Simultaneous Formulation, Estimation and Evaluation of Ofloxacin Microbeads

 

Chandana Pasupuleti¹, Abdul Saleem Mohammad²*, Nuha Rasheed³, Kathula Umadevi², Duggi Adilakshmi¹

¹Department of Pharmaceutics, St. Mary’s Pharmacy college, Deshmukhi (V), Pochampally (M), Behind Mount Opera, Nalgonda (Dist)-508284, Telangana, India.

²Department of Pharmaceutical Analysis and Quality Assurance, St. Mary’s Pharmacy College, Deshmukhi (V), Pochampally (M), Behind Mount Opera, Nalgonda (Dist)-508284, Telangana, India.

³Department of Pharmaceutics, Nizam Institute of Pharmacy, Deshmukhi (V), Pochampally (M), Behind Mount Opera, Nalgonda (Dist)-508284, Telangana, India.

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

ABSTRACT:

The aim for the present study was to develop a delivery system wherein the retention of ofloxacin could be achieved for increasing local action in gastric region against Helicobacter pylori. Therefore the present investigation is concerned with the development of rice bran oil entrapped zinc pectinate beads containing ofloxacin, which after oral administration were designed to prolong the gastric residence time, thus to increase the bioavailability of the drug. A suitable method of analysis of drug by UV spectrophotometry was developed. Ofloxacin showed maximum absorption at a wavelength 294.5 nm in pH 1.2 hydrochloric acid buffer. The value of regression coefficient (r²) was found to be 0.999, which showed linear relationship between concentration and absorbance. Preformulation study for drug and polymer compatibility by DSC and FTIR gave confirmation about the purity of the drug and showed no interaction between drug and the polymers.

 

 

1. INTRODUCTION:

The aim for the present study was to develop a delivery system wherein the retention of ofloxacin could be achieved for increasing local action in gastric region against Helicobacter pylori.¹ Therefore the present investigation is concerned with the development of rice bran oil entrapped zinc pectinate beads containing ofloxacin, which after oral administration were designed to prolong the gastric residence time, thus to increase the bioavailability of the drug.²

 

A suitable method of analysis of drug by UV spectrophotometry was developed. Ofloxacin showed maximum absorption at a wavelength 294.5 nm in pH 1.2 hydrochloric acid buffer. The value of regression coefficient (r2) was found to be 0.999, which showed linear relationship between concentration and absorbance. Preformulation study for drug and polymer compatibility by DSC and FTIR gave confirmation about the purity of the drug and showed no interaction between drug and the polymers.^{3, 4}

 

Floating Drug delivery system are designed to prolong the gastric residence time after oral administration, at particular site and controlling the release of drug is especially useful for achieving controlled plasma level as well as improving bioavailability. These systems are retained in the stomach for a longer period of time and thereby improve the bioavailability of drugs.⁵ Effective oral drug delivery may depend upon the factors such as gastric emptying process, gastrointestinal transit time of dosage form, drug release from the dosage form and site of absorption of drugs.^{53, 54.} Most of the oral dosage forms possess several physiological limitations such as variable gastrointestinal transit, because of variable gastric emptying leading to nonuniform absorption profiles, incomplete drug release and shorter residence time of the dosage form in the stomach.⁶ This leads to incomplete absorption of drugs having absorption window especially in the upper part of the small intestine, as once the drug passes down the absorption site, the remaining quantity goes unabsorbed. All the above requirements can be met and effective delivery of the drugs to the absorption window, for local action and for the treatment of gastric disorders such as gastro-esophageal reflux, can be achieved by floating drug delivery systems (FDDS). The concept of this system was described as a method for overcoming the difficulty experienced by some people of gagging or choking while swallowing medicine pills. It was suggested that this difficulty could be overcome by providing pills having density of less than 1.0 gm/ml, so that pills will float on water surface.^{7, 8, 9} Since then many types of gastric retention drug delivery systems were tested to overcome the limited region and times for drug absorption in gastrointestinal tract. The hydrodynamic balanced system (HBS) also called floating drug delivery system (FDDS) as an oral dosage form (capsule or tablet) designed to prolong the residence time of the dosage form within the GIT.^{1, 55, 56.}

 

