Optimization of HPMC K100M and Sodium Alginate Ratio in Metronidazole Floating Tablets for the Effective Eradication of Helicobacter pylori

 

Ashok Thulluru1*, S. Shakir Basha1, C. Bhuvaneswara Rao2, Ch. S. Phani Kumar,  Nawaz Mahammed1, K. Saravana kumar1

1Sree Vidyanikethan College of Pharmacy, A. Rangampet, Tirupati-517102, Chittoor (Dist.), A. P.

2Krishna Teja Pharmacy College, Chadalawada Nagar, Renigunta Road, Tirupati-517506, Chittoor (Dist.), A. P.

3Adarsa College of Pharmacy, G. Kothapalli-533285, Gokavaram (Md.), E. G. (Dist.), A.P.

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

 

ABSTRACT:

Aim and Objective: The objective of the present study is the Formulation and evaluation of metronidazole floating tablets (MZFT) that are designed to retain in the stomach for a long time for better eradication of Helicobacter pylori (H. pylori), a main cause of peptic ulcer. Methods: Optimization of ratio of synthetic and natural polymers; HPMC K100M and sodium alginate respectively was studied. Drug-excipent compatibility by physical observation and FT-IR studies. Pre-compression studies on directly compressible blends, post-compression studies: Wt. variation, hardness, thickness, floating characteristics, release profiles and kinetics; in vivo X-ray radiographic studies in rabbit and accelerated stability studies as per ICH guidelines of optimized formulation were studied. Results: Physical observations and FT-IR studies revealed that there was no interaction between the drug and any of the proposed polymers. All the directly compressible blends have good flow characteristics. Post-compression parameters: Wt. variation, hardness, thickness are in acceptable limits. Drug release kinetics of batch F8 (HPMC K100M: Sodium alginate ratio; 14:1 respectively) suggests it extends the drug release up to 8 h, with a zero order release profile (r2 = 0.999). Drug release process is predominantly by diffusion (as Higuchi r2 = 0.885); and the mechanism of diffusion is by super case-II transport (as Korsemeyer-Peppas, n = 1.033). It is exhibiting floating lag time of 10.3 sec; total floating time and matrix integrity were maintained up to 8 h. Hence F8 is an optimized batch. It passes the test for stability as per ICH guidelines. X-ray radiographic studies of BaSO4 loaded placebo of optimized F8 batch in rabbit, concludes the in vivo floating of MZFT up to 8 h. Conclusion: These stomach targeted effervescent floating tablets could maintain the minimum inhibitory concentration for sufficient time to allow for local eradication and thereby achieve better efficiency of therapy with improved patient compliance, reduced costs and minimized side effects caused by immediate release dosage forms. Optimization of ratio of synthetic and natural polymers (HPMC K100M and sodium alginate) plays a major role in the success of formulation of MZFT.

 

KEYWORDS: Metronidazole floating tablets, HPMC K100M, sodium alginate, in vitro buoyancy studies, in vivo X-ray radiographic studies.

 

 


INTRODUCTION:

Oral route is one of the most extensively utilized routes for administration of dosage forms. But variable and short gastric emptying time results in incomplete drug release from the oral controlled release dosage forms (OCRDF) which leads to diminished efficacy of the administered dose1. To improve the performance of OCRDF, one of the concepts in novel drug delivery is Gastro-retentive drug delivery systems (GRDDS). A GRDDS can be defined as a system which remains in the stomach for a sufficient time interval against all the physiological barriers, releasing the active moiety in a controlled manner2. A GRDDS can be a useful tool in delivery of drugs that are primarily absorbed in the duodenum and upper jejunum or those that have an absorption window in the gastrointestinal tract (GIT)3-5. Such delivery system is appropriate for drugs which are locally active in the gastric mucosa, for example, antibiotic administration for Helicobacter pylori eradication6,7 and in the treatment of peptic ulcer and gastritis8,9. Drugs that are less soluble and degraded by the alkaline pH may get benefit by being incorporated in GRDDS for prolonged gastric retention and consequent improved oral bioavailability and therapeutic efficacy by possible reduction of dose size10,11. Various GRDDS include floating drug delivery systems (FDDS), bio-adhesive, swelling, expanding and high density systems. Floating systems are more popular in comparison with the other described GRDDS12-14 because they do not have any adverse effect on the motility of the GIT15. Based on the mechanism of floating, two systems of FDDS are effervescent and non-effervescent systems. Effervescent systems contains carbonates (eg. sodium bicarbonate) and/or organic acids (eg. citric acid/tartaric acid) in their formulation to produce carbon dioxide (CO2) gas, when comes in contact with gastric fluids. The CO2 gas entrapped in the matrix system reduces the density of the system and makes it buoyant. The non-effervescent systems are based on the mechanism of swelling of polymer or bio-adhesion to mucosal layer in GIT16-19. Hydrophilic polymers are actually one of the most used excipients to control drug delivery from an oral pharmaceutical dosage form including GRDDS and may be classified as either synthetic or natural. Carbopols and hydroxypropyl methylcellulose (HPMC), a semi-synthetic cellulose derivative, have been used by other investigators to prepare MZ FT20-24. In spite of the advent of many synthetic polymers, use of natural polymeric materials has gained a lot of importance during the last two decades in drug delivery field. Incorporation of natural polymers in various drug delivery systems seems to be an active area of research and development due to obvious advantages including being biocompatible, inexpensive and ready availability25. These polymers, particularly those with pronounced swelling properties have been frequently employed in the formulation of different gastro-retentive products26. Drug delivery systems targeted to stomach which are based on the utilization of various natural polymer offer superiority over other systems. Moreover, these polymers are safe, nontoxic, and capable of chemical modification and gel forming nature. Natural polymers which have been explored for their promising potential in stomach-specific drug delivery include alginates27, xanthan gum28, chitosan28, locust gum29, guar gum30,31, pectin, gellan gum, karaya gum, psyllium husk, starch, etc32,33. In the last decade, the number of patients suffering from peptic ulcer and gastric cancer due to H. pylori infection has increased tremendously. H. pylori are spiral, gram-negative, microaerophilicrod-shaped bacteria with multiple flagella34,35. H. pylori which remains on the luminal surface of the gastric mucosa under mucous gel layer, is highly motile, and produces enzyme urease to alter the surrounding pH to protect itself from gastric acid35. The current therapy for the treatment of H. pylori involves use of proton pump inhibitors with antibiotics and has drawbacks like poor patient compliance and increased bacterial resistance due to higher multiple dosage of antibiotics36,37. There could be one or several reasons for the failure of antibiotic therapy against H. pylori. Firstly, the organism resides in the mucus gel close to the acidic environment of the gastric fluid. Many antibacterial agents, such as penicillin and erythromycin, degrade rapidly in acidic medium. Secondly, the drug must diffuse into the mucus layer and the bacterial glycocalyx to furnish concentrations sufficient for antibacterial activity. For eradication of H. pylori in the stomach the concentrations of antibacterial agents reaching the site of infection from tablets or capsules might not be bactericidal against organisms located in the mucus layer and protected by the glycocalyx. Lastly, the contact time of antibacterial drugs with the organism needs to be sufficiently long for successful eradication of H. pylori from the gastric mucosa, which can be achieved through a GRDDS38,39. Delivering drug at the site of infection for a longer period of time is one of the approaches to improve the efficacy of antibiotic therapy40,41. Metronidazole (MZ) is an active adjunct in treatment of H. pylori42 with the commonly reported side effects including anorexia, nausea, vomiting, and epigastric pain. Metallic taste, mouth dryness, probably caused by the presence of high concentrations of the drug in the saliva, and furring of the tongue are also reported43. Therefore, certain MZ floating systems were developed for better eradication of H. pylori, including: floating MZ tablets20-24,42 and beads25,43-47. Such dosage forms for MZ would be beneficial in delivering higher concentrations of the antibacterial agent in the gastric mucosa where H. pylori resides ensuring better microorganism eradication. Furthermore, such treatment may lead to drug dose reduction which will be an additional valuable advantage47. Results of literature review directed us to formulate MZFT with the combination of synthetic and natural polymers (HPMC K100M and sodium alginate) respectively. The objective of the present study is to optimize the ratio of these polymers in extending the release of MZ up to 8 h.

