INTRODUCTION:

The ideal object of drug delivery system points to the two aspects, most namely spatial placement and temporal delivery of drug. Spatial placement release to targeting of a drug to a specific organ or tissue, while temporal delivery refers to controlling the rate of drug delivery to the target tissue.¹ An approximately designed sustained release drug delivery system can be a major advance towards solving these two problems. It is for their reason that the science and technology responsible for development of Sustained Release pharmaceuticals have been and continue to be focus of a great deal of attention in both industrial and academic laboratories. The fact that coupled with the intrinsic inability of conventional dosage forms to achieve spatial placement is a compelling matter for investigation of Sustained Release drug delivery system³. A multiple units dose consists of many mini depots, pellets, mini tablets or microencapsulated crystals contained in a capsule or in a tablet.

These mini depots are dispersed and distributed throughout the gastrointestinal tract when the capsule or tablet disintegrates. A multiple units tablets may thus be divided at ingestion without loss of the depot effect, as the sub unit act as self-contained depots.Pellets are agglomerates of fine powders or granules of bulk drugs and excipients.

They consist of small, free-flowing, spherical or semi-spherical solid units, typically from about 0.5 mm to 1.5 mm, and are intended usually for oral administration¹¹. Implants of small, sterile cylinders formed by compression from medicated masses are also defined as pellets in pharmacy. Pellets can be prepared by many methods, the compaction and drug-layering techniques being the most widely used today.¹³A novel drug is a widely used as bicyclic antidepressant drug. As per Biopharmaceutical Classification class 1 drug it is highly soluble in water and highly permeable and it is necessary and challenging to control the drug release. Absolute bioavailability is 45%.Multi Unit Particulate System offers several advantages such as Improve GIT absorption, Minimize local irritation, Offers high degree of flexibility, Reduces dose dumping, Reduces inter and intra subject variability.

An antidepressant drug having half-life about 5-7 hrs, so it will more suitable in the controlled release dosage form. Extrusion and Spheronization technique is a novel manufacturing approaches that use innovative formulation and processing equipment. Hence, in this work, an attempt was made to formulate extended release multi unit particulate system for this novel antidepressant drug in order to achieve even drug dissolution profiles over 24 hrs.

MATERIALS AND METHODS:

API Procured by Cadila Health care ltd Ankleshwar Gujrat , Microcrystalline Cellulose (Avicel pH 101), Microcrystalline Cellulose (Avicel pH 102 Microcrystalline Cellulose (Avicel pH 200 Microcrystalline Cellulose (Avicel pH 301 Microcrystalline Cellulose (Ran Q pH 101 were procured by FMC Biopolymer (Signet), Mumbai, Hydroxy Propyl Methyl Cellulose 15 cps, Hydroxy Propyl Methyl Cellulose 6 cps Hydroxy Propyl Methyl Cellulose (Methocel K4M) were gifted by Shinetsu polymers (Colorcon),Mumbai, Eudragit NE 30 D, Eudragit RL 30 D, Eudragit RS 30 D were procured by Degussa, Bombay, Ethyl Cellulose 7 cps Colorcon Talc Luzenac Aerosil 200 Degussa, Mumbai, India

DRUG ESTIMATION:

Though drug is soluble in Distilled water and Methanol, hence both medium were used for calibration curve.

Calibration curve of drug in distilled water:

Ø Preparation of stock solution:

An accurately weighed 10 mg. Drug was dissolved and diluted to 100 ml with purified water to produce 100 μg/ml

Ø Preparation of sample solution:

Different dilution of stock solution with purified water were made to obtain solution having concentration 10,20,30,40,50 μg/ml. Absorbance was measured at 227 nm for this solutions against purified water as blank. Calibration curve of drug in distilled water has been shown fig -1. The concentration and absorbance data has been shown in table no.7. The calibration curve shows that the relation between concentration and absorbance is linear (R²=0.9996)

Figure No:-1 Calibration curve of drug in distilled water

Calibration curve of drug in methanol:

Ø Preparation of stock solution:

An accurately weighed 10 mg. Drug was dissolved and diluted to 100 ml with methanol to produce 100 μg/ml

Ø Preparation of sample solution:

Different dilution of stock solution with methanol was made to obtain solution-having concentration 10,20,30,40,50 μg/ml. Absorbance was measured at 227 nm for these solutions against methanol as blank.

Calibration curve of drug in methanol has been shown below. The concentration and absorbance data has been shown in table. It can be seen from calibration curve of the drug that the relation between concentration and absorbance is linear (R²=0.9973)

Figure No:-2Calibration curve of DRUG in methanol at 229.5 nm

PREFORMULATION STUDY:

Preformulation studies are the first step in the rational development of dosage form of a drug substance. The objective of pre formulation studies are to develop a portfolio of information about the drug substance, so that this information useful to develop formulation. Preformulation can be defined as investigation of physical and chemical properties of drug substance alone and when combined with excipients.

Preformulation investigations are designed to identify those physicochemical properties and excipients that may influence the formulation design, method of manufacture, and pharmacokinetic-biopharmaceutical properties of the resulting product. Followings are the tests carried out for the preformulation study.

Organoleptic Characteristics:⁶

The color, odor, and taste of the drug were characterized and recorded using descriptive terminology.