2. MATERIALS AND METHODS:

Table 1. List of materials

Materials	Source
Ofloxacin	Apex Formulations Pvt. Ltd, India
Low methoxy pectin (LMP)	Krishna Pectins pvt. Ltd, India
Gellan gum (GG)	Sigma-Aldrich Chemicals, India
Xanthan gum (XG)	Sigma Aldrich, USA
Karaya gum (KG)	Morning Star Enterprises, India
Rice bran oil (RBO)	Sri Anjaneya  Agrotech Pvt.Ltd, India
Zinc chloride	High purity laboratory chemical, India

 

 Equipments:

Table 2. List of   equipments

Equipments	Model / Company
UV-Visible Spectrophotometer	Spectrophotometer UV-1601, Shimadzu, Japan
Electronic balance	Sartorious BS/BT, Mumbai, India
Differential scanning calorimeter(DSC)	DSC-60, Shimadzu, Japan
Fourier transform infrared radiation	Shimadzu, model 840, Japan
USP dissolution apparatus	Tab Machines, Mumbai, India
Scanning electron microscope	JEOLJSM-840A
Environmental chamber	Remi Electronics, Mumbai
Magnetic stirrer	Remi Electronics, Mumbai
Dial thickness meter	Mitutoyo 2046F, Japan

3. METHODOLOGY:

Development of calibration curve

Ofloxacin equivalent to 100 mg was weighed accurately and added to 100 ml volumetric flask.^{28, 35.} It was dissolved in 100 ml of 0.1 N hydrochloric acid buffer (pH 1.2) to get a stock solution A. From the stock solution A, 10 ml was pipetted out and transferred to another 100 ml volumetric flask and the volume was made up with 0.1 N hydrochloric acid buffer to get a stock solution B. From the stock solution B, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 1.6, and 0.8 ml were pipetted out and diluted to 10 ml with 0.1 N hydrochloric acid buffer to get 1, 2, 3, 4, 5, 6, 7 and 8 µg/ml solutions. ^10-12.

 

Absorbance of each of these solutions is recorded spectrophotometrically at 294.5 nm (Spectrophotometer UV-1601, Shimadzu, Japan).

 

Drug polymer compatibility studies

Differential scanning calorimetry (DSC)

Physical mixture of ofloxacin and other polymers were subjected to compatibility study using differential scanning calorimetry (DSC) (DSC-60, Shimadzu, Japan). For DSC, aluminium pans were used to place the samples. The heating rate was kept at 10 ºC rise per min up to 350 ºC to better integrate the information. Nitrogen gas was used for purging at 30 ml/min. ^{13, 14, 15}

 

Fourier transform infrared radiation (FTIR)

The Fourier Transform Infrared Radiation measurement (FTIR) spectral measurements were taken at ambient temperature using IR spectrophotometer (Shimadzu, model 840, Japan).^36-39.  Spectra of drug and polymer were taken and analyzed for any major interaction. These were done qualitatively in order to assess the pattern of peaks and for comparison purpose. The FTIR spectra of the drug with polymers were taken.⁴⁹

 

Preparation of floating zinc pectinate beads

Ofloxacin, LMP, GG, XG and KG were passed through sieve no 80 separately. Ofloxacin (20 % w/w of dry polymer weight) was dissolved in distilled water. LMP (3 % w/v) alone and polymer mixtures (3 % w/v) containing LMP and GG, LMP and XG, and LMP and KG in three different ratios were dissolved in above dispersion and one formulation with polymer mixtures (3 % w/v) containing GG, XG, KG and LMP. To the above mixture rice bran oil (25 %w/w) was added and stirred to form a homogeneous emulsion. The drug-loaded emulsion was extruded through a 23 G syringe needle into zinc chloride solution (5 % w/v) maintained under gentle agitation. The beads were allowed to remain in the same solution for 30 min to improve their mechanical strength. The formed beads were separated, washed with water and allowed to dry at room temperature overnight.^16-19.

Table 3 lists the formulation variables for different formulations of ofloxacin loaded floating beads. Blank beads without ofloxacin were also prepared using the same technique.^50-52

 

Table 3 Formulation variables of various ofloxacin bead formulations

Formulation Code	LMP : GG (3% W/v)	LMP: XG (3% w/v)	LMP:KG (3% W/v)	LMP: GG: XG:KG    (3% w/v)	Oil (%w/w)
F1	9:1	-	-	25	25
F2	8:2	-	-	-	25
F3	7:3	-	-	-	25
F4	-	9:1	-	-	25
F5	-	8:2	-	-	25
F6	-	-	9:1	-	25
F7	-	-	8:2	-	25
F8	-	-	7:3	-	25
F9	-	-	-	8:0.66:0.66:0.66	25

