In-vitro Characterization and Pharmacokinetic investigation of self-Micro-Emulsifying Tablets of Cinnarizine

Bibaswan Mishra^1*, Prasanta Kumar Biswal², Nihar Ranjan Pani², Prasanna Kumar Dixit³

¹Institute of Pharmacy and Technology, Salipur, Cuttack, Odisha, India

²Gayatri College of Pharmacy, Sambalpur, Odisha, India

³Department of Zoology, Berhampur University, Ganjam, Odisha, India

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

ABSTRACT:

The present study aims to design and develop a self- micro-emulsifying tablets of cinnarizine with a suitable adsorbent of self microemulsion liquid to enhance the dissolution and oral bioavailability. The tablets were prepared by wet granulation compression of the self-micro-emulsifying granules. The granules were characterized through flow property. Droplet size distribution of disintegrated SMET emulsion sample was found to be within 3.86 ± 3.77 to 5.41 ± 2.93 μm which infers that all the SMETs showed good emulsification properties with low globule size. The tablets were tested for weight variation, friability, hardness, drug content, disintegration and in-vitro dissolution profile. The pharmacokinetic study of SMET of cinnarizine formulation was performed in rabbits and the pharmacokinetic parameters were compared with a piece of commercial tablet. The tablets showed acceptable physical properties with disintegration time less than 13 sec. The dissolution profile of selected formulation revealed more than 80 percent drug released in just 5 minutes. The pharmacokinetic parameters such as C_max and AUC_0-∞ of F7 found 1.5 and 1.8 times more than that of commercial product respectively. The results infer that the prepared of SMET formulation of cinnarizine is a potential formulation with profound reproducibility may be manufactured for commercial batch.

KEYWORDS: Self-micro-emulsifying tablets; In vitro dissolution; Oral bioavailability; Pharmacokinetic parameter; cinnarizine.

INTRODUCTION:

Self-emulsifying drug delivery system (SEDDS) is a delivery approach to a wide range of drugs which are biopharmaceutically challenged. It is formulated from a broad range of oils, surfactants and co-surfactants. This system emulsifies upon gentle agitation which improves the solubility of the hydrophobic drug in-vivo bypassing the dissolution step. This eventually leads to increased bioavailability^1,2. Though there are many novel delivery approaches has been utilised to improve the bio availability of poorly soluble drugs by the pharmaceutical scientists in recent days^3,4,5, SEDDS has gained a tremendous applicability to a wide range of drugs.

The basic reasons are (i) drugs are available in the solution form after spontaneous emulsification in the dissolution medium; (ii) the tiny droplets provides a large effective interfacial area for better absorption. SEDDS can be categorised as Self-micro emulsifying drug delivery systems (SMEDDS) and Self-nano-emulsifying drug delivery systems (SNEDDS) according to the size of the particle it produces in the medium^1,2,6.

Adsorption of liquid SMEDDS into solid carrier producing free flowing powders reduce the risk of instability and can be compressed into tablet called self-micro-emulsifying tablets (SMETs). The formation of microemulsion from SMET and its characteristics depend upon the physical and chemical attraction between the liquid self- micro-emulsifying formulation and the adsorbing solid carrier.

The aim of the present study was to develop and formulate self-micro emulsifying tablets of cinnarizine (CIN). Cinnarizine, a piparizine derivative anti histaminic drug used for controlling vomiting due to motion sickness and vertigo. The pH dependant erratic absorption of cinnarizine is an obstacle in the development of suitable dosage form. Hence it was an attempt to increase the bioavailability by present the drug directly into the solution form for better absorption independent of pH of the medium⁷. The pharmacokinetic study of SMET of cinnarizine formulation containing 10 mg of CIN was performed in rabbits and the pharmacokinetic parameters were compared with a piece of commercial tablet at the equivalent dose (DIZZIGO).

MATERIALS AND METHODS:

Materials:

Cinnarizine was obtained as a gift sample from Macleods pharmaceutical limited, Mumbai, India. Linoleic acid, Tween 80 and Polyethylene glycol 400 were procured from S.D Fine chemical Ltd, Mumbai, India. Maltose, Microcrystalline Cellulose (MCC), Cross carmelose sodium (CCS), and PVP K-30 were procured from Qualigens, Mumbai India. All other chemicals used were of analytical grade.

