INTRODUCTION:

Aqueous solubility is one of the key determinants in development of new chemical entities as successful drugs. The Biopharmaceutics Classification System was introduced by the US Food and Drug Administration (FDA) to assess oral drug products. In this system, drugs are classified into four groups based on the ability of a given drug substance to permeate biological membranes and aqueous solubility. A given drug substance is considered ‘highly soluble’ when the highest dose strength is soluble in 250ml water or less over a pH range 1 to 7.5, and is considered ‘highly permeable’ when the extent of absorption in humans is determined to be =90% of an administered dose (in solution), based on mass balance or related to an intravenous reference dose.

Cyclodextrins comprise a family of three well-known industrially produced major, and several rare, minor cyclic oligosaccharides. The three major CDs are crystalline, homogeneous, nonhygroscopic substances, which are torus-like macro-rings built up from glucopyranose units.

The α-cyclodextrin (Schardinger’s α-dextrin, cyclomaltohexaose, cyclohexaglucan, cyclohexaamylose, αCD, ACD, C6A) comprises six glucopyranose units, βCD (Schardinger’s β-dextrin, cyclomaltoheptaose, cycloheptaglucan, cycloheptaamylose, βCD, BCD, C7A) comprises seven such units and γCD (Schardinger’s γ-dextrin, cyclomaltooctaose, cyclooctaglucan, cyclooctaamylose, γCD, GCD, C8A) comprises eight such units.

MATERIALS AND METHOD:

Domperidone was obtained as a gift sample from IPCA Laboratories, Ratlam. β-Cyclodextrin, Hydroxy propyl-β-Cyclodextrin were obtained from Roquette Fereres, France. All other chemicals used in the study were of analytical grade and used as received.

PREPARATION OF INCLUSION COMPLEXES:

Kneading Method:

Domperidone and the various cyclodextrin were weighed in different ratio and transferred to mortar and kneaded for 45 min. using alcohol-water mixture in ratio 1:1, sufficient solvent was added to maintained paste like consistency. The resulting paste was then dried in oven at 50^οC for 24 hours. The dried complexes were grounded in mortar for 2 min and passed through sieve no. 100. The prepared complexes were stored in glass vials and used for further studies.

Ultrasonification Method:

Domperidone and the various Cyclodextrins were weighed in different ratio as shown in Table 1 and transferred to beaker using alcohol-water mixture in ratio 1:1, sufficient solvent was added to maintained paste like consistency. The resulting paste was then ultrasonificated for 6 hours. Throughout Ultrasonification paste like consistency was maintained using alcohol-water. Then it was dried in oven at 50^οC for 24 hours. The dried complexes were passed through sieve no. 100. The prepared complexes were stored in glass vials and used for further studies.

Physical Mixture:

Physical mixtures were prepared by simply blending Domperidone and CDs with 1:1 molar ratio uniformly in a mortar.

Table 1: Composition of physical mixture

S.N.	Composition	Ratio (M)
1	Domperidone:HP-β-CD(PMHP1)	1:1
2	Domperidone:M-β-CD( PMM1 )	1:1

‘M’ represents molar ratio

EVALUATIONS OF INCLUSION COMPLEXES:-

UV Interference:

Scanning of inclusion complexes were performed to evaluate whether there is any interference in UV detection of inclusion complexes compared to control (drug) which can depict the drug polymer interaction if any.

Method:

The UV interference of each inclusion complexes was determined using powder equivalent to 10 mg of Domperidone and was dissolved in 20 mL of 0.1M HCl using the mechanical shaker for 20 min. and to the solution obtained 0.1M HCl was added and volume made to 50 mL. The solution was then filtered through Whatman filter paper No.42 and required dilutions were made and finally dilutions were scanned.

Drug content:

Method:

The percent drug content of each inclusion complexes were determined using powder equivalent to 10 mg domperidone and was dissolved in 20 mL 0.1M HCl using the mechanical shaker for 20 min. and to the solution obtained 0.1M HCl was added and volume was made to 50 mL. The solution was then filtered through whatman filter paper no.42 and required dilutions were being made and absorbance was taken at 284.20 nm.

DISSOLUTION STUDIES:

The dissolution studies on pure drug and inclusion complexes (equivalent to 10 mg of drug) were performed.

Dissolution medium: 0.1M HCl (pH1.2) – 900 mL

Speed – 100 rpm

Temperature – 37 ºC ± 0.5 ºC

Apparatus – USP II (Rotating paddle type)

Method- During dissolution study 10 mL aliquot was withdrawn at different time intervals of 5, 10, 15-------60 min. and same was replaced with equal volume of fresh medium. The withdrawn sample were filtered through Whatman filter paper no.42 and absorbance were measured at 284.20 nm for 0.1M HCl

Stability studies:

The inclusion complex (USM1) and (USHP2) were selected as optimized inclusion complex and stability study was carried out at

i) 25ºC ± 2ºC and 75 ± 5 %R.H.

ii) 40ºC ± 2ºC and 75 ± 5 %R.H.

for the period of three months.