Properties	Results
Description	Crystalline
Taste	Highly bitter
Odor	Bitter
Color	White

Table No : 1

Solubility of drug:^6,7

Drug is BCS Class –I drug. It is very highly soluble in water, also soluble in methanol, and 0.1N HCL. It’s solubility in water is about 572 mg/ml.

Sieve Analysis:^7,8

Standard sieves of different meshes were available as per the specifications of USP; sieves were arranged in a nest with courses at the top. A sample of the 40 # passed powder is placed on top sieve. This sieve set was fixed to the mechanical shaker apparatus and shaken for a certain period of times. The powder retain on each sieve was weighed and percentage of powder retained on each sieve was calculated using the initial weight taken.

Bulk Density :^7,8

An accurately weighed quantity of powder, which was previously passed through sieve # 40 [USP] and carefully poured into graduated cylinder. Then after pouring the powder into the graduated cylinder the powder bed was made uniform without disturbing. Then the volume was measured directly from the graduation marks on the cylinder as ml. The volume measure was called as the bulk volume and the bulk density is calculated by following formula;

Bulk density = Weight of powder / Bulk volume

Tapped Density^7,8

After measuring the bulk volume the same measuring cylinder was set into tap density apparatus. The tap density apparatus was set to 300 taps drop per minute and operated for 500 taps. Volume was noted as (Va) and again tapped for 750 times and volume was noted as (Vb). If the difference between Va and Vb not greater than 2% then Vb is consider as final tapped volume. The tapped density is calculated by the following formula

Tapped density = Weight of powder / Tapped volume

Carr’s Index [Compressibility Index] ⁷

It is one of the most important parameter to characterize the nature of powders and granules. It can be calculated from the following equation-

Carr’s index = Tapped density - Bulk density / Tapped density X 100

Haussner’s Ratio⁸

Haussner’s ratio is an important character to determine the flow property of powder and granules. This can be calculation by the following formula-

Value < 1.25 indicate good flow (=20% Carr)

While > 1.50 indicate poor flow (=35% carr)

Between 1.25 and 1.5, adding Glidant will improve flow. The index of carr is a one point determination and does not reflect the ease or speed with which consolidation occur. Indeed some materials have high index suggesting poor flow but may consolidate rapidly, which is essential for uniform filling on tablet machines when the power flows at nearly equal to bulk density in to the die and consolidates to approaching tapped density prior to compression.

Table No :-2 Result of Preformulation Parameters

Parameter	Results
Parameter	API	MCC (Avicel pH 101)	HPMC (15cps)	TALC	AEROSIL
Loss on Drying (%w/w)	0.3%	5.0%	5-7%	6.5%	2.5%
Bulk Density (gm/cm³)	0.211	0.32%	0.341%	0.277%	0.035%
Tapped Density (gm/cm³)	0.300	0.45%	0.557%	0.534%	0.05%
Compressibility Index	29.41%	28.88%	38.77%	48.12%	30%
Haussner’s Ratio	1.417	1.40	1.63	1.92	1.42
Particle size	57.41µm	20-200µm	10-300µm	44-74µm	7-16nm

FORMULATON OF PELLETS OF ANTIDEPRESSANT DRUG:

Preparation of drug containing pellets:^11,12

Extended release pellets of drug were prepared by wet granulation technique using Microcrystalline Cellulose pH 101 was passed through the 30# sieve and dry blended in rapid mixer granulator till uniform mixing obtained. Hydroxypropyl methylcellulose was passed through 30# sieve and dissolved in a sufficient quantity of purified water using continuous stirring with mechanical stirrer, till thick transparent paste was obtained. Now dry blend was granulated using previously made solution and add extra water if necessary. The prepared wet mass was transfer in to extruder of 1 mm screened sized die. Start extruder at 50 rpm and collect road shape pellets.Now above extruded product was transfer in to sheronizer and start it on 800 rpm, continuously observed it and collects it after perfect round shape was obtained. It would be Approximately in 10 min.These pellets were added in to mechanical sifter for the size separation through 12-24# sieve.Sprinkle extra talc for reducing clumping formation or reduce the static charges between pellets.

Preparation of Coating Solution:

First of all, Talc and Aerosil was sifted through 40# sieve. Mixed both excipients and homogenize using water in homogenizer till very fine particles in solution were obtained, and collect it from homogenizer and mixed with Eudragit NE 30D polymer using mechanical stirrer for the continuous stirring, which help to prevent settlement of talc at the bottom of the mixing tank, solution was sifted through the 100# sieve, and used for the coating on the previously prepared pellets.

Polymer coating on drug containing pellets:

Transfer the previously prepared drug pellets into a Fluidised Bed Coater and set the parameters as per mentioned below, and coating was started to achieve build up in pellet weight.

Curing on the pellets:

At 60ºC for 2 hrs curing was done on the pellets after polymer coating.

Capsule filling:^17,18

Capsule filling was done by laboratory scale capsule filling machine or by manual method.

Table no: - 3 Composition of formulation of optimization for core pellets :

Ingredients	Batch No.
Ingredients	F1	F2	F3	F4	F5	F6	F7	F8	F9
API	60	40	45	30	30	60	50	45	40
Methocel K4M		0.6
HPMC 15 cps			0.3	0.8	0.5	0.3	0.35	0.4	0.45
RanQ pH 101		59.4
Avicel pH 101	40						49.65	54.6	59.55
Avicel pH 102			54.7	69.2
Avicel pH 301					69.5
Avicel pH 200						39.7
P. Water	q.s.	q.s	q.s	q.s	q.s	q.s	q.s.	q.s	q.s.

