Evaluation of Manihot esculenta Tuber Starch as Tablet Binder

G. Gopi¹*, A. Elumalai², P. Jayasri³

¹Department of Pharmaceutics, Mahathi College of Pharmacy, CTM X Road, Chittoor (Dt), Madanapalle, Andhra Pradesh, 517 319.

²Department of Pharmacognosy, Anurag Pharmacy College, Ananthagiri (V), Kodad (M), Nalgonda (Dt), Andhra Pradesh, 508 206.

³Department of Pharmacognosy, Santhiram College of Pharmacy, Srinivas Nagar, Kurnool (Dt), Nandyal, Andhra Pradesh, 518 501.

ABSTRACT:

The purpose of the present study was to investigate the efficacy of Manihot esculents tuber starch as a disintegrant to paracetamol tablets at a concentration of 2-10%. The prepared tablets were evaluated for weight variation, thickness, hardness, uniformity, disintegration time and drug dissolution rate. The prepared tablets showed high disintegration and dissolution rate, because of its high swelling factor and low viscosity. The formulated tablet showed less disintegration time using extracted starch used as disintegrant. Dissolution studies showed the drug release from the prepared tablets containing 7.5-10%w/w was 80-90% in 1 hr. From the above results the extracted starch formulations showed good disintegrant and dissolution properties.

KEYWORDS: Manihot esculenta, disintegration and dissolution rate.

INTRODUCTION:

Herbs are non- polluting renewable resources for sustainable supply of cheaper pharmaceutical excipients or products. New and improved binders continue to be developed to meet the needs of conventional drug delivery systems in general and that of tablet manufacturing in particular¹. Binders are agents used to impart cohesive qualities to the powdered material during the production of tablets. They impart cohesiveness to the tablet formulation, which ensures that the tablets remain intact after compression as well as improving the free flowing quality². Binders have been used as solutions in the formulations and the method of preparation. The choice of a particular binding agent depends on the binding force required to form granules and its compatibility with the other ingredients particularly the active drug³. Starches from different sources have been evaluated and used as excellent binders in either mucilage or the dry powdered form^4-6. Maize and potato starches have been in common use and recently cassava starch appeared in the British pharmacopoeia as an official starch for use as binder. Their use has increased in the tropics where previously recognized starches are unavailable. Apart from starches, other natural gums, gelatin, sugar solutions, modified natural and synthetic polymers have been employed with considerable success as binders. In all evaluation, the type and binder concentrations have direct effect on the crushing strength, friability, disintegration time and tablet dissolution⁷.

The cassava plant (Manihot esculenta Crantz, family Euphorbiaceae) is one of the staple food crops in most regions of Africa, Asia, and Latin America⁸. The parts of the plant that are commonly utilized are the roots and leaves. Cassava leaves have also been used against many disorders, such as rheumatism, fever, headache, diarrhoea, and loss of appetite^{9, 10.} Leaves reportedly also possess anti-haemorrhoid, anti-inflammatory and antimicrobial activity^{11, 12}. In India, cassava is used for the treatment of ringworm, tumour, conjunctivitis, sores and abscesses.

In the present study, an effort was made to access the efficacy of Manihot esculenta starch as a tablet binder.

MATERIALS AND METHODS:

Objectives

The present study was performed with following objectives:

a. Isolation of starch from tubers of Manihot esculenta

b. Preparation of granules

c. Evaluation of formulated tablets.

Isolation of starch

The outer layer of tubers was peeled off and the white part was washed and cut into pieces. The tubers were powdered in blender and washed in distilled water. The washing steps were repeated until the supernatant was clear and starch was free of colour. The starch was dried in hot air oven at 45⁰±2⁰C. The extracted starch was passed through 60 # sieve to get the fine particle size. Size reduction was done to increase the surface area.

Preparation of Granules

Paracetamol and extracted starch were passed through sieve # 40 and mixed for 20 minutes using laboratory scale double (twin) cone mixer. Granules were prepared by wet granulation method at the concentration of 2.0, 5.0 and 10.0 % w/v, the damp mass was passed through sieve # 12 and granules were dried at 50^⁰ for 1hour in a tray drier. The dried material was then passed through sieve # 16.

Evaluation of granules

The granules prepared were evaluated for flow properties, bulk density, tapped density Carr’s index and Hausner’s ratio. Bulk density was measured by taking accurately weighed powder into a gradated cylinder of tapped density apparatus and the volume was measured and recorded as bulk volume. The cylinder was tapped until powder bed volume reached a constant value and the volume was recorded as tapped volume. The bulk density, tapped density, and compressibility index were calculated using the equation¹³.

Bulk density = Mass / bulk volume

Tapped density = Mass / tapped volume

Compressibility index = [tapped density – bulk density] / tapped density

Carr’s index (CI) and Hausner’s ratio

Carr’s index (CI) and Hausner’s ratio were calculated by the following formula¹⁴

Carr’s index = {(Tapped density – Bulk density) / Tapped density} X 100

Hausner’s ratio = Tapped density / Bulk density

Angle of Repose (φ)

The angle of repose is used to characterize a flow property of the powder material. It was determined by conventional fixed height funnel method.

