Table no1: Formulation Table Of Diclofenac Potassium

With different polymers

Ingredients	F1	F2	F3
carbopol	0.3%	-----	-----
Pluronic F-127	----	13%	----
Carbo-pluronic	-----	-----	0.3%/13%
Diclofenac potassium	0.1%	0.1%	0.1%
Phenyl ethyl alcohol	0.5%	0.5%	0.5%
Sodium chloride	0.9%	0.9%	0.9%
Aqueous vehicle	Q.S	Q.S	Q.S
pH	7.1	7.2	7.2
Drug content in mg mean±S.D*	48.74±0.017	49.37±0.12	49.56±0.010
% drug content	97.48	98.74	99.12

S.D*= standard deviation N =3

Table no 2: Physicochemical Evaluation Of Diclofenac Potassium Sol-Gel

Tests	F1	F2	F3
Visual appearance	+	+	+
Clarity	+	+	+
pH	7.1	7.25	7.25
Test for sterility	--	--	--
Drug content in mg mean±S.D*	49.87±0.011	49.80±0.08	49.81±0.012
% drug content	99.74	99.6	99.62

S.D*= standard deviation N =3

MATERIALS:

Carbopol : B.F Goodrich company, Pluronic: BASF’,Sodium chloride: precision Scientific Co, Mumbai, Phenyl ethyl alcohol: pal pharmacy Mumbai, diclofenac potassium : Brown and burk pharmaceutical ,bangalore

EXPERIMENTAL:

1. Preparation Of Formulations:

The formulation are briefly described here

A. 0.1% w/v diclofenac potassium conventional solution:

Solution containing Phenyl ethyl alcohol as preservative base was prepared. Diclofenac potassium was added to preservative base, P^Hwas adjusted. The formulations were sterilized by membrane filtration and was filled and sealed in amber colored glass vials.

B. 0.1% w/v diclofenac potassium in-situ sol-gel with carbopol:

The 0.3% Carbopol solutions were prepared by dispersing the required amount in distilled, deionized water with continuous stirring until completely dissolved. 0.5%v/v phenyl ethyl alcohol and 0.1%w/v diclofenac potassium was added. P^Hwas adjusted and filter through 75µm filter cloth filled and sealed in amber colored glass vials

C. 0.1% w/v diclofenac potassium in-situ sol-gel with pluronic:

Pluronic solutions (13% (w/v)) were prepared by cold method 13%w/v of Poloxamer 407 was slowly added to cold distilled water under constant stirring. The dispersion was kept in the refrigerator (6-12 h) until a clear solution was formed.0.5%v/v phenyl ethyl alcohol and 0.1%w/v diclofenac potassium was added. P^Hwas adjusted and filter through 75µm filter cloth filled and sealed in amber colored glass vials

D. 0.1% w/v diclofenac potassium in-situ sol- gel with Carbopol/Pluronic solutions:

The 0.3% Carbopol solutions were prepared by dispersing the required amount in distilled, deionized water with continuous stirring until completely dissolved. To this the required quantity of pluronic was added with constant stirring. The dispersion was then kept in the refrigerator for 6-8hrs until it was clear solution.0.5%v/v phenyl ethyl alcohol and 0.1%w/v diclofenac potassium was added. P^Hwas adjusted and filter through 75µm filter cloth filled and sealed in amber colored glass vials

Table no.3: Percentage Drug Release Profile of Diclofenac Potassium from Different Polymers in Situ Sol-Gel

	% DRUG CONTENT mean±S.D*
SL. NO.	Carbopol/ pluronic	pluronic	carbopol	control
1	35.54±0.114	41.53±0.145	43.45±0.142	99.45±0.113
2	43.67±0.121	51.45±0.211	56.54±0.159
3	50.23±0.201	56.89±0.121	60.57±0.111
4	57.54±0.153	62.30±0.217	66.24±0.112
5	63.35±0.162	70.21±0.111	73.28±0.124
6	68.00±0.218	74.45±0.126	78.45±0.114
7	73.45±0.135	78.45±0.124	83.34±0.125
8	78.53±0.154	85.68±0.131	88.21±0.145