** Quantities of excipients were taken in %.

According to this results, it may be concluded that Avicel pH101 is the most suitable MCC grade, hence pellets prepared using F9 formula was in perfect round pellets. Hence all the trials were taken on the basis of formula F9.

Total weight of pellets was 432.258mg.

Table No :-4 Composition of Formulation of For Optimization Extended Drug Release From Pellets :

Ingredients	FORMULATIONS
Ingredients	F9A	F9B	F9C	F9D	F9E	F9F	F9G	F9H	F9I
Ethyl cellulose 7 cps	2.5%	5.0%	------	------	------	------	------	------	------
Hypromellose 6 cps	2.5%	----	5.0%	------	------	------	------	------	------
Eudragit RL30D	-----	----	------	5.0%	------	------	------	------	------
Eudragit RS30D	----	----	------	------	10.0%	------	------	------	------
Eudragit NE30D^**	----	----	------	------	----	5.0%	8.0%	15.0%	13.0%

**Talc and Aerosil were added in the coating solution with the polymer dispersion. Weights of coated pellets are 488.45 mg.

OPTIMIZATION OF FORMULATION:

Ø sELECTION OF EXCIPIENTS:

· Choice of Excipients:

MCC was mostly used in the pelletization formulations. Avicel pH 101 having very good properties for obtaining round shape pellets than the other grades of avicel.

HPMC was taken since it is soluble in water and makes clear solution in water, and also having good polymeric properties.

Eudragit NE 30D was taken because it gives pH independent drug release profile. Wyeth Pharma Ltd patented ethyl cellulose coating on the pellets.

Aerosil and Talc are best antisticking agent in the pellets, and extra talc was sprinkled on the pellets at the time of coating to reduce static charge of pellets.

· Proportion of Excipients :

Quantity of drug and MCC was decided on basis of that if drug was taken 60% and MCC was 40% then pellets having rod shape and dumbelled shape.

Quantity of binder was decided on basis that if binder was taken in higher proportion then, pellets would be taken more time for getting round shape, and it may be affected on the invitro drug dissolution study.

Quantity of Eudragit NE 30D was decided as per required coating on the pellets to get extended release property as per market preparation.

Quantity of Talc was decided as per reducing static charge between pellets.

Ø factorS affecting PROCESS:

· wet granulation method:

Addition of water is very critical step in the formulation since if water is in higher amount then bigger sized pellets obtained rather then the required.

Table No :- 5 Process Parameters for RMG:

PROCESS	IMPELLER	CHOPPER	TIME
Dry Blending of API and MCC	Fast speed	----------	10 min.
Addition of binder solution	Fast speed	Slow speed	2-4 min.
Addition of water	Fast speed	Fast speed	1 min.

· Extrusion and Spheronization technique:

In Screw extruder, small size of pellets was obtained than the roller extruder.

At the slow speed of sheronizer long shaped pellets were obtained, whereas at very high-speed fines would be produced.

· Coating of core pellets:

The process parameters should be as per following to achieve a suitable pellets.

Table No :-6 Process Parameters for Fluidized Bed Coater:

PROCESS PARAMETERS	OBSERVATION
Inlet air temperature	30°C-40°C
Bed Temperature	25°C-30°C
Atomization air pressure	2-4 kg/cm²
Peristaltic pump speed	10-60 RPM

· Curing of the pellets:

Because of aqueous coating on the pellets curing was necessary for established

film of the polymer. If curing time is more it effects the drug release due to more established film of the Eudragit NE 30D.

RESULT AND DISCUSSION:

EVALUATION OF PELLETS:

Prepared pellets of F9I were evaluated by the following methods.

Table No :- 7

SR. NO.	PARAMETERS	OBSERVATION
1	Color	White to off-white
2	Appearance	Shined pellets
2	Flow	Free flowing
3	Shape	Round

Density:

The density of pellets can be affected by changes in the formulation and/or process, which may affects other process or factors, such as capsule filling, coating, and mixing.

The density of the pellets can measure by USP-I auto tapered density apparatus. On the basis of tapped density capsule size would be calculated for the capsule filling of the desired quantity. After testing density, following result was obtained and it indicate pellets were suitable to “0” size capsule shell.

Table No :- 8

SR. NO.	PARAMETERS	RESULT
1	Bulk Density	0.769gm/ml
2	Tapped Density	0.816gm/ml

PARTICLE SIZE ANALYSIS:

Particle size analysis was done by the Sieve analysis by USP sieve shaker. Pellets were passed from the 12# and retained from the 24# sieve.

By the particle size analysis uniform pellets were obtained which were useful for the capsule filling.

ASPECT RATIO:¹⁶

Aspect ratio was done for the pellet’s spherocity, for the flow property.

