Materials and methods

Evaluation of the binding and disintegrating properties of gum obtained from the stem bark of Cinnamomum zeylanicum

Materials

The bark of C. zeylanicum was obtained from Effiduase in the Ashanti region, Ghana, and authenticated at the Department of Herbal Medicine, Faculty of Pharmacy and Pharmaceutical Sciences, Kwame Nkrumah University of Science and Technology (Kumasi, Ghana) by a botanist. It was given a specimen voucher number of KNUST/ HM1/2018/SB002. Diethyl ether, ethanol (96%), paracetamol powder, acacia powder, starch powder, talc, magnesium stearate and lactose were obtained from UK Chemicals, Kumasi. All other reagents used were of analytical grade.

Extraction of gum from Cinnamomum zeylanicum bark

Distilled water (7 L) was added to 200 g C. zeylanicum powdered bark and allowed to stand for 24 h at room temperature (27 °C). The mixture was then boiled for 15 min, allowed to cool and filtered with a calico strainer to remove any debris to obtain the gum. Ethanol (96%) was used in purifying the gum obtained via precipitation. The precipitated gum was filtered, washed with diethyl ether and dried in a hot air oven at 60 °C for 12 h.8 The dried gum was milled, passed through a sieve with an aperture size 180 µm and appropriately stored for use.

Determination of moisture content

A mass of 1 g of the gum was transferred into a dried crucible of known weight and placed in an oven at 105 °C for 5 h. The crucible containing the gum was removed and allowed to cool at room temperature and weighed.

Swelling index and water holding capacity of Cinnamomum zeylanicum gum

An amount of 0.5 g C. zeylanicum gum (CZG) was transferred into a measuring cylinder, tapped and its volume recorded as V0 . It was then dispersed in 10 mL of distilled water and allowed to stand for 24 h. The volume occupied by the gum was observed after 24 h (V24) and calculated as: Swelling index = V24 - V0 V0 x 100 Contents in the measuring cylinder used for determination of the swelling index were also used to determine the water holding capacity as described by Ofori-Kwakye’s group.

Determination of the pH of CZG

Cinnamomum zeylanicum gum (0.1 g) was dispersed in 10 mL of water and stirred for complete dissolution. The pH was then checked with a pH meter (MW101, Milwaukee Instruments, Rocky Mount, NC, USA).11 This was done in triplicate.

Determination of moisture content

A mass of 1 g of the gum was transferred into a dried crucible of known weight and placed in an oven at 105 °C for 5 h. The crucible containing the gum was removed and allowed to cool at room temperature and weighed.

Swelling index and water holding capacity of Cinnamomum zeylanicum gum

An amount of 0.5 g C. zeylanicum gum (CZG) was transferred into a measuring cylinder, tapped and its volume recorded as V0 . It was then dispersed in 10 mL of distilled water and allowed to stand for 24 h. The volume occupied by the gum was observed after 24 h (V24) and calculated as: Swelling index = V24 - V0 V0 x 100 Contents in the measuring cylinder used for determination of the swelling index were also used to determine the water holding capacity as described by Ofori-Kwakye’s group.

Determination of the pH of CZG

Cinnamomum zeylanicum gum (0.1 g) was dispersed in 10 mL of water and stirred for complete dissolution. The pH was then checked with a pH meter (MW101, Milwaukee Instruments, Rocky Mount, NC, USA).11 This was done in triplicate.

Compatibility studies on formulated granules (Paracetemol powder, CZG)

Paracetamol powder, CZG and formulated granules were individually scanned using a Fourier transform infrared spectrophotometer (Bruker Alpha II, Germany) over 500–3500 cm-1 wavelengths. Their spectra were then superimposed to assess the presence or absence of principal bands of paracetamol in the formulated tablets.

Determination of the flow property of CZG

Cinnamomum zeylanicum gum (30 g) was weighed (M) and transferred into a 100-mL measuring cylinder and the initial volume (V0) recorded. The measuring cylinder was tapped on a bench until a constant volume (Vf ) of the gum was obtained. The bulk density, tapped density, Carr’s index and Hausner ratio were calculated as: Bulk density = M V0 Tapped density = M Vf Carr’s index = (Tapped density - bulk density) Tapped density x 100 Hausner ratio = Tapped density Bulk density The fixed height method was also used in the angle of repose determination. The gum was allowed to freely flow through a clamped funnel to form a heap. The height (h) and diameter (d) of the heap were determined. Using the equation below, the angle of repose (α) was calculated: tan (α) = h/(0.5 d)

Formulation of tablets

The wet method of granulation and the technique of doubling the bulk were employed in preparing 12 batches of paracetamol granules. CZG was used as a binder (10% w/v, 15% w/v and 20% w/v) for Batches 1–3 (B1–B3) and as a disintegrant (5% w/w, 7.5% w/w and 10% w/w) for B7–B9. Acacia gum and starch were used as a standard binder and disintegrant, respectively, at the same concentrations stated above for B4–B6 and B10–B12, respectively. All ingredients except talc and magnesium stearate were accurately weighed and mixed together with water as the granulating fluid to form a damp mass. This was then screened with a mesh (2360 µm) and dried at 60 °C for 2 h in an oven. The dried granules were screened with a 1180 µm sieve, mixed with magnesium stearate and talc and compressed into tablets using a single punch tableting machine (TDP 5, Herun, China). Sixty (60) tablets were compressed from each batch to cater for all quality control tests. The constituents of the formulated tablets are given in Table 1.

