Formulation and In vitro Evaluation of Sustained Release Matrix Tablet of Azathioprine

Dr. Y. Krishna Reddy*, A. Nagaraju

Department of Pharmaceutics, Nalanda College of Pharmacy, Jawaharlal Nehru Technological University, Hyderabad, Telangana.

*Corresponding Author E-mail: rajinisuralabs1@gmail.com

ABSTRACT:

The main aim of present work was to formulate and evaluate sustain release matrix tablets of Azathioprine, an Antirheumatic Agents. Sustain release formulation are those which delivers the drug locally or systemically at a predetermined rate for a fixed period of time. The matrix tablet was prepared by direct compression method using by various concentration of Ethyl cellulose, Sodium Alginate and HPMC K4M various release retardant polymer. The powder mixtures were subjected to various pre-compression parameters such as angle of repose, bulk density, tapped density and Carr’s index shows satisfactory result and the compressed tablets are evaluated for post-compression parameters such as weight variation, thickness, hardness, friability, drug content, In-vitro dissolution studies. In-vitro dissolution studies were carried out for 12 hours using 0.1 N HCL for first 2 hours and pH 6.8 phosphate buffer for 12 hours and the result showed that formulations A7 showed good dissolution profile to control the drug release respectively. Formulation containing higher concentration of HPMC K4M polymer sustained the drug release for the period of 12 hours. The kinetics studies the optimized formulation followed Peppas release kinetics.

KEYWORDS: Azathioprine, Ethyl cellulose, Sodium Alginate and HPMC K4M, Direct compression and Sustained release matrix tablets.

INTRODUCTION:

The Important role of novel drug delivery system that improve the therapeutic effectiveness of incorporated drugs by providing sustained, controlled delivery and or targeting the drug to desired site. The aim of any drug delivery system is to provide a therapeutic amount of drug to the specific site in the body to achieve promptly and then maintain the desired drug concentration.¹

The design of oral sustained release delivery systems is subjected to several interrelated variables of considerable importance such as the type of delivery system, the disease being treated, the patient, the length of therapy and the properties of the drug. Sustain release system includes any drug delivery systems that achieves slow release of drug over prolong period of time.² Matrix tablets are considered to be the commercially feasible sustained action dosage forms that involve the least processing variables, utilize the conventional facilities and accommodate large doses of drug. There remains an interest in developing novel formulations that allow for sustained the drug release using readily available, inexpensive excipient by matrix-based formulation. During the last two decades there has been remarkable increase in interest in sustained release drug delivery system. This has been due to various factors like the prohibitive cost of developing new drug entities, expiration of existing international patients, discovery of new polymeric materials suitable for prolonging the drug release, and the improvement in therapeutic efficiency and safety achieved by these delivery systems. Now a days the technology of sustained release is also being applied to veterinary products also.^2,3,4

ADVANTAGES:

(i) Patient compliance:

Lack of compliance is mainly observed with chronic disease which required long term treatment, as success of drug therapy depends on the patient ability to comply with the drug treatment. Patient compliance is affected by a various factor, like knowledge of disease process, patient faith in treatment, and understanding of patient related to a strict treatment schedule. Also the complication of therapeutic regimens, the cost of therapy and local or systemic side effect of the dosage form. This problem can be resolved to some extent by administering sustained release drug delivery system.

(ii) Reduced 'see-saw' fluctuation:

Drug concentration in the systemic circulation and tissue compartments show ‘see saw’ pattern frequently when the drug administration in conventional dosage form. The magnitudes of these fluctuations mainly depend on drug kinetics such as the rate of absorption, distribution, elimination and dosing intervals. The 'see-saw' pattern is more prominent just in case of drugs with biological half-life less than four hours, since recommended dosing intervals are rarely less than four hours. A well designed sustained release drug delivery system can widely reduce the frequency of drug dosing and also mainta in a steady drug concentration in blood circulation and target tissue cells.