 

 

Evaluation of physicochemical parameters of floating beads of zinc pectinate

Determination of bead diameter

The diameter of a sample of gel beads (25 beads) of each formulation was determined using a dial thickness meter. Measurement for each sample was repeated ten times. Mean diameter and standard deviations were  recorded.^{20, 21, 22.}

 

Drug Content

An accurately weighed sample of beads (100 mg) was crushed in a mortar and added to 100 ml of 0.1N hydrochloric acid buffer (pH 1.2). This mixture was kept overnight under stirring to elute complete drug from the polymer matrix.^{45, 46, 47, 48.} The mixture was filtered and analyzed spectrophotometrically at a wavelength of 294.5 nm (UV spectrophotometer, 1601, Shimadzu, Japan) against blank bead mixture, which was treated similarly. The drug content of each formulation was recorded as mg/100 mg of gel beads.^{23, 24.}

 

Drug Entrapment Efficiency

The percentage drug entrapment efficiency (% EE) of each bead formulation was calculated using the following equation: ^{40, 54}

 

Actual Drug Content

EE (%) = ----------------------------------------             X 100

Theoretical Drug Content

 

Determination of swelling index

The swelling behavior of the zinc pectinate beads was studied in 0.1 N HCl (pH 1.2)¹⁸ buffer. Approximately 100mg of beads were taken in a dissolution basket and weighed (W₁); the baskets along with the beads were immersed in 0.1N HCl buffer.

 

The weight (W₂) of the basket along with the beads was determined for 8 h: every 30 minutes for the first 2 h, and then every h after that.^25-27.

 

 The swelling index (SI) of each formulation was calculated using the following equation:

                   W2 – W1

   % SI = --------------------                 X 100

                       W1

 

Buoyancy studies

The time between the introduction of the FDDS into the medium and its buoyancy to the upper one third of the dissolution vessel (floating lag time) and the time for which the formulation constantly floated on the surface of the medium (floating duration) were measured simultaneously as a part of dissolution studies by visual observation.^{14, 29, 30.}

 

In vitro drug release studies

In vitro release characteristics of ofloxacin floating gel beads (n=3) were evaluated employing USP XIV dissolution testing apparatus 2 (paddle method). The dissolution test was performed using 500 ml of 0.1 N HCl buffer as dissolution medium maintained at 37±0.5 ºC. The contents were stirred at 50 rpm. A 5 ml aliquot of the solution was withdrawn at predetermined time intervals for 8 h and fresh 5 ml dissolution media was replaced to maintain sink condition.The sample aliquots were analyzed spectrophotometrically at a wavelength of 294.5 nm (UV spectrophotometer, 1601,Shimadzu, Japan).^{55, 31, 32}

 

Stability studies

Stability studies were carried out according to ICH guidelines by storing the formulation F1 at 40±2°C and relative humidity 75±5 % for a period of two months in a programmable environmental test chamber (CHM-10S, Remi Instruments Ltd., Mumbai, India). The samples were withdrawn at 30 and 60 days and analyzed for the drug content, floating behavior and in vitro drug release.^{54, 56}

 

 

 

 

Scanning electron microscopy (SEM)

Morphological examination of the surface and external structure of the dried beads of formulation F1, F4 and F7 (Both drug loaded and blank beads) was performed using a scanning electron microscope (SEM) (model JEOL, JSM-840A). The samples were gold coated prior to the scanning.^{41, 42, 54.}

 

4. RESULTS

An attempt was made formulate oil entrapped floating zinc pectinate beads of ofloxacin, since it is required to act locally in the stomach and proximal region of small intestine. The drug and polymers were subjected for compatibility studies to ensure drug polymer compatibility. The gel beads were prepared by emulsion gelation method. The prepared beads were evaluated for various physicochemical parameters such as size and morphology, drug entrapment efficiency, floating characteristics, swelling studies, and in vitro release studies by conventional method.

 

Development of calibration curve

 

Figure 1 Calibration curve of ofloxacin

 

Compatibility study

Differential scanning calorimetry (DSC)

The DSC themograms of physical mixture of ofloxacin and the polymers showed that characteristic peaks of polymers and ofloxacin peaks were still present in the physical mixture but slightly shifted from their original positions (Figure 2. To 7).