Hot stage microscope was used for the measurement of the height and width of the pellets. Aspect ratio was calculated from following formula:

Length of pellets

Aspect ratio = ----------------------

Width of pellets

Table No :- 9 OBSERVATION OF ASPECT RATIO

Sr.No.	Length (mm)	Width (mm)	Aspect ratio
1	1422.0	1369.0	1.038
2	1260.8	1212.3	1.040
3	1188	1103.2	1.076
4	1104.1	1077.8	1.024
5	1238.8	1169.5	1.059

Aspect ratio should be very near to 1 for the best spherical shape. Aspect ration of F9I was found to be 1.047, it indicates that pellets have good spherecity and flow property

Figure No:-3Aspect ratio of pellet-I

Figure-4Aspect ratio of pellet-II

ASSAY:^24,.25

Assay of drug was carried out by the HPLC method by the following formula.

v Buffer solution: Dissolve 1.74 gm of dipotasium hydrogen phosphate in 1000 ml of water. Adjust pH to 7.0 with 10% orthophosphoric acid.

v Mobile Phase: Prepare a filtered and degassed, mixture of above solution and acetonitrile in 35:65 ratio.

v Diluent : Use mobile phase as a diluent.

v Solution Preparation :

1) Standard preparation: Transfer accurately weighed quantity of about 56 mg of drug in about 25 ml of diluent and sonicate to dissolve. Make up volume up to the mark with diluent and mix. Dilute 5.0 ml of this solution to 50.0 ml with diluent and mix.

2) Sample preparation: Transfer accurately weighed quantity equivalent to 100 mg of drug to a 200 ml of volumetric flask. Add about 150 ml of diluent and sonicate with occasional shaking for about 45 minutes. Make volume up to the mark with diluent and mix. Dilute 5.0 ml 0f this solution to 25 ml with diluent and mix. Filter the solution through 0.45 µm Millipore PVDF filter, collect the filtrate by discarding first few ml of the filtrate.

v Chromatographic System:

Column : Inersil ODS 3V, (25 cm X 4.6 mm),5µm

Detector : 227nm

Flow rate : 1.0 ml/minute

Injection volume : 10 µl

Column temperature: 45ºC

v System suitability: Chromatograph the standard preparation and record the peak responses as directed-under procedure. The column efficiency for analyte peak is not less than 2000 theoretical plates. The tailing factor for analyte peak in not more than 2.0. The relative standard deviation for five replicate standard injections is not more than 2.0%.

v Procedure: Separately inject mobile phase, standard preparation and sample preparation into the chromatograph. Run the chromatogram and measure the responses for the analyte peak. Follow the injection sequences as mentioned below.

Table No :- 10

SR. NO.	SAMPLE	NO. OF INJECTIONS
1	Mobile phase	1
2	Standard preparation	5
3	Sample preparation	1

Calculate quantity in mg of drug per net content of pellet by using following formula.

ATi WS 5 200 P 277.40

Drug Content = ------ × ----- × ------ × ------× -----×--------- × NT

AS 50 50 WTi 100 313.87

Where,

ATi = Peak area of sample injection of the respective strength

AS = Peak are of standard injection

WS = Weight of working standard taken in mg

WTi = Weight of sample taken in mg (i = 1and2)

P = Percentage purity of working standard (on as is basis)

277.40 = Molecular weight of Drug

313.87 = Molecular weight of drug with salt

NT- Net content for respective strength

Drug content (practically)

Assay = ----------------------------------------- × 100

Drug content (Theoretically)]

RESULT:

v FOR UNCOATED PELLETS:

Pellets were tested by above mentioned method for the drug content in pellets, the assay found to be 99.83% in the F9 formulation.

v FOR COATED PELLETS:

Pellets were tested by above mentioned method for the drug content in pellets, the assay found to be 99.83% in the F9I formulation.

SCANNING ELECTRON MICROSCOPY:²⁷

These studies were done for the pellet’s shape and surface study. Figure No. 38-41 found the shape and surface of the pellets prepared by different grades of the Microcrystalline Cellulose were in desired qualities.

(A) Figure No:-5 AVICEL pH 101

(B) Figure No:-6AVICEL pH 102

(C) Figure No:-7 AVICEL pH 301

(D) Figure No:-8 AVICEL pH 200

IN-VITRO DRUG DISSOLUTION PROFILE:

In-vitro drug dissolution study was performed for the % drug release of the API from the formulation at the regular time interval. Following are the major parameters for the In-vitro dissolution study for the pellets.

MEDIUM : Water; 900 ml

APPARATUS : USP-I (Basket)

RPM : 100

TIME INTERVAL :1,2,3,4,5,6,8,10,12,16,20,24 hrs.

TEMPERATURE : 37ºC ± 0.5ºC

1) Standard preparation: Transfer an accurately weighed quantity of about 45 mg of drug working standard into a 100 ml volumetric flask. Add about 50 ml of dissolution medium and sonicate to dissolve. Make volume up to the mark with dissolution medium and mix. Dilute 5.0 ml of this solution to 10.0 ml with dissolution medium and mix.

2) Sample preparation: Set the dissolution parameters of the instruments as mentioned above. Place 150 mg equivalent drug into the basket. Now take 3 ml of the solution at the above mentioned time interval and dilute it with 25.0 ml of water and mix. Filter the solution through 0.45 µm Millipore PVDF filter; collect the filtrate by discarding first few ml of the filtrate.

Now, check the absorbance of the solution at 227 nm using water as a blank.

