Indo American Journal of Pharmaceutical Research, 2014
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ISSN NO: 2231-6876
INDO AMERICAN JOURNAL OF PHARMACEUTICAL RESEARCH
FORMULATION AND OPTIMIZATION OF PROLONGED RELEASE NASAL IN SITU GEL FOR TREATMENT OF MIGRAINE M. D. Godbole*, Priti W. There, P.V. Dangre Department of Pharmaceutics, Kamala Nehru College of Pharmacy, Butibori Nagpur-441108 ARTICLE INFO Article history Received 12/02/2014 Available online 21/03/2014 Keywords In Situ Nasal Gel, Zolmitriptan, Poloxamer 407, Migraine.
ABSTRACT The nasal route has been found to be useful in targeting drugs to the central nervous system. The nasal mucosa offers numerous benefits as a target tissue for drug delivery. Systemic delivery of drug via nasal route is associated with the several positive factors such as relatively large surface area available for absorption and avoidance of first pass effects. The poor bioavailability and therapeutic response exhibited by the conventional nasal sprays and drops due to rapid nasal elimination of the drug may be overcome by the use of in situ gelling systems that are instilled as drops into the nasal cavity and undergo a sol-to-gel transition. The purpose of this research was to develop and optimize nasal in situ gel of Zolmitriptan by using Cold method. The effect of two independent process variables like combination of thermoreversible polymers and bioadhesive polymer on gelation time, gelation temperature and drug release of nasal in situ gel containing Zolmitriptan was optimized using 32 factorial design. The observed responses were coincided well with the predicted values, given by the optimization technique. The optimized the optimized nasal in situ gel shows gelation time 59.73±0.02, gelation temperature 31.93±0.11, and drug release 65.2±0.23 after 8 hrs. Compatibility studies of drug and excipients were carried out using FTIR. The developed formulations were characterized for gelation time, gelation temperature, bioadhesive strength, gel strength, viscosity, in-vitro drug release, ex -vivo drug release and in-vitro, ex -vivo drug release kinetics.
Copy right © 2014 This is an Open Access article distributed under the terms of the Indo American journal of Pharmaceutical Research, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Please cite this article in press as M. D. Godbole, et al. Formulation and Optimization of Prolonged Release Nasal in Situ Gel For Treatment of Migraine. Indo American Journal of Pharm Research.2014:4(02).
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Corresponding author M. D. Godbole, Department of Phramaceutics, Kamala Nehru College of Pharmacy, Butibori, Nagpur-441108, India
[email protected] +91-9960919316
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INTRODUCTION Migraine is a physiological condition, in which a person suffers from tremendous headache. Generally, this headache affects only one side of the head and body. Migraine attacks are more common to those persons who take too much of stress or are work alcoholic. In such people, the blood flow in the brain muscles drops, as a result of too much load, squeezing the arteries. When the person suddenly relaxes, these tight brain muscles expand, stretching the blood vessel walls. The blood pumped with each heartbeat, then, pushes the vessels further, causing immense pain. [1] Nasal drug delivery system offers lucrative way of drug delivery of both topical and systemic therapies. The high permeability, high vasculature and low enzymatic environment of nasal cavity are well suitable for systemic delivery of drug molecules via nose. Advantages of Nasal Drug Delivery System: 1. Drug degradation is absent. 2. Hepatic first – pass metabolism is absent. 3. Rapid drug absorption. 4. Quick onset of action. 5. The bioavailability of larger drug molecules can be improved by means of absorption enhancer or other approach. 6. Better nasal bioavailability for smaller drug molecules. 7. Drugs which cannot be absorbed orally may be delivered to the systemic circulation through nasal drug delivery system. 8. Convenient route when compared with parentral route for long term therapy. [2] Factors affecting Nasal drug absorption:
Nasal drug Absorption
Properties of the formulation
Prodrugs Enzymatic inhibitors Absorption enhancer Mucoadhesive Drug delivery system [3]