Methods:

Preparation of self-emulsifying liquid:

A self-emulsifying system was prepared containing CIN and linoleic acid (oily mix), PEG 400 as surfactant and tween 80 as co-surfactant (table-1). The oily mix consisting of CIN and linoleic acid as oil base at a ratio of 1:1 was accurately weighed and taken into screw capped glass vial. The mixture was melted in a water bath at 37°C. PEG 400 and tween 80 at appropriate proportion (table-1) were added to the oily mix and stirred with a magnetic bar until a transparent solution was obtained.

Preparation of self-micro-emulsifying tablets:

SMETs containing CIN were prepared according to the formula specified in table-1. The self-emulsifying drug solution was initially mixed with maltose using mortar and pestle to form a semisolid paste. Appropriate amount of cross carmelose sodium was grinded with the above mixture for 1 min to obtain the dry emulsion based granules. Then micro crystalline cellulose was blended with the granules in a polybag for 5 minutes. PVP of 12mg/tablet was added to the blended mixture and granulated with ethanol. The prepared ethanolic mass were dried at 45° C in a hot air oven, then the dried mass were passed through 16 mesh sieve to get the free flowing granules. Remaining quantity of CCS and MCC were blended to the dried granules and subjected to direct compression with tablet compression machine (Lab press, Model-1049, Ahmadabad, India) using 8mm die punch.

Characterization of self-emulsifying granules:

The flow properties of the self-emulsifying granules were determined from the compressibility index and Hausner’s ratio.

Compressibility Index of the powder:

Compressibility index is the simplest way for measurement of flow ability of powder. The compressibility index (CI) was calculated as follows,

CI= [(Tapped density- Bulk density)/ Tapped density] X 100

Hausner’s ratio of the powder:

Hausner’s ratio is also used to characterise the powder flowability. It was calculated using the following formula,

Hausner’s ratio = Tapped density/Bulk density

Characterization of self-micro-emulsifying tablets:

The prepared SMETs were evaluated for weight variation, friability, hardness, drug content, disintegration and in-vitro dissolution profile⁸.

Weight Variation:

Ten tablets were selected randomly from each formulation and weighed individually using digital balance. The weight variation of individual tablet from its mean value was calculated.

Table-1 Formulation of self-micro-emulsifying tablets of cinnarizine

Name of ingredients	Quantity (mg/tablet)
Name of ingredients	F1	F2	F3	F4	F5	F6	F7	F8
Self-micro-emulsifying liquid solution
Cinnarizine	10	10	10	10	10	10	10	10
Linoleic acid	10	10	10	10	10	10	10	10
Tween 80	5	5	5	5	5	5	5	5
PEG 400	5	5	5	5	5	5	5	5
Compression of Self-micro-emulsifying tablets
CCS	50	50	50	50	60	60	60	60
Maltose	100	100	80	80	100	100	80	80
MCC	30	40	30	40	30	40	30	40

PEG 400; polyethylene glycol 400, CCS; cross carmelose sodium, MCC; Microcrystalline cellulose

Hardness Test:

Hardness is an indication of tendency of tablet to withstand the mechanical shocks while handling. The hardness of the tablets were determined using Monsanto hardness tester by placing the tablet between two plunges. The force required to crack the tablet was recorded. The experiment was conducted for five tablets and the average was reported.

Friability Test:

Twenty tablets in random were selected for the test. The initial weight was measured and transferred into Roche friabilator. The friabilator was operated at 25 rpm for 4 minutes. Then the intact tablets were withdrawn and reweighed. The percentage friability was calculated as follows

Friability = [(Initial weight – final weight) / initial weight] x 100

Content uniformity study:

Ten tablets were individually weighed and crushed. A quantity of powder equivalent to the mass of one tablet (10 mg) was dissolved in 100 mL of 0.1 N HCl, pH 1.2 with vigorous stirring. The solution was filtered through a cellulose acetate membrane filter (0.45 µm). The drug content was determined using UV-visible spectrophotometer (Shimadzu UV-1700, Japan) at a wavelength of 253 nm after a suitable dilution with the same medium.