 

MATERIALS:

MZ is a gift sample received from M/s Dr. Reddy’s Laboratories, Hyderabad, India. Hydroxy Propyl Methyl Cellulose (HPMC K100M) and Micro crystalline cellulose (Avicel PH 101) were received as gift samples from Colorcon Asia Pvt. Ltd., Mumbai, India. Sodium alginate (SA), is purchased from Arihant trading Co. Ltd., Bangalore. Magnesium stearate, sodium bicarbonate, talc and Barium sulphate were purchased from S.D. Fine-Chemicals Ltd., Chennai, India. All the excipients used in study are of analytical grade.

 

METHODS:

Drug-excipient compatibility / FT-IR studies:

FT-IR spectra of pure drug and drug: polymer (1:1) physical mixtures were recorded out, in the region of 400-4000 cm-1at spectral resolution of 2 cm-1, by the direct sampling method with isopropyl alcohol as solvent, using (Agilent technologies Cary 630 FT-IR, Japan) and the comparative FT-IR spectra were shown in (Fig.1).

 

Standard calibration curve:

100 mg of MZ pure drug was dissolved in 10 mL of methanol in a 100 mL volumetric flask and the volume was adjusted with 0.1 N HCl [stock solution-I (SS-I); 1000 µg/mL] and then placed in an sonicator for 10 min. 10 mL of SS-I was taken into a 100 mL volumetric flask and the volume was adjusted with 0.1 N HCl (100 µg/mL). The above solution was subsequently diluted with 0.1N HCl to obtain the series of working dilutions containing 2, 4, 6, 8 and 10 µg/mL of PH solution. The working dilutions were analyzed at 269 nm by using a double beam UV-Vis spectrophotometer (Agilent technologies Cary 60 UV-Vis, Japan). The standard calibration curve was plotted by taking conc. on X-axis and absorbance on Y-axis48.

 

Preparation of MZFT Tablets:

All the tablet batches were prepared by direct compression method, by keeping the amount of MZ constant as 300 mg per tablet. The composition of other excipients is varied as mentioned in formulation table (Table 1).

 

Function of Excipients:

HPMC K100M is a synthetic controlled release (CR) polymer, SA is a natural CR polymer, micro crystalline cellulose (Avicel PH 101) is directly compressible diluent, Sodium bicarbonate is an effervescent agent, magnesium stearate is lubricant and talc is glidant.


 

 

Fig.1. FT-IR spectra of a) MZ; b) MZ and HPMC K100M; c) MZ and SA

 

Table 1: Formulation table of MZFT

Ingredients

F1

F2

F3

F4

F5

F6

F7

F8

Metronidazole

200

200

200

200

200

200

200

200

HPMC K100M

70

80

90

100

110

120

130

140

Sodium alginate

80

70

60

50

40

30

20

10

Sodium bicarbonate

50

50

50

50

50

50

50

50

MCC

30

30

30

30

30

30

30

30

Mg Stearate

10

10

10

10

10

10

10

10

Talc

10

10

10

10

10

10

10

10

Total

450

450

450

450

450

450

450

450

 


 

 

Procedure:

MZ and all other excipients excluding magnesium stearate and talc were co-sifted through SieveNo. # 40 (ASTM), blended in a poly bag for 10 min and lubricated with Sieve No. # 60 (ASTM) passed magnesium stearate and talc by mixing in the same poly bag, for additional 2-3 min. Tablets were compressed on a tabletting machine (Minipress by Clit, 10 stations, Chamunda Pharma Machinary Pvt. Ltd., India.) fitted with a 5 mm standard flat circular punches with an avg. wt. of 450 mg and avg. hardness of 6.0 kg/cm2.

