Preparation and Evaluation of New Metronidazole Gel Using
Hydroxypropyl Methylcellulose
Kazuhiro WATANABE*l, Seigo NAKAMURA*2, Toshio SHIMAMOTO*3,
Shunji URAMATSU*3, Kouzo KISHI*3, Toshinobu UEMURA*3,
and Hitoshi SHINIKE *3*1

Pharmacy Practice and Research Center, Showa Pharmaceutical University,
3-3165 Higashi-Tamagawagakuen, Machida 194-8543, Japan*2
Breast Surgical Oncology, Breast Center, St. Luke's International Hospital,
9-1 Akashi-cho, Chuo-ku, Tokyo 104-8560, Japan*3
Daido Chemical Corporation,
4-4-28 Takeshima, Nishiyodogawa-ku, Osaka 555-0011, Japan(Accepted on May 18, 2009)

Abstract: We use metronidazole carbopol gel (MTZ-Gel) to manage odor from cancerous skin ulcers inadvanced breast cancer patients. However, application to affected areas has presented problems to bonding
between the affected areas and gauze, which makes the gauze difficult to remove.

Therefore, we developed®

MTZ-SW Gel with Sangelose as a raw material, and clinically evaluated its effectiveness and applicability.
Overall, our findings suggest that MTZ-SW Gel is effective and clinically useful for treating cancerous skinulcers.

We previously conducted a clinical study of MTZ-SW Gel, and reported its efficacy, safety, andapplicability.

In this study, to maintain the quality of this preparation, we evaluated its consistency andspreadability by pharmaceutical assessment.
spreadability.

MTZ-SW Gel was softer than MTZ-Gel, with a greater

A stability test of MTZ-SW Gel showed that there were no differences in the MTZ content of

this preparation between two conditions, 28 and 40°C, demonstrating its stability over 60 days.

On a drug

release test, the rates of MTZ release from MTZ-SW Gel and MTZ-Gel after 8 h were 97.6 and 89.7%,
respectively, suggesting a higher drug release rate from the base of MTZ-SW Gel.
Key words: hospital preparation, metronidazole, hydroxypropyl methylcellulose, cancerous malodor,
breast cancer

Introduction
Cancerous skin ulcers in breast cancer patients are accompanied by malodors caused
by infections, pain due to inflammation, as well as bleeding and exudate, which decrease
the quality of life (QOL) of patients markedly.

Among these, malodors caused by

infections (cancerous malodor) are very offensive and distressing symptoms for not only
patients themselves, but also their surrounding families and health care professionals.
Contact Address: Kazuhiro Watanabe, Pharmacy Practice and Research Center, Showa Pharmaceutical
University, 3-3165 Higashi-Tamagawagakuen, Machida 194-8543, Japan
E-mail: kazunabe@ac.shoyaku.ac.jp-1-Cancerous malodor is said to be caused mainly by infections of the dead tissues ofcancerous lesions by anaerobic bacteria such as Bacteroides and Peptostreptococcus spp13).

As for the therapeutic drug, external preparations containing metronidazole (MTZ),

which has a wide antibacterial spectrum against anaerobic bacteria, as active ingredientare effective1-3), and the MTZ external preparations are recommended in the guidelines ofthe World Health Organization4) and the American Society of Clinical Oncology5) for thetreatment of cancerous malodors.

However, since the MTZ external preparations havenot been approved in our country, the MTZ external preparations are prepared by theirown pharmaceutical departments in many hospitals to apply to the patients6).
At the St. Luke’s International Hospital, MTZ-carbopol 934-P Gel (MTZ-Gel)contained in the 5th edition of Byoin Yakkyoku Seizai7) has been prepared, and the clinicalefficacy, safety and benefit etc. have been reported8, 9).

However, when dressing theaffected area, it was found that to remove the gauze was difficult due to the bouning
between the protective gauze coated with MTZ-gel and the affected area. To solve thisproblem, we developed MTZ-Sangelose Gel (MTZ-SW Gel) using hydrophobizedhydroxypropyl methylcellulose (Sangelose®)10, 11) which was applied as the vehicle of gel
for the cosmetics and the quasi-drugs in recent years.
already conducted using MTZ-SW Gel.

The clinical evaluation has been

As the results, the malodor improvement effectof MTZ-SW Gel was equivalent to MTZ-Gel, and it was suggested that MTZ-SW Gel has
the possibility of decreasing the irritating sensation which is the adverse event comparedto MTZ-Gel.