Evaluation of tablets Weight uniformity test

Twenty tablets were randomly selected from each batch and individually weighed to calculate average weight. The average weight and percentage deviation of each tablet were determined as described in the British Pharmacopoeia.14

Evaluation of tablets Friability test

Ten tablets from each batch were randomly selected and weighed. They were then placed in a friabilator (EF-2W, Roche, Switzerland) regulated at 4 min at a speed of 25 rpm (revolutions per minute). Afterwards, the tablets were removed from the friabilator, dedusted and reweighed.15 The percentage friability was calculated as: Friability (%) = W0 - W W0 x100 where W is the final weight and Wo is initial weight.

Disintegration test

Six tablets from a batch were selected at random and each tablet placed in a tube of the basket-rack assembly in an Erweka disintegration apparatus (ZT 320 series, Germany). The basket rack was placed in a water bath regulated thermostatically at 37±2 °C and observed until all the tablets had disintegrated completely.12 This procedure was repeated for all batches.

Uniformity of dimension and hardness test of tablets

Ten tablets were randomly selected from each batch. Their diameters and thickness were determined using vernier calipers. The hardness of ten randomly selected tablets from each batch was determined with a Veego hardness tester (DIGITAB-SPV, India). The tensile strength was calculated as: Tensile strength= 2F πDt where D is the diameter, t is the tablet thickness and F is the diametrical break force of the tablet. Uniformity of drug content Ten tablets from each batch were randomly selected. Each tablet was crushed, dissolved in 50 mL of HCL (0.1 M) and the mixture topped up to 100 mL using 0.1 M HCL. The mixture was filtered and its absorbance determined at 245 nm using a UV spectrophotometer (DU-8800R, Drawell, Shanghai). A standard calibration curve was used to calculate the average drug content for three determinations.

In vitro dissolution studies

In vitro drug release of the tablets was determined using the USP II dissolution apparatus (DT6, Erweka, Germany) at 50 revolutions per minute. Six (6) tablets each for all batches were evaluated. A tablet was put in each vessel containing 900 mL of the dissolution medium, HCL (0.1 M), at 37±0.5 °C. A volume of the medium (10 mL) was drawn at time intervals (5, 15, 30, 45 and 60 min) and filtered using Whatman filter paper number 5 with a pore size of 2.5 μm. The volumes taken were replaced to maintain sink conditions. A UV-visible spectrophotometer (Alpha II, Bruker, Germany) was used to check the absorbance of the filtrates at a wavelength of 245 nm. The average drug release profile for three determinations was carried out using a standard calibration curve.16 The various batches of tablets which passed the dissolution profile were analysed for their similarity factor (f2) using the equation: Similarity factor (f2) = 50xlog {1+ (1/n) ∑t=1n (Rt −Tt )2 }-0.5 x 100 where n = dissolution time points, Rt = dissolution value for reference at time t, and Tt = dissolution value at time t.

Article TitleEvaluation of the binding and disintegrating properties of gum obtained from the stem bark of Cinnamomum zeylanicum

Abstract

Excipients are the various ingredients, apart from the active pharmaceutical ingredients, which are added to pharmaceutical formulations. Excipients obtained from natural sources are preferred over those from synthetic sources because they are cheap, biocompatible and readily available. Gums are made up of carbohydrate units which are linked by glycosidic bonds. This study was aimed at evaluating the potential binding and disintegrating properties of gum obtained from the bark of Cinnamomum zeylanicum, which was obtained from Effiduase in the Ashanti region of Ghana. The gum was extracted using 96% ethanol and the moisture content, Fourier transform infrared spectroscopy spectra, water holding capacity, swelling index and flow properties of the gum were determined. The gum was used to formulate tablets at different concentrations (10% w/ v , 15% w/ v and 20% w/ v ) as binder with acacia as the standard. The gum was also used to formulate tablets at different concentrations (5% w/ v , 7.5% w/ v and 10% w/ v ) as disintegrant with starch as the standard. Quality control tests were then conducted on all formulated tablets. The gum exhibited good flow and physicochemical properties. All formulated tablets passed the uniformity of weight test, friability test, disintegration test, hardness test, uniformity of dimensions test and drug content. All batches of tablets, except Batch 7, passed the dissolution test. Based on the study carried out, C. zeylanicum gum can be used as an alternative excipient to acacia and starch as a binder and a disintegrant, respectively.


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