 

 

Figure 2 DSC thermogram of pure ofloxacin

 

Figure 3 DSC thermogram of ofloxacin and LMP

 

 

Figure 4 DSC thermogram of ofloxacin, LMP and GG

   Figure 5 DSC thermogram of ofloxacin, LMP and KG (physical    mixture)

 

Figure 6 DSC thermogram of ofloxacin, LMP and XG (physical      Mixture)

Figure 7 DSC thermogram of ofloxacin, LMP, GG, KG and XG (physicalmixture)

 

Fourier transform infrared radiation (FTIR)

Following characteristic bands are seen for ofloxacin (Figure: 8)

O-H stretching band at 3300 cm-1

C-H stretching (aliphatic) 2936.17cm-1

C-H stretching (aromatic) 2785.3cm-1

C=O stretching 1712.89cm-1

 

All the above bands associated with the pure drug are present in the FTIR spectra of drug in combination with gellan gum, karaya gum and xanthan gum (Figure: 9 to 13). This shows that there is no chemical interaction taking place between drug and excipients.

 

 

Figure 8 FTIR spectra of pure ofloxacin

 

 

 

Figure 9 FTIR spectra of ofloxacin and LMP  (physical mixture)

 

Figure 10 FTIR spectra of ofloxacin, LMP and GG (physical mixture)

 

 

Figure 11 FTIR spectra of ofloxacin, LMP and KG (physical Mixture)

 

 

Figure 12 FTIR spectra of ofloxacin, LMP and XG (physical mixture)

 

 

Figure 13 FTIR spectra of ofloxacin, LMP, GG, KG and XG (physical mixture)

Evaluation of physicochemical parameters of floating zinc pectinate beads:

Particle size analysis

The prepared beads were almost spherical and translucent. The mean surface diameter of 10 formulations was between 1.691±0.022 (mean±SD) and 2.099±0.041 (mean±SD) (Table 1).

 

Drug entrapment efficiency

The percent drug entrapment efficiency for various ofloxacin floating bead formulations was found to vary between 57.49% and 78.81% (Table 3).

 

Floating properties

The floating ability of prepared beads was evaluated along with dissolution studies. The beads without oil sink immediately in 0.1 N HCl (pH 1.2), while beads containing sufficient amount of rice bran oil (25%) demonstrated instantaneous and excellent floating ability (Table 4).

 

 

In vitro release profile

Conventional method

In vitro drug release study of ofloxacin floating beads was carried in 0.1N HCl (pH 1.2), for a period of 8 h. In the 0.1N HCl, the beads exhibited a biphasic release profile as an initial rapid drug release phase (burst effect) was followed by a sustained, gradually increasing drug release phase after 1 h extending up to 8 h.

 

Formulation F contained only LMP could not sustain the ofloxacin release up to 8 h. It released complete drug at the end of 4 h. Whereas formulations containing GG; F1, F2 and F3 released 87.51%, 74.33 and 74.76% of drug respectively at the end of 8 h and the release profile is shown in figure 14. The formulations containing XG; F4 and F5 released 80.74% and 59.85% of the drug at the end of 8 h respectively. The release profile from these beads is shown in figure 15. The formulations containing KG; F6, F7 and F8 released 76.41%, 68.52% and 66.00% of the drug at the end of 8 h respectively. The release profile from these beads is shown in figure 16. The formulations containing GG, XG and KG released 62.40% of the drug at the end of 8 h respectively. The release profile from these beads is shown in figure 16.

         

Table 4 Characterization of floating zinc pectinate beads

Formulation code	Mean Diameter ± SD(mm)	Drug content (mg)	%EE	%Swelling Index
F1	1.751±0.023	1.236±0.017	78.81	2.42
F2	1.841±0.022	1.620±0.054	69.16	1.79
F3	1.898±0.018	1.551±0.054	72.13	2.21
F4	2.193±0.017	1.681±0.023	76.20	1.01
F5	1.836±0.017	1.621±0.063	60.61	3.75
F6	2.057±0.069	1.362±0.035	74.28	1.22
F7	2.009±0.027	1.713±0.111	65.40	2.10
F8	2.099±0.041	1.417±0.027	62.98	1.74
F9	2.008±0.063	1.434±0.240	58.95	0.72

 

Table 5 Buoyancy characteristics of floating zinc pectinate beads

 

Table.6 In vitro release characteristics of formulation F

 

 

 

 

Table  7. In vitro release characteristics of formulation F1

 

Table 8. In vitro release characteristics of formulation F2

 

Table .9. In vitro release characteristics of formulation F3

 

Table 10. In vitro release characteristics of formulation F4

Table 11 In vitro release characteristics of formulation F5

Table 12. In vitro release characteristics of formulation F6

 

 

 

Table 13. In vitro release characteristics of formulation F7

 

 

 

 

Table 14. In vitro release characteristics of formulation F8

 

 

 

 

Table 15. In vitro release characteristics of formulation F9

 

 

 

 

 

Figure 14 Comparison of in vitro dissolution characteristics of F with F1, F2, F3 containing GG

 

 

 

Figure 15 Comparison of in vitro dissolution characteristics of F with F4, F5 containing XG.