In situ forming polymeric formulations are drug delivery systems that are in sol form before administration in the nasal cavity, but once administered, undergo gelation in situ, to form a gel. The formation of gel depends on factors like temperature modulation, pH change, presence of ions and ultra violet irradiation, from which the drug gets released in a sustained and controlled manner. In the recent years, nasal route has been identified as promising drug delivery route for systemic therapy. Mucoadhesive in situ gel formulations have demonstrated increase in the residence time in the nasal cavity as well enhancement of the permeation characteristics of the drug. The in situ gel forming polymeric formulations offer several advantages like sustained and prolonged action in comparison to conventional drug delivery systems. [4] Thermoreversible polymers are a novel state of matter having both solid and liquid like properties which can be delivered as a fluid and solidifies within the body’s microenvironment where the temperature is higher than the sol-gel transition temperature. The formulation has the advantage to prevent the anterior leakage of dosage form, reduce the taste impact and enhance the nasal bioavailability. [5] Poloxamers or pluronic are the series of commercially available difunctional triblock copolymers of non-ionic nature. They comprise of a central block of relatively hydrophobic polypropylene oxide surrounded on both sides by the blocks of relatively hydrophilic polyethylene oxide. Due to the PEO/PPO ration of 2:1, when these molecules are immersed into the aqueous solvents, they form micellar structures above critical micellar concentration. They are regarded as PEO-PPO-PEO copolymers. Chemically they are oxirane, methyl, and polymer with oxirane a poly (polypropylene) (oxyethylene) a block copolymer. The pluronic triblock copolymers are available in various grades differing in molecular weights and physical forms. Pluronics also undergo in situ gelation by temperature change. They are triblock copolymers consisting of poly (oxyethylene) and poly (oxypropylene) units that undergo changes insolubility with change in environment temperature. [6] In the present investigation, Zolmitriptan was selected as a model drug in the development of nasal in situ gel. The Zolmitriptan is a serotonin (5-HT1) agonist used for the treatment of migraine with or without aura. The absolute oral bioavailability is about 40 to 50%. The half-life of Zolmitriptan is 2.5 to 3 hrs and it undergoes hepatic metabolism. [7] Because of these characteristics, it was selected as a model for the nasal in situ gel.
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Characteristic of the Drug
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Physiological factors of Nasal Mucosa
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Pharmaceutical formulators often face the challenge of finding the appropriate combination of independent process variables (factors) that will produce the product with optimum properties. However, this can be easily analyzed and understood using established statistical design of experiment tools such as factorial designs are considered the most effective in estimating the influence of individual process variables with minimum experimentation and time, where all factors are studied in all possible combinations. [8] Based on factorial design of experiment, the optimization technique encompasses the generation of model equations for the investigated responses over the experimental design to determine the optimum formulation(s). The present investigation aims at developing a statistically optimized nasal in situ gel of Zolmitriptan using 32-factorial design. MATERIALS: Zolmitriptan was provided by Glenmark pharmaceuticals Ltd. (Mumbai, India), Poloxamer 407 and Poloxamer 188 was provided by BASF (Mumbai, India), HPMC K4M was kindly provided by Colorcan Asia Pvt. Ltd. (Goa, India), Glycerine was purchased from Crown Chemicals. Potassium dihydrogen phosphate and Sodium hydroxide was purchased from Fischer Scientific, Mumbai. Benzylkonium chloride was purchase from (Hyderabad, India). All chemicals and reagents used were of analytical grade. Preparation of nasal in situ gel containing Zolmitriptan Nasal in situ gel of Zolmitriptan was prepared using cold method. Cold method involved slow addition of polymer, drug and additives in cold water with continuous agitation. The formed mixture was store overnight at 4 oC. Polymer (poloxamer 188 in concentration 8 % w/w and poloxamer 407 in concentration 16, 17 and 18 % w/w.) drug (Zolmitriptan in 2.5 % w/w) Mucoadhesive polymer HPMC K4M (0.5%, 1.0%, 1.5%) and other additives were mixed in cold water with continuous agitation. The formed mixtures were stored overnight at 4oC. The nasal gel formulation having satisfactory gelation temperature (30 oC-37oC) was selected as optimized formulation. [9] Table 1: Composition of formulation batches Composition (%w/v) Zolmitriptan Poloxamer 407 Poloxamer 188 HPMC K4M Glycerine Benzylkonium chloride Distilled water qs (ml)