 

Pre-compression Studies:

Directly compressible tablet blends of MZFT were evaluated by pre-compression studies [angle of Repose (θ), bulk density (BD), tapped density (TD) Carr’s Index (CI) and Hausner’s Ratio (HR)] as per standard methods49-52. The consolidated results of pre-compression studies were tabulated in (Table 2).

 

Table 2: Results of pre-compression studies of MZFT

F

code

AR

(°)

BD

(g/cc)

TD

(g/cc)

CI

(%)

HR

(  )

F1

26.16±1.03

0.37±0.03

0.38±0.02

9.76

1.11

F2

24.58±0.89

0.38±0.02

0.40±0.03

11.63

1.13

F3

25.16±0.61

0.39±0.03

0.41±0.02

4.88

1.05

F4

24.71±1.30

0.36±0.04

0.39±0.03

7.69

1.08

F5

25.36±0.46

0.40±0.03

0.44±0.05

11.36

1.13

F6

26.56±1.44

0.38±0.03

0.45±0.03

15.56

1.18

F7

26.15±1.90

0.37±0.03

0.44±0.01

15.91

1.19

F8

24.26±1.23

0.39±0.02

0.48±0.01

18.75

1.23

 

Post-compression Studies:

The wt. uniformity of tablets were determined by using an electronic balance (Shinadzu-BL-220H, Japan.), thickness was measured using a verniercalipers (Mitutoyo Corporation, Japan.), friability was carried out on Roche friabilator (M/s. Elite Scientific Equipment, Germany.) and hardness was measured using a Monsanto hardness tester (Singla-Hardness tester, India.) as per the standard methods53, 54.

 

 

 

Assay:

Five tablets from each batch (n=3), were randomly selected and crushed in a mortar with pestle; the quantity of blend equivalent to 100 mg of MZ was suspended in 100 mL of 0.1N HCl in a volumetric flask and sonicated for 2 min. The dispersion was filtered through 0.45µm membrane filter, suitably diluted and analyzed spectrophotometrically55-57.

 

In Vitro Buoyancy Studies:

Was characterized by floating lag time (FLT), total floating time (TFT) and matrix integrity (MI) up to 8 h, as per the method described by (Rosa et al., 1994)58. Three tablets from each batch (n=3), were randomly selected. A tablet was dropped into 100 mL of 0.1 N HC1 in a beaker. The time required for the tablet to rise to surface and duration of time it constantly floated on medium were noted as FLT and TFT, respectively. During this study, whether the swollen matrix was intact or disintegrated was observed, to confirm the matrix integrity. The consolidated results of in vitro buoyancy studies are tabulated in (Table 3). In vitro floating images of optimized formulation MZFT-F8 was shown in (Fig.2).

 

 

Fig.2. In vitro floating images of optimized MZFT-F8 at A) Initial, B) After 5 sec, C) After 10 sec and D) After 10.3 sec onwards


 

 

 

 

 

Table 3: Results of post-compression studies of MZFT

F Code

Avg. wt. (mg)

Thickness (mm)

Hardness (kg/cm2)

Friability (%)

Assay (%)

FLT

(sec)

TFT

(h)

MI

up to 8h

F1

454.7±1.22

4.02±0.15

5.26±1.36

0.415

97.71±1.21

42.0 ± 0.07

> 8

+

F2

452.7±1.55

4.04±0.23

5.9±0.79

0.232

100.57±0.72

28.0 ± 0.18

> 8

+

F3

452.6±1.16

4.04±0.34

5.66±0.28

0.449

99.71±0.81

38.0 ± 0.13

> 8

+

F4

448.5±1.22

4.02±0.22

5.03±0.33

0.349

101.9±0.64

18.7 ± 0.72

> 8

+

F5

452.5±1.14

4.04±0.18

5.83±0.28

0.534

98.85±0.32

51.3 ± 0.82

> 8

+

F6

451.5±1.28

4.02±0.24

5.1±1.014

0.236

97.73±0.61

16.5±0.25

> 8

+

F7

449.8±1.53

4.03±0.18

5.66±0.763

0.519

103.9±0.85

55.6±0.23

> 8

+

F8

450.4±1.70

4.02±0.42

5.33±0.208

0.232

101.33±1.21

10.3±0.07

> 8

+

 


In Vitro Dissolution Studies:

Three tablets from each batch, were randomly selected (n=3). Dissolution was performed with the USP-II (paddle) dissolution apparatus (Disso 2000, Labindia Analy. Inst. Pvt. Ltd., India.), each flask was filled with 900 mL of 0.1N HCl; speed of paddle was maintained at 50 rpm, the temperature was kept constant at 370C ± 0.50C. At time points: 1, 2, 3, 4, 5, 6, 7 and 8 h. 5 mL of dissolution media was withdrawn, filtered through 0.45µm membrane filter, suitably diluted and analyzed at the predetermined λmax at 277 nm for MZ, using a double beam UV-Vis spectrophotometer (Agilent technologies Cary 60 UV-Vis, Japan). Each sample withdrawn was replaced with an equal amount of fresh 0.1 N HCl, to keep the volume constant. In vitro dissolution profiles of MZFT were shown in (Fig.5).