 

 

 

Figure 16 Comparison of in vitro dissolution characteristics of F with F6, F7, F8 containing KG and F9.

Analysis of release pattern

To analyze the drug release from the beads, the in vitro dissolution data was fitted to:

a) Zero order (Cumulative percentage drug released Vs Time)

b) First order (Log cumulative percentage drug remaining Vs Time)

c) Higuchi release model (Cumulative percentage drug released Vs Square root of time)

d) Korsemeyer and peppas model (Log percentage drug released Vs Log time).

 

 

Figure 17 First order plot of F (◊), F1 (■), F2 (▲), F3 (×)

 

 

Figure 18 Higuchi plot of F (◊ ), F1 (■), F2 (▲), F3 (×)

 

Figure 19 Korsemeyer and peppas plot for F (◊), F1 (■), F2 (▲), F3(×).

 

Figure 20 First order plot of F (◊), F4 (■), F5 (▲), F6 (×)

 

 

 

 

Figure 21 Higuchi plot of F (◊), F4 (■), F5 (▲), F6 (×)

 

 

 

Figure 22 Korsemeyer and peppas plot for F (◊), F4 (■), F5 (▲), F6 (×)

 

                                                                                                                      

Figure 23 First order plot of F (◊), F7 (■), F8 (▲), F9 (×)

 

 

 

Figure 24 Higuchi plot of F (◊), F7 (■), F8 (▲), F9 (×)

 

 

 

Figure 25. Korsemeyer and peppas plot for F (◊), F7 (■), F8 (▲), F9 (×)

                                

                              

 

Table 16 Kinetics of release pattern

S.No.	Formulation Code	r2 for zero order equation	r2 for first order equation	r2 for Higuchi equation	N value for Peppas equation	r2 for Peppas equation
1	F	0.606	0.944	0.870	0.198	0.998
2	F1	0.683	0.992	0.887	0.225	0.986
3	F2	0.657	0.980	0.880	0.246	0.983
4	F3	0.567	0.762	0.793	0.170	0.979
5	F4	0.583	0.823	0.815	0.185	0.976
6	F5	0.567	0.695	0.810	0.206	0.915
7	F6	0.503	0.715	0.753	0.154	0.967
8	F7	0.604	0.779	0.832	0.189	0.995
9	F8	0.692	0.840	0.899	0.247	0.995
10	F9	0.634	0.774	0.863	0.226	0.988

 

 

The optimized formulation F1 was processed in to grapghs for Comparision of different orders of drug release. The data were processed for regression analysis using MS-Excel statistical functions. 

 

The optimized formulation F1 was processed in to grapghs for Comparision of different orders of drug release. The data were processed for regression analysis using MS-Excel statistical functions. 

 

Table  17 In vitro release characteristics of formulation F1

 

 

 

The Figure 26 drug release profile fitted in zero order

 

The Figure 27 drug release profile fitted in first order

 

 

The figure 28 drug release profile fitted in higuchi model

 

The figure 29 drug release profile fitted in korsemeyer peppas model

5.6 Stability studies

In view of potential utility of the formulation, stability studies were carried out on formulation F1 for two months according to ICH guidelines. At the end of each month, the formulations were subjected to drug assay, floating behavior and in vitro release studies. The results are shown in Table 18

 

Table 18 Stability study of formulation F1

Time	Drug Content ± SD (mg)	Floating behaviour		Drug release at the end of 8h
		FLT (min)	Floating duration (h)
Zero month	1.236±0.017	0	24	87.51±1.14
First month	1.222±0.021	0	24	80.21±1.21
Second month	1.182±0.056	0	24	75.32±1.32

 

 

Scanning electron microscopy

The scanning electron microscopy of blank and drug loaded beads (both external and internal structure) are shown in figure 1 and.2.