S.D*= standard deviation N =3

Table no 4: Viscosity Table Containing Different Polymer Sol-Gel In 7.2 Ph Simulated Lacrimal Fluid

RPM	Viscosity (CPS) mean±S.D*
RPM	Carbopol	Pluronic	Carbopol/pluronic
10	385±0.126	423±0.208	480±0.145
20	310±0.132	325±0.216	362±0.162
30	270±0.145	283±0.163	300±0.232
50	210±0.201	232±0.141	264±0.131
60	187±0.136	227±0.182	235±0.124
100	110±0.210	117±0.216	132±0.212

S.D*= standard deviation N =3

2. Evaluation of the eye drops:

Physicochemical evaluation:

The prepared formulations were subjected to the following parameters like visual appearance, pH, clarity, and drug content.

Microbiological Evaluation:³

Antimicrobial efficacy studies were performed on the prepared formulation to ascertain the biological activity of sol-to-gel systems against microorganisms as per the guidelines in I.P 1996.

In Vitro Drug Release Profile:

The in vitro drug release was studied using a USP rotating paddle apparatus as reported by Hong-Ru-Lin et al¹. 3ml of the solution was placed in a dialysis tube with cellophane membrane covered cells.. Simulated lacrimal fluid 7.4 (900ml) maintained at 37⁰C was used as the dissolution medium. The paddle speed was 75rpm and aliquots were withdrawn at intervals of every hour for six hours. After each aliquot was withdrawn, it was replaced with an equal quantity of fresh medium. The amount of drug released was estimated by measuring the absorbance of the aliquots at 274nm.

6. Biological Evaluation:

A. Eye irritation test:

The eye irritation potential for the prepared eye drops was assessed by the Draize test², on albino rabbits, 3 rabbits weighing between 2-2.5 kg were used for the study. The eye drops were installed in one of the eye of each rabbit for 2 day. The degree of irritation was assessed and scored as proposed by Drazie²

Fig no 1:

B. Efficacy study²: This study was carried out on albino rabbits, weighing between 2-2.5 kg, 3 rabbits were used for the study. Inflammation was induced in both eyes of the rabbits using 25µl turpentine liniment I.P and the ability of the formulation under test for the faster recovery from the induced inflammation was assessed.²

The rabbit’s eye received eyewash with water for injection I.P To the right eye and left eye of each rabbit 25µl of turpentine liniment I.P was instilled with the help of micro pipette into each eye and left over night. This is done to balance the inflammation stress on both the eye. The next day to the left eye one drop of the formulation was instilled where as the right eye served as control.

After every 6 hours, the eye was examined for the presence of gel and based on the observation again 1 drop was given and scoring was done until the eye returned to its normal level.

Rheological Behaviors of polymer with diclofenac potassium:^1,6,7

The rheological` properties of sol-gel were measured using a Brookfield viscometer LVD++ model. The measurements were made by using disc spindle number 2 at 35⁰C. All measurements were performed in triplicate with good reproducibility and the standard deviations were all within 3%. This temperature was maintained through out the experiment, by placing the beaker containing 200ml solution in a large beaker of about 1000ml containing water maintained at 38⁰C.

RESULTS AND DISCUSSION:

The result of the evaluation of the prepared eye drops are:

Physicochemical evaluation:

Table 2. Clarity of all the formulations was found to be satisfactory. Terminal sterilization with autoclaving had no effect on the physicochemical properties of the formulations. The pH was within acceptable range and hence would not cause any irritation upon administration of the formulation. The drug content was found to be in acceptable range for all the formulations. Percent drug content in all four formulations were in the range 98.3 - 103.3% indicating uniform distribution of drug.

Fig no 2:

Biological evaluation:

A. Eye irritation study:

In order to evaluate the formulation for irritation to the eye. The draize system was used. The Draize system of scoring is based on the reaction of individual components of the eye to the solution instilled under test. Reflex tearing, conjunctival redness are multiplied by a factor of 2, however damage to the cornea or the iris are more severe reactions and their severity scores are multiplied by a factor of 5.In our study the only parameter that could be scored were conjunctival, redness appearing immediately after instillation and reflex tearing occurring on instillation. The sum of the scores of all tissues response for a marginally irritating substance is rated as 49. In our cases, the sum of the score was zero for the formulation. Which indicated that the solution were non irritating to the eye.

