey korsmer Pappas model with exponent n value of0.745. which proves that the formulation non anomalous or non fickan release model.(fig. 2)

Fig. 11: predicted and observed value of optimised formulation (F3)

Statistical data

Anova study was used to analysis stastiacal data of research and all parameter were within range and found to be significant (Drug release &Viscosity). fig no.11&12.

Fig. 12: Anova result for drug release

Fig. 13: Anova result for viscosity

RESULTS

In situ nasal gel formulation Zolmitriptan with 0.3 % of Gellan Gum and 0.13% HPMC K100 is a novel promising nasal drug delivery system for a antimigraine drug Zolmitriptan, which would enhance nasal residence time owing to increased viscosity and mucoadhesive characteristics; furthermore it also exhibited a good residence time due to which there will be controlled and sustained release of drug.

CONCLUSION

In conclusion, this study demonstrated that the use of in situ gelling vehicle of gellan gum incorporating mucoadhesive polymer and HPMC K100 could effective and safe. which eventually improve the nasal residence time and absorption of Zolomitriptan. Finally from this study it was concluded that use of controlled release polymer(HPMC k 100) ion-sensitive(gellan gum) nasal in situ gel drug delivery was very novel beneficial and effective in In- situ nasal drug delivery system of Zolmitriptan drug.

ACKNOWLEDGEMENT

We are thankful to Emcure Pharmaceuticals, pune for providing Zolmitriptan drug. we are also thankful to government college of Pharmacy Aurangabad for providing all nessesary facilities.

CONFLICT OF INTERESTS

Declared None

REFERENCES

  1. K Jadhav, M Gambhire. Nasal drug delivery system-factors affecting and applications. Curr Drug Ther 2007;2:27-38.

  2. Akhtar. Enhanced bioavailability of drugs via intranasal drug delivery system. IRJP 2012;7:68-74.

  3. S Badgujar, M Sontakke. Formulation and evaluation of Sumatriptan succinate nasal in-situ gel using Fulvic acid as novel permeation enhancer. IJPRD 2010;2:8.

  4. Merkus, Schipper. Absorption enhancers in nasal drug delivery: efficacy and safety. J Controlled Release 1993;24:201-8.

  5. J Coos Verhoe, Nicolaas GM Schipper, Stefan G Romeijn. The potential of cyclodextrins as absorption enhancers in nasal delivery of peptide drugs. J Controlled Release 1994;29:35l-60.

  6. S Horvat, A Feher. Sodium hyaluronate as a mucoadhesive component in nasal formulation enhances delivery of molecules to brain tissue. Eur J Pharm Biopharm 2009;72:252–9.

  7. K Ketousetuo. Development of oxytocin nasal gel using natural mucoadhesive agent obtained from the fruits of Dellinia indica. L Sci Asia 2007;33:57-60.

  8. L Illum, N Farraj, H Critchley, SS Davis. Nasal administration of Gentamicin using a novel microsphere delivery system. Int J Pharm 1988;46:261-5.

  9. U Bertram, R Bodmeier. In situ gelling, bioadhesive nasal inserts for extended drug delivery: in vitro characterization of a new nasal dosage form. Eur J Pharm Sci 2006;27:62–71.

  10. E Marttin, G Nicolaas. Nasal mucociliary clearance as a factor in nasal drug delivery. Adv Drug Delivery Rev 1998;29:13–38.

  11. Nasal spray and inhalation solution, suspension, and spray drug products —chemistry, manufacturing, and controls documentation, US Department of health and human services food and drug administration. CDER; 2002.

  12. N Nandgude, R Thube. Formulation and evaluation of pH induced in-situ nasal gel of salbutamol sulphate. Int J Pharm Sci Nanotechnol 2008;1:177-82.

  13. R Shah, Mehta M. Design and evaluation of pH dependant mucoadhesive in situ gel of Sodium cromoglycate for nasal delivery. IJAPR 2011;2:64-77.

  14. P Edman. Characterization of degradable starch microspheres, delivery system for drugs, as a nasal. Int J Pharm 1990;62:187-92.

  15. E Gavini, B Hegge, G Rassu, V Sanna, C Testa. Nasal administration of Carbamazepine using chitosan microspheres: in vitro/in vivo studies. Int J Pharm 2006;307:9–15.

  16. M Alfadhela, U Puapermpoonsiria, SJ Ford, FJ McInnesa. Lyophilized inserts for nasal administration harboring bacteriophage selective for Staphylococcus aureus: in vitro evaluation. Int J Pharm 2011;416:280–7.

  17. Bertram U, Bodmeier R. In situ gelling, bioadhesive nasal inserts for extended drug delivery: in vitro characterization of a new nasal dosage form. Eur J Pharm Sci 2006;2(7):62–71.

  18. H Nazar, DG Fatouros, SM van der Merwe. Thermosensitive hydrogels for nasal drug delivery: the formulation and characterization of systems based on N-trimethyl chitosan chloride. Eur J Pharm Biopharm 2011;77:225–32.

  19. S Basu, A Bandyopadhyay kumar. Development and characterization of mucoadhesive in situ nasal gel of midazolam prepared with ficus carica mucilage. Am Assoc Pharm Sci 2010;11:1223-31.