Method:

The inclusion complexes were placed in amber coloured bottles and put at above specified conditions for 3 months. After every month inclusion complexes were analyzed for drug content.

RESULT AND DISCUSSIONS:

U V Intereference:

In order to study the possibility of any drug polymer interaction, the scanning of the various inclusion complexes were carried out in 0.1M HCl and scanning results indicated that there was no interference or shifting of lmax of domperidone which reflects no drug polymer interaction.

Table 2 : UV interference of inclusion complexes

S. N.	Inclusion complexes	0.1M HCl	Distilled Water
1	KNHP1	-	-
2	KNHP2	-	-
3	USHP1	-	-
4	USHP2	-	-
5	KNM1	-	-
6	KNM2	-	-
7	USM1	-	-
8	USM2	-	-

(- indicate no interference)

Drug content:

Drug content of all inclusion complexes were in the range of 78.94 - 88.43%. This indicates the proper loading of drug in inclusion complexes and effectiveness of kneading method and Ultrasonification.

Table 3 : Percent drug content in inclusion complexes

S.N.	Composition	*Drug content (%)**
1	KNHP1	78.94±0.289
2	KNHP2	80.67±0.771
3	USHP1	83.09±0.254
4	USHP2	85.33±1.56
5	KNMP1	83.58±0.985
6	KNMP2	82.74±0.258
7	USM1	87.81±0.357
8	USM2	88.43±0.159

* Represents mean ± S.D. (n= 3)

SOLUBILITY AND DISSOLUTION:

The solubility of all inclusion complexes was studied in distilled water and 0.1M HCl. The data indicated that solubility increased in all cases but highest increase was found in inclusion complexes prepared by Ultrasonification with HP-b-CD prepared in 1:2 M (USHP2) and in methylated betacyclodextrin prepared in 1:1 ratio (USM1).

The mean dissolution curve of Domperidone from various binary systems with CD’s is present in Fig.1-2. It is evident at a glance that all system with CD’s exhibited better dissolution properties than pure drug alone. Statistically significant difference in term of dissolution were found in all the Domperidone M-β-CD system and corresponding one with HP-β-CD reflecting stronger interaction. The greater ability of M-β-CD in Domperidone amorphization could explain the better dissolution properties of the drug. As for the influence of the preparation method, an analog trend was observed with both CD’s; the greatest improvement of drug dissolution was obtained with Ultrasonification product, followed in order by Kneading and finally by physical mixture. The increased dissolution rate (physical mixture) is attributable both to improvement in drug wettability and to formation of readily soluble complexes in dissolution medium. Further improvement obtained with Kneading and Ultrasonification could be explain by both the more intimate contact between drug and carrier and the decrease of drug crystallinity, as well as a phenomenon of at least partial drug inclusion complexation. On the contrary, the influence of the preparation method was clearly more marked in case of product with M-β-CD, where Kneaded and Ultrasonification product showed an increase in dissolution efficiency of 90 or 110%, in comparison to corresponding physical mixture. The best performance of these product seemed to confirm that drug inclusion complexation occurred substantially only in such systems, thus allowing to obtain the highest dissolution improvement.

Table 4: Solubility of Domperidone from various inclusion complexes

S. N.	Inclusion complexes	Solubility in distilled water (mg/100mL)	Solubility in 0.1M HCl (mg/100mL)
1	Domperidone	0.4933±0.002	0.72±0.00001
2	PMM1	0.613±0.0001	0.7966±0.007
3	PMHP1	0.602±0.0002	0.7266±0.0006
4	KNHP1	1.59±0.098	1.96±0.0001
5	KNHP2	1.323±0.026	1.726±.0003
6	USHP1	1.879±0.037	2.179±0.0001
7	USHP2	3.266±0.98	3.863±.00008
8	KNM1	1.27±0.010	1.94±0.0003
9	KNM2	1.349±0.101	1.659±0.0004
10	USM1	4.663±0.080	5.043±0.0006
11	USM2	2.229±0.094	2.817±0.0009

* Represents mean ± S.D. (n= 3)

Dissolution data of inclusion complexes also indicated that there is increase in dissolution as compared to pure drug and maximum increase was observed in case of inclusion complexes (USHP2) and (USM1). But data of solubility and dissolution studies indicate that there was a decrease in both the solubility and dissolution as compared to (USHP2) and (USM1). The batch (USHP2) and (USM1) was considered as optimized batch since it showed statistically significant difference in both solubility and dissolution characteristic as compared to batch USHP2 and USM1.

Fig. 1: Solubility of Domperidone from various inclusion complexes.