(iii) Total dose reduction:

To treat a diseased condition less amount of total drug is used in Sustained release drug delivery systems. By reducing the total amount of drug, decrease in systemic or local side effects are observed. This would also lead to greater economy.

(iv) Economy:

The initial unit cost of sustained release products is usually greater than that of conventional dosage form because of the special nature of these compounds but importantly average cost of treatment over an prolong period of time may be less.^{5, 6, 7}.

DISADVANTAGES OF SUSTAINED RELEASE DOSAGE FORM:

· Dose dumping: Dose dumping may occur with faulty formulation.

· Reduced potential for dose adjustment.

· Cost is more than conventional dosage form.

· Increase potential for first pass metabolism.

· For proper medication patient education is necessary.

· Possible reduction in systemic availability.

· Poor in vivo and in vitro correlations.^{2, 4, 9}.

AIM AND OBJECTIVE:

1. Aim:

The Aim of the present work is to formulate and evaluate the Azathioprine Sustained release tablets using Various polymers such as Ethyl cellulose, Sodium Alginate and HPMC K4M.

2. Objective:

1. The objective of this study was to develop sustained release matrix tablets Azathioprine by studying the following points:

2. The objective of this present study is to reduce the dosing frequency of Azathioprine So prepared Sustained release dosage form for prolong its duration of action, and reduced side effects.

3. The present work is aimed at preparing and evaluating sustained-release (SR) matrix tablets of Azathioprine using different polymers.

4. To study the effect of nature of the polymer and drug: polymer ratio on the rate of drug release.

5. To study the effect of method of preparation of tablets Wet granulation method on the rate of drug release.

6. To Study the effects of the Pre-compression & Post-compression variables on the characteristics of Azathioprine sustained release matrix tablets.

MATERIALS AND METHODS:

Azathioprine was Provided by SURA LABS, Dilsukhnagar, Hyderabad. Ethyl cellulose, was purchased from Loba Chemie Pvt. Ltd Mumbai, India, Sodium Alginate and Magnesium stearate was purchased from Merck Specialities Pvt Ltd, Mumbai, India, HPMC K4Mwas purchased from Aravind Remedies (AR), Chennai, India, PVP K 30Unify chemicals, Jothi Aromas and DK Enterprises, India., Lactose and Talc was purchased from S.D. Fine Chemicals, India.

METHODOLOGY:

Table 1: Formulation of Sustained release tablets

INGREDIENTS (MG)	FORMULATION CODES
	A1	A2	A3	A4	A5	A6	A7	A8	A9
Azathioprine	50	50	50	50	50	50	50	50	50
Ethyl cellulose	15	30	45	-	-	-	-	-	-
Sodium Alginate	-	-	-	25	50	75	-	-	-
HPMC K4M	-	-	-	-	-	-	12.5	25	37.5
PVP K 30	5	5	5	5	5	5	5	5	5
Lactose	121	106	91	111	86	61	128.5	111	98.5
Magnesium stearate	4	4	4	4	4	4	4	4	4
Talc	5	5	5	5	5	5	5	5	5
Total weight	200	200	200	200	200	200	200	200	200

RESULTS AND DISCUSSION:

The present work was designed to developing Sustained tablets of Azathioprine using various polymers. All the formulations were evaluated for physicochemical properties and in vitro drug release studies.

Standard graph of Azathioprine in 0.1N HCL:

The scanning of the 10µg/ml solution of Azathioprine in the ultraviolet range (200-400nm) against 0.1 N HCL the maximum peak observed at l_max as 620 nm. The standard concentrations of Azathioprine (2-10 µg/ml) was prepared in 0.1N HCL showed good linearity with R² value of 0.999, which suggests that it obeys the Beer-Lamberts law.

