Bioadhesive Microbeads of Ketoprofen for Controlled and Site Specific Delivery

 

R. Sivakumar1*, N. Narayanan2 and N.N. Rajendran1

1Swamy Vivekanandha College of Pharmacy, Tiruchengode-637 205.(TN)                2College of Pharmacy, Madras Medical College, Chennai-600 003, India

*Corresponding Author E-mail: rrsk1879@gmail.com

 

ABSTRACT:

The objective of this work was to design mucoadhesive oral controlled release drug delivery system for ketoprofen to target the small intestine. Mucoadhesive microbeads containing Ketoprofen were prepared by ionic gelation method using sodium alginate, pectin, and xanthan gum as polymers. The prepared beads were coated with 1% chitosan solution and dried. The dried beads were filled into hard gelatin capsules and coated by a enteric polymer. All microbeads were nearly spherical in shape with rough surface with the mean particle size of 1.6 mm – 1.8 mm. Of the six formulations prepared and evaluated formulas A6 were found satisfactory results. The release followed zero order release with non-Fickian diffusion.

 

KEYWORDS: Ketoprofen, ionic gelation, beads, mucoadhesion, small intestine

 


INTRODUCTION:

Multiple-unit solid dosage forms such as microspheres or beads have gained in popularity as oral drug delivery systems because of more uniform distribution of the drug in the gastro intestinal tract, more uniform drug absorption, reduced local irritation and elimination of unwanted intestinal retention of polymeric material, when compared with non-disintegrating single – unit dosage forms1-2 Multiparticulate offer greater advantages over single unit system as they disperse uniformly in GI tract, offer flexibility and less inter and intra individual variability in formulation process. Multiparticulates present several advantages in comparison to single unit dosageforms that they exhibit higher residence time and more predictable gastric emptying3.

 

Alginate is linear, naturally occurring polysaccharide extracted from brown algae. Pectin, Xanthan gum and Chitosan is a naturally occurring bio compatible mucoadhesieve polysaccharide has received major attention in drug delivery system4. Chitosan is a biodegradable and bio compatible polymer that due to its cationic nature has good mucoadhesive and membrane permeability-enhancing properties

 

Ketoprofen is a widely used non steroidal anti inflammatory drug for the treatment of rheumatoid arthrities, ankylosing spondilities. Besides the drug is also administered as sustained release dosage form. Conventional dosageform of ketoprofen shows low efficacy due to the quick decrease of plasma drug concentration below the therapeutic range. The biological half life of the drug is 2-3 h and so requires frequent dosing owing to fairly fast elimination from the body. The drug is reported to cause irritation to the stomach which may attract poor patient compliance. Although the sustained release formulation of the drug will provide better patient compliance yet the possibility of gastric irritation due to release of the drug in the stomach from the sustained release formulation cannot be ruled out5-6.

 

Ketoprofen shows poor solubility in lower pH and so absorption from the stomach is a matter of concern for better bioavailability of drug. Ketoprofen is well absorbed from all segments of the gastro intestinal tract except stomach, Delivery of the drug to small intestine  is the most desirable  keeping in view that the  drug is better soluble in higher pH of the environment and better absorption due to the large epithelial area results from mucosa, villi and microvilli of the small intestine. The specific aim of this study was to design novel bioadhesive micro beads of ketoprofen to target the small intestine.

 

MATERIALS AND METHODS:

Ketoprofen USP was procured from BEC chemicals Mumbai, India. Sodium alginate, Pectin, Xanthan gum and Calcium chloride were obtained from SD Fine Chemicals Mumbai, India. Chitosan (MW 150 kDa ) was obtained from Central Fisheries Laboratory, Cochin India. Eudragit L100 was obtained from Loba Chemie Pvt Ltd Mumbai, India. All other materials and solvent used of analytical grade.

 

Preparation of drug loaded beads:

The mucoadhesieve microbeads containing ketoprofen were prepared by the ionic gelation method7. All polymeric solutions (1% w/v of sodium alginate, pectin and xanthan gum) were prepared by dissolving polymers in de-ionized water to get the viscosity of 45 centipoises. Weighed quantity of ketoprofen was dispersed into aqueous polymeric solution. The resultant solution was introduced drop wise using a syringe kept at a distance of 3cm and at an average rate of 2ml/min, using a nozzle of 0.3mm inner diameter, into a gently agitated solutions of 5 % calcium chloride for 1 h. The gel beads were separated by filtration, rinsed with distilled water and dried at 40 C for 30 minutes. The gelled beads were coated by membrane forming step where the beads were suspended in a solution of chitosan8 (1 % w/v in acetic acid) for 1 minute. The micro beads were allowed to harden for 24 h in a dessicater and filled into the hard gelatin capsules (size 00). All the batches were prepared with composition shown in Table 1.

