Conductometric method development and validation to estimate acamprosate calcium in API and marketed formulation

INTRODUCTION

Acamprosate calcium (calcium 3-acetamidopropane-1-sulfonate; Figure 1) is a calcium salt of acetylhomotaurine which is used for the treatment of alcohol dependence, which acts by stabilizing the chemical balance in the central nervous system, by blocking glutaminergic N-methyl-D-aspartate receptors and activation of gamma-aminobutyric acid (GABA) type A receptors (Rhee et al., 2008a; Saivin et al., 1998; Zornoza et al., 2003). This drug is available since 1989 in the tablet strength of 333 mg (Lipha Pharmaceuticals Inc., 2002). It is approved by the US Food and Drug Administration (FDA) as an antidipsotropic agent and is used to decrease alcohol hankering (Espino and Cruz, 2005). The chemical formula of acamprosate calcium is C₁₀H₂₀N₂O₈S₂ Ca with molecular weight 400.48 g/mol. The physical properties of this drug are white and odorless powder, which is freely soluble in water and insoluble in organic solvents like ethanol and dimethylformamide.

Figure 1. Acamprosate calcium. [Click here to view]

The literature survey reports on the capillary zone electrophoresis method (Blanchin et al., 2000; Fabre et al., 1999). The Liquid Chromatography mass spectrometry (LCMS) method for bioanalytical analysis, LC-fluorometric, and electrochemical detection was reported in human plasma, dog plasma, and urine (Chabenat et al., 1987, 1989; Ghosh et al., 2011; Girault et al., 1990; Hammarberg et al., 2010; Kanala et al., 2013; Rhee et al., 2008a; Rhee et al., 2008b; Xu et al., 2009). A few methods are developed and validated for organic acids by conductometric titration method (Umarov et al., 2020). Hence, no work has been reported on the electrical conductivity method for the quantitative estimation of acamprosate calcium. In this research, a new cost-effective, precise, and regression co-efficient on electrical conductivity method on acamprosate calcium in pure and marketed formulation is reported.

MATERIALS AND METHODS

SPECIFICITY

The specificity of the method was studied by measuring the conductance of a solvent as blank and the prepared standard solution of acamprosate calcium (50 μg/ml).

LINEARITY

The linearity method was developed by measuring the electrical conductivity of different concentrations of acamprosate calcium. Dilutions containing 50–250 μg/ml acamprosate calcium were prepared and electrical conductivity was measured using electrical conductometer. The calibration curve was obtained by plotting the concentration versus electrical conductivity (μs), and the correlation coefficient (r²) was found to be 0.9999.

LIMIT OF DETECTION/LIMIT OF QUANTIFICATION

LOD is the lowest amount of analyte which can be detected but not quantified. It can be determined using following formula:

$\mathit{LOD}=3.3\frac{\sigma }{\mathit{S}}.$

LOQ is the lowest amount of analyte which can be quantitatively determined as precision using the following formula:

$\mathit{LOQ}=10\frac{\sigma }{\mathit{S}}.$

where σ = standard deviation;

S = Slope of the calibration curve.

PRECISION

The precision was carried out in terms of intraday and interday. The electrical conductivity of three replicate solutions of acamprosate calcium at three different concentrations was measured, and % Relative Standard Deviation (RSD) values of each solution for its electrical conductivity were measured.

RUGGEDNESS

Ruggedness was carried out by changing the analyst to check the reproducibility of standard results and the %RSD was found to be less than 2%.

ACCURACY

Accuracy was found by means of recovery experiments, by the determination of %mean recovery of sample at three different levels: 50%, 100%, and 150%. At each level, three determinations were carried out and %mean recovery was calculated.

ASSAY

Twenty tablets of acamprosate calcium (333 mg label claim) were taken and powdered. A measure equivalent to 73.19 mg was weighed and added to a 50 ml volumetric flask, and the final volume was made up to 50 ml with diluents and shaken for 5 minutes. The solution was filtered by Whatman filter paper. From the filtered solution, 0.5–2.5 ml solution was added to 10 ml volumetric flask to make a final volume up to 10 ml using distilled water.

