Formulation and Evaluation of mucoadhesive buccal patches of Terbutaline Sulphate

 

Suresh A. Marnoor

Lecturer, Department of Pharmaceutics, Shree Ambabai Talim Sanstha’s Diploma in Pharmacy College,

Miraj-416 414, District-Sangli, Maharashtra, India

 

 

ABSTRACT:

The aim of the study was to develop and optimize formulations of mucoadhesive patches of Terbutaline sulphate. The patches were prepared by the solvent casting method using Hydroxyl propyl methyl cellulose (HPMC E-15) as basic polymer along with Carbopol 934, Eudragit RL 100, and Chitosan were taken in different concentration. The patches were found to be smooth in appearance, uniform in thickness, weight uniformity, drug content, swelling behavior, and surface pH. Terbutaline Sulphate Buccal patch of Formulation 5 (TBP5) containing 400 mg of HPMC, 200 mg of Eudragit RL 100 have optimum bioadhesive strength, in-vitro residence time showed a release of 83.40 % after 15 hours and can meet the ideal requirement for sustained release buccal devices, which can be good way to bypass the extensive hepatic first pass metabolism and increase bioavailability.

 

 

INTRODUCTION:

Bronchial Asthma is a disease of airways that is characterized by increased responsiveness of the tracheobronchial tree to a variety of stimuli resulting in widespread spasmodic narrowing of the air passages.¹ Asthma affects more than 250 million people and the numbers are increasing.² It has been reported that over 50 million people suffer from Asthma in central and southern Asia and is predicted to increase rapidly in the coming years.  The increase is likely to be particularly dramatic in India. An absolute 2% increase in the prevalence of asthma in India would result in an additional 20 million people with the disease.³

 

Terbutaline sulphate is a selective β 2 adrenergic receptor agonist widely used in the treatment of bronchial asthma, emphysema and other chronic obstructive lung diseases. It can be given orally, parenterally or by inhalation. Orally it undergoes high first pass metabolism in the gut wall and liver and the bioavailability is only 15%. Only about 10% to 20% of inhaled dose reaches the lungs and the rest is swallowed. There are also reports about the harmful effects of aerosol bronchodilator therapy.^4,5 Among various Transmucosal routes, buccal mucosa is the most suited for local, as well as systemic delivery of drugs. Buccal films have direct access to the systemic circulation through the internal jugular vein.⁶ The buccal route was chosen because of its good accessibility, easy removal of the dosage form, relatively low enzymatic activity and natural clearance mechanism for elimination of the drug from buccal area. Buccal route shows satisfactory patient compliance, avoidance of hepatic first pass metabolism and thereby increasing the bioavailability of Terbutaline sulphate.

 

The present study will be carried out with an attempt to develop mucoadhesive buccal drug delivery system of terbutaline sulphate. The buccal mucoadhesive films were prepared by solvent casting technique using various polymers like HPMC, Carbopol-934, Eudragit RL 100 and Chitosan.

 

MATERIALS AND METHODS:

Materials:  

Terbutaline sulphate was obtained from Leben Laboratories Pvt. Ltd., Maharashtra, India All other solvents, reagents and chemicals used were of either Pharmacopoeial or analytical grade.

 

 

 

Table No.1: Formulation of mucoadhesive buccal patches of Terbutaline Sulphate

 

 

Methods:

Preparation of Buccal Patches:

Formulation Code TBP 1: Soak 500 mg of Hydroxy Propyl methyl cellulose in 2 ml of ethanol for 24 hrs. Dissolve 10 mg of drug in 1 ml of water. Add 1.5 ml of methanol, 1.5ml of dichloromethane, 2 ml of ethanol and 0.005 ml of glycerol to the above solution. The solution was mixed for about 30 minutes using the magnetic stirrer. The polymer drug solution was poured within a bangle (4.5 cm) placed over mercury substrate in a petridish. The rate of evaporation of solvent was controlled at room temperature by inverting cut funnel over the petridish. After 12 hrs dried patches were collected and stored in desiccators.