 

Enteric Coating:

Eudragit L100 (10 % w/w) was dissolved in 50 ml of   isopropyl alcohol (IPA). In this solution Caster oil (5%) and titanium dioxide (0.5%) were mixed with methanol(10%) and methelene chloride(1%) solution. This mixture was added to the IPA. Finally the volume was adjusted to 100 ml using isopropyl alcohol. Weight equivalent to 50 mg of ketoprofen containing microbeads were filled into hard gelatin capsules and the capsules were coated with the prepared enteric coating solution using dipping and drying technique. At each stage the pellets were kept in an hot air oven for 30 minutes at 45 C. The capsules were weighed and the weight gain limited to (8 %w/w) indicating completion of enteric coating.

 

FT-IR and Differential Scanning Calorimeter (DSC) Analysis:

Infra red spectrum of microbeads loaded with ketoprofen were taken by using Perkin Elmer .DSC scanning of ketoprofen and beads loaded with ketoprofen.

 

Particle size, shape and surface morphology:

Particle size analysis was carried out by using Malvern master seizer. The SEM analysis of microbeads was done sing Jeol Jsm S 300 Scanning electron microscope 9-12.

 

Degree of Swelling:

Swelling was measured as a function of pH. The degree of swelling was measured gravimetrically by weighing the particles prior to and after swelling13. The dried microbeads were first weighed and then immersed in the phosphate buffer pH 6.8 until equilibrium was reached. Subsequently, they were removed from the buffer solution, carefully blotted with a tissue paper and then they were re-weighed. The degree of swelling was calculated using the following formula13.

Degree of Swelling = W2 – W1 X 100 / W1

Where W1 and W2 are the weight of dry beads and swollen beads respectively.

 

Drug loading and Encapsulation efficiency:14-15

100 mg of accurately weighed microbeads were crushed in a glass mortar-pestle and the powered microspheres were suspended in 25 ml of phosphate buffer (6.8) for 12 h at room temperature to release the entrapped drug. After 12 h the solution was filtered using micro-pore filter and the filtrate was diluted and analyzed for the ketoprofen content using UV spectrophotometer at 256 nm wave length. The amount of ketoprofen present in the microbeads were determined using a calibration curve. The drug loading and entrapment efficiency were determined for all batches using Equation (1) and (2), respectively14.

 

Drug Loading % (Actual Drug Content)

                           Weight of ketoprofen in microspheres

Drug Loading    = ----------------------------------------- X 100

                                 Microspheres sample weight

 

Encapsulation efficiency % (EE)

                Actual weight of ketoprofen in sample

EE   =    ----------------------------------------------------- X 100

                     Theoretical weight of ketoprofen

 

 

Test for Mucoadhesion:16

Mucoadhesieve properties of the Ketoprofen multiparticles were evaluated using everted sac technique. The animal study protocols have been approved by the International Animal Ethical Committees (IACC meeting proposal, Ref No: 14/243, Dated 26.2.2008, Madras Medical College, Chennai-3).Un fasted rats (400g, male) are sacrificed and intestinal tissue was exercised and flushed with 10 ml of ice cold phosphate buffered saline, pH 7.2 containing 200mg/dl glucose(PBSG). 6 cm segments of jejunum were everted using a stainless steel rod and lightly washed with PBSG to remove the contents. Ligatures were placed at both ends of the segment and the sac was filled with 1-1.5 ml of PBSG. Tissue was maintained at 4 C prior to incubation. The sac was introduced into a 15 ml tube containing 60 mg of bioadhesieve multiparticles and 5 ml of PBSG. The sacs were introduced into a 15 ml glass tube containing 60 mg of microspheres and 5 ml of PBSG. The sacs were incubated at 37 C and agitated end - over - end. After 30 min the sacs were removed, and the solution of PBSG and unbound microparticles was centrifuged for 30 min. The supernatant fluid was discarded. The sedimented particles were washed three times with 5ml of distilled water and centrifuged for 30 minutes. The multiparticles were dried by lyophilization for 24 h. The weight of the bound particles was determined by subtraction of the tarred weight of the tube and lyophilized particles. The results are expressed as percent binding10.