PHo1 2.5 16 8 0.5 0.5 0.01 10
PHo2 2.5 16 8 1.0 0.5 0.01 10
PHo3 2.5 16 8 1.5 0.5 0.01 10
PHo4 2.5 17 8 0.5 0.5 0.01 10
PHo5 2.5 17 8 1.0 0.5 0.01 10
PHo6 2.5 17 8 1.5 0.5 0.01 10
PHo7 2.5 18 8 0.5 0.5 0.01 10
PHo8 2.5 18 8 1.0 0.5 0.01 10
PHo9 2.5 18 8 1.5 0.5 0.01 10
Experimental design: 32(two-factor and three-level) factorial design was employed for optimization of nasal in situ gel containing Zolmitriptan. Combination of Poloxamer 407 and Poloxamer 188 (X 1), HPMC K4M (X2) were selected as independent variables (factors), which were varied at three levels (low, middle and high). Gelation time (Y1), Gelation temperature (Y2) and drug release after 8 hrs (Y3%) as dependent variables (responses). STAT-EASE, design expert, 8.0.0 software was used for generation and evaluation of the statistical experimental design. The design including investigated factors and responses are shown in table 1 and 2. For optimization effect of various independent variables upon measured responses were modeled using following mathematical model (MLRA) equation involving independent variables and their interactions for various measured responses generated by 32 factorial design is following: Y= β0+β1X1+β2X2+β3X1X2+β4X12+β5X22+β6X1X22+β7X12X2+β8X12X22
………1
Where Y is the dependent variable, while β0 is the intercept is the arithmetic average of all quantities outcomes of 9 runs, β 1 to β8 are the coefficient computed from the observed experimental values of the independent variable(s). The terms X 1X2 and Xi2 (i=1,2) are the interaction and polynomial terms, respectively. The statistical validity of the polynomials was established on the basis of Yates’s ANOVA provision in the Design Expert Software. Subsequently, feasibility as well as grid search was performed to locate the composition of optimum formulations. Also, three-dimensional response surface graphs were generated by the Design Expert Software.
Dependent variables Y1= Gelation time
X2= HPMC K4M
Y2=Gelation temperature Y3= % Drug release (after 8 hr)
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Independent variables X1= Combination of Poloxamer 407 and 188
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Table 2: Independent and dependent variables
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Table 3: Factors and Levels with their real values Factors Combination of Poloxamer 407 and 188 HPMC K4M
High level (1) 18 1.5
Middle level (0) 17 1.0
Low level (-1) 16 0.5
Evaluation of nasal in situ gel: pH of the gels: The pH of each batch was measured using pH meter which was calibrated using buffers of pH 4 and pH 8 before the measurements. [10] Measurement of Gelation Temperature by Visual Inspection: It was determined by using method described by Miller and Donovan technique. A 2ml aliquot of solution was transferred to a test tube, immersed in a water bath. The temperature of water bath was increased slowly. [11] The sample was then examined for gelation, which was said to have occurred when the meniscus would no longer moves upon tilting through 90 0. Viscosity Studies: Gels Viscosity was measured by using Brookfield RVDV+Pro. The gel were exposed to spindle (S- 96), rotated at various speed ranging from 5-100 rpm. The apparent viscosity values of studied gels were carried out at 4 ± 1 0 C and 37 ± 10C temperatures. [12]
Determination of Gel strengh: Gel strength was measured by dropping ironball (6mm diameter and1.045g weight) on the surface of preformed gel (5 ml) in a 10 ml measuring cylender. The distance travelled by ball for specific period of time was measured. Determination of Mucoadhesive Strength: Individual samples of nasal gel formulations were applied to the base of inverted glass vial using double sided adhesive tape to secure the gel in position. The distance between two vials was adjusted in such a way that the gel sample remain adhere to mucosal membrane. Sufficient pressure was applied on both side of the vial for 10 sec to allow proper adhesion of the gel to mucosa. A constant weight was added to the pan connected to the other arm of modified balance which pulls the vial away from the other vial. The weight required for detaching the two vials was noted.