 

Formulation Code TBP 2 and TBP 3: Two different polymer solutions were prepared by dissolving 300 mg of Eudragit RL-100 in 3 ml blend mixture of methanol and dichloromethane, 200 mg Carbopol-934 in water in separate beakers. Further preparation was continued according to TBP 1.

 

Formulation Code TBP 4: Chitosan was dissolved in 1.25% acetic acid solution by stirring with glass rod and the solution was continuously stirred for 24 hrs using magnetic stirrer and filtered using nylon mesh. Different concentrations of Chitosan were prepared. Further preparation was continued according to TBP1.

 

Formulation Code TBP 5 and TBP 6:  The solution of Eudragit RL100 was added to the above solution (Polymeric solution of Hydroxy propyl methyl cellulose). The solution of Chitosan was added to another solution (Carbopol-934). The solution was mixed for 30 minutes using magnetic stirrer. Further preparation was continued according to TBP1.

 

Evaluation of Terbutaline Sulphate Buccal Patches:

Folding Endurance: ⁷

Folding endurance has been done to check flexibility of the patch to align properly to the buccal mucosa. Folding endurance of the patches was determined by repeatedly folding one patch at the same place till it broke or folded up to 245 times at the same place without breaking gave the value of folding endurance of patch(n=3).

 

Thickness:

The thickness of the patch was measured using vernier calipers with a least count of 0.01 mm at different spots of the patches. The thickness was measured at different spots of the patch and average was taken. Like that thickness of five patches were measured (n=5).    

 

Weight Uniformity:

For evaluation of patch weight five patches of every formulation were taken and weighed individually on a digital balance (n=5).The average weights were calculated.

 

Swelling Study:⁸

Buccal patch was weighed (W1), placed in 2% agar gel plates and incubated at 37 ^o C for 2 hours. At regular 30 minute time intervals, the patch was removed from the petridish and excess surface water was removed carefully using the filter paper. The swollen patch was then reweighed (W2) and swelling index (SI) was calculated.

 

Radial Swelling:⁸

The diameter of buccal patch was measured (S1), placed in 2% agar gel plates and incubated at 37 ⁰C for 2 hours. At regular 30 minute time intervals, the patch was removed from the petridish and excess surface water was removed carefully using the filter paper. The diameter of swollen patch was then measured (S2) and swelling index (SI) was calculated. So that we can get difference in diameter after each interval.

 

Content Uniformity: ⁹

The drug content was then determined after proper dilution and analyzed at 279 nm using a UV-spectrophotometer. The experiments were carried out on 3 patches (n=3). Average is reported as Assay value.

 

Mucoadhesive Strength: ¹⁰

Fresh pork buccal mucosa was used. The mucosal membrane was separated and it was washed with distilled water and then with phosphate buffer pH 6.8 at 37⁰ C. Mucoadhesive strength of the patch was measured on a modified physical balance using the method. The weight, in gram, required to detach the patch from the mucosal surface gave the measure of Mucoadhesive strength.

 

Percentage Moisture Loss (PML): ¹⁰

This test was carried out to check the integrity of patches at dry condition. Three 1cm diameter patches was cut out and weighed accurately and kept in desiccator’s containing fused anhydrous calcium chloride. After 72 hours the patches were removed, weighed.

 

Percentage Moisture Absorption (PMA): ¹⁰

This test was carried out to check the physical stability of the buccal patches at high humid conditions. Three patches weighed accurately then the patches were placed in desiccator containing powdered aluminium chloride. After 3 days the patches were removed, weighed and percentage moisture absorption was calculated.

 

In -Vitro Residence Time: ¹¹

The In vitro residence time was performed (n=2) after application of the patches on freshly cut pork buccal mucosa. The fresh pork buccal mucosa was fixed on a glass plate using cynoacrylate glue. The glass plate is attached with help of string to the disintegration apparatus above 2.5 cm from the bottom. One side of each patch was wetted with one drop of phosphate buffer pH 6.8 and pasted to the pork buccal mucosa. The beaker was filled with 800 ml of isotonic phosphate buffer pH 6.8 and was kept at 37⁰C±1⁰C. After 2 minutes disintegration apparatus was started to simulate the buccal cavity environment, and patch adhesion was monitored until 12 hours. The time required for the patch to detach from the pork buccal mucosa was recorded as the in vitro residence time.