 

 

Fig. 5. In vitro dissolution profiles of initial, 1, 2 and 3M accelerated stability samples of optimized MZFT-F8

 

 

Drug Release Kinetics:

The in vitro drug release data of all batches were fitted into zero order, first order, Higuchi and Korsemeyer- Peppas models to ascertain the drug release kinetics. The drug release from the hydrophilic matrix whether depends on drug’s concentration or not was explained by zero and first order models. Higuchi model describes whether the drug release is predominantly by diffusion or not. The Korsemeyer- Peppas model further explains the mechanism of diffusion59-62. The respective models were defined by the equations below.

 

Zero Order:

Qt= Q0+ K0t   Eq.No.1

 

First order:

log Q = log Q0-K1t / 2.303    Eq.No.2

 

Higuchi model:

Qt= KHt1/2 Eq.No.1           Eq.No.3

Korsemeyer-Peppas model:

Mt /M = Kt n                       Eq.No.4

 

Where Qt is the amount of drug dissolved at time, t; Q0 is the initial amount of drug in the solution at time t=0, Q is the amount of drug remaining at time, t; Mt/Mis the fraction of drug released at time, t and n is diffusion exponent. K0, K1, KH and K refer to the rate constants of respective kinetic models. Drug release mechanisms based on n-values, for cylindrical shape, as per Korsmeyer-Peppas model, were tabulated in (Table 4). The consolidated drug release kinetic data of MZFT were tabulated in (Table 5).

 

Table 4: Drug release mechanisms for cylindrical shape in Korsmeyer-Peppas model

Diffusion Exponent (n)

Overall drug diffusion mechanism

0.45

Fickian diffusion

0.45 < n < 0.89

Non-Fickian diffusion

0.89

Case II transport

n > 0.89

Super Case II transport

 

 

Table 5: Results of drug release kinetics of MZFT

F code

Zero

First

Higuchi

Krosmeyer-Peppas

r2

r2

r2

r2

n

F1

0.881

0.704

0.964

0.97

0.667

F2

0.895

0.686

0.964

0.973

0.691

F3

0.910

0.685

0.966

0.985

0.701

F4

0.936

0.562

0.958

0.986

0.733

F5

0.978

0.562

0.928

0.997

0.854

F6

0.993

0.736

0.902

0.998

0.903

F7

0.998

0.860

0.879

0.998

0.987

F8

0.999

0.882

0.871

0.997

1.033

 

 

In vivo x-ray Imaging Studies:

In vivo residence time of BaSO4 loaded placebo of optimized formulation MZFT-F8 was studied by x-ray imaging studies in a rabbit model63. An adult male New Zealand white strain, rabbit of one year old age and weighing approximately 2-2.5 kg was used for this study. The rabbit was fasted overnight before the start of the study. The tablets were administered through plastic tubing followed by flushing of 25-30 mL of water. During the entire study, the rabbits had free access to water only. X-ray images were taken using (Wipro Ge Dx300, SV diagnostic centre, Nethaji road, Tirupati, India) at before administration, 1st, 2nd, 4th, 6th and 8th h after the administration and are shown in (Fig.5). The protocol (SVCP/IAEC/I-006/2017-18 dated on 15. 12. 2018) for in vivo study was approved by the institutional animal ethical Committee (IAEC) of Sree Vidyanikethan College of Pharmacy, Tirupati-517 102, Chittoor (Dist.), A.P., and is in accordance with guidance of committee for the purpose of control and supervision of experiments on animals (CPCSEA), Ministry of Social Justice and Empowerment, Govt. of India.

 

 

Accelerated Stability Studies:

Stability studies of the optimized MZFT-F8, packed in 10 CC HDPE containers up to 3 months were carried according to International Conference on Harmonization (ICH) guidelines; in a humidity chamber (NSW-175, Narang Scientific work, India) maintained at 45°C ± 2°C and 75% ± 5% RH64. At the end of every month up to 3 months, the samples were withdrawn and evaluated for post compression studies. The consolidated results of accelerated stability studies were tabulated in (Table 6). Comparative in vitro dissolution profiles of initial and accelerated stability samples were shown in (Fig.6). The chemical stability of drug in the 3M-accelerated stability sample of optimized MZFT-F8; which will influence it’s in vitro and in vivo dissolution characteristics, was investigated using FT-IR studies as per the procedure mentioned earlier.

 


 

Fig .6. Comparative FT-IR spectra of a) MZ and b) 3M-accelerated stability sample of optimized MZFT-F8

 

 

Table 6: Results of accelerated stability studies of optimized MZFT-F8

Time

Interval

Avg. wt.

(mg)

Thickness

(mm)

Hardness

(kg/cm2)

Friability

(%)

Assay

(%)

FLT

(sec)

TFT

(h)

MI

up to 8h

Initial

448.5±1.22

4.02±0.22

5.33±0.21

0.349

101.33±1.21

10.3±0.07

> 8

+

1 M

449.2±1.05

4.01±0.11

5.22±0.11

0.432

100.07±0.18

11.2 ±0.59

> 8

+

2M

447.8±1.12

4.02±0.07

5.21±0.07

0.446

99.84±0.21

15.5 ±0.63

> 8

+

3 M

446.9±1.21

4.03±0.15

5.18±0.15

0.451

99.56±0.12

15.85 ±0.55

> 8

+

 


RESULTS AND DISCUSSION:

Drug-Excipient Compatibility / FT-IR Studies:

The FTIR spectrum of metronidazole was characterized by principal absorption peaks at 1360.18 cm-1 (NO stretching vibration), this peak was completely disappeared in inclusion complex, 3453.77 cm-1 (N-H stretching vibration), 1080.54 cm-1 (C-OH stretching vibration). The IR bands of pure MZ and MZ: polymer(s) (1:1 ratio physical mixtures) shows no significant shifts or reduction in intensity of the FTIR bands. Hence there was no incompatibility problem between the drug and polymers used in the study64. (Fig.1)

 

Standard Calibration Curve:

Is defined by a straight line equation, y = 0.025x + 0.002, following linearity with a regression coefficient (r2 = 0.999). This method obeyed Beer’s law in the concentration range of 0-10 µg/mL. This method was suitable for the estimation of MZ.