Table: 5 Cumulative % drug (Domperidone) dissolved in 0.1 M HCl

S. N.	Time (Min.)	0.1 M HCl*
1	0	0
2	5	38.36±0.193
3	10	42.63±0.563
4	15	50.61±0.573
5	20	55.48±0.532
6	25	59.36±.506
7	30	60.68±.472
8	35	60.94±0.929
9	40	61.36±0.887
10	45	61.50±0.811
11	50	61.78±0.463
12	55	61.77±0.474
13	60	62.57±0.402

*Represent mean ± S.D. (n =3)

Fig.2: Dissolution profile of Domperidone in 0.1M HCl

Fig.3: Dissolution profile of Domperidone:Hydroxypropyl betacyclodextrin inclusion complexes in 0.1M HCl

Table 6: Cumulative % drug dissolved from inclusion complexes prepared using hydroxy propyl betacyclodextrin in 0.1M HCL

S.N.	Time (min)	Batch code*
S.N.	Time (min)	PMHP1	KNHP1	KNHP2	USHP1	USHP2
1	0	0	0	0	0	0
2	5	40.72±0.136	51.18±.0712	54.45±0.712	62.97±0.135	73.77±0.135
3	10	43.31±0.568	57.16±0.567	58.18±0.567	70.45±0.557	91.78±0.557
4	15	52.15±0.139	62.18±0.458	63.54±0.458	74.95±0.4	99.20±0.4
5	20	58.28±0.500	66.16±0.717	67.87±0.141	92.45±0.129	100.93±0.129
6	25	60.75±0.379	69.83±0.169	70.86±0.186	94.72±0.182	--
7	30	63.21±0.498	75.78±0.378	75.54±0.375	96.11±0.351	--
8	35	64.63±0.368	79.42±0.556	80.19±0.498	97.25±0.526	--
9	40	65.02±0.286	84.49±0.575	83.64±0.498	99.18±0.569	--
10	45	65.41±0.182	87.16±0.465	89.15±0.537	99.93±0.608	--
11	50	66.42±0.621	90.75±0.340	94.12±0.337	99.88±0.337	--
12	55	67.09±0.289	96.38±0.243	98.14±0.239	100.27±0.189	---
13	60	68.08±0.286	97.67±0.500	99.08±0.512	100.63±0.137	--

* Represents mean ± S.D. (n=3)

Table 7: Cumulative % drug dissolved from inclusion complexes prepared using methylated betacyclodextrin in 0.1M HCl

S.N.	Time (min)	Batch code*
S.N.	Time (min)	PMM1	KNM1	KNM2	USM1	USM2
1	0	0	0	0	0	0
2	5	39.41±0.135	50.14±0.193	56.26±0193	88.98±0.350	89.56±0.455
3	10	42.96±0.55	55.16±0.586	59.67±0.643	98.03±0.818	95.22±0.965
4	15	51.48±0.4	58.40±0.576	62.33±0.634	99.93±0.044	97.60±0.910
5	20	57.27±0.12	64.59±.601	65.35±0.658	100.81±0.310	99.41±0.826
6	25	59.74±0.129	67.27±0.584	71.31±0.641	--	100.18±0.826
7	30	63.22±0.168	74.08±0.791	76.00±0.843	--	--
8	35	63.97±0.548	74.31±0.541	78.79±0.541	--	--
9	40	65.34±0.610	80.70±0.513	81.90±0.548	--	--
10	45	65.39±0.691	84.74±0.499	85.48±0.552	--	--
11	50	66.39±0.482	89.16±0.757	90.04±0.811	--	--
12	55	67.05±0.321	94.65±0.474	95.76±0.529	--	--
13	60	68.04±0.621	99.33±0.550	99.76±0.657	---	--

*Represents mean± S.D. (n=3)

Table: 8 Drug content of inclusion complex (USM1) and (USHP2) stored at varying temperature and 75± 5% R.H.

Month	Drug content*
	Inclusion complex (USM1)		Inclusion complex (USHP2)
	25ºC ± 2ºC	40ºC ± 2ºC	25ºC ± 2ºC	40ºC ± 2ºC
0	87.81±0.357	87.81±0.357	85.33±1.56	85.33±1.56
1	88.01± 0.357	87 .98 ± 0.032	84.92 ± 0.78	84.54 ± 0.704
2	87.99 ± 0.02	87.59 ± 0.753	84.82 ± 0 .083	84.34 ± 0.936
3	87.85 ± 0.852	87.24 ± 0.562	85.80 ± 0.892	84.39 ± 0.501

*Represents mean ± S.D. (n = 3)

Fig 4: Dissolution profile of Domperidone:Methylated Betacyclodextrin inclusion complexes in 0.1M HCl

Stability studies:

A result of stability study indicated that the inclusion complex (USHP2) and (USM1) was stable and there was no significant changes observed in the drug content (P>0.05).

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Received on 17.08.2011 Modified on 20.09.2011

Research J. Pharm. and Tech. 4(11): Nov. 2011; Page 1761-1765