Table 2: Standard curve of Azathioprine in 0.1N HCL

Concentration (µg/ ml)	Absorbance
0	0
2	0.175
4	0.331
6	0.492
8	0.658
10	0.835

Fig. 1: Calibration curve of Azathioprine in 0.1 N HCL at 620 nm

Standard Curve of Azathioprine in Phosphate buffer pH 6.8:

The scanning of the 10µg/ml solution of Azathioprine in the ultraviolet range (200-400nm) against 6.8 pH phosphate the maximum peak observed at the l_max as 624 nm. The standard concentrations of Azathioprine e (2-10µg/ml) prepared in 6.8 pH phosphate buffer showed good linearity with R² value of 0.999, which suggests that it obeys the Beer-Lamberts law.

Table 3: Standard curve of Azathioprine in Phosphate buffer pH 6.8

Concentration (µg / ml)	Absorbance
0	0
2	0.137
4	0.258
6	0.378
8	0.495
10	0.612

Fig.2: Calibration of Azathioprine in Phosphate buffer pH 6.8

EVALUATION PARAMETERS:

Pre-compression parameters:

Table4: Pre-compression parameters of powder blend

Formulation Code	Angle of Repose	Bulk density (gm/ml)	Tapped density (gm/ml)	Carr’s index (%)	Hausner’s Ratio
A1	27.20± 1.39	0.35± 0.02	0.43± 0.02	15.28± 0.36	1.16± 0.03
A2	28.00± 2.05	0.37± 0.02	0.41± 0.30	17.35± 0.85	1.18± 0.04
A3	28.63± 1.12	0.34± 0.02	0.45± 0.02	18.36± 1.99	1.14± 0.02
A4	27.00± 1.94	0.34± 0.01	0.44± 0.015	11.30± 0.74	1.18± 0.06
A5	27.54± 1.55	0.36± 0.01	0.41± 0.02	14.55± 3.16	1.17± 0.03
A6	28.00± 1.97	0.35± 0.01	0.44± 0.01	21.53± 0.86	1.17± 0.05
A7	28.43± 0.90	0.38± 0.01	0.43± 0.01	17.23± 1.09	1.24± 0.04
A8	28.60± 1.94	0.35± 0.02	0.41± 0.01	12.54± 0.12	1.30± 0.05
A9	28.52± 2.37	0.34± 0.02	0.42± 0.015	13.52± 0.11	1.58± 0.13

Tablet powder blend was subjected to various pre-compression parameters. The angle of repose values was showed from 27.00±1.94 to 28.63±1.12, it indicates that the powder blend has good flow properties. The bulk density of all the formulations was found to be in the range of 0.34±0.01 to 0.38±0.01 (gm/ml) showing that the powder has good flow properties. The tapped density of all the formulations was found to be in the range of 0.41±0.01 to 0.45±0.02 showing the powder has good flow properties. The compressibility index of all the formulations was found to be ranging from 11.30±0.74 to 21.53±0.86 which showed that the powder has good flow properties. All the formulations were showed the Hausner’s ratio ranging from 1.14±0.02 to 1.58±0.13 indicating the powder has good flow properties.

Post compression parameters for tablets:

Table 5: Post Compression Parameters of Tablets

Formulation codes	Average Weight (mg)	Hardness (kg/cm^2)	Friability (% loss)	Thickness (mm)	Drug content (%)
A1	198.24	4.8	0.56	3.25	95.12
A2	200.04	3.9	0.86	3.61	98.65
A3	196.35	3.8	0.76	3.85	99.31
A4	195.82	4.1	0.82	3.49	97.83
A5	198.75	3.5	0.56	3.72	99.12
A6	199.54	4.0	0.49	3.50	96.58
A7	197.92	3.7	0.59	3.15	98.45
A8	199.35	3.1	0.68	3.59	97.39
A9	200.01	3.6	0.72	3.67	95.20