Disintegration Time:

The Disintegration time of the SMETs were calculated using the USP Disintegration test apparatus (Veego, Mumbai, India). One tablet was placed in each tube of the apparatus containing 900 ml of distilled water and the apparatus was started. The time required to pass the tablet mass completely through the mesh of the tube was considered as disintegration time.

Droplet size and turbidity measurements:

The disintegrating fluid containing the emulsion from the SMETs were considered to determine droplet size and turbidity. The fluid were centrifuged at 1000 rpm for 5 min to separate the emulsion layer at supernatant from adsorbed solid materials present in SMETs. The droplet size and turbidity of the emulsion were determined as follows^9,
10.

Droplet size analysis:

The droplet size distribution of emulsion was determined by laser diffraction analysis using Coulter particle size analyser (Beckman Coulter, Mumbai, India) with a particle size measurement range of 0.04–2000 μm. Samples were placed into small volume module and the data were collected for 60 sec. Particle size was measured from the volume size distribution.

Turbidity measurement:

Digital Nephelo-Turbidity (Model 132, Systronics, Ahmedabad) was used to find out the turbidity of 30 ml of the resultant emulsions in nephlometric turbidity units (NTU).

Dissolution study:

The in vitro dissolution study of each batch of SMET containing CIN was carried out using USP Dissolution apparatus, type-I. The rotating speed was fixed at 75 rpm in 900ml of 0.1 N HCl, pH 1.2 at dissolution medium, maintained at 37±0.5°C. The drug release was estimated as a function of time. Aliquot of 5ml of sample was drawn at each 5 min interval and same amount of fresh dissolution medium was replaced. The drug release was estimated by analysing the aliquots using UV-visible spectrophotometer (Model UV-1700, Shimadzu, Japan) at a wavelength of 253 nm after suitable dilution

Analysis plasma sample:

Chromatographic condition:

CIN in blood plasma was analysed by reverse-phase high-performance liquid chromatography (HPLC, Shimadzu Prominence LC 20 AT, Japan) equipped with the Pinnacle II C18 column (150mm× 4.5 mm, 5 μm) by following the little deviation in method described by Puttemans et al ¹¹. The mobile phase was consisting of a mixture of methanol and phosphate buffer (pH = 7.0 and ionic strength 0.1) at the ratio of 9:1. The mobile phase was pumped at a flow rate of 1 ml/min. The UV detector (Shimadzu Prominence SPD 20A UV/VIS detector, Japan) was set at 248 nm. Meclozine was considered as internal standard for plasma sample processing. The retention time of cinnarizine and meclozine was 7.2 and 11.4 min respectively.

Plasma sample processing:

An aliquot quantity of 190 μL of rabbit plasma sample was taken in a 2 mL stopper centrifuge tube. To this, 10μL of internal standard (Meclozine) solution (100μg/mL) was spiked and mixed for 20 sec. The drug was extracted by vortexing with 1.5 mL of methanol in a spinix vortexer (TARSONS, Kolkata, India) for 10 min followed by centrifugation at 10000 rpm for 5 min at 4° C. The supernatant was withdrawn and dried using nitrogen evaporator. The residue was reconstituted with 100 μL of mobile phase and 20 μL was injected onto HPLC for analysis.

In vivo Pharmacokinetic study:

The single dose pharmacokinetic study of F7 formulation containing 10 mg of cinnarizine (F7) and a piece of commercial tablet (DIZZIGO-25 mg) equivalent to 10 mg of CIN were studied in white male albino rabbits. The protocols of study were approved and conducted according to the guidelines of the Institutional Ethical Committee at the Gayatri College of Pharmacy, Odisha, India (Committee for Prevention, Control and Supervision of Experimental Animals, Reg. no. 1339/ ac/10/CPCSEA). The rabbits weighing 1.7 – 2.2 kg were housed with free access to food and water, except for the final 12 h before experimentation. After a single oral administration of tablet (F7) and a piece of commercial tablet of CIN through feeding tube, 2 mL of blood samples were collected from the marginal ear vein at 0.25, 0.5, 1, 2, 3, 4, 6, 9, 12 and 24 h time points into heparinized collection tubes. The blood was immediately centrifuged (10000 rpm) for 10 min at an ambient temperature. The supernatant plasma layer was separated and stored at −20 °C until analysed.