 

Pre-compression Studies:

The angle of repose of all the directly compressible blends of MZFT are ranging between 24°.26’ to 26°.56’, CI and HR were found to be in the range of 14.88 to 18.75% and 1.05 to 1.23 respectively, indicating excellent flow properties and compressibility of the blends. (Table 2)

 

Post-compression Studies:

As the % wt variation of all batches is within ± 7.5% w/w, they passed the % wt. variation test as per United States Pharmacopoeia-30, National Formulary-25 (USP 30-NF 25). The thickness of tablets was found to be between 6.21 to 6.32 mm. The hardness of tablets was found to be between 5.9 to 6.33 kg/cm2, indicating satisfactory mechanical strength. The % friability was NMT 1.0% w/w for all the formulations, which is an indication of good mechanical resistance to physical erosion of the tablet. As the % assay of all batches is within 97.17-103.9 %, they passed the content uniformity test as per USP 30-NF 25. (Table 3)

 

In Vitro Buoyancy Studies:

The FLT was found to be NMT 1 min for all the formulations. Among them MZFT-F8 (HPMC K 100M: SA: 14:1), had a lowest FLT of 10.3±0.07 and retained its MI and TFT up to 8 h. (Table 3 and Fig.3)

 

In Vitro Dissolution Studies:

As the conc. of HPMC K100M increases, there is an increased viscosity of the gel matrix and decrease in the effective diffusion coefficient of the drug65. Other factors that may contribute to differences in drug release profiles include; differences in water penetration rate, water absorption capacity, polymer swelling and drug: polymer ratio66,67. Among all factors, drug: polymer ratio is important factor affecting the rate of drug release from the matrix, which has to be optimized68. The pH independent, zero order release profile of bio pharmaceutics classification system (BCS) class-I drugs (High Permeability, High Solubility) like MZ can be attained from the hydrophilic matrix systems, by combining the semi synthetic polymers like, HPMC K100M with natural polymers like Sodium alginate36. The combined matrix when exposed to gastric fluids, HPMC hydrates first to form a gel layer at the surface of the tablet, while the natural polymer, SA due to lesser hydration rate than HPMC remains insoluble. The resulting matrix system acts as a barrier for diffusion of highly soluble drugs like MZ and extends its release68, 69. All the formulations with SA in combination with HPMC K100M are able to extended MZ release up to 8 h. Among all the batches, MZFT-F8 (HPMC K 100M:SA:14:1 respectively) extends the release of MZ up to 8 h with a better zero order release profile (r2 =0.999) is considered as an optimized one. (Fig. 5)

 

Drug release Kinetics:

Among all the batches, MZFT-F8, fitted best to the zero order kinetics (as zero order, r2 = 0.999), indicating the drug release from the matrix does not depends on its conc. Drug release process is predominantly by diffusion (as Higuchi, r2= 0.871; i.e. r2 > 0.8); and the mechanism of diffusion is by super case-II transport i.e. a combination of both diffusion and erosion (as Korsemeyer- Peppas, n=1.033). (Table 4)

 

In vivo x-ray Imaging Studies:

X-ray images of a rabbit taken at before administration, 1st, 2nd, 4th, 6th and 8th after the administration of BaSO4 loaded placebo of optimized MZFT-F8 was strong enough in withstanding repetitive gastric contractions and able to retain in gastric region up to 8 h and above. (Fig.4)

 

Fig. 3. In vitro dissolution profiles of MZFT

 

Fig.4. X-ray images of BaSO4 loaded placebo of optimized MZFT-F8 in a rabbit model at A) Before administration, B) 1st h, C) 2nd h, D) 4th h E) 6th h and F) 8th h.

 

Accelerated Stability Studies:

As there were no significant differences in post compression studies (wt. variation, thickness, hardness, friability and in vitro dissolution studies) and floating characteristics (FLT, TFT and MI) of initial and accelerated stability samples of optimized MZFT-F8 in the HDPE pack, it passes the test for stability (Table 6). Comparative FT-IR spectra in (Fig.6), reveals there is no significant change in the functional groups of the MZ due to interaction with polymers and other excipients used in the formulation.

 

CONCLUSION:

In the view of above findings, effect of combination of synthetic and natural polymers (HPMC K100M and sodium alginate) respectively, in extending the release of MZ from its effervescent GRFT was better understood. It was further concluded that the optimization of the proportion of HPMC K100M and SA, had significant effect on extending the release profiles of MZ in gastric region. Among the various combinations of HPMC K100M and SA; MZFT-F8 (HPMC K 100M : SA :: 14:1 respectively) forms a better matrix for the extending the release of MZ in gastric pH up to 8 h, with a better zero order release profile (r2 = 0.999), FLT of 10.3 ± 0.07 s, TFT and a better MI up to 8 h. Hence it is an optimized formulation. A combination hydrophilic matrix design of this kind can serve as an alternative strategy for extending the release of other BCS class I drugs (High Permeability, High Solubility) and their salt forms, which are having shorter elimination half-life (t1/2 < 5 h) for extending their release in gastric region.

 

ACKNOWLEDGEMENTS:

The authors are thankful to Dr. M. Mohan Babu, Chairman and visionary, Sree Vidyanikethan Educational Trust, Tirupati, Dr. C. K. Ashok Kumar, Principal and Dr. S. Mohana Lakshmi, Vice Principal; Sree Vidyanikethan College of Pharmacy, Tirupati, for providing us the required facilities and being a constant support to carry out this research work.