In addition, from the results of evaluation for the impression of use, MTZ-

SW Gel was assessed as a "water-retentive" and "easy peeling" preparation, and it wassuggested that MTZ-SW Gel is a clinically useful preparation which overcomes the
problem of MTZ-Gel that to remove the gauze was difficult due to the bounding between
the affected area and the protective gauze.12)
This time, we conducted the pharmaceutical evaluation on the physical properties ofthe preparation and the stability of active ingredient to ensure the quality of MTZ-SW Gel
preparation as the hospital preparation.
Materials and Methods
1. Raw Materials
For the preparation of MTZ-SW Gel and MTZ-Gel, following raw materials wereused: Metronidazole (2-methyl-5-nitroimidazol-1-ethanol, MTZ) (Tokyo Chemical
Industry Co., Ltd.); Sangelose® 60L and Sangelose® 90L (Daido Chemical Corporation) as
the vehicle of gel; propylene glycol (Maruishi Pharmaceutical Co., Ltd.) and sodium-2-hydroxide (Koso Chemical) as the solubilizing agent.

For Water for injection, themedicinal product contained in the Japanese pharmacopoeia was used.

All other reagentsused in each test were the guaranteed grade or analytical grade reagents.
2. Preparation of MTZ-SW Gel
MTZ-SW Gel was prepared as follows: 0.8g of MTZ were weighed and weredispersed well with 10 mL of propylene glycol in a mortar.

Separately, to 90 mL ofwater for injection, previously warmed at 70°C, 0.25 g of Sangelose® 60L and 0.75 g ofSangelose® 90L were added slowly and mixed.

This solution was cooled to 40°C, andthen previously prepared MTZ suspension was added, and mixed thoroughly.

MTZ-Gel,which was used as the control preparation in each pharmaceutical test, was preparedaccording to the method described in the 5th edition of Byoin Yakkyoku Seizai7) (Table 1).

3. Experimental Methods
The pharmaceutical evaluation was conducted by performing the consistency andspreadability test, the stability test of the preparation, and the release test of MTZ from the
preparation.

Thirty grams each of prepared MTZ-SW Gel and MTZ-Gel were filled inplastic containers, stored for 60 days, and used as the sample.
3-1 Consistency
For the measurement of consistency, the penetrometer (Rigo Co., Ltd., JIS) wasused.13-15) The consistency was obtained from the average value of 10 times
measurements in which the distance at 5 seconds after the penetration of the penetrometer
needle was measured.

The consistencies of MTZ-SW Gel and MTZ-Gel were measured

immediately after preparation (Day 0).
3-2 Spreadability-3-For the measurement of spreadability, a spreadmeter (Rigo Co., Ltd., JIS) wasused.13, 15, 16) The spreadability was obtained from the average value of 5 times
measurements in which the diameters of spread were measured after 10, 50, 150, 200, 300,
400, 500, 600, 700, 800 and 900 seconds at room temperature.

The spreadabilities of

MTZ-SW Gel and MTZ-Gel were measured immediately after preparation (Day 0).
3-3 Stability Test
The stability of MTZ-SW Gel was evaluated by observing the changes ofappearance immediately after preparation (Day 0) and after 14, 30 and 60 days, and also
determining the concentration of MTZ in the MTZ external preparation by using the High
Performance Liquid Chromatography (HPLC).17-20)

The preparation procedure of thesample for measurement was as follows: Thirty milligrams each of MTZ-SW Gel were
weighed exactly, and a mixture of methanol and water (1:1) containing 200 μg ofranitidine (SIGMA-ALDRICH, USA) as the internal standard was added to make 10 mL.
These solutions were sonicated for 5 minutes to make homogeneous.

The obtained

solutions were filtered with DISMIC®-3JP (pore size: 0.5 μm; Advantec Toyo Kaisha,Ltd.), and 20 μL each of these filtrates were injected into HPLC.

The concentration of

MTZ was calculated from the average of 5 times results using the calibration curve
prepared from the ratio of peak area between MTZ and the internal standard.
HPLC conditions: Pump: HITACHI L-7100 (Hitachi, Ltd.); Detector: HITACHI L7420 (UV wavelength: 324 nm; Hitachi, Ltd.); Column oven: Shimadzu CTO-10AS(Column temperature: 30°C; Shimadzu Corporation); Column: TSK-GEL ODS-80TM(250 mm x 4.6 mm i.d., 5 μm; Tosoh Corporation); Injection syringe: Hamilton Syringe
MICROLITER #705 (Hamilton Compnay, USA); Mobile phase: A mixture of acetonitrile
and 0.1 mol/L potassium dihydrogen phosphate (KH2PO4) buffer solution, pH 7.4 (1:9);
Flow rate: 1.0 mL/min.
3.4 Release Study
The release of MTZ from MTZ-SW Gel and MTZ-Gel was determined using Franztype diffusion cells.13, 21, 22)

A cellulose membrane (cellulose tube size 30/32, Sanko-

Jyunyaku Co., Ltd.) was placed in a Franz type diffusion cell, LG-1084-MPC (Laboratory
Glass Apparatus, USA) and 0.31 g of newly prepared MTZ-SW Gel or MTZ-Gel wascoated onto the membrane in the donor cell.