 

Surface pH: ¹²

A combined glass electrode was used for this purpose. The patches were allowed to swell by keeping it in contact with 1 ml of distilled water (pH 6.5 ± 0.05) for 2 hours at room temperature, and the pH was noted by bringing the electrode in contact with the surface of the patch and allowing it to equilibrate for 1 minute.

 

In Vitro Drug Release: ¹²

This was carried out in a USP dissolution apparatus type 1 (six-station dissolution apparatus, Electro lab, India).  The dissolution medium, 500 ml phosphate buffer pH 6.8, maintained at 37 ± 0.5 0C was kept in a dissolution flask. The patch was attached to end of the shaft (without basket), which was rotated at 50 rpm. Samples (4ml) were collected at intervals of 1h and the withdrawals were compensated using equal volumes of phosphate buffer pH 6.8 kept at the same temperature. The concentration of drug released in the medium was assayed spectrophotometrically at 279 nm after suitable dilution with the dissolution medium.

 

Selection of optimum formulation:

TBP 5 has been selected as an optimum formulation because it extended the release of Terbutaline Sulphate till 15 hrs and it is having satisfactory Mucoadhesive strength as well as in-vitro residence time.

 

RESULTS AND DISCUSSIONS:

λ max of Terbutaline Sulphate:

From 1mg/ml Terbutaline Sulphate solution, suitable dilutions were made and scanned for maximum absorbance using UV visible spectrophotometer (double beam) in the range from 200 to 400 nm and 279 nm was observed as absorption maximum, So that 279 nm used as λmax for the estimation of Terbutaline Sulphate.

 

Calibration curve of Terbutaline Sulphate phosphate buffer pH 6.8:

Terbutaline Sulphate in phosphate buffer pH 6.8 showed good linearity (r²= 0.996) over the concentration range of 2-10μg/ml at λ max 279 nm, with slope = 1.020x.

 

 

Table No.2: Spectrophotometric data for construction of standard graph Terbutaline Sulphate:

Concentration(mg/ml)	Absorbance
0	0
0.2	0.2354
0.4	0.4256
0.6	0.6235
0.8	0.8254
1	0.9941

 

 

Figure No.1:  Standard graph of Terbutaline Sulphate

 

Infrared (IR) absorption spectroscopy: Drug-Excipient Interaction Studies:

Compatibility studies were performed using IR spectrophotometer. In the present study, it has been observed that there is no chemical interaction between Terbutaline Sulphate and the polymers used. There were no changes in these main peaks in IR spectra of mixture of drug and polymers, which shows that there were no physical interactions.

 

 

Figure No.2: IR Spectrum of Drug and Polymer Mixture

 

 

Ex Vivo Drug Penetration Studies:

The Ex vivo drug Penetration Studies carried out through the porcine buccal mucosa membrane. The cumulative amount of Terbutaline Sulphate penetrated through the buccal mucosal membrane was maximum of 23.4 % drug in 8 hr (table 4).

 

Table No.4: Ex vivo Cumulative percentage permeation of Terbutaline Sulphate

Time in Hrs	Mg/sqcm	CPP±SD (n=3)
0	0	0
1	27.49	1.969±0.309
2	66.12	4.56±0.257
3	104.13	7.85±0.0309
4	134.12	10.16±0.412
5	183.15	13.64±0.039
6	225.92	16.28±0.412
7	275.98	19.15±0.257
8	327.12	23.4±0.670

 

Evaluation of Terbutaline Sulphate Buccal Patches:

Physical Appearance and Surface Texture:

All the patches were uniform, clear, flexible and continuous and can be easily removed from the petridish after drying.

 

Folding Endurance

Patches did not show any cracks even after folding for more than 268 times. Hence it was taken as the end point..

 

Thickness Uniformity

The patch thickness was found in range of 0.175 to 0.326 mm. The patch thicknesses was observed by using digital vernier callipers, the order of patch thickness was found TBP5>TBP3>TBP4>TBP1>TBP2>TBP6.