 

REFERENCES:

1.      Adibkia K, Hamedeyazdan S, Javadzadeh Y. Drug Release Kinetics and Physicochemical Characteristics of Floating Drug Delivery Systems. Expert Opin Drug Deliv. 2011; 8(7): 891-903.

2.      Pawar Vk, Kansal S, Garg G, Awasthi R, Singodia D, Kulkarni GT. Gastroretentive Dosage Forms: A Review With Special Emphasis on Floating Drug Delivery Systems. Drug Deliv. 2011; 18(2): 97-110.

3.      Ali J, Arora S, Ahuja A, Babbar Ak, Sharma Rk, Khar Rk, et al. Formulation and Development of Hydrodynamically Balanced System for Metformin: In Vitro and In Vivo Evaluation. Eur J Pharm Biopharm. 2007; 67(1): 196-201.

4.      Baki G, Bajdik J, Pintye-Hodi K. Evaluation of Powder Mixtures and Hydrophilic Gastroretentive Drug Delivery Systems Containing Zinc Acetate and Sodium Bicarbonate. J Pharm Biomed Anal. 2011; 54(4): 711-6.

5.      Yao H, Xu L, Han F, Che X, Dong Y, Wei M, et al. A Novel Riboflavin Gastro-Mucoadhesive Delivery System Based on Ion-Exchange Fiber. Int J Pharm. 2008; 364(1): 21-6.

6.      Rajinikanth PS, Mishra B. Floating In Situ Gelling System for Stomach Site-Specific Delivery of Clarithromycin to Eradicate H. Pylori. J Cont Rel. 2008; 125(1): 33-41.

7.      Gisbert JP, Torrado S, M De La Torre P, Mcnicholl AG, Torrado S. Amoxicillin Gastric Retention Systems for Helicobacter pylori Treatment. Gastroenterology. 2011; 140(5 Suppl 1): S-880.

8.      Jang SW, Lee JW, Park SH, Kim JH, Yoo M, Na DH, et al. Gastroretentive Drug Delivery System of Da-6034, a new flavonoid derivative, for the Treatment of Gastritis. Int J Pharm. 2008; 356(1-2): 88-94.

9.      Guan J, Zhou L, Nie S, Yan T, Tang X, Pan W. A Novel Gastric-Resident Osmotic Pump Tablet: In Vitro and In Vivo Evaluation. Int J Pharm. 2010; 383(1-2): 30-6.

10.   Jimenez-Martinez I, Quirino-Barreda T, Villafuerte-Robles L. Sustained Delivery of Captopril from Floating Matrix Tablets. Int J Pharm. 2008; 362(1-2): 37-43.

11.   Kavimandan NJ, Lakshman JP, Matharu AS, Royce AE, Teelucksingh NR, Ogorka J. Extended Release Gastro-Retentive Oral Drug Delivery System for Valsartan. Ep2061438; 2009.

12.   Talukder R, Fassihi R. Gastroretentive Delivery Systems: A Mini Review. Drug Dev Ind Pharm. 2004; 30(10): 1019-28.

13.   Streubel A, Siepmann J, Bodmeier R. Drug Delivery to the Upper Small Intestine Window Using Gastroretentive Technologies. Curr Opin Pharmacol. 2006; 6(5): 501-8.

14.   Murphy CS, Pillay V, Choonara YE, Du Toit LC. Gastroretentive Drug Delivery Systems: Current Developments in Novel System Design and Evaluation. Curr Drug Deliv. 2009; 6(5): 451-60.

15.   Singh BN, Kim KH. Floating Drug Delivery Systems: An Approach to Oral Controlled Drug Delivery Via Gastric Retention. J Cont Rel. 2000; 63(3): 235-59.

16.   Yeole P.G. Floating Drug Delivery System: Need and Development. Ind. J.Pharm Sci. 2005;  67: 265-272.

17.   Shweta Arora. Floating Drug Delivery: A Review. AAPS Pharm Sci Tech. 2005; 47: 268-272.

18.   AV Mayavanshi, SS Gajjar. Floating drug delivery systems to increase gastric retention of drugs: A Review. Research J. Pharm. and Tech. 2008; 1(4): 345-348.

19.   S Vijaya Kumar, Manoj Kumar Deka, Manish Bagga, M Sasi Kala, Guru Sharan. A Systematic Review on Floating Drug Delivery System. Research J. Pharm. and Tech. 2011; 4(1): 19-25.

20.   Gutiérrez-Sánchez PE, Hernández-León A, Villafuerte-Robles L. Effect of Sodium Bicarbonate on the Properties of Metronidazole Floating Matrix Tablets. Drug Dev Ind Pharm. 2008; 34(2):171-80.

21.   Cedillo-Ramírez E, Villafuerte-Robles L, Hernández-León A. Effect of Added Pharmatose DCL11 on the Sustained-Release of Metronidazole from Methocel K4M and Carbopol 971P NF Floating Matrices. Drug Dev Ind Pharm. 2006; 32(8): 955-65.

22.   Lara-Hernández B, Hernández-León A, Villafuerte-Robles L. Effect of Stearic Acid on the Properties of Metronidazole/Methocel K4M Floating Matrices. Brazilian J Pharm Sci. 2009; 45: 497-505.

23.   Asnaashari S, Khoei NS, Zarrintan MH, Adibkia K, Javadzadeh Y. Preparation and Evaluation of Novel Metronidazole Sustained Release and Floating Matrix Tablets. Pharm Dev Technol. 2011; 16(4): 400-7.

24.   Murthy RSR. Biodegradable Polymers, Controlled and Novel Drug Delivery. 1st Ed. New Delhi: CBS Publishers; 1997. p. 27-51.