Calculation of Pharmacokinetic parameters:

The first order elimination rate constant (K_E) was estimated by the least square regression of plasma concentration–time data points of the curves describing the terminal log-linear decaying phase. t_1/2 was derived from K_E (t_1/2 =0.693/ K_E). The area under the plasma concentration–time curve from zero to the last measurable plasma concentration at time t (AUC_0−t) was calculated using the linear trapezoidal rule. The area was extrapolated to infinity (AUC_0−∞) by addition of C_t/K_E to AUC_0−t, where C_t is the last detectable drug concentration. The absorption rate constant (K_a) was determined by residual method. The maximum observed CIN concentration (C_max) and the time at which C_max was observed (T_max) were reported directly from the profile. The AUMC; area under the first moment curve was calculated by trapezoidal rule. Volume of distribution (V_d) and total clearance rate (TCR) were calculated using Eqs. (1) and (2) respectively. The mean residence time (MRT) was determined by AUMC divided by AUC. The clearance (Cl) was calculated as dose divided by AUC with extrapolation to infinity (AUC_0−∞).

V_d = (D⁰_G .AUMC)/ (AUC) ² (1)

TCR = K_E. V_d = (V_d. 0:693) / t_1/2(2)

RESULT AND DISCUSSION:

Characterisation of self-emulsifying granules:

The flow properties of self-emulsifying granules were characterised by determining the compressibility index and Housner’s ratio (table-2). The compressibility index and Housner’s ratio of various formulation were found to be in the range of 4.18-5.42 and 1.04-1.05 which showed that the granule have good flow properties for tablet compression.

Evaluation of self-micro-emulsifying tablet:

Weight variation, hardness and friability:

The result of weight variation, hardness and friability for all the formulations are depicted in table-2. It was observed that the percent weight variation was within the pharmacopoeia limit i.e. ±7.5% of the total tablet weight. The hardness of all SMETs were found to be reasonable with sufficient strength and integrity. The result of friability testing of all batches of SMETs were less than 1%. The outcome signifies that the SMETs having sufficient strength to withstand the mechanical risk during transportation.

Content uniformity test

The drug content of all batches of SMETs are depicted in table-2. All the formulation showed more than 99% drug content with acceptable deviation from the mean value.

Disintegration Time

The result of disintegration test for the SMETs is depicted in table-2. It was observed that as the concentration of CCS was increased, the disintegration time (DT) of the tablets were decreased. Similarly the concentration of MCC is inversely proportional to the DT of tablets as the DT of F-2, F-4, F-6 and F-8 (MCC, 40 mg/tab) were less than the DT of F-1, F-3, F-5 and F-7 (MCC, 30 mg/tab) respectively. The DT was found to be insignificant with change of maltose concentration. However the DT of all the tablet formulation were very short which infers the rapid bursting of tablets.

Particle size and turbidity of oil globules

Droplet size distribution of disintegrated SMET emulsion sample was found to be within 3.86 ± 3.77 to 5.41 ± 2.93 μm (Table-3) which infers that all the SMETs showed good emulsification properties with low globule size. Turbidity (in NTU) shown in table-3 were measured for the same samples utilized for particle size analysis.

In vitro Drug Release Study:

The in vitro drug release profile of each batch of SMETs is shown in figure-1. It was observed from the data that the rate of drug release increases as the concentration of super disintegrant (CCS) in the tablet increases. Comparing the batch F1 with F2 and F3 with F4, it can be conferred that MCC also played a significant role in increasing the drug release. But the role of maltose is found to be insignificant on the release pattern of drug. As amount of ingredients present in F-7 less and showing a considerable dissolution profile, the cost of the F-7 will be minimum. Hence F-7 formulation was selected for further part of evaluation.