 

Table 19 Formulation code for SEM

S.No	Formulation code
1	F0 drug unloaded (LMP:GG, 9:1)
2	F1 drug loaded (LMP:GG, 9:1)
3	F4 drug loaded (LMP:XG, 9:1)
4	F7 drug loaded (LMP:KG, 9:1)

 

 

Figure 5.7.1 Scanning electron microscopy of (a) external and (b) surface morphology of drug loaded floating beads (F0)

 

 

Figure 5.7.2 Scanning electron microscopy of (a) external and (b) surface  morphology of drug loaded floating beads (F1)

 

Figure 30 Scanning electron microscopy of (a) external and (b) surface morphology of drug loaded floating beads (F4)

 

Figure 31 Scanning electron microscopy of (a) external and (b) surface morphology of drug loaded floating beads (F7)

 

 

DISCUSSION:

Oral drug delivery systems represent one of the frontier areas of controlled drug delivery systems. Floating drug delivery systems belongs to oral controlled drug delivery system group, which are capable of floating in the stomach for prolonged period of time. In the present work an attempt has been made to prepare oil entrapped floating zinc pectinate beads containing ofloxacin to target the drug to stomach mucosa for prolonged period of time. The prepared beads are evaluated for their physicochemical properties such as size and morphology, drug entrapment efficiencies, swelling behavior, floating characteristics and in vitro drug release characteristics.

 

Differential Scanning Calorimetry (DSC)

The thermograms obtained by subjecting the pure ofloxacin and physical mixtures of ofloxacin and polymers showed no possible drug polymer incompatibility. The DSC thermograph of pure ofloxacin showed one endothermic peak at 274.5⁰C (Figure 5.2.1.1). The DSC thermograms of physical mixture of ofloxacin and the polymers showed no characteristic peaks of the polymers, and ofloxacin peaks were still present but slightly shifted from their original positions (Figure 5.2.1.2 to 5.2.1.6) which could be possibly due to an ionic interaction and this characteristic features of drug melting suggested  no problem of incompatibility. Some modification of drug peak, such as changes in area, shape or peak temperature were found, but they arose simply because of the  mixing of the components.

 

Fourier transform infrared radiation (FTIR)

All the bands associated with the pure drug were present in the FTIR spectra of drug in combination with gellan gum, karaya gum and xanthan gum. This showed that there is no chemical interaction taking place between drug and polymers.^{44, 49.}

 

Preparation of floating zinc pectinate beads

Pectin with low degree of esterification (DE) can form gel by ionotropic gelation with Zn²⁺ ions. When an emulsion of rice bran oil containing pectin was dropped into zinc chloride solutions, spherical gel beads were then formed instantaneously in which intermolecular cross-links were formed between the metallic zinc ions and negatively charged carboxyl groups of the pectin molecules (Figure: 6.2.1). The gel beads were easily formed without any sophisticated equipment. It was found that homogenization of emulsion is a must as without homogenization; the oil separated from the pectin solution despite being mixed by stirrer.43 Pectin helped to emulsify the mixture of water and oil phase during the homogenization process. However the emulsifying property was limited when the oil concentration was increased to more than 30%w/w. At and above this concentration the oil started eluting from the beads. The oil-entrapped beads were spherical, translucent and slightly yellowish. It was found that a minimum of 25%w/w rice bran oil was necessary to impart satisfactory buoyancy to the beads (Table 2).

 

 

Figure 31 Diagram to illustrate the proposed model of emulsion-gelation process by which the oil entrapped zinc pectinate gel beads are formed.⁴³

 

 

Physicochemical parameters of floating zinc pectinate  beads

Bead diameter

The formed beads were spherical. The mean particle diameter of the blank oil entrapped zinc pectinate beads containing no drug were found to be 1.691±0.022 (mean±SD), but the drug loading to the beads increases the size of the beads of, e. g. it was found that the mean diameter of formulation F was increased to 1.693±0.015 (mean±SD) upon drug loading. It was found that incorporation of copolymers such as GG, KG and XG to the bead formulations result in further increasing of the bead diameter as in case of formulations F1 to F9 (Table 1). As the process parameters were kept constant, the added materials were responsible for the change in the size of the zinc pectinate beads.¹⁴

 

Scanning electron microscopy

The scanning electron micrographs of external and internal surfaces of both blank and drug loaded beads of formulation F1, F4 and F7 are shown in Figure 5.9.2, 5.9.3 and 5.9.4. The beads (both blank and drug loaded) were spherical and the external surface was smooth with slightly rougher surface/shrinkage which could be due to drying. The internal surface of the blank beads shows sponge-like nature with little droplets of entrapped oil which imparts buoyancy to the beads. In the drug loaded beads the internal surface is slightly sponge like which is due to the drug and rate controlling polymer are uniformly dispersed in the polymer matrix.^38,40,43,50

 

Drug entrapment efficiency

The percentage drug entrapment efficiency (%EE) of the ofloxacin loaded beads are shown in Table 1.

