METHOD FOR SIMULTANEOUS QUANTIFICATION OF DICLOFENAC AND PARACETAMOL IN A FORMULATION USING FTIR SPECTROSCOPY

Abstract

ABSTRACT The present invention discloses a method for the simultaneous estimation of diclofenac and paracetamol in a pharmaceutical formulation via transmission Fourier Transform Infrared (FTIR) spectroscopy. The method comprises preparing a pelletized sample for transmission analysis, obtaining FTIR spectra, and applying multivariate calibration. The method of the present invention quantifies both APIs (diclofenac and paracetamol) with high specificity, precision, accuracy, and robustness. The method provides a routine pharmaceutical quality control, and a non-destructive technique to reduce sample preparation time and operational costs.

Specification

Description:METHOD FOR SIMULTANEOUS QUANTIFICATION OF DICLOFENAC AND PARACETAMOL IN A FORMULATION USING FTIR SPECTROSCOPY

FIELD OF THE INVENTION
The present invention, in general, relates to an analytical method for the simultaneous quantification of diclofenac and paracetamol in combination tablet formulations. Further, the present invention, in particular, relates to facilitating non-destructive, rapid, and cost-effective quantification of these active pharmaceutical ingredients (APIs) and to meet the needs of routine quality control