IN VITRO DISSOLUTION ENHANCEMENT OF ... patel.pdfhydroxy propyl beta cyclodextrin[4]. Cyclodextrins...

Vol-2, Issue-1, 2011 ISSN: 0976-7908 Patel et al

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PHARMA SCIENCE MONITOR AN INTERNATIONAL JOURNAL OF PHARMACEUTICAL SCIENCES

IN VITRO DISSOLUTION ENHANCEMENT OF ALBENDAZOLE

BY PREPARATION OF INCLUSION COMPLEXS WITH HP- ß

CYCLODEXTRIN

Vipul P. Patel*1, Rajesh K. Parikh1, Mukesh C. Gohel1, Tushar R. Desai2,

Dipen R. Bhimani 3, Pravin R. Tirgar3

1Department of pharmaceutical technology, L.M. College of pharmacy, Gujarat University, Ahmedabad, Gujarat, India. 2Department of pharmaceutical technology, R.K. College of Pharmacy, Gujarat technological university, Kasturbadham, Rajkot, Gujarat, India. 3Department of pharmacology, R.K. College of Pharmacy, Gujarat technological university, Kasturbadham, Rajkot, Gujarat, India.

ABSTRACT With the introduction of combinatorial chemistry and high throughput screening, the properties of new chemical entities shifted towards higher molecular weight and increasing lipophilicity that results in decreasing aqueous solubility. It is not surprising that many drug candidates have poor water solubility since the initial selection of drug candidates are based on activity alone. Other physiochemical and biopharmaceutical properties such as permeability, biopharmaceutics and metabolism are rarely considered during the selection process. The aim of this study was to increase dissolution rate of albendazole poorly soluble drugs from BCS class II by complexation process. Complexation was prepared using cyclodextrine. Different techniques were employed for preparation of complexation with cyclodextrin like physical mixture, cogrinding, kneading technology, solvent coevaporation. The physical properties of the prepared solid mass of ABZ was characterized by in vitro dissolution studies, UV-V spectroscopy, Fourior transform infrared spectroscopy, differential scanning calorimetry (DSC) and X-ray powder differaction spectroscopy. Additionaly, phase solubility studies were performed to support the in vitro dissolution study. The results of Fourior transform infrared spectroscopy shows the compatibility of drug with cyclodextrin, while differential scanning calorimetry (DSC) and X-ray powder differaction spectroscopy showed the confirmation of complexation of cyclodextrin with Abz. Key words: Albendazole, BCS class II drugs, complexation, Cyclodextrin Dissolution enhancement, Insoluble drug delivery system



INTRODUCTION

Albendazole (ABZ), methyl [5-(propyl-thio)-1-H-benzimidazole-2yl] carbamate,

is a broad spectrum antihelmintic drug with low aqueous solubility, which may limit its

oral absorption [1]. The albendazole therapy is very important in systemic cestode

infections specially in inoperable or disseminated cases of hydatidosis[2] and

neurocysticercosis[3]. The biggest problem of albendazole is its low and erratic

availability as a result of its low aqueous solubility. One possible way of overcoming this

problem is to alter the physical properties of the drug by forming a complexation with

hydroxy propyl beta cyclodextrin[4].

Cyclodextrins (CDs) are a group of structurally related cyclic oligosaccharides

that are formed by enzymatic cyclization of starch. The three most common naturally

occurring CDs are a-cyclodextrin (aCD), b-cyclodextrin (bCD) and g-cyclodextrin (gCD)

consisting of six, seven and eight (a-1,4)-linked a-D-glucopyranose units, respectively.

The CD molecules are cone-shaped with a somewhat hydrophobic central cavity and

hydrophilic outer surface. They are capable of forming inclusion complexes with many

drugs by taking up a whole drug molecule, or more frequently, some hydrophobic part of

it, into the cavity[5].