AT WS 5 DT P 277.4

% drug release = ------ × ------- × ------ × ------- × ------- ×--------- × 100

AS 100 100 LC 100 313.87

Where,

AT = Absorbance of sample

AS = Absorbance of standard

DT = Dilution of sample preparation

WS = Weight of working standard in mg

LC = Label claim

277.4 = Molecular weight of API

313.87 = Molecular weight of API with salt

P = Percentage purity of working standard

Figure No:-9 Graphical presentation of %Drug dissolution versus Time (hrs.) :

EVALUATION OF CAPSULE:

DESCRIPTION:

White to off-white pellets filled in size “0” hard gelatin capsules with dark orange colored cap printed with “ZA-37” in black ink and white body printed with “150 mg” in black ink. The capsule should be free of all physical defects.

Filled weight in the capsule shell was 488.45 mg.

ASSAY:²⁷

Assay of drug was carried out by the HPLC method by the following formula.

v Buffer solution: Dissolve 1.74 gm of dipotasium hydrogen phosphate in 1000 ml of water. Adjust pH to 7.0 with 10% orthophosphoric acid.

v Mobile Phase: Prepare a filtered and degassed, mixture of above solution and acetonitrile in 35:65 ratios.

v Diluent: Use mobile phase as a diluent.

v Solution Preparation:

2) Sample preparation: Remove as completely as possible content of not fewer than 20 capsules, accurately counted and weighed and mix the content. Calculate the net content. Transfer accurately weighed quantity of capsule content equivalent to 100 mg of drug to a 200 ml of volumetric flask. Add about 150 ml of diluent and sonicate with occasional shaking for about 45 minutes. Make volume up to the mark with diluent and mix. Dilute 5.0 ml 0f this solution to 25 ml with diluent and mix. Filter the solution through 0.45 µm Millipore PVDF filter, collect the filtrate by discarding first few ml of the filtrate.

v Chromatographic System:

Column : Inersil ODS 3V, (25 cm X 4.6 mm), 5µm

Detector : 227nm

Flow rate : 1.0 ml/minute

Injection volume : 10 µl

Column temperature: 45ºC

Table No :- 11

SR. NO.	SAMPLE	NO. OF INJECTIONS
1	Mobile phase	1
2	Standard preparation	5
3	Sample preparation	1

Calculate quantity in mg of drug per average net content of capsule by using following formula.

ATi WS 5 200 P 277.40

Drug (mg/cap) = ------ × ----- × ------ × ------× -----×--------- × NT

AS 50 50 WTi 100 313.87

Where,

ATi = Peak area of sample injection of the respective strength

AS = Peak are of standard injection

WS = Weight of working standard taken in mg

WTi = Weight of sample taken in mg (i = 1and2)

P = Percentage purity of working standard (on as is basis)

277.40 = Molecular weight of Drug

313.87 = Molecular weight of drug with salt

Drug content (practically)

Assay = -- ---------------------------------- × 100

Drug content (Theoretically)

RESULT : Capsules were tested by above method for the drug content in capsules, which were shown 99.83% in the final formulation.

CONTENT UNIFORMITY:

1) Standard preparation: Transfer an accurately weighed quantity of about 51 mg of drug working standard to a 100 ml volumetric flask. Add about 50 ml of water and sonicate to dissolve. Make volume up to the mark with water and mix. Dilute 5.0 ml of this solution to 100.0 ml of water and mix.

2) Sample preparation: Weigh and transfer the content of one capsule in to 200 ml volumetric flask, add about 100 ml of water and sonicate with occasional shaking for about 30 minutes. Filter the solution through 0.45-µm filters; collect the filtrate by discarding first few ml of the filtrate.

3) Procedure: Measure the absorbance of standard and sample preparation in 1 cm cell on suitable spectrophotometer at 227 nm, using water as a blank.

Calculate the quantity in percentage of API using the following formula.

AT WS 5 DT P 277.4

%Drug release = ------ × ------- × ------ × ------- × ------- ×--------- × 100

AS 100 100 LC 100 313.87

Where,

AT = Difference in the absorbance of sample and empty capsule shell preparation

AS = Absorbance of standard

DT = Dilution of sample preparation

WS = Weight of working standard in mg

LC = Label claim

277.4 = Molecular weight of API

313.87 = Molecular weight of API with salt

P = Percentage purity of working standard

Table No:-12 OBSERVATION OF DRUG CONTENT UNIFORMITY

SR. NO.	% ASSAY
1	98.4
2	97.1
3	99.5
4	98.7
5	96.4
6	100.1
7	100.0
8	99.1
9	98.2
10	101.3
Maximum	101.3
Minimum	96.4
Average	98.88
%RSD	1.47

RESULT:

From the above result, it found that RSD in F9I was found 1.47% (NMT 5.0%), it indicates that the drug was uniformly distributed in capsules.

IN-VITRO DRUG DISSOLUTION PROFILE:³⁰

MEDIUM : Water; 900 ml

APPARATUS : USP-I (Basket)

RPM : 100

TIME INTERVAL :1,2,3,4,5,6,8,10,12,16,20,24 hrs.

TEMPERATURE : 37ºC ± 0.5ºC

1) Empty capsule shell preparation: Remove the content of not less than six capsules and cleaned it properly. Dissolve six capsule shells in a 900 ml of dissolution medium. Dilute 3.0 ml of this solution to 25.0 ml with dissolution medium and filter the solution through 0.45 µm Millipore PVDF filter, collect the filtrate by discarding first few ml of the filtrate.