Table-2 Characterisation of Self-micro-emulsifying tablet formulations

Parameters	F1	F2	F3	F4	F5	F6	F7	F8
Evaluation of granules
CI (%)	5.42	5.17	5.09	5.18	5.42	4.18	4.63	4.91
Hausner’s ratio	1.05	1.05	1.05	1.05	1.05	1.04	1.04	1.05
Evaluation of Tablets
Weight Variation (mg)	222.05 ±3.19	235.64 ±2.13	209.21 ±2.96	217.31 ±2.56	221.59 ±1.94	231.58 ±1.85	215.83 ±2.37	234.43 ±2.87
Hardness (Kg/cm²)	3	3.5	3	3.5	3	4	3	3.5
Friability (%)	0.48	0.41	0.38	0.69	0.57	0.49	0.63	0.54
Content uniformity (%)	99.03 ±3.19	99.83 ±2.98	99.18 ±3.01	99.59 ±3.29	100.01 ±2.94	100.74 ±3.09	99.59 ±2.37	100.45 ±2.45
DT (sec)	12.83	10.83	12.67	10.00	6.67	6.5	6.67	6.33

CI; Compressibility index, DT; Disintegration time

Table-4 Comparison of pharmacokinetic parameters of single dose administration of F7 and commercial tablet of cinnarizine to rabbits

Pharmacokinetic parameters; n=3	Observed value
Pharmacokinetic parameters; n=3	F7	Commercial Tablet
Maximum plasma concentration, C_max (μg/mL)	4.56 ± 0.62	3.01 ± 0.43
Time required to reach maximum plasma concentration, t_max (h)	1.14 ± 0.42	1.17 ± 0.37
Area under the curve, AUC_0-∞ (hr μg/mL)	37.64 ± 14.28	22.43 ± 3.56
Elimination rate constant, K_E (h^-1)	0.16 ± 0.01	0.17 ± 0.02
Elimination half life, t_1/2 (h)	4.42 ± 1.02	4.02 ± 0.39
Area under moment curve, AUMC_0-∞(hr²μg/mL)	251.78 ±131.28	138.69 ± 26.25
Mean residence time, MRT (h)	6.69 ± 0.43	6.18 ± 1.17
Absorption rate constant, K_a (h^-1)	1.13 ± 0.09	1.14 ± 0.11
Absorption half life, (t_1/2)_a (h)	0.61 ± 0.02	0.61 ± 0.06
Volume of distribution, Vd (L)	10.17 ± 0.87	16.02 ± 3.47

Figure-1 Dissolution profile of cinnarizine from SMETs

*a, SMET of cinnarizine (F7); b, Commercial tablet of cinnarizine

Figure-2 Comparison of mean plasma drug concentration versus time profile between commercial tablet and SMET of cinnarizine after single oral administration to rabbits.

CONCLUSION:

In the present study the influence of excipients such as cross carmelose sodium, maltose and microcrystalline cellulose on tablet performances, especially dissolution time of Cinnarizine SMET was accessed. The quantitative effect of these ingredients at different concentration were found out. Droplet size of disintegrated SMET emulsion sample of CIN was in micron range (3.86 ± 3.77 to 5.41 ± 2.93 μm). The pharmacokinetic parameters such as C_max and AUC_0-∞ of F7 found 1.5 and 1.8 times more than that of commercial product respectively. It infers that the prepared of SMET formulation of cinnarizine is a better formulation with profound reproducibility may be manufactured for commercial batch.

CONFLICT OF INTEREST:

The authors declare no conflict of interest

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Received on 26.06.2017 Modified on 18.07.2017

Research J. Pharm. and Tech 2017; 10(10):3492-3497.

DOI: 10.5958/0974-360X.2017.00625.4

Parameters	F1	F2	F3	F4	F5	F6	F7	F8
Particle size (μm)	3.92± 3.77	3.92± 4.56	4.47± 3.45	4.94±4.19	5.16±3.98	5.41±2.93	4.72±3.71	4.18±4.41
Turbidity (NTU)	17.73±5.67	18.49± 6.31	22.84±6.39	20.74±4.73	17.84±6.84	17.19±5.12	23.99±6.09	22.68±5.37