MATERIALS AND METHODS

ABZ were kindly supplied by Pramukh pharmaceutical pvt. ltd. (Gujarat, India),

HPbCD was supplied by Mepro Pharmaceutical pvt. Ltd (Gujarat, India). All the

products and materials used in this study comply with the pharmaceutical and analytical

standards, respectively.

All the research work was carried out at L.M. College of Pharmacy, Ahmedabad

during year 2008-2009.

Phase solubility study [6]:

Phase solubility study for ABZ was performed as described by Higuchi and

Connors. Excess amount of ABZ was added into 100 ml 0.1 N HCL containing carrier at

various concentrations and shaken for 96 h at room temp on a shaker (time period of 96

hr was previously determined for achievement of albendazole equilibilium). After

equilibilium, the suspensions were filtered through 0.45 μm Millipore membrane. filters.

The first 15% of the filtrate was discarded to avoid any potential loss of the drug, because



of absorption by the filter until and the subsequent filtrate was collected. The filtrate was

appropriately diluted by methanol and the concentration of the albendazole in the filtrate

was determined by UV spectrophotometer (UV-1601PC, Shimadzu) at 291 nm. Earlier

experiments showed that the presence of different carrier did not interfere with the assay

at the concentration employed. Solubility measurements were performed in triplicate.

Methods of preparation [7]:

Preparation of physical mixture (PM): The physical mixture of ABZ with hydroxy

propyl β cyclodextrin was prepared in 1:1.5, 1:2 and 1.5 geomatrix ratio by means of

spatula for 20 minutes and passed through 80 mesh screen.

Preparation of cogrinding product (CG): For co-grinding product, ABZ with hydroxy

propyl β cyclodextrin were mixed and triturated in glass mortar pestle for 20 minutes and

passed through 80 mesh screen.

Preparation of kneaded product (KN): The kneaded product was prepared by addition

of drug into the paste of cyclodextrin, and triturating the resultant mixture till cracking

sound appear. The resultant mass was dried at room temp. and pass through 80 mesh

screen.

Preparation of co-evaporated product (CE): For the preparation of co-evaporated

product, an aqueous solution of cyclodextrin was added to a methanolic solution of

albendazole. The resulting mixture was stirred for 1 hour and evaporated at 45-50 °c until

nearly dry. The resulting mass was allowed to dry at room temp for two consecutive

days. These dried mass pulverized and pass through 80 mesh screen.

Characterization

UV Spectroscopy: UV spectra were obtained on a UV spectrophotometer, Shimadzu

(L.M. College of pharmacy, Ahmedabad) with a wavelength range of 200 nm- 400 nm.

Fourier transform infrared (FTIR): Fourier transform infrared (FTIR) spectra were

obtained on a spectrophotometer (L.M. college of pharmacy, Ahmedabad) with a

resolution of 2 cm -1 from 3500 to 600 cm-1. Pellets were prepared by gently mixing the

sample with potassium bromide (1:100 ratio).

Differential scanning calorimetry (DSC): DSC measurements were made on a Pyris-

calorimeter (Perkin-Elmer). Approximately 3–5 mg samples were accurately weighed

into standard aluminum pans. An empty pan was used as reference. The samples were



heated from room temperature to 290 ◦C with scan rates 5◦C/min. All DSC curves were

normalized to a sample mass of 1 g. The instrument was calibrated using indium (melting

point, 156.61 °C; enthalpy of fusion, 28.71 J, g–1).

X Ray diffraction: The physical state of albendazole in pure drug powder and in

optimized mass was evaluated by powder X-ray diffraction. Powder X-ray diffraction

(XRD) patterns were determined with an X-ray diffractometer (SICART Mota bazaar,

Vallabh Vidyanagar), employing Ni-filtered CuKα

radiation source operating at 30

kVoltage and a current of 40 mA.