 

Table No.5: Thickness of Patches:

Sr. No	Formulation code	Thickness in mm ± SD (n=5)
1	TBP1	0.264±0.110
2	TBP2	0.231±0.018
3	TBP3	0.301±0.031
4	TBP4	0.276±0.028
5	TBP5	326±0.0079
6	TBP6	0.175±0.0063

 

 

Weight Uniformity

For evaluation of patch weight five patches of every formulation were taken and weighed individually on a digital balance (n=5).The average weights were calculated.

 

Table No.6: Mean weight (mg) of Polymeric patches

Sr. No	Formulation Code	Weight in mg± SD (n=5)
1	TBP1	48.95±0.62
2	TBP2	30.28±1.13
3	TBP3	29.98±0.69
4	TBP4	15.08±0.93
5	TBP5	59.37±1.01
6	TBP6	19.16±1.28

 

Swelling Study

Swelling was done on bases of area as well as weight of the patch which was found to be in order of TBP5>TBP1>TBP2>TBP3>TBP6>TBP4. From table-7 it indicates that the formulas which were having maximum concentration of HPMC E-15 and Eudragit RL100 were having maximum swelling.

 

Table No.7: Swelling study based on weight

Sr. No.	Formulation Code	% increase in weight ±SD (n=3)
1	TBP1	63.13±0.58
2	TBP2	41.28±1.02
3	TBP3	43.18±0.96
4	TBP4	24.86±0.67
5	TBP5	68.28±1.42
6	TBP6	30.02±0.73

 

 

Content Estimation:

The drug content uniformity values were between 95.14% and 100.8% as compare to theoretical values. The observed results of content uniformity indicated that the drug was uniformly distributed throughout the patch.

 

Table No.8: Content Estimation:

Sr. No.	Formulation Code	% Drug content (n=3)
1	TBP1	96.54±0.107
2	TBP2	98.13±0.133
3	TBP3	97.21±0.118
4	TBP4	99.01±0.109
5	TBP5	99.81±0.023
6	TBP6	101.08±0.176

 

 

 

Mucoadhesive Strength and Force of adhesion:

The swelling state of the polymer has been reported to be crucial for its bioadhesive behavior. The Ex vivo mucoadhesive strength (bioadhesive strength) of polymeric buccal patches was found to be in the following order TBP5>TBP1>TBP6>TBP3>TBP4> TBP2.

 

Table No.9: Mucoadhesive Strength and Force of adhesion

Sr. No.	Mucoadhesive Strength ±SD (n=3)	Force of adhesion (N)±SD(n=3)
1	13.051±0.061	0.108±0.0010
2	7.065±0.076	0.092±0.0009
3	11.105±0.089	0.123±0.0008
4	9.105±.0.065	0.091±0.0004
5	16.15±0.024	0.161±0.0009
6	11.105±0.091	0.110±0.0005

 

Percentage Moisture Loss (PML) and Percentage Moisture Absorption (PML and PMA):

Checking the physical stability of the patch at high humid conditions and integrity of the patch at dry conditions, the patches were evaluated for PML and PMA. The observed results of PML were shown in the table. The observed PML was in order of TBP1>TBP2>TBP4>TBP3>TBP6>TBP5. PMA was in order of TBP5>TBP1>TBP4>TBP2>TBP3>TBP6 It shows that formulations containing maximum concentration HPMC E-15 and Eudragit RL100 are having more percentage loss of moisture as well as absorption.

 

Table No.10: Percentage Moisture Loss (PML)

Sr. No.	Formulation code	PML
1	TBP1	8.28±0.25
2	TBP2	7.08±0.85
3	TBP3	6.1±0.24
4	TBP4	6.3±0.25
5	TBP5	4.15±0.32
6	TBP6	4.78±0.20

 

Table No. 11: Percentage Moisture Absorption (PMA)

 

Sr. No.	Formulation code	PMA
1	TBP1	6.24±0.15
2	TBP2	5.924±0.24
3	TBP3	5.00±0.12
4	TBP4	6.97±0.14
5	TBP5	6.90±0.23
6	TBP6	4.01±0.20

 

Surface pH:

The maximum surface pH from all the formulations was found to be 6.91± 0.054(table 12) and the minimum was 6.49± 0.073 which were in the salivary pH (5.5 to 7.0). The results reveal that all the formulations provide an acceptable pH in the range of 5.5 to 7.0 (salivary pH). Hence, they may not produce any local irritation to the oral mucosal.