Figure 2. Standard calibration curve of acamprosate calcium at 250 V. [Click here to view]

RESULT

LIMIT OF DETECTION (LOD)/LIMIT OF QUANTIFICATION (LOQ)

The LOD value obtained was 6.05 μg/ml and LOQ value was found to be 18.34 μg/ml. Both results are in the acceptance range.

PRECISION

The precision indicating the value was precise and low, and %RSD is <2%. The results are given in Tables 1 and 2.

Table 1. Intraday precision results of acamprosate calcium. [Click here to view]

Table 2. Interday precision results of acamprosate calcium. [Click here to view]

RUGGEDNESS

Ruggedness was carried out at different conditions to check the expected values from one analyst to another and the %RSD shows less than 2%. The data of ruggedness are recorded in Table 3.

ACCURACY

Accuracy and recovery studies were carried out and the %mean recovery of the sample was recorded at three different levels: 50%, 100%, and 150%. Individual recovery and %mean recovery were found to be greater than 98%, which indicates that the method development is accurate and recovery values were in the range. The %mean recovery values are shown in Table 4.

ASSAY

The assay was carried out by using tablet formulation of label claim 333 mg (ACAMPROL) and the values were obtained in an acceptable range. The results were in the range of 102%–104%.

DISCUSSION

In the present research work, an attempt has been made to develop a simple conductometric method. This method was found to be economic, simple, and rugged for estimation of acamprosate calcium. The proposed method results and outcomes are compared with other research works published earlier on acamprosate calcium.

Table 3. Results of ruggedness for acamprosate calcium. [Click here to view]

Table 4. Results of accuracy studies for acamprosate calcium. [Click here to view]

The literature survey reveals that acamprosate calcium can be analyzed by few chromatographic methods (Chabenat et al., 1987; Girault et al., 1990; Hammarberg et al., 2010). The published work has some limitation like use of costly solvents, hazardous chemicals, costly instruments, non-robust method, and longer time of analysis. Hence, in our proposed method, we have used water as a solvent which is universal and cheaper and the instrument cost is low. It is very simple in carrying out and is cost-effective for the method developed and analysis.

All the values obtained in the method were found to be within the acceptance range as per the ICH norms.

UV-spectrophotometric trials were carried out with different solvents such as menthol, water, etc., but they did not get the peaks at the acceptable range and it showed less than 205 nm because the acamprosate calcium drug does not contain chromophore. Furthermore, it was carried on electrical conductometric meter and the linear regression coefficient value was found to be 0.9999, Acamprosate calcium contains a cation charge and the solvent used was the distilled water. The method was developed on an electrical conductometric meter as this method is cheap, cost-effective, and no work has been reported on acamprosate calcium. The current method development and validation represent an alternative method in the laboratory which can be employed for routine analysis in the pharmaceutical industry.

CONCLUSION

The present research is a cost-effective, simple, and accurate electrical conductivity method for quantity estimation of acamprosate calcium in tablet dosage form developed as per the ICH guidelines. The method is economic, rapid, and does not need any sophisticated instruments. Hence, it may be employed for routine quality control analysis of acamprosate calcium in Active Pharmaceutical Ingrident (API) and marketed formulation.

ACKNOWLEDGMENTS

The authors are thankful to Principal Dr. S. S. Jalalpure for his support and guidance and to the Department of Pharmaceutical Chemistry, KLE College of Pharmacy. The authors are also thankful to Mr. Nikhil Gawas, Mr. Onkar S. Supe, and Ms. Sushmita Hiremath for help during the research work.

ETHICAL APPROVAL

Not applicable.

CONFLICT OF INTEREST

The authors declare that there is no conflict of interests.

FUNDING

This work did not receive any funds to declare from any national and international agency.

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