25.   Bechgaard H, Ladefoged K. Distribution of Pellets in the Gastrointestinal Tract. The Influence on Transit Time Exerted by the Density or Diameter of Pellets. J Pharm Pharmacol. 1978; 30: 690-2.

26.   Javadzadeh Y, Hamedeyazdan S, Adibkia K, Kiafar F, Zarrintan MH, Barzegar-Jalali M. Evaluation of Drug Release Kinetics and Physico-Chemical Characteristics of Metronidazole Floating Beads Based on Calcium Silicate and Gas-Forming Agents. Pharm Dev Technol. 2009; 15(4): 329-38.

27.   Eftaiha AF, Qinna N, Rashid IS, Al Remawi MM, Al Shami MR, Arafat TA, et al. Bioadhesive Controlled Metronidazole Release Matrix Based on Chitosan and Xanthan Gum. Mar Drugs. 2010; 8: 1716-30.

28.   Jagdale SC, Patil S, Kuchekar BS. Application of Design of Experiment for Floating Drug Delivery of Tapentadol Hydrochloride. Computational and Mathematical Methods in Medicine. 2013:1-7.

29.   Abdelbary A, El-Gazayerly ON, Nashwa A. El-Gendy NA, Ali AA. Floating Tablet of Trimetazidine Dihydrochloride: An Approach for Extended Release with Zero-Order Kinetics. AAPS Pharmscitech. 2010; 11(3): 1058-67.

30.   Garg R, Das Gupta G. Preparation and Evaluation of Gastroretentive Floating Tablets of Silymarin. Chem Pharm Bull. 2009; 57(6): 545-9.

31.   Jain GK. Gums and Mucilages: Versatile Excipients for Pharmaceutical Formulations Drug Delivery Systems. Asian J of Pharm Sci. 2009; 4: 309-23.

32.   Ganesh K, Archana D, Preeti K. Natural Polymers in the Development of Floating Drug Delivery Systems: A Review. J of Pharm and Life Sci. 2013; 2(4): 165-78.

33.   Marshall BJ. Unidentified Curved Bacilli in Gastric Epithelium in Active Chronic Gastritis. Lancet. 1983; 1: 1273-5.

34.   Marshall BJ, Warren JR. Unidentified Curved Bacilli in the Stomach of Patients with Gastritis and Peptic Ulceration. Lancet. 1984; 1: 1311-5.

35.   Narkar M, Sher P, Pawar A. Stomach-Specific Controlled Release Gellan Beads of Acid-Soluble Drug Prepared by Ionotropic Gelation Method. AAPS Pharmscitech. 2010; 11(1): 267-77.

36.   Shah S, Qaqish R, Patel V, Amiji M. Evaluation of the Factors Influencing Stomach-Specific Delivery of Antibacterial Agents for Helicobacter pylori Infection. J Pharm Pharmacol. 1999; 51: 667–72.

37.   Emara LH, Abdou AR, El-Ashmawy AA, Badr RM, Mursi NM. In Vitro Evaluation of Floating Matrix Tablets of Amoxicillin and Metronidazole for the Eradication of Helicobacter pylori. Int J Pharm Pharm Sci. 2012; 4(3): 671-81.

38.   Amiji MM. Tetracycline-Containing Chitosan Microspheres for Local Treatment of Helicobacter pylori Infection. Cellulose. 2007; 14: 3-14.

39.   Umamaheshwari RB, Suman R, Jain Nk. Anti-Helicobacter pylori Effect of Mucoadhesive Nanoparticle Bearing Amoxicillin in Experimental Gerbils. AAPS Pharmscitech. 2004; 5: 60-8.

40.   Sung JJ, Chung SC, Ling Tk. Antibacterial Treatment of Gastric Ulcers Associated with Helicobacter pylori. N Engl J Med. 1995; 332 (3):139-42.

41.   Dollery C. Therapeutic Drugs. 2nd Ed. Vol. 2, Edinburgh: Churchill Livingstone; 1999.

42.   Yang L, Eshraghi J, Fassihi R. A New Intragastric Delivery System for the Treatment of Helicobacter pylori Associated Gastric Ulcer: In Vitro Evaluation. J Cont Rel. 1999; 57(3): 215–22.

43.   Sriamornsak P, Asavapichayont P, Nunthanid J, Luangtana-Anan M, Limmatvapirat S, Piriyaprasarth S. Wax-Incorporated Emulsion Gel Beads of Calcium Pectinate for Intragastric Floating Drug Delivery. AAPS Pharmscitech. 2008; 9(2): 571-6.

44.   Sriamornsak P, Sungthongjeen S, Puttipipatkhachorn S. Use of Pectin as a Carrier for Intragastric Floating Drug Delivery: Carbonate Salt Contained Beads. Carbohydr Polym. 2007; 67(3): 436-45.

45.   Ishak Ra, Awad Ga, Mortada Nd, Nour Sa. Preparation, In Vitro and In Vivo Evaluation Of Stomach-Specific Metronidazole Loaded Alginate Beads As Local Anti-Helicobacter Pylori Therapy. J Cont Rel. 2007; 119(2): 207-14.

46.   Murata Y, Sasaki N, Miyamoto E, Kawashima S. Use of Floating Alginate Gel Beads for Stomach-Specific Drug Delivery. Eur J Pharm Biopharm. 2000; 50(2): 221-6.

47.   Jeong B, Kim SW, Bae YH. Thermosensitive Sol-Gel Reversible Hydrogels. Adv Drug Deliv Rev. 2002; 54: 37-51.

48.   Rupali Sanjay Joshi, Nilima S. Pawar, Sameer Sarvesh Katiyar, Amol Trimbak Shinde, Devendra Bhaskar Zope. Effective Quantitation of Metronidazole in Injectable Pharmaceutical Dosage Form Using UV Spectroscopy. Research J. Pharm. and Tech. 2012; 5(4): 494-496.