Table 6: Dissolution Data of Azathioprine Tablets

TIME (hr)	CUMULATIVE percent drug released
	A1	A2	A3	A4	A5	A6	A7	A8	A9
0	0	0	0	0	0	0	0	0	0
0.5	25.95	13.68	12.30	18.75	12.93	15.91	10.35	08.76	05.95
1	31.60	27.15	20.18	25.26	21.59	22.10	16.91	18.89	11.35
2	49.24	34.63	26.59	37.14	28.34	34.55	27.86	26.24	18.25
3	54.15	43.27	35.75	42.81	34.24	41.96	35.64	30.32	22.17
4	66.67	54.19	48.12	59.68	45.90	47.57	40.82	36.75	30.93
5	72.39	62.01	52.94	67.05	55.11	54.35	45.14	44.09	35.86
6	86.76	79.43	57.76	73.93	62.37	60.86	51.82	48.16	41.15
7	93.14	85.65	65.82	86.38	67.25	65.14	56.31	54.36	45.04
8		95.37	72.31	95.15	76.94	76.75	63.79	60.12	53.93
9			79.46		87.50	84.92	71.53	65.78	57.72
10			84.25		97.12	90.65	78.17	71.79	60.31
11			94.76			99.34	86.92	77.31	65.82
12							98.51	85.45	72.65

Figure 3: Dissolution study of Azathioprine Sustained tablets (A1 to A9)

In vitro drug release studies:

The formulations prepared with different polymers by direct compression method. The tablets dissolution study was carried out in paddle dissolution apparatus using 0.1N HCL for 2 hours and 6.8 pH phosphate buffers for remaining hours as a dissolution medium.

From the tabular column 8.5 it was evident that the formulations prepared with Ethyl cellulose as retarding polymer in low concentrations the polymer was unable to produce the required retarding action to the tablets. As the concentration of polymer increases the retarding nature was also increased. Ethyl cellulose in the concentration of 40mg showed good % drug release i.e., 94.76 in 11 hours.

Where as in case of formulations prepared with Sodium Alginate as retarding polymer, the formulations with 75mg concentration of polymer showed complete drug release in 11 hours only, whereas the concentration of polymer increases the retarding nature increases. The Formulation Containing Sodium Alginate in 75mg Concentration Showed good retarding nature with required drug release in 11 hours i.e., 99.34%.

Where as in case of formulations prepared with HPMC K4M as retarding polymer, the formulations with 12.5 mg concentration of polymer showed complete drug release in 12 hours only, The Formulation Containing HPMC K4M in 12.5Mg Concentration Showed good retarding nature with required drug release in 12 hours i.e., 98.51%.

From the above results it was evident that the formulation A7 is best formulation with desired drug release pattern extended up to 12 hours.

Drug and excipient compatibility studies:

FTIR STUDY:

Fig. 4: FTIR Graph of pure drug

Fig. 5: FTIR Graph of Optimised Formulation

From the FTIR data it was evident that the drug and excipients doses not have any interactions. Hence they were compatible.

CONCLUSION:

The aim of the present study was to develop a sustained release tablet of Azathioprine to maintain constant therapeutic levels of the drug for over 12 hrs. Azathioprine sustained release tablets are prepared by direct compression method with different polymers. The pre-formulation studies like angle of repose, bulk density, tapped density Hausner’s ratio and Carr’s index of all formulations were found to be within the standard limits. FTIR studies revealed that there was no chemical interaction between drug and other excipients. The powder mixtures were compressed into tablet and evaluated for post-compression parameters like weight variation, thickness, hardness, friability and drug content. All the formulation batches showed acceptable results. The in-vitro drug release was studied with USP Type-II dissolution apparatus in both simulated gastric fluid and intestine fluid for a period of 12 hours. Results showed that formulations containing higher concentration of HPMC K4M i.e. A7 (98.51%). The in-vitro drug release follows Peppas release kinetics mechanism.

АCKNOWLEDGEMENT:

The Authors arе thankful to Sura Labs, Dilshukhnagar, Hydеrabad for providing thе necessary facilities for the research work.

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Received on 17.02.2020 Modified on 19.03.2020

Accepted on 11.04.2020   ©Asian Pharma Press All Right Reserved

Asian J. Pharm. Tech. 2020; 10(2):65-70.

DOI: 10.5958/2231-5713.2020.00013.6