Figure 1: Modified balance assembly for measuring bioadhesive strength of formulations.
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In-vitro Diffusion study: In vitro diffusion study of formulated in situ gels was carried out on Franz diffusion cell. Franz diffusion membrane was used as diffusion membrane. Diffusion cell was filled with phosphate buffer pH 6.4; diffusion membrane was mounted on cell. The temperature was maintained at 34-37°C. At predetermined time points, 1 ml samples were withdrawn from the acceptor compartment, replacing the sampled volume with phosphate buffer pH 6.4, after each sampling, for a period of 480 min. The samples withdrawn were filtered and used for analysis. Blank samples were run simultaneously throughout the experiment to check for any interference. The amount of diffused drug was determined at 222.80 nm using on UV visible spectrophotometer, Shimadzu UV 1800. [14]
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dynes/cm2 was determined from the minimal weight that detached the mucosal tissue from surface of each formulation. Mucoadhesive Strength (dynes/cm 2) = mg/A, Where, m = weight required for detachment in gram, g = Acceleration due to gravity (980cm/s2), A = Area of mucosa exposed. [13]
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Ex vivo permeation studies using diffusion cell: The ex vivo permeation studied was conducted using ship nasal mucosal membrane. The ship nasal mucosal membrane was mounted in between the donor and the receptor compartment of the diffusion cell. The position of the donor compartment was adjusted so that the mucosa just touches the permeation medium. Formulation equivalent to contain 5 mg of drug was taken in the donor compartment which was in contact with the mucosal surface of the membrane, while the receptor compartment was filled with 30 ml of saline and its temperature was maintained at 37 °C. The content of the receptor compartment was stirred using a magnetic stirrer. An aliquot of 1 ml was withdrawn from the receptor compartment at suitable time intervals and replaced with the same volume of fresh medium. These samples were analyzed spectrophotometrically at 222.8 nm. [15] Analysis of In-vitro and Ex-vivo drug release kinetics and mechanism: In order to predict and correlate the In-vitro and Ex-vivo release behavior of Zolmitriptan from nasal in situ gel in phosphate buffer 6.4. It is necessary to fit into a suitable mathematical model. The In-vitro and Ex-vivo drug release data were evaluated kinetically in different mathematical models. Zero-order model: Q= kt + Qo Where Q represents the drug released amount in time t, Q o is the start value of Q and k is the rate constant. First-order model: Q= Qoekt Where Q represents the drug released amount in time t, Qo is the start value of Q and k is the rate constant. Hickson-crowell model: Q1/3= kt + Qo1/3 Where Q represents the drug released amount in time t, Q o is the start value of Q and k is the rate constant. Weibull model: m= 1- exp – [- (t)b/a] Where m represents the drug released amount in time t, a is the time constant and b is the shape parameter. Korsmeyer-Peppas model: Q= ktn Where Q represents the drug released amount in time t, k is the rate constant and n is the diffusional exponent, indicative of drug release mechanism. The accuracy and prediction ability of these models were compared by calculation of squared correlation coefficient (R 2) using KinetDS 3.0 2007 software. Fourier transform-infrared (FTIR) spectroscopy: FTIR spectroscopy of Poloxamer 407, Poloxamer 188, HPMC K4M, pure Zolmitriptan, Optimized nasal in situ gel containing Zolmitriptan was performed to analyze excipient-drug interaction analysis, if occurred. Samples were reduced to powder and analyzed as KBr pellets by using a FTIR spectroscope (IR Affinity 1). The pellet was placed in the sample holder. Spectral scanning was taken in wavelength region between 4000 and 600 cm-1 at resolution of 4 cm-1 with 1 cm/s scan speed. [16] Stability study: Stability studies of Zolmitriptan nasal gel was performed under actual storage condition (refrigeration condition). Gels are stored in clean, dry, airtight, moisture proof bottles, kept away from light. The gel samples were withdrawn at 0, 15, 30 days intervals and evaluated for Zolmitriptan content.
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Gelation time = 60.14 – 2.60 X1 – 16.17 X2 – 1.65 X1X2 +0.73 X12 +10.73 X22 [R2 = 0.999, F-value = 736.62, P