 

 

Table No.12: Surface pH:

Sr. No.	Formulation Code	Surface pH (n=3)
1	TBP1	6.56±0.032
2	TBP2	6.49±0.073
3	TBP3	6.75±0.048
4	TBP4	6.59±0.021
5	TBP5	6.91±0.054
6	TBP6	6.79±0.056

 

In Vitro Residence Time:

In vitro residence time of the patch was determined which was found in order of TBP5>TBP1>TBP3> TBP2>TBP6>TBP4. (table 13) The formulas which contain higher proportion of HPMC E-15 and Eudragit RL100 was having higher in vitro residence time. Chitosan is also having somewhat positive effect on the in vitro residence time. As the proportion of the Chitosan increases the in vitro residence time decreases so it has negative effect on the in vitro residence time. Ghoshal SK et al also concluded the same conclusion by comparing in vitro residence time of the films having combination of various polymers.

 

Table No.13: In vitro residence time

Sr. No.	Formulation Code	In vitro residence time in minute
1	TBP1	299.9±10.12
2	TBP2	243.6±13.94
3	TBP3	268±9.85
4	TBP4	171±12.01
5	TBP5	332.5±8.89
6	TBP6	211.5±12.13

 

 

 

 

Table No.14: Cumulative Percentage Release of Terbutaline Sulphate from TBP1, TBP2, TBP3, TBP4, TBP5 and TBP6 Buccal patches.

Time in Hrs	TBP1 (n=3)	TBP2 (n=3)	TBP3 (n=3)	TBP4 (n=30	TBP5 (n=3)	TBP6 (n=3)
0	0.00	0.00	0.00	0.00	0.00	0.00
1	4.64±0.60	4.97±0.62	5.68±0.61	7.45±0.95	4.61±0.55	5.71±0.55
2	7.13±0.52	10.09±0.61	9.00±0.57	12.67±0.92	7.75±0.72	9.11±0.43
3	11.75±0.31	12.51±0.55	12.83±1.2	14.82±0.75	14.54±0.72	16.28±1.31
4	14.35±0.17	14.47±0.09	16.63±1.3	17.66±0.65	15.85±0.65	19.25±0.75
5	19.68±0.56	21.45±0.08	20.55±1.5	21.17±0.95	18.55±0.55	25.45±0.85
6	22.45±0.54	24.59±0.75	23.58±1.2	25.35±0.65	24.33±0.85	29.45±1.05
7	25.15±0.95	29.87±0.72	27.53±0.91	32.25±1.25	30.02±0.50	35.78±0.95
8	27.85±0.12	32.45±1.7	28.57±0.55	35.59±0.85	33.14±1.00	43.02±0.85
9	38.23±0.57	42.32±1.0	43.25±0.94	42.84±0.55	36.49±0.89	51.14±1.45
10	48.61±1.2	52.01±0.20	48.15±1.2	52.25±0.95	45.61±0.55	55.58±095
11	58.23±1.2	56.45±0.65	59.25±0.12	62.55±.45	47.65±0.75	65.25±1.15
12	64.00±1.1	65.81±1.8	71.15±1.0	72.12±0.42	55.45±0.72	72.35±0.85
13	76.16±1.0	78.12±0.25	77.35±1.0	78.25±.35	66.03±1.2	81.45±0.96
14	81.95±0.55	85.43±0.58	88.23±1.0	88.41±.65	77.26±0.65	95.45±0.95
15	94.45±0.33	97.22±0.43	92.25±0.74	98.32±0.55	83.40±1.0	97.18±0.00

 

 

Figure No.3: Cumulative Percentage Release of Terbutaline Sulphate from TBP1, TBP2, TBP3, TBP4, TBP5 and TBP6 formulations.