2) Standard preparation: Transfer an accurately weighed quantity of about 45 mg of drug working standard into a 100 ml volumetric flask. Add about 50 ml of dissolution medium and sonicate to dissolve. Make volume up to the mark with dissolution medium and mix. Dilute 5.0 ml of this solution to 10.0 ml with dissolution medium and mix.

3) Sample preparation: Set the dissolution parameters of the instruments as mentioned above. Place 150 mg equivalent drug into the basket. Now take 3 ml of the solution at the above mentioned time interval and dilute it with 25.0 ml of water and mix. Filter the solution through 0.45 µm Millipore PVDF filter, collect the filtrate by discarding first few ml of the filtrate.

Now, check the absorbance of the solution at 227 nm using water as a blank.

AT WS 5 DT P 277.4

% drug release = ------ × ------- × ------ × ------- × ------- ×--------- × 100

AS 100 100 LC 100 313.87

Where,

AT = Difference in the absorbance of sample and empty capsule shell preparation

AS = Absorbance of standard

DT = Dilution of sample preparation

WS = Weight of working standard in mg

LC = Label claim

277.4 = Molecular weight of API

313.87 = Molecular weight of API with salt

P = Percentage purity of working standard

**Above results was average of the 6 samples.

Figure No:-10 Graphical presentation of %Drug dissolution versus Time (hrs.)

Figure No:-11 Graphical presentation of %Drug dissolution versus Time (hrs.)

KINETIC RELEASE STUDY MECHANISM OF DRUG RELEASE:^36,37

Several mathematical methods can be used to describe the kinetic behavior of the drug release mechanism from reservoir capsules, the most suitable being the one that best fits the experimental results. The choice of a specific model for a particular data set depends on the shape of the plot obtained, as well as on the understanding mechanism.

The kinetics of drug release from hydrophobic – hydrophilic barrier capsules was determined by finding the best fitting of the dissolution data (amount of drug released Vs time) to distinct models; zero-order (a), first-order (b) and Higuchi model (c).

Q_t = Q_o + k_ot ----(a)

Where, Q_t is the amount of drug released at time t, Q_o is the amount of drug in the solution at t = 0 (usually Q_o= 0), and k_o is the zero-order release constant.

Q_{t =}Q_∞ (1- e^-k₁^t) ----(b)

Where, Q_∞being the total amount of drug in the matrix and k₁is the first-order kinetic constant.

Q_{t =}k_Ht^1/2 ----(c)

k_H,representing the Higuchi rate constant.

Moreover, to better characterize the drug release behavior for the polymeric systems under study, and particularly to gain some insight on the corresponding mechanism the korsmeyer-peppas (d) semi-empirical model was applied.

Q_t / Q_{∞ =}ktⁿ ----(d)

Where, Q_t / Q_{∞ is} the fraction of drug released at time t, k is a constant comprising the structural and geometric characteristics of the capsule, and n is the release exponent, is a parameter that depends on and is used to characterize the release mechanism. For the case of capsules, in particular, 0.5<n<1.0 to anomalous (non-fickian) transport, n>1.0 to a super case II transport.

DRUG RELEASE MODELS:

First order release equation:

ln (100-Q) = lnQ₀-k

Where, Q is the amount of drug release at time t

K₁first order release constant

The regression coefficient (R²) value obtained from the log %ARR (Amount Remaining to Release) versus time, nearer to 1 indicating first order release.

Zero order release:

Q = K₀t

Where, Q is the amount of drug release at time t

K₀ is the Zero order release constant t is the time

Regression value of plot of amount of drug release versus time t gives the idea of release mechanism.

R²value nearer to 1 indicating zero order release.

Higuchi square root of time equation:

Q = K_Ht^1/2

Where, Q is the amount of drug release at time t

K_H is the Higuchi square root of time release constant

The regression coefficient of the percentage drug release versus square root of time, closer to 1 indicating anomalous release.

Table no:-13 COMPARISION OF FORMULATION WITH MARKETED PREPARATION:

Wyeth Pharmaceutical LTD., are innovator of this formulation.

Formulation	DRUG RELEASE MODELS
Formulation	First order	Baker & Lonsdale	Hixson & Crowell’s	Zero order	Higuchi
F9A	0.7987	0.8219	-0.7323	0.9374	0.9720
F9B	0.7875	0.8154	-0.7040	0.9301	0.9710
F9C	0.7619	0.8051	-0.7039	0.9143	0.9579
F9D	0.8261	0.9537	-0.7183	0.9466	0.9715
F9E	0.8500	0.9359	-0.8058	0.9564	0.9648
F9F	0.8661	0.9757	-0.7894	0.9723	0.9914
F9G	0.8688	0.9799	-0.7869	0.9829	0.9913
F9H	0.8971	0.9938	-0.7926	0.9813	0.9924
F9I	0.9045	0.9976	-0.8005	0.9872	0.9982

From above result it may be concluded that final formulation follows Higuchi’s square root model.