  20. L Pereswetoff-Morath. Microspheres as nasal drug delivery systems. Adv Drug Delivery Rev 1998;29:185–94.

  21. Mi Lan Kang a, Chong Su Cho. Application of chitosan microspheres for nasal delivery of vaccines. Biotechnol Adv 2009;27:857–65.

  22. A Yenet, Nisha M Joseph. Newer advancement in nasal drug delivery system. IJPSR 2010;1:10.

  23. S Basu, AK Bandyopadhyay. Nasal drug delivery: an overview. Int J Pharm Sci Tech. 2010;4(1):1-20.

  24. HS Mahajan, VK Tyagi, RR Patil, SB Dusunge. Thiolated xyloglucan: synthesis, characterization and evaluation as mucoadhesive in situ gelling agent. Carbohydr Polym 2013;91:618–25.

  25. E Bjiirk, S Bjurstriim, P Edman. Morphologic examination of rabbit nasal mucosa after nasal administration of degradable starch microspheres. Int J Pharm 1991;75(1):73-800.

  26. AP Kulkarnia. Evaluation of polaxomer-based in situ gelling system of articaine as a drug delivery system for anesthetizing periodontal pockets-an in vitro study. Indian J Dent 2012;3:201-8.

  27. H Mahajan, B Tatiya, P Nerkar. Ondansetron loaded pectin based microspheres for nasal administration: in vitro and in vivo studies. Powder Technol 2012;221:168–76.

  28. G Fundueanua, M Constantinb, A Dalpiaza. Preparation and characterization of starch/cyclodextrin bioadhesive microspheres as platform for nasal administration of Gabexate Mesylate (Foys) in allergic rhinitis treatment. Biomater 2004;25(1):159–70.

  29. C Callens, E Adriaens, K Dierckens, JP Remon. Toxicological evaluation of a bioadhesive nasal powder containing a starch and Carbopol 974 P on rabbit nasal mucosa and slug mucosa. J Controlled Release 2001;76:81–91.

  30. M Amidi, G Stefan, R Borchard, H Junginger. Preparation and characterization of protein-loaded N-trimethyl chitosan nanoparticles as nasal delivery system. J Controlled Release 2006;111:107–16.

  31. F McInnes, P Thapa, AJ Baillie, PG Welling. In vivo evaluation of nicotine lyophilized nasal insert in sheep. Int J Pharm 2005;304:72–82.

  32. DJ Yadav. Formulation and evaluation of thermo sensitive in situ gel of salbutamol sulphate for nasal. Int J Pharm Pharm Sci 2012;4 Suppl:188.

  33. Rozier C Mazuel, J Grove, B Plazonnet. Functionality testing of Gellan gum, a polymeric excipient material for ophthalmic dosage forms. Int J Pharm 1997;153:191–8.

  34. GR Sanderson. Gellan gum. In P. Harries (Ed.) Food gels New York: Elsevier Science; 1990. p. 201–32.

  35. D Schmaljohann. Thermo-and pH-responsive polymers in drug delivery. Adv Drug Delivery Rev 2006;58(15):1655–70.

  36. CP Pujara, Z Shao, MR Duncan, AK Mitra. Effects of formulation variables on nasal epithelial cell integrity: biochemical evaluation. Int J Pharm 1995;114:197-203.

  37. S Pund, G Rasve, G Borade. Ex vivo permeation characteristics of venlafaxine through sheep nasal mucosa. Eur J Pharm Sci 2013;48:195–201.

  38. RSR Murthy, RJ Majithiya, PK Ghosh. Thermo reversible mucoadhesive gel for nasal delivery of Sumatriptan. AAPS Pharm Sci Tech 2006;7(3):E1.

  39. HS Mahajan, SG Gattani. In situ gels of metoclopramide hydrochloride for intranasal delivery: in vitro evaluation and in vivo pharmacokinetic study in rabbits. Drug Delivery 2010;17:19–24.

  40. V Jitendra, K Shinde, S Mali. In-situ mucoadhesive nasal gels of metoclopramide hydrochloride: preformulation and formulation studies. J Pharm Res 2008;1:1.

  41. V Gaikwad. Formulation and evaluation of in-situ gel of metoprolol tartrate for nasal delivery. J Pharm Res 2010;3(4):788-93.

  42. S Khan, J Desai, Shivakumar HG. Formulation and evaluation of in-situ gel of Diltiazem hydrochloride for nasal delivery. Scholar Res Library 2011;3(1):371-81.

  43. D Badgujar, A Manish, S Sontakke. Formulation and evaluation of sumatriptan succinate nasal in situ gel using fulvic acid as novel permeation enhancer. Int J Pharm Res Dev 2010;2(8):7.

  44. Hyun-jong Cho, Prabagar Balakrishnan. Poloxamer/ Cyclodextrin/Chitosan-Based Thermo reversible Gel for Intranasal Delivery of Fexofenadine Hydrochloride. J Pharm sci 2011;100(2):681-91.

  45. NA Peppas, JJ Shalin. A simple equation for the description of solute release III. Coupling ofdiffusion and relaxation. Int J Pharm 1989;57:169–72.