% Fines

For determination of % fines, the dried granules were placed on sieve no 60. The sieve was shaken gently and from the weight of the material that passed through the sieve, % fine was calculated.

Preparation of Tablets

Magnesium stearate, talc and aerosol 200 were mixed with prepared granules. These granules were punched to tablets using Rotary punching machine.

Characterization of Tablets

Tablet Thickness

The thickness of 10 tablets each selected at random from the formulated tablets was determined using a vernier calliper and the mean of these readings was taken as the mean tablets thickness.

Tablet weight uniformity

Twenty tablets were weighed individually using a digital balance with the precision of 0.05 mg and readability of 0.1 mg, from which the mean was calculated and percentage deviations determined.

Crushing Strength

The crushing strengths of tablets were determined individually with the Monsanto hardness tester, following 10 tablets were used and the mean crushing strength was calculated.

Friability

The friability of 10 tablets was determined using Roche friabilator (Electrolab, Mumbai). This device subjects the tablets to the combined effect of abrasions and shock in a plastic chamber revolving at 25 rpm and dropping the tablets at a height of 6 inches in each revolution. Preweighed sample of tablets was placed in the friabilator and were subjected to 100 revolutions. Tablets were dedusted using a soft muslin cloth and reweighed.

The friability (F) is given by the formula; F = (1 – W_o / W) x 100

Disintegration Test

The disintegration time of tablets was determined according to the method described in the British Pharmacopoeia 1998. Six tablets were placed in each compartment of the disintegration apparatus, with water thermostated at 37 ± 10 C as the medium. The tablets were considered to have passed the test after the 6 tablets passed through the mesh of the apparatus in 15 minutes.

Table 1: Properties of Manihot esculenta starch

Properties	Manihot esculenta starch
Cold water solubility (gm/dm3)	0.72
Bulk density (gm/ml)	0.653
Tapped density (gm/ml)	0.8971
Hausner’s ratio	2.2571
Carr’s compressibility index	27.7654
Angle of repose (degrees)	34.25

Table 2: Post Formulation Study of Paracetamol Tablets

Parameters	Formulations
	P1(2.5%)	P2(5%)	P3(7.5%)	P4(10%)
Hardness (kg/cm2)*	5.2±0.42	5.76±0.28	5.4±0.17	5.1±0.13
Friability (%)*	0.57±0.02	0.56±0.03	0.51±0.01	0.56±0.06
Weight variation (mg)*	501±3.76	504±3.10	503±1.65	505±3.65
Disintegration time(minutes)*	11.07±0.93	11.31±0.52	12.79±0.65	12.44±0.42
Thickness (mm)	4.1	4.1	4.2	4.2
Diameter (mm)*	11.6	11.6	11.6	11.6
Content uniformity (%)*	98.43±1.05	98.23±0.76	98.75±0.49	98.23±0.41
Dissolution time(After 60 minutes)*	72.46±0.12	80.71±0.23	74.25±0.23	81.33±0.16
Dissolution time(After 90 minutes)*	81.39±0.67	96.64±0.45	79.38±0.83	92.51±0.92
CSFR	9.354	9.537	10.556	10.693
CSFR/DT	0.664	0.727	0.890	0.974

RESULTS AND DISCUSSION:

The compressibility index and angle of repose indicated that the powder is having good flow with moderate compressibility. The Manihot esculenta starch exhibited a lesser solubility in cold water with values 0.72gm/dm3. The low bulk and tapped densities of Manihot esculenta starch indicate that materials were not highly porous and are poor flowing powders. The low bulk density results when the void spaces created by larger powder particles were not filled by smaller particles in distribution leading to consolidation of powder particles. The confirmation of the non free flowing nature of Manihot esculenta starch was gotten from the fact their Hausner’s ratio of 2.2571, which indicate low inter particulate friction powder.15 However, Manihot esculenta starch possessed better flow properties and it was confirmed by Carr’s compressibility index of 27.7654.

The post formulation study of Paracetamol tablets was shown in Table 2. The hardness of the tablets was within the acceptable range of 5-7 kg/cm2. It observed that the hardness increased with increasing binder concentration. The Manihot esculenta starch tablet hardness was generally higher at all concentrations of application, an indication that lower concentration of Manihot esculenta starch could be used to achieve the same level of binding. The friability of all the formulations was below 1.0%. The weight variation of all the formulations was within the range of 501-507mg. Disintegration time of all the formulations are within the official limits of B.P. (1998). The tablet thickness of all formulations was similar and this can be attributed to their similar bulk and tapped densities and same compression force used. The diameter of all the tablets was 11.6 mm. The drug content is more than 98% in all tablet formulations. The crushing strength to friability ratio (CSFR) can be used as a measure of mechanical strength of the formulated tablets. The CSFR and CSFR/DT values increased with increasing binder concentrations.

CONCLUSION:

Thus the Manihot esculenta tuber starch was found to be a better binding agent, being food article, free from toxicity and is also economic. Manihot esculenta starch studies are further going to explore its role in drug delivery systems including its release retardant properties and mucoadhesive nature.

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Received on 03.05.2012

Accepted on 05.06.2012

© A&V Publication all right reserved

Research Journal of Pharmaceutical Dosage Forms and Technology. 4(3): May-June 2012, 192-194