 

 


TABLE 1: COMPOSITION OF KETOPROFEN MICRO BEADS

S. No

Composition

1:1 (g)

1:2 (g)

1:3 (g)

1:4 (g)

1:5 (g)

1:6 (g)

1

Ketoprofen USP

1.00

1.00

1.00

1.00

1.00

1.00

2

Sodium alginate

0.70

1.40

2.10

2.80

3.50

4.20

3

Pectin

0.20

0.40

0.60

0.80

10.00

12.00

5

Xanthan Gum

0.10

0.20

0.30

0.40

0.50

0.60

 

 

TABLE 2: CHARACTERIZATION OF MICRO BEADS

 

Code

Drug: Polymer

Particle size(mm)

Loading Capacity (%)

Encapsulation         Efficiency (%)

Swelling

(%)

Bioadhesion(%)

A1

1:1

1.60±0.4

36.42± 7.4

83.72±5.3

15±2

48.0 ± 6.2

A2

1:2

1.64±0.3

37.23±2.2

84.45±3.2

21±2

49.8 ± 4.8

A3

1:3

1.68±0.2

39.78±2.5

86.64±2.3

29±3

54.3 ± 3.9

A4

1:4

1.73±0.3

41.35±1.9

87.36±3.4

38±3

54.09 ± 5.1

A5

1:5

1.75±0.2

43.82±4.3.

89.88±4.3

44±4

58.5 ± 2.9

A6

1:6

1.81±0.3

44.21±3.4

89.13±2.9

44±3

63.3 ± 4.7

 

 


Drug Release Study:17-20

The drug release study was carried out using USP XX111 basket apparatus at 37  + 0.5 C and at constant speed of 50 rpm using 900 ml of 0.1 N Hcl (2 h) and  phosphate buffer pH 6.8 (12 h) as a dissolution medium. Weight equivalent to 50 mg of ketoprofen containing microbeads of enteric capsules were used for the test. Five milliliters of sample solution was withdrawn at predetermined intervals and equal amount of fresh dissolution medium was replaced immediately after withdrawal of the test sample. The samples were filtered, diluted suitably and analyzed by UV spectrophotometer method at 256 nm. The percentage of drug release is shown in (Fig.2).The release mechanism were also analyzed for the cumulative drug release profile..

 

RESULTS AND DISCUSSIONS:

Ketoprofen microbeads were successfully prepared by ionic  gelation method. Acceptable range for angle of repose was between 22 to 25. The particle size of the beads was between 1.6mm – 1.81 mm. As previously found in other studies one can observe that the presence of drug generally results in an increase of particle size, this behavior can be possibly related to a corresponding increase in the precursor of droplet size. The SEM studies of chitosan coated beads showed that they were nearly spherical in shape with rough surface (Fig. 1). The loading capacity ranged from ~36 % to ~ 48 %. The drug entrapment efficiency of different formulations were found to be between in the range of ~83 % to ~89 %. The effects of polymer concentration were studied and the entrapment efficiency was higher (77.3%) for formulation A6 and lower for formulation A1. The drug entrapment efficiency of microbeads increasing with increase in concentration of polymers. This is because the increase in polymer concentration resulted in formation of larger beads entrapping more drug. The swelling of calcium alginate beads in phosphate buffer is related to Ca2+ and Na2+ exchange. Also the chitosan membrane reduces the permeability and possesses swelling resistance when exposed to the aqueous media. In this case chitosan coated beads to swell in buffer solution is increased with increasing polymer concentration. The bio adhesion of microbeads was between ~ 46% to ~ 62% (Table.2). It   indicates increase the polymer concentration, the percent of the bio adhesion increases. The ketoprofen release profile from microbeads is characterized by an initial phase of rapid drug release followed by a more gradual release (Fig.2). All profiles were characterized by initial burst release phase followed by a slow and controlled release phase. The initial burst release could be attributed to both rapid swelling of microbeads reflecting the contribution of both rapid diffusion of water into the microbeads leading to formation of porous structure quickly upon contact with water, and rapid loss of water pore and /or surface associated drug. The release mechanism of each drug in all the formulations was initially characterized in terms of the different exponent n. The ability of polymeric matrix to absorb enough water is an important factor in the form of the gel layer, which controls the drug release. From the analysis of swelling data, it was possible to conclude that the polymers under investigation accept water at different rates.  In the geometry of the formulations, these n values signify a non-fickian or anomalous mechanism of drug release. In the anomalous process of drug, Fickian diffusion through the hydrated layer of the polymeric matrix and polymeric chain relaxation /erosion are both involved. The contribution of these two mechanisms to the overall release is considered to be addictive.

 

Fig.1:  SCM Photograph of ketoprofen Microbeads

 

Fig.2: Cumulative in vitro drug release of ketoprofen from microbeads

 

ACKNOLEDGEMENTS:

Authors thanks to Dr. M. Karunanidi, Chairman, Vivekanandha Groups of Educational Institutions for encouraging research work.

 

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Received on 13.09.2010          Modified on 25.09.2010

Accepted on 30.09.2010         © RJPT All right reserved

Research J. Pharm. and Tech. 4(3) March 2011; Page 385-388