DISCUSSION:

v Discussion of Analytical Method:

Analytical method suitable to determine the contents of drug was developed and validated according to the ICH guidelines. Drug shows the absorption maxima at 227nm in purified water and at 229.5nm in methanol.

v Discussion of preformulation study:

In the preformulation study drug and excipients were characterized for bulk and tapped density. Results of the computed compressibility index and Hauser’s ratio show that the all material has sufficient compressibility and flow properties. Compatibility of the excipients used in the formulation with API was done by mixing them in determine ration and kept at 60°c for 2 week and 40°C/75%RH for one month. The samples were evaluated by physical observation and DSC for initial sample. Results of the compatibility study relives that the drug was compatible with the all excipients used in the formulation.

v Discussion of the experimental design:

ER pellets was formulated using API and MCC in 40:60 ratio. The core pellet-containing drug, which prepared by wet granulation technique. The aqueous coating was done by fluidized bed coating Eudragit NE 30D. The prepared pellet was evaluated for physical parameter, Assay, aspect ratio, density and in vitro drug release.

v Evaluation of Capsules

In the evaluation of the capsules pellets were filled in “0” size white orange colored hard gelatin capsule shell printed with 150 mg which is dose strength. Assay was done by HPLC method which given 99.83% in final formulation. Related substances was determined, which shows there was not any unknown impurities in the capsule, only known impurities was seen in the capsules. Content uniformity test was shown 1.47% RSD which was acceptable. In vitro drug dissolution studies was done and it was very near to innovator sample.

SUMMARY AND CONCLUSION:

Drug is an anti-depressant drug. It is under goes extensive first pass metabolism resulting in an oral bioavailability of 45 % and it shows variable absorption from GIT. MUPS oral drug delivery system offers several advantages such as rapid absorption, reducing peak plasma fluctuation and ease of administration and termination of therapy. Hence in the present work pellets of drug were prepared with the objective of avoiding first pass metabolism and controlling the release of drug for prolog period of time. In the present work, the drug containing pellets were prepared by wet granulation technique, coating with Eudragit NE 30 D and then filled in hard gelatin capsule shell. The Extended released pellets containing drug was prepared using an extrusion-spheronization technique. Amount of Microcrystalline cellulose (Avicel pH101), Hypromellose 15 cps and Eudragit NE 30D were taken as the formulation variables for optimizing to keep round shape of pellets and percentage release of drug. The pellets were evaluated for Physical characterization, Assay, Sizing, Aspect ratio, density, SEM, In-vitro drug release and Binder’s concentration tends to very effective pellets shape and size. Percentage release of drug tended to very non-linear with polymer type and percentage of coating on the pellets. The formulation with 0.45% HPMC, 65.94% MCC and 13% Eudragit NE 30D coating was consider as a best product with respect to perfect size and shaped pellets and In-vitro drug release study. Multiunit particulate drug delivery system gives unique release pattern, which was seen in F9I formula. This product was further subjected to stability study, the results of which indicated no significant change with respect to Shape, color, surface and in vitro drug release.

ACKNOWLEDGEMENT:

Authors are thankful to Prof.(Dr.) B. Jayakar, Pprincipal Vinayaka Missions College of Pharmacy, Salem, Tamilnadu and Cadila Healthcare ltd. Gujarat providing all the facilities for this research Project.

REFERENCE:

1) Joseph R Robinson; Sustained and controlled release drug delivery ; Marcel Dekker, New York; 1987; 72-76.

2) Remington; the Science and practice of pharmacy; Lippincott williams and wilkins 20^th edition; 2002; 903-914.

3) Gwen M Jantzen; Joseph R Robinson; Sustained, controlled and targeted Drug Delivery; Marcel dekker, 2^nd edition; 1989; 29-32.

4) Robert S Langer; Donald L wise; Medical Applications of Controlled Release (1) ; 1984; 42.

5) Ashoka V Bhosle; Rahul V Tukawalw and sanjay D Sawant; Oral Novel DrugDelivery System; The Eastern Pharmacist; 2002;41-43.

6) Raymond C. Rowe, Pual J Sheskey, Paul J Weller, “Handbook of Pharmaceutical Excipients”, 4^th edition, American Pharmaceutical association, pp. 108,297,462,161,64

7) M E Aulton; “Pharmceutics” The Science of dosage form design; Churchill livingstone; 2^nd edition; 2002; 414-418.

8) Joshep R Robinson; Vincet H Lee; Controlled drug delivery; 1987; Marcel dekker, 2^nd edition; 376-391.

9) Herbert A. Liberman and Leon Lachman, “The Theory and Practice of IndustrialPharmacy”, III^rd Edition, Verghese Publication House,171,293.

10) R K Verma; D M Krishna; S Garg; Formualtion aspects in the development of osmotically controlled oral drug delivery systems; J controlled release; 2002(79); 7-27.

11) Asa Tunon; Preparation of tablet from reservoir compression behaviour and drug release, Uppasala University, 2003, 15-16

12) R C Heading; J Nimmo; L F Prescott and P, Tothill; By J Pharmaceutics.; 1973;47;415.

13) Gajdos, B., Rotary granulators - Evaluation of process technology for pellet production using factorial design. Drugs Made Ger. 27, 30-36,1984.

14) Cox, P.H. and Spanjers, F.The preparation of sterile implants by compression.Pharm. Weekblad 105, 1970, 681-684.

15) Ghebre-Sellassie, I., Pellets: A general overview. In Ghebre-Sellassie, I (ed.), Pharmaceutical Pelletization Technology. Marcel Dekker, Inc., New York, USA, Vol. 37, 1989, pp. 1-13.