In vitro dissolution characterization: In vitro dissolution studies were carried out in

900 ml of 0.1 N hydrochloric acid containning 0.05 % w/v SLS using USP dissolution

apparatus with an aggitation of 100 RPM. SLS was used to maintain sink condition.

Powder sample equivalent to 200 mg of drug was filled in empty capsule shell and

immersed in the dissolution medium. The dissolution sample (10 ml) withdrawn at

different time intervals was filtered through a membrane filter (0.45 µm). This filtered

sample was diluted sufficiently by 0.1 N HCL and assayed spectrophotometrically at 291

nm. The cumulative percentage of drug release after 15 min, 30 min, 45 min, 60 min, 90

min, 120 min, 150 min, 180 min, 210 min and 240 min is measured.

TABLE 1: Formulation batches for Abz- Hydroxy propyl beta cyclodextrin

complexation

Methods of preparation

Drug to polymer ratio

Batch code

1:1.5 B1 1:2 B2

Physical Mixture

1:2.5 B3

1:1.5 B4

1:2 B5 Cogrinding product

1:2.5 B6

1:1.5 B7

1:2 B8 Kneaded product

1:2.5 B9

1:1.5 B10

1:2 B11 Co-evaporated product

1:2.5 B12



RESULTS AND DISCUSSION

Phase solubility study:

Figure 1 Phase solubility study of Abz with Hydroxy propyl Beta cyclodextrin Above

figure shows that solubility profiles of ABZ in 0.1 N HCL influenced by carrier material concentration at room temp. The solubility curve with correlation coefficient squared

values (r2) >0.95 (r2=0.95) was regarded as a straight line (AL type) (Higuchi and Connors, 1965).

UV Spectroscopy: Formulation excipients selected on the basis of preliminary tests,

which demonstrates no interference of these excipients with the λmax of ABZ.

The complex formation with cyclodextrin alters the original UV absorption

spectrum of the molecule usually bathochromic shift and or band broadening occurs. The

shift of the UV absorption maxima upon complex formation may be explained by a

particular shielding of the excitable electrons in the CD cavity [8].

Figure 2 Photographic image showing λmax of albendazole



Figure 3 Photographic image showing λmax of albendazole after complexation

FTIR

The spectrum for ABZ showed N-H stretching vibration at 3323 cm -1, bending

vibration at 1525-1630 cm -1 and aliphatic C-H at 2958 cm -1. The spectrum for ABZ has

NH stretching vibration at 3323 cm-1

due to carbamate-NH. PM of ABZ showed

superimposed spectra of ABZ and hydroxy propyl beta cyclodextrin which proves the

compatibility of excipients with the ABZ. Reduction in intensity of transmittance

occurred also for NH bending vibrations of ABZ (1525-1630 cm -1) in our optimized

batch containing solid binary system. From these results, it can be speculated that drug-

carrier hydrogen bonding existed in these solid binary system, causing reduced drug

recrystallization [9].

Figure 4 Fourier transforms infrared spectroscopy of Albendazole



Figure5 Fourier transform infrared spectroscopy of PM

Figure 6 Fourier transforms infrared spectroscopy of kneaded product albendazole

Differential scanning calorimetry (DSC): The DSC thermograms of albendazole,

albendazole (PM), and the inclusion complexes of albendazole are illustrated into the

Figure. Physical mixture showing almost similar identical melting endotherm and spectra

are overlapable which proves the compatibility of used excipients. The complex

formation was suggested by a decrease in enthalpy of dehydration/desolvation when

compared to the PM. The DSC curve of albendazole shows a sharp melting endotherm at



198°C. The melting endotherms into the prepared complexes are of decreased intensity

with lowering of melting temp. and more flattened compared with that in the pure drug,

probably due to greater disorder in the crystal structure.

