Two Spectrophotometric Methods for Determination of Ornidazole in Tablets

G. Mubeen*, Vaneeta Prakash and Kadri Uvesh

Al-Ameen College of Pharmacy, Bangalore - 560 027 (India).

Two simple, precise and accurate colorimetric methods have been developed and validated for determination of Ornidazole in bulk and tablet formulation. These methods involves formation of complex diazonium salt of reduced Ornidazole with Metacresol reagent and Resorcinol reagent which shows absorption maxima (lmax) at 425 nm and 435 nm respectively. The linearity was observed in the concentration range of 5-40 μg/mL and 8-20 μg/mL for method A and method B respectively. The assay result was found to be in good agreement with label claim. The recovery studies were carried out at three different levels. The methods were validated statistically and by recovery studies and they were found to be accurate, precise and reproducible for determination of Ornidazole in bulk and solid dosage form.

Ornidazole; Colorimetry; Validation

Introduction

Ornidazole^1,2 is an antimicrobial agent, chemically α-chloromethyl-2-methyl-5nitro-1H-imidazole-1-ethanol, with molecular formula. It is not an official drug in any pharmacopoeia. Literature review revealed that few methods^3-8 are available for the determination of Ornidazole in bulk and solid dosage form.

The present study describes accurate, precise and reproducible colorimetric methods for estimation of Ornidazole in bulk and tablet formulation. The method was validated by using various parameters as per ICH guidelines.

Experimental

Instruments and Materials

Pure Ornidazole was obtained as gift sample from Sun Pharmaceutical Limited, Mumbai, India. The Shimadzu UV-Visible spectrophotometer 1601 was used with spectral bandwidth 3 nm and wavelength accuracy (with automatic wavelength correction) 0.5 nm. All the apparatus and instruments were calibrated and validated before starting the experimental work.

Material and Methods

Preparation of reduced Ornidazole solution

100 mg of Ornidazole was taken in a round bottom flask, 3 gm of the zinc granules, 10 ml of the hydrochloric acid and 25 ml of the distilled water was added, the mixture was refluxed at 80^oC for 10 min. The solution mixture was filtered through Whattmann paper no. 42 and the volume was made upto 100 ml, so that the final concentration was 1 mg/ml. 10 ml of this solution was further diluted to 100 ml to get 100 mcg/ml solution of reduced Ornidazole.

Method A

Procedure

To 1 ml of std and sample solution in 10 ml volumetric flask, 1 ml of 1 % sodium nitrite, 1 ml of ethanol, 1.5 ml of 1 % metacresol was added. The solution mixture was kept for 30 min at 5^oC. The volume was made upto 10 ml with the distilled water. The absorbance was measured at 425 nm against the reagent blank.

Method B

Procedure

To 1 ml of std and sample solution in 10 ml volumetric flask, 1 ml of 3 % sodium nitrite, 0.1 ml of 0.1N NaOH and 0.3 ml of 0.1 % of resorcinol was added and the solution kept for 5 min at 5^oC and the volume was made upto 10 ml with distilled water. The absorbance was measured at 435 nm against the reagent blank.

Validation of Analytical method

Validation is the process of establishing documented evidence which provides a high degree of assurance that a specific process will consistently produce a product meeting its predetermined specifications and quality attributes. Both the methods were validated by various parameters as per ICH guidelines (Table 1).

Linearity

The linearity of Ornidazole was found to be 5-40 µg/mL and 8-20 µg/mL and the linear regression value was found to be R² = 0.9979 and 0.9991 for method A and method B respectively.

Precision

As the values of % RSD of all precision study were within the acceptable limits (less than 2 %). Hence the methods provide good precision and reproducibility.

Sensitivity

Absorbance of standard solutions of Ornidazole was measured at 425 nm and 435 nm for method A and method B respectively. Sandell’s sensitivity⁹ for Ornidazole was calculated from formula.

_(µgcm-3_{AU) =} ^{Conc. of drug (µg100 mL-1 ) / Absorbance} _{× 0.001}

The Sandell’s sensitivity for Ornidazole at 425 nm and 435 nm for method A and method B was found to be 0.0236 µgcm^-3AU and 0.1027 µgcm^-3AU respectively.

Accuracy

Accuracy of the method was determined in the terms of % recovery of standard Ornidazole. Results of the recovery study were found to be within the acceptance criteria 100 ± 10%, indicates sensitivity of the method towards detection of Ornidazole and non interference of excipients in the method (Table 2).

Procedure for analysis of Ornidazole in tablet formulation:

Brand name: Orni, Ornizin, Dazolic. Giro, Ornida Manufacturer: Sun Pharmaceutical Limited, Mumbai, India.

Preparation of reduced Ornidazole sample solution

20 tablets were weighed, powdered and accurately weigh equivalent to 100 mg of Ornidazole was taken in a round bottom flask, 3 gm of the zinc granules, 10 ml of the hydrochloric acid and 25 ml of the distilled water was added, the flask was refluxed at 80^oC for 10 min. The solution mixture was filtered through whattmann paper no. 42 and the volume was made upto 100 ml. 10 ml of this solution was further diluted to 100 ml to get 100 mcg/ml solution of reduced Ornidazole.

Method A

Procedure To 1 ml sample solution in 10 ml volumetric flask, 1 ml of 1 % sodium nitrite, 1 ml of ethanol, 1.5 ml of 1 % metacresol was added. The solution mixture was kept for 30 min at 5^oC. The volume was made upto 10 ml with the distilled water. The absorbance was measured at 425 nm against the reagent blank.

Method B

Procedure

To 1 ml of sample solution in 10 ml volumetric flask, 1 ml of 3 % sodium nitrite, 0.1 ml of 0.1N NaOH and 0.3 ml of 0.1 % of resorcinol was added and the solution kept for 5 min at 5^oC and the volume was made upto 10 ml with distilled water. The absorbance was measured at 435 nm against the reagent blank.

Recovery studies

To check the accuracy of the proposed method, recovery studies were carried out at three different levels. The standard bulk drug was added at 3 different levels to the preanalyzed sample solution and then reanalyzed.

Results and Discussion

Ornidazole is an antimicrobial agent. Two colorimetric methods were developed and validated for determination of Ornidazole in bulk and tablet formulation. They showed absorption maxima (ëmax) at 425nm and 435 nm and the linearity were observed in the concentration range of 5-40 µg/mL and 8-20 µg/mL for method A and method B respectively. The % recovery was found to be in range of 100-102 % and 100-101 % for method A and method B respectively, indicating no interference by excipients in the methods. The % RSD less than 2 indicated that the method was accurate and precise. The method was found to sensitive with respect to Sandell’s sensitivity.

Hence the developed method was found to be simple, accurate, precise and reproducible.

Table 1: Validation Parameters

Table 2: Recovery studies (Method A and Method B)

*Average of three readings

 Table 3: Analysis of tablet formulation