49.   Cooper J, Gunn C, Powder flow and compaction, In: Carter SJ, eds. Tutorial Pharmacy. New Delhi, India: CBS Publishers and Distributors; 1986; 211-233.

50.   Aulton M.E., Wells T.I., Pharmaceutics: The Science of Dosage Form Design, London, England: Churchill Livingstone; 1988.

51.   Remington, The Science and Practice of Pharmacy, 19th Ed., Vol. I, Pg: 1669-1670.

52.   Leon Lachman, Herbert A.Lieberman, Joseph L. Kanic, Theory and practice of industrial pharmacy. 3rd Ed. Mumbai: Varghese publishing house; 1991, Pg: 297-303.

53.   USP 30, NF 25, USP Convention, Rockville; 2007. Pg: 2648.

54.   Sandhya Chandrakar, Kushagra Nagori, Mukesh Sharma, Sujata Gupta, Harsha Solanki, Kalyani Dewangan, Garima Sharma, Vandana Devi Sahu, Manisha Majumdar, D. K. Tripathi, Amit Alexander, Ajazuddin. Formulation and Evaluation of Floating tablet of Metronidazole for eradication of Helicobacter pylori. Research J. Pharm. and Tech. 2016; 9(7): 870-874.

55.   Archana Kajale, B. V, Bakde, M. A. Channawar. Metronidazole Benzoate - A Drug for Colon Targated Drug Delivery. Research J. Pharm. and Tech. 2012; 5(7): 978-984.

56.   Ajazuddin, Tripti Banjare, Amit Alexander, Palak Agrawal, Akansha Bhandarkar, Aditi Bhatt, Swapnil Gupta, Hemlata Sahu, Shradha Devi Diwedi, Pankaj Sahu, Siddharth Kumar Sahu, Pooja Yadav, Kailash Sahu, Deeksha Dewangan, Hemlata Thapa, Deepika, Sonam Soni, Mukesh Sharma, D. K. Tripathi. Formulation and Evaluation of Colon Specific Matrix Tablet of Metronidazole. Research J. Pharm. and Tech. 2018; 11(5): 2040-2044.

57.   R. Sivakumar, V. Ganesan, Markand Viyas, N.N. Rajendran, M. Kommala. Metronidazole Encapsulation within Chitosan Coated Eudragit RL Microsphers for Site Specific Delivery. Research J. Pharm. and Tech. 2011; 4(6): 993-996.

58.   Rosa M, H. Zia, T. Rhodes. Dosing and testing in-vitro testing of a bioadhesive and floating drug delivery system for oral application, Int. J. Pharm, 1994; 105: 65-70.

59.   Suvakanta Dash, PadalaNarasimha Murthy, LilakantaNath and PrasantaChowdhury. Kinetic modeling on drug release from controlled drug delivery systems, ActaPoloniaePharmaceutica - Drug Research, 2010; 67(3): 217-223.

60.   Higuchi T. Mechanism of sustained action medication. Theoretical analysis of rate of release of solid drugs dispersed in solid matrices, J.Pharm. Sci.1963; 52: 1145-1149.

61.   Korsmeyer RW, Gurny R, Doelker E, Buri P and Peppas NA. Mechanisms of solute release from porous hydrophilic polymers, Int. J. Pharm., 1983; 15: 25-35.

62.   Gangadharappa H, Srirupa B, Anil G, Gupta V, Kumar P, Development, in vitro and in vivo evaluation of novel floating hollow microspheres of Rosiglitazone Maleate, Der Pharmacia Lettre, 2011; 3(4): 299-316.

63.   http://www.ich.org/fileadmin/Public_Web_Site/ABOUT_ICH/Organisation/SADC/Guideline_for_Stability_Studies.pdf

64.   Tabassum H. Aaraf, Hasumati A. Raj, Vineet C. Jain, Vishnu Sutariya. Development and Validation of Ratio derivative Spectrophotometric Method for Estimation of Metronidazole Benzoate and related Impurity in Bulk and Pharmaceutical Formulation. Asian J. Pharm. Tech. 2015; 5(2): 66-70.

65.   J.W. Skoug, M.V. Mikelsons, C.N. Vigneron, N.L. Stemm. Qualitative evaluation of the mechanism of release of matrix sustained release dosage forms by measurement of polymer release, J. Cont. Rel. 1993; 27: 227-245.

66.   L.S. Wan, P.W. Heng, L.F.Wong. Relationship between swelling and drug release in a hydrophilic matrix, Drug Dev. Ind., Pharm.1993; 19: 1201-1210.

67.   Masheer Ahmed Khan. Effect of Swelling and Drug Release Relationship of Sustained Release Matrices containing different Grades of Hydroxypropyl Methylcellulose. Research J. Pharma. Dosage Forms and Tech. 2013; 5(4): 232-236.

68.   Mughal MA, Iqbal Z, Neau SH. Guar Gum, Xanthan Gum, and HPMC can define release mechanisms and sustain release of Propranolol Hydrochloride, AAPS Pharm SciTech., 2011; 12(1): 77-87.

69.   G. Sridhar, S. Sivaneswari, N. Preethi, B. Mounika, G. Hemalatha, S. Vasudeva Murthy. Influence of natural gums as sustain release carriers on release kinetics of valsartan matrix tablets. Res. J. Pharm. Dosage Form. and Tech. 2014;  6(3): 188-193.

 

 

 

 

 

Received on 29.01.2019            Accepted on 28.02.2019           

© Asian Pharma Press All Right Reserved

Asian J. Pharm. Tech.  2019; 9(3):195-203.

DOI: 10.5958/2231-5713.2019.00033.3