Figure 7 DSC curve of albendazole

Figure 8 DSC curve of albendazole PM



Figure 9 DSC curve of albendazole kneaded product

X Ray diffraction

The Albendazole presented in a crystalline form as demonstrated by various

intense diffraction peaks in the figure. The crystalline peaks located at 7.01º, 11.22º,

13.83º, 17.87º, 19.50º, 20.71º, 22.10º, 27.10º, and 28.16º (2 θ) corresponding to

albendazole crystals were observed. Albendazole had a more intense peak at 7.01º,

11.22º, 17.87º, 19.50º, 20.71º, 22.10º, 27.10º, and 28.16º in addition to relatively less

intense peaks at 13.83º, 54.01º. XRD patterns of kneaded systems showed reduced

diffraction intensity as indicated in Fig 10 and 11.

Figure 10 XRD patterns of pure albendazole



Figure 11

XRD patterns of inclusion complex of albendazole

TABLE 2: In vitro dissolution profiles of albendazole from batch B1-B6

Time

(Minutes)

B0 B1 B2 B3 B4 B5 B6

DP15 6.2 8.1 9.6 11.1 9.3 10.1 13.4

DP30 8.9 11.0 13.4 17.5 12.4 14.2 19.2

DP45 10.2 13.6 15.2 19.3 15.9 17.8 21.4

DP60 11.8 16.8 18.5 21.7 18.4 20.5 23.6

DP90 13.6 18.1 22.3 25.3 19.7 23.8 24.9

DP120 15.2 19.7 23.5 27.2 20.9 26.2 26.9

DP150 19.4 24.3 25.6 28.5 24.8 28.4 29.7

DP180 22.8 26.7 28.2 30.8 28.3 31.4 33.1

DP210 25.3 30.5 31.6 32.4 30.5 35.9 36.8

DP240 28.5 33.9 35.7 37.1 35.2 37.6 39.8



TABLE 3: In vitro dissolution profiles of albendazole from batch B7-B12

Time (Minutes) B7 B8 B9 B10 B11 B12

DP15 13.6 19.58 23.8 12.2 19.4 22.0

DP30 19.2 25.29 29.8 19.8 25.8 30.7

DP45 24.5 30.77 33.6 25.2 31.2 35.6

DP60 29.6 36.20 39.3 30.1 36.5 39.8

DP90 33.6 40.09 44.6 34.1 41.7 45.0

DP120 35.9 45.11 48.3 36.0 46.3 50.2

DP150 38.6 49.39 51.7 38.4 49.4 50.9

DP180 41.5 54.11 55.8 41.9 55.4 56.2

DP210 45.2 58.28 60.0 46.5 58.6 59.4

DP240 48.6 62.69 63.4 49.7 63.1 64.2

Figure 12 Comparative dissolution profile of batch B1- B6



Figure 13 Comparative dissolution profiles of batch B7-B12

CONCLUSION

The aim of this work was to improve the dissolution rate of albendazole which is

required for improving the dosage form characteristic and also to reduce fluctuation in

dissolution profile as well as for better invivo characterization. Many techniques are

known to improve dissolution rate of poorly soluble drugs amongst these preparation of

physical mixture, co-grinding techniques, kneading techniques and solvent co-evaporated

techniques are selected in this research work because of its ease of preparation, ease of

optimization, and reproducibility. Amongst these techniques kneading method and

solvent co-evaporated methods found to be more effective than previous two techniques..

In case of albendazole as alone hydroxy propyl beta cyclodextrin cannot produce

satisfactory enhancement in dissolution rate and also due to limits of using polymer

concentration, third polymer as an acid solubilizer may added which increase the binding

property of ABZ with hydroxy propyl beta cyclodextrin and may be helpful for

improving further dissolution rate.

ACKNOWLEDGEMENTS

This work was entirely dedicated to my research guide Dr. M.C. Gohel and Dr

R.K. Parikh for their valuable cooperation and suggestion in my research work.



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For Correspondence: Vipul P. Patel R.K. College of pharmacy, Kasturbadham, Rajkot, Gujarat, India. MO- 09712902310, Email: [email protected]

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