The receptor cell was filled with Ringer's

solution (JP) as the solvent, and the cumulative permeated amount of MTZ from the donor-4-

cell to the receptor cell at a temperature of 37°C was determined by HPLC.

The samples

were collected after 0.5, 1, 1.5, 2, 3, 4 and 8 hours.
Results
1. Consistency
The measurement results of the consistency of MTZ-SW Gel and MTZ-Gel
immediately after preparation (Day 0, 28°C) were more than 400 x 10-1 mm for MTZ-SW
Gel and 330 x 10-1mm for MTZ-Gel, respectively.
2. Spreadability
The measurement results of the spreadability of MTZ-SW Gel and MTZ-Gel
immediately after preparation (Day 0, 28°C) were as follows: Y-intercept: 3.08 cm for
MTZ-SW Gel and 3.03 cm for MTZ-Gel; slope: 0.58 for MTZ-SW Gel and 0.24 for MTZGel (Fig. 1).

3. Stability Test
As for the appearance of MTZ-SW Gel, although no change was observed for 60
days when stored at 28°C and 40°C, the crystallization of white needle shapsed crystal
was observed after 1 day similar to MTZ-Gel when stored at 4°C.

In the stability test of

MTZ-SW Gel, the concentration of MTZ in MTZ-SW Gel was determined by HPLC, and-5-

the time-course changes were observed.

Almost no change of the concentration of MTZ

was observed up to 60 days from preparation in MTZ-SW Gel stored at both 28°C and
40°C (Fig. 2).

4. Release Study
The cumulative permeation ratio of MTZ at 0.5, 1, 1.5, 2, 3, 4 and 8 hours after were25.9, 42.2, 56.3, 66.5, 76.1, 82.8, 88.8 and 89.7% for MTZ-Gel, 42.0, 70.4, 82.6, 91.6,
95.4, 97.0, 97.4 and 97.6% for MTZ-SW Gel, respectively.

At each measurement time

up to 8 hours after preparation, MTZ-SW Gel showed higher value than MTZ-Gel (Fig. 3).

Discussion-6-

Hydrophobized hydroxypropyl methylcellulose (Sangelose®), a cellulose derivative,
is a gel vehicle which obtained hydrophilic property by introducing a small quantity oflong-chain alkyl group (hydrophobic group) to hydroxypropyl methylcellulose.
Sangelose® has two types of gel vehicle: Sangelose® 60L which has a fluidity andSangelose® 90L which has a thickening property.

It is able to adjust the hardness,

viscosity and spreadability of gel by using the products selectively or together.

In

addition, they are gel vehicles which have high water retentivity and shape retentivity, andhave good compatibility with skin and good impression of use, and they therefore havebeen applied for cosmetics and quasi-drugs.10, 11, 23, 24) So we prepared new MTZ gel
preparation, MTZ-SW Gel, by using this Sangelose® as the gel vehicle to perform thepharmaceutical evaluation.

In addition, for the decision of MTZ-SW Gel formulation,

we prepared various gels of which the mixing ratio and the concentration of two types ofSangelose® 60L and 90L were adjusted in order to improve the impression of use of MTZGel which had been so far used until now, and the nurses who had been actually involved
caring the cancerous skin ulcer were asked to confirm the impression of use for the gels.
In the results of physical property test, it was found that MTZ-SW Gel is softer andmore spreadable than MTZ-Gel.

In the results of stability test, no changes were observed

up to 60 days under the storage conditions of 28°C and 40°C, and it was confirmed that
MTZ-SW Gel is stable same as MTZ-Gel.

From the results of the release study, MTZ-

SW Gel showed greater value when compared with MTZ-Gel, suggesting that thereleasability of MTZ from the vehicle is high.

In the future, we would like to clarify thereason why MTZ-SW Gel could overcome the problem of MTZ-Gel that to remove thegauze was difficult due to the bouning between the affected area and the protective gauzefrom the view point of the water retentivity and shape retentibity of the gel in thefundamental experiments using the models, etc.
In addition, although the results are not shown in this report, it is noted as thecharacteristic of MTZ-SW Gel that the preparation of gel is easy.

The time required toprepare MTZ-SW Gel is about 30 minutes, and it can be shortened to 1/4 when comparedwith about 120 minutes required for MTZ-Gel which have been prepared conventionally,
and we consider that it leads to efficiency improvement of businesses for thepharmaceutical department preparing the hospital preparations.
From the above, we consider that MTZ-SW Gel is assured the same pharmaceutical-7-

quality as MTZ-Gel in the pharmaceutical evaluation.

We would like to increase thenumber of cases in the clinical evaluation in the future to study the evaluation of
usefulness including the QOL of the patients.

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