16) Ghebre-Sellassie, I., Gordon, R., Fawzi, M.B. and Nesbitt, R.U., Evaluation of ahigh-speed pelletization process and equipment. Drug Dev. Ind. Pharm. 11, 1985, 1523-1541

17) Peh, K.-K. and Yuen K-H., Development and in vitro evaluation of a novel

18) Multiparticulate matrix controlled release formulation of theophylline. Drug Dev. Ind.Pharm. 21 (13), 1995, 1545-1555.

19) Bechgaard, H., Christensen, F. N., Davis, F. N., Davis, S. S., Hardy, J. G., Taylor, M. J.,Whilley, D. R., Wilson, C. G., Gastrointestinal transit of pellet systems in ileostomy subjects and the effect of density. J. Pharm. Pharmacol. 37(10), 1985, 718-21.

20) Sastry, K., V., S. and Fuerstenau, D., W.,. Kinetic and process analysis of the agglomeration of particulate materials by green pelletization, in Agglomeration 77, (K. V. S. Saatry, ed.), AIME, 1973, pp.381-402.

21) Nellore R.V. et al. 1998, "Development of Metoprolol tartrate extended-release matrix tablet formulations for regulatory policy consideration". Journal of Controlled Release, 50: 247-256.

22) Claudio Nastruzzi, Rita Cortesi, Elisabetta Esposito, Alberto Genovesi, Influence of Formulation and Process Parameters on Pellet Production by Powder Layering Technique, AAPS PharmSciTech. 2000; 1(2): article 9.

23) L. Hanysova, M. Vaclavkova, J. Dohnal and J. Klimes, Stability of Ramipril in the solvents of different pH, Journal of Pharmaceutical and Biomedical Analysis, Volume 37, Issue 5 , 29 April 2005, Pages 1179-1183.

24) Raluca-Ioana Stefan, Jacobus F. van Staden, Camelia Bala and Hassan Y. Aboul-Enein, On-line assay of the S-enantiomers of enalapril, Ramipril and pentopril using a sequential injection analysis / amperometric biosensor system, Journal of Pharmaceutical and Biomedical Analysis, Volume 36, Issue 4 , 19 November 2004, Pages 889-892.

25) Fukumori, Y.; Coating of multiparticulates using polymeric dispersions - formulation andprocess considerations, in Ghebre-Sellassie (ed.), Multiparticulate oral drug delivery, MarcelDekker, Inc., New York, (1994), 79 – 111.

26) Otilia May Yue KOO and Paul Wan Sia Heng Dept. of Pharmacy, National university of Singapore, Chem. Pharm. Bull. 49(11) 1383-1387 (2001)

27) H. Steckel, F. Mindermann-Nogly Production of chitosan pellets by extrusion/spheronization, European Journal of Pharmaceutics and Biopharmaceutics 57 (2004) 107–114

28) P.B. Deasy , M.F.L. Law Use of extrusion-spheronization to develop an improved oraldosage form of indomethacin, International Journal of Pharmaceutics 148 (1997) 201- 209

29) Garg SK, Islam AS, Kumar N, Sehgal M, Bhargava VK Effect of 'Mentat' on the pharmacokinetics of single and multiple doses o phenytoin in rabbits. 47(2) 104-107(1999)

30) G. Tomer, F. Podczeck, J.M. Newton The influence of model drugs on the preparation of pellets by extrusion“´¬–”²ª› spheronization: II spheronization parameters, International Journal of Pharmaceutics 231 (2002) 107–119

31) Delphine Blanque, Hilke Sternagel , Fridrun Podczeck, J. Michael Newton Some factors influencing the formation and in vitro drug release from matrix pellets prepared by extrusion/spheronization, International Journal of Pharmaceutics 119 (1995) 203-211

32) Consuelo Souto, Alberto Rodríguez, Silvia Parajes and Ramón Martínez -Pacheco A comparative study of the utility of two superdisintegrants in microcrystalline cellulose pellets prepared by extrusion–spheronization, European journal of Pharmaceutics and Biopharmaceutics 61 (1-2) 2005, 94-99.

33) Dashevskya, K. Kolterb, R. Bumpier pH-independent release of a basic drug from pellets coated with the extended release polymer dispersion Kollicoat SR 30 D and the enteric polymer dispersion Kollicoat MAE 30 DP, European Journal of Pharmaceutics and Biopharmaceutics 58 (2004) 45–49

34) Michelle F.L Law and Patrick B Deasy Use of hydrophilic polymers with microcrystalline cellulose to improve extrusion–spheronization, European journal of Pharmaceutics and Biopharmaceutics, 45(1), 57-65 (1998)

35) Reena Singh, S. S. Poddar, and Amit Chivate Sintering of Wax for Controlling Release From Pellets, AAPS PharmSci Tech. 2007; 8(3): Article 74. DOI: 10.1208/pt0803074

36) ICH topic 8 Pharmaceutical guidelines, Note for Guidence on Pharmaceutical Developments, (EMEA/CHMP167068 /2004)

37) ICH Q1A (R2), Stability Testing Guidelines, Stability testing of a new drug product and new drug substance.

Received on 26.07.2008 Modified on 23.09.2009

Research J. Pharm. and Tech. 3(1): Jan. - Mar. 2010; Page 277-286