 

The percentage entrapment efficiency of the beads was obtained in the range of 57.49 % to 78.81 %. Formulation F1 showed the highest drug entrapment and formulation F showed the lowest entrapment of drug. The low drug entrapment efficiency of the F formulation may be attributed to the highly porous nature of the zinc pectinate matrix, due to which the drug may diffuse back into the cross linking solution from the bead matrix during cross linking period.³³

 

The drug entrapment also increases with addition of the copolymers into the bead formulation. Here zinc chloride was used as cross linking agent, as, calcium chloride reacted with ofloxacin and tends to solubilize the drug in the cross linking medium itself.⁵²

 

Swelling index

The swelling behavior study of the beads was performed in 0.1 N HCl. There was no such a change in the swelling ratio of the beads in 0.1 N HCl was observed.¹⁸ The beads were also not swollen much or eroded during the dissolution studies in 0.1 N HCl. Thus, from these results, it could be assumed that the drug release was not under the control of the swelling behavior but rather was controlled by the dissolution of the ofloxacin in the dissolution medium and diffusion of the ofloxacin through polymer matrix.³³

 

Buoyancy studies

The floating ability of prepared beads was evaluated along with dissolution studies. The beads without oil sank immediately in 0.1 N HCl (pH 1.2), while beads containing sufficient amount of rice bran oil (F to F9) demonstrated instantaneous and excellent floating ability. It was found that a minimum of 25 %w/w of rice bran oil was necessary

 

to impart buoyancy to the gel beads (Table 2). Thus, floating ability was found to be directly related to the amount of oil entrapped in the polymer matrix. The beads remained afloat throughout the study period (8 h) and the beads continued to float till 24 h (Table.2). It was found that varying the polymer and copolymer concentrations in the bead formulations did not affect the floating lag time or the floating duration of the beads in the dissolution media.

 

In vitro drug release studies

The in vitro drug release profile of all the bead formulations (F to F9) by conventional method is shown in Table 1 to 4.. The gel beads in the 0.1 N HCl (pH 1.2), exhibited a biphasic release profile as an initial rapid drug release phase was followed by a slower and sustained, gradually increasing drug release phase after  1 h.

 

Formulation F released 74.47 % of the drug within 1 h but could not sustain the drug release over the following 7 h and released 99.14 % drug at the end of 3 h.

 

Formulations F1, F2 and F3, which contains GG along with LMP, released 87.51 %, 74.33 % and 74.76 %of drug respectively at the end of 8 h (Figure 1).

 

Formulations F4, F5 and F6, which contains KG along with LMP, released 80.74 %, 59.85 % and 76.41 % of the drug at the end of 8 h respectively (Figure 2).

 

Formulations F7 and F8 which contains XG along with LMP, released 68.52 % and 66.00 % of the drug at the end of 8 h respectively (Figure 3).

 

Formulations F9 which contains LMP along with GG, KG, XG, released 62.40 % of the drug at the end of 8 h respectively (Figure 3).

 

The results show that incorporation of rate controlling polymers such as GG, KG and XG to the bead formulations can sustain the drug release from the oil entrapped zinc pectinate beads. Incorporation of these copolymers into the zinc pectinate matrix increases the viscosity of the polymers matrix and correspondingly decreases the drug release. Results also show that as the concentration of the copolymers increases in the formulation, the drug release is further decreased and more sustaining of drug release is observed because as the concentration of copolymers is increased the viscosity of the polymer matrix is further enhanced.

 

Kinetics of drug release

The in vitro release data of all the batches were fitted to zero order, first order, Higuchi and Korsemeyer and Peppas equations. It was observed that for the formulation F, F1 and F2 the r² was higher when fitted to first order equation (r² = 0.944), which indicates that a first order release from the formulation F, whereas all the other formulations, F3 to F9 followed Higuchi model. The n values of the Korsemeyer-peppas model for all the formulations was found to be less than 0.5 (n<0.5), so it suggested that the drug release from the beads followed fickian (case I) diffusion.

 

Stability studies

At various time intervals, samples were evaluated for the stability studies. There were no more difference in the drug content and the floating properties at the various sampling intervals. The in vitro drug release profiles were super imposable which confirms the stability of the product.