 

 

 

CONCLUSION:

The Terbutaline Sulphate buccal patches were prepared by the method of solvent casting technique and were evaluated. The mean thickness and weight of buccal polymeric patches increased with an increase in the amount of polymer percentage. The TBP5 had maximum thickness and weight which had two polymers at maximum concentrations is used. The patches were evaluated for swelling study which indicates that the formulas which were having maximum concentration of HPMC E-15 and Eudragit RL100 were having maximum swelling.

 

The ex-vivo mucoadhesive strength was higher in case higher concentration of HPMC E-15 and Eudragit RL100. The increase in mucoadhesive strength may be due to the formation of a strong gel that penetrates deeply into the mucin molecules. The patches were evaluated for PMA and PML. It shows that formulations containing maximum concentration of HPMC E-15 and Eudragit RL 100 are having more percentage loss of moisture as well as absorption. The observed surface pH of the all formulation was found to be in between 6.49 to 6.91. This is in the range of salivary pH. The formula which contains higher proportion of HPMC E-15 and Eudragit RL100 was having higher in vitro residence time. Chitosan is also having somewhat positive effect on the in vitro residence time.

 

In vitro drug release has been performed for all formulation till 15 hrs which indicates that HPMC E-15 and Eudragit RL100 combined formulation is extending the drug release at higher extent while Corbopl-934 and Chitosan combined formulation is having very less capacity to extend the drug release. IR studies indicated that Terbutaline Sulphate showed complete entrapment within the polymer carrier; physical bonding (hydrogen bonding) is suggested. There was no chemical interaction.

 

So we conclude that, Terbutaline Sulphate Buccal Patch of HPMC E-15 and Eudragit RL100 can meet the ideal requirement for sustained release buccal devices, which can be good way to bypass the extensive hepatic first pass metabolism and increase its bioavailability.

 

LIST OF ABBREVIATIONS:

pKa-pH corresponding to an equal concentration of ionized and unionized drug

PMA- Percentage moisture absorption

PML-Percentage moisture loss

r²-Correlation coefficient

RH-Relative humidity

SD-Standard deviation

T½-Plasma half life

TMDD-Transmucosal Drug Delivery

UV-Ultraviolet       

w/w-Weight by Weight

λmax-Maximum wavelength of absorbance

 

REFERENCES:

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2.     Available from URL -The Global Asthma Report 2014, http://www.globalasthmareport.org/

3.     Available from URL-http://www.ginasthma.org/local/uploads/files/GINABurdenReport_1.pdf

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5.     Available from URL -Terbutaline Sulpahte, http://en.wikipedia.org/wiki/Terbutaline

6.     Peeush Singhal, Gajendra Singh Jadoun, Mukesh Sinha, Shubhini A.S, Formulation and evaluation of buccal patches of terbutaline sulphate. International Journal of Pharmacy and Pharmaceutical Sciences. 2010;1(4), 440-449,

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8.     Pharmacopoeia of India, 3rd Edn., Vol. II, Controller of Publications, Ministry of Health, Govt. of India, New Delhi. 1996; 634.

9.     Gupta A, Garg S, Khar RK. Measurement of bioadhesive strength of muco- adhesive buccal tablets: design of an in-vitro assembly. Indian Drugs. 1992; 30: 152-155.

10.   Han RY, Fang JY, Sung KC, Hu YP. Mucoadhesive buccal disks for novel Nalbuphine prodrug controlled delivery: Effect of formulation variables on drug release and mucoadhesive performance. International Journal of Pharmaceutics. 1999; 177(2): 201-209.

11.   Bottenberg P, Cleymaet R, Muynek CD. Development and testing of bioadhesive, fluoride-containing slow-release tablets for oral use. Journal of Pharmacy and Pharmacology. 1991; 43: 457-64.

11.  Panigrahi L, Ghoshal SK. Design and Characterization of Mucoadhesive buccal patches of Terbutaline Sulphate. Acta Poloniae Pharmaceutica. 2004; 61(5): 351-60.

 

 

 

 

 

 

 

Received on 15.07.2016       Modified on 28.08.2016

Accepted on 10.10.2016     ©A&V Publications All right reserved