B. Efficacy study:

The efficacy studies were carried out by using rabbits. The anti inflammatory response (the decrease in inflammation) versus time profiles for the various formulation were carried out. The anti inflammatory responses shown by the 0.3% Carbopol formulation was slightly higher than 13%w/v pluronic formulation However, the anti inflammatory responses was significantly higher for Carbopol/Pluronic formulation. These results indicate that the overall anti inflammatory responses were greater for the drug-containing combination polymer formulations than the individuals and control. Besides the control formulation showed faster in vitro release rates, higher initial in vivo pharmacological responses were not observed.

These in vivo results, along with the rheogram as well as in vitro drug release studies, demonstrate that the Carbopol/ Pluronic solution may significantly prolong the drug contact time and thus increase its pharmacological response.

In vitro release study:

FIG. 1 shows the cumulative amount of diclofenac potassium released versus time profiles for various drug-containing polymer solutions and the drug-without polymers. For the drug-without polymer, almost all of the diclofenac potassium released immediately after the start of release experiment. The results indicated that the 0.3% Carbopol/13% Pluronic mixture showed better sustaining effect amongst the formulations

Rheological study:

The rheological behaviors of various polymer solutions were investigated as a function of temperature and pH. All measurements were performed in triplicate with good reproducibility and the standard deviations were all within 3%.FIG. 2 shows the shear stress versus shear rate flow curves of the Carbopol solution [0.3% (w/v)], Pluronic solution[13% (w/v)] as well as the mixture of Carbopol [0.3%(w/v)], Pluronic [13% (w/v)] solution in simulated lacrimal fluid.

For all of the polymer systems studied, the shear stresses at pH 7.4 and 37° C. The observed phase transition for the Carbopol solution was mediated by the pH 7.4, which could be attributed to ionization of the Carbopol polymer. The increase in shear stress for the Pluronic solution at physiological conditions was mediated by temperature. It consists of poly(oxyethylene) and poly(oxypropylene) units, Poly(oxyethylene) (PEO) is predominantly hydrophilic whereas poly(oxypropylene) (PPO) is hydrophilic at low temperatures and becomes more hydrophobic at higher temperatures. When PEO and PPO units are combined, they show amphiphilic characteristics and aggregation phenomena. This copolymer forms micelles. The formation of micelles may increase the viscosity of the delivery system and thus lead to the sol-gel transition. The shear stress of the Carbopol/ Pluronic solution was significantly greater than that of the Carbopol or Pluronic solution, respectively, at each shear rate. This observation can be explained by the formation of crosslinks between the two polymers: the water molecules act as cross linking agent to form hydrogen bonds between the carboxyl groups of Carbopol and ether groups of Pluronic, which lead to the formation of a three-dimensional network and stronger gel.

CONCLUSION:

A combination of diclofenac potassium with different polymers was developed as an ophthalmic dosage form, it was a clear solution. The eye drops were found to be non-irritating to rabbit eyes and were found to be effective in faster recovery from the inflammation. The above investigation clearly indicates that the gel strength of the polymer solution in the physiological condition can be enhanced significantly by combining the two individual solutions. An ophthalmic solution containing 0.3% (w/v) of Carbopol and 13% (w/v) of Pluronic could flow freely at non-physiological condition and form gel at physiological condition. The mixed polymer solution was easy to administer into the eye as drops and forms stronger gel following the phase transition. The results support that the combined Carbopol as well as Pluronic solution can be a promising in situ gelling vehicle for ophthalmic drug delivery system.

ACKNOWLEDGEMENTS:

The author likes to thanks Jagdale Scientific research foundation, Bangalore for help in carrying out the work at its research centre.

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Received on 07.08.2009

Accepted on 10.09.2009

Research Journal of Pharmaceutical Dosage Forms and Technology. 1(2): Sept.-Oct. 2009, 158-161