Formulation and Development of Bilayer Tablet for Irritable Bowel Disease

1.1 Irritable Bowel Syndrome (IBS)

In the last two decades, Irritable Bowel Syndrome (IBS) has gained considerable attention in the health-care field due to its increasingly high prevalence, sometimes debilitating effects and diverse symptom representation. IBS is a chronic functional bowel disorder in which abdominal pain or discomfort is associated with defecation or change in bowel habits often in the absence of detectable structural abnormalities. Bloating, distension and disordered defecation are the commonly associated feature (World Gastroenterology Organization Global guideline, 2009). Usually conventional dosage form produce wide ranging fluctuation in drug concentration in the blood stream and tissues with consequent undesirable toxicity and poor efficiency. This factor such as repetitive dosing and unpredictable absorption led to the concept of controlled drug delivery systems. The goal in designing sustained or controlled delivery systems is to increase effectiveness of the drug by localization at the site of action and providing uniform drug delivery. Bi-layer tablet is suitable for sequential release of two drugs in combination (Shila V. D. et al, 2013). The first time establish diagnostic criteria to define IBS was made in the 1970s by Manning and colleagues. The Manning and colleagues compared symptoms in patients with abdominal pain who turned out either to have or not to have disease (Manning et al, 1978). Over the past 10 years considerably more attention has been paid to IBS, and the successive Rome working parties have elaborated more detailed, accurate, and useful definitions of the syndrome.

Manning criteria:

1. Pain relieved by defecation

2. More frequent stools at onset of pain

3. Looser stools at onset of pain

4. Visible abdominal distension

5. Passage of mucus per rectum

6. Sense of incomplete evacuation (Spiller R. et al, 2007)

1.2 Symptoms of Irritable Bowel Syndrome

• Symptoms vary and are often associated with food intake and, characteristically, with defecation
• Symptoms interfere with daily life and social functioning in many patients.
• Symptoms sometimes seem to develop as a consequence of an intestinal infection (postinfectious IBS) or to be precipitated by major life events, or occur during a period of considerable stress
• Symptoms may develop abdominal pain and cramping.
• A change in bowel habits, such as diarrhoea.

MATERIAL AND MATERIAL:

Preformulation Studies:

Determination of Melting Point

Take a capillary tube and seal one end by heating it. Fill the capillary tube with drug powder upto 2-3mm high. Put the capillary tube in Melting point apparatus and increase the temperature slowly. Note down the temperature when the drug starts melting and again note the temperature when the drug gets completely melted.

Determination of wavelength using UV spectrophotometric analysis:

50mg of Dicyclomine Hydrochloride was weighed and dissolved into 50ml of distilled water to prepare a 1000µg/ml stock solution from which a 10µg/ml dilution was prepared. Baseline correction was performed using distilled water and sample was run between 200-400nm wavelength range in spectrum mode. 50mg of Metronidazole was weighed and dissolved into 50ml of distilled water to prepare a 1000µg/ml stock solution from which a 10µg/ml dilution was prepared. Baseline correction was performed using distilled water and sample was run between 200-400nm wavelength range in spectrum mode by using Shimadzu 1800 UV visible spectrophotometer (Jethara S.I. et at, 2012).

Preparation of calibration curves:

The calibration curve of Dicyclomine Hydrochloride were prepared in distilled water and 6.8 pH phosphate buffer by using Shimadzu 1800 UV visible spectrophotometer. Accurately weighed 50mg of Dicyclomine Hydrochloride was transferred into a 50ml volumetric flask and the volume was made up with distilled water to obtain a 1000µ g/ml stock solution of Dicyclomine Hydrochloride. From the stock solution 1ml was taken and transferred into a 10ml volumetric flask and rest of the volume was made up with methanol to obtain a 100µg/ml of solution from which 1 to 10µg/ml dilutions were prepared. Same procedure was followed for distilled water, phosphate buffer 6.8 to prepare calibration curve respectively. The calibration curve of Metronidazole were prepared in distilled water and 1.8 pH phosphate buffer by using Shimadzu 1800 UV visible spectrophotometer. Accurately weighed 50mg of Metronidazole was transferred into a 50ml volumetric flask and the volume was made up with methanol to obtain a 1000µg/ml stock solution of Metronidazole. From the stock solution 1ml was taken and transferred into a 10ml volumetric flask and rest of the volume was made up with methanol to obtain a 100µg/ml of solution from which 1 to 10µg/ml dilutions were prepared. Same procedure was followed for distilled water, phosphate buffer 7.2 to prepare calibration curve respectively (Jethara S.I. et at, 2012).

Determination of solubility of Dicyclomine Hydrochloride in various medium:

The solubility of Dicyclomine Hydrochloride in various medium was determined by shake flask method. In this method 2ml of each solvent was taken into a vial and an excess amount of Dicyclomine Hydrochloride was added. The vials were sealed properly and stirred for 10min. They were then kept on orbital flask shaker at 37°C for 24h. After solubilization of Dicyclomine Hydrochloride, an extra amount of Dicyclomine Hydrochloride was added to the vials containing drug-solvent mixture. The process was repeated until saturation solubility of Dicyclomine Hydrochloride, indicated by presence of undissolved drug. The mixtures were then kept at room temperature for 24 h. and centrifuged using remi12c micro-centrifuge at 3000 rpm for 15min. The supernatant were separated and diluted with respective solvents. The drug concentration was analyzed spectrophotometrically at 247nm using UV-visible spectrophotometer (Shimadzu- 1800).