 

CONCLUSION:

Ofloxacin is an antibacterial fluoroquinolone. It is widely prescribed in gastric ulcers, duodenal ulcers, Zollinger-Ellison syndrome and gastroesophageal reflux disease. Ofloxacin exhibit pH dependent solubility. It is are more soluble in acidic pH and slightly soluble in neutral or alkaline pH conditions. However, precipitation of the drug occurs in intestine, which adversely affects the absorption in the lower sections of the intestine. So there is need for systems that reside in the stomach over a relatively long period and release the active compound in a sustained manner.³⁴

 

Plasma half life of ofloxacin is 5-8 hrs with an oral bioavailability of 95% and the preferable dose is 200-400 mg once daily in morning.⁶³

 

The aim for the present study was to develop a delivery system wherein the retention of ofloxacin could be achieved for increasing local action in gastric region against Helicobacter pylori. Therefore the present investigation is concerned with the development of rice bran oil entrapped zinc pectinate beads containing ofloxacin, which after oral administration were designed to prolong the gastric residence time, thus to increase the bioavailability of the drug. A suitable method of analysis of drug by UV spectrophotometry was developed. Ofloxacin showed maximum absorption at a wavelength 294.5 nm in pH 1.2 hydrochloric acid buffer. The value of regression coefficient (r2) was found to be 0.999, which showed linear relationship between concentration and absorbance. Preformulation study for drug and polymer compatibility by DSC and FTIR gave confirmation about the purity of the drug and showed no interaction between drug and the polymers.

 

Various formulations of floating beads of ofloxacin were developed using polymers like LMP alone and mixture of LMP with rate controlling polymers such as GG, KG and XG. The beads were prepared by emulsion gelation method. Rice bran oil was used to impart buoyancy to the beads due to its low density. The beads were spherical in nature and them evaluation of the drug content and entrapment efficiencies showed that beads formulated using LMP alone resulted in poor drug content and entrapment.

 

Beads formulated with mixture of LMP and GG showed the highest drug content and entrapment compared to other formulations.

 

The beads did not swell much or erode in the dissolution media, which suggested that drug release was dependent on the dissolution and diffusion of the drug through the polymer matrix.

 

The buoyancy studies on the beads proved that a minimum of 25% w/w of rice bran oil was required to impart satisfactory buoyancy to the beads. The beads showed instantaneous and excellent buoyancy and remained afloat on the dissolution medium throughout the study period.

The in vitro drug release study showed that LMP alone could not sustain the drug release for sufficient period of time whereas incorporation of rate controlling polymers such as GG, KG and XG as copolymers can effectively sustain the drug release from the bead formulations. The results showed that beads formulated with mixture of LMP and GG (F1) showed the highest drug release compared to other formulations. So the formulation F1 was selected as optimum formulation.

 

The selected formulation showed no more changes in drug content, floatability or in vitro drug release profile after storage at 75±5 % RH at 40±2 °C during stability study for two months. Thus, the objective of the present work of formulating a dosage form ofloxacin by using a low density oil and different proportions and combinations of release rate controlling polymers has been achieved with success.

 

SUMMARY

The aim of the study was to develop and physically characterize the oil entrapped floating zinc pectinate beads of ofloxacin. Ofloxacin is an antibacterial fluoroquinolone. It is intended to act at the stomach mucosa. Ofloxacin is are more soluble in acidic pH and slightly soluble in neutral or alkaline pH conditions. However, precipitation of the drug occurs in intestine, which adversely affects the absorption in the lower sections of the intestine.

 

Different types of matrix forming polymers such as LMP, GG, KG and XG were used for the present study. Rice Bran oil was used to impart buoyancy to the beads. Drug and polymers were subjected for the compatibility study using DSC and FTIR which suggested that there is no interaction between the drug and polymer.

 

All the bead formulations showed satisfactory floating characteristics. All the formulations were subjected for in vitro release study using pH 1.2 hydrochloric acid buffer in conventional dissolution apparatus. The results indicated that LMP alone cannot sustain the drug release but mixture of LMP with other copolymers sustains the drug release for more than 8 h. To analyze the mechanism of drug release from the beads, the in vitro release data was fitted into various release models. It was observed that the release of the drug followed Higuchi model and the mechanism of drug release was found to by fickian diffusion.

 

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Received on 01.07.2016       Accepted on 28.07.2016     

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