Determination of solubility of Metronidazole in various medium:

The solubility of Metronidazole in various medium was determined by shake flask method. In this method 2ml of each solvent was taken into a vial and an excess amount of Metronidazole was added. The vials were sealed properly and stirred for 10min. They were then kept on orbital flask shaker at 37°C for 24h. After solubilization of Metronidazole, an extra amount of Metronidazole was added to the vials containing drug-solvent mixture. The process was repeated until saturation solubility of Metronidazole, indicated by presence of undissolved drug. The mixtures were then kept at room temperature for 24 h. and centrifuged using Remi12C micro- centrifuge at 3000RPM for 15min. The supernatant were separated and diluted with respective solvents. The drug concentration was analyzed spectrophotometrically at 274 nm using UV- visible spectrophotometer (Shimadzu-1800) (Ryakala H. et al, 2015).

Drug-excipient compatibility study:

The compatibility of the drug was assessed by drug-excipient interaction study. The drug was mixed with various excipients in a 1:1 ratio in glass vials which were properly sealed and kept undisturbed at 40°C temperature for 14 days. After 14 days incompatibility was confirmed by TLC.

Selection of excipients:

• HPMC K4M, Eudragit RLPO and RSPO for combined release profile by combination of HPMC, RL and RSPO in different ratio for delivering a sustain release formulation of Dicyclomine with no interaction of drug and polymer it should be time independent release profile of the drug.

• Microcrystalline cellulose as diluents and bulking agent to increasing a bulk of drug.

• PVP-K30 as binder for make slurry of drug and Excipient to help a wet mass and granule formulation.

• Isopropyl alcohol as solvent for wetting.

• Magnesium stearate as a lubricant for lubrication.

• Talc as glidant.

Formulation and development:

Preparation of Metronidazole Immediate release layer by Direct Compression

• Weigh all Ingredients as per the quantities defined in table no. 6.3

• Pass all the ingredients through sieve #80 and collect individuals in polybags.

• Mix measured quantity of Metronidazole, sodium starch glycolate and PVP-K30 for 15 minutes in a polybag.

• Magnesium stearate and talc was added to it and blend for 5 min in pastle mortar.

• Compress final blend using B-Tooling, multiple rotatory compression machine using 8 mm round shaped punches and corresponding dies.

Table no. 6.3 Formula for Immediate release layer

Preparation   of   Dicyclomine   Hydrochloride   Sustained   release   layer   by   Wet Granulation

• Weigh all Ingredients as per the quantities defined in tablet no. 2.

• Pass all the ingredients through sieve no #80 and collect in separate polybags.

• Prepare binder solution by dissolving PVP-K30 in Isopropyl alcohol.

• Mix all material expect lubricant for 15 min.

• Add binder solution to the above step and mix until uniform dough mass granules are formed.

• Pass all granules through #12 no. sieve.

• Dry all the granules at 50-55?C temperature.

• Add Magnesium stearate and Talc and blend it for 5 Minute.

• Compress final blend using B-tooling, multiple rotatory compression machine using 8 mm round shape punches and corresponding dies.

Selection of polymers and suitable experimental design

The polymers, viz. HPMC K4M, Eudragit RLPO and Eudragit RSPO were selected owing to their releasing rate controlling ability, stability and compatibility with drug. Successful use of polymer is known to provide the formulation with sustained drug release property. A central composite design for two factor three level was selected to optimize the variable response. The two factors, viz. Sustained release Polymer X1 Eudragit RSPO and Binding agent Polymer X2 PVP-K30 of each polymer blend, were required by the experimental design and the factor level were suitably coded. The amount of Magnesium stearate was kept constant, while Isopropyl alcohol was taken in a sufficient quantity to maintain a constant tablet mass of 200mg. time taken to release 50% of drug were taken as the variable response.

Table no. 6.4 Sustained release layer formula optimization

Formulation optimization:

a. Variables: These are the measurement, values which are characteristics of data there are two type of variable Dependent variable independent variable, Independent variable are the variable which are not dependent any other value. Lubricant concentration, Polymer ratio, etc. Dependent variable dependent on the concentration of independent variable used.

b. Factor: Factor is assigned variable such as Ratio of polymer grade, Temperature, concentration, Lubricating agent polymer ratio. A quantitative factor has numerical value to it eg. Concentration (1%, 2%, 3%.) Drug polymer ratio (1:1) (1:2) (1:1:1 etc) Qualitative factors which are not numerical. Polymer grade, Humidity condition, type of equipment are discrete nature.

c. Levels: The level of a factor are the values of designation to the factor eg. Concentration 1 % one level while 2% with another level usually level are indicated as low or middle or high level. Normally for ease of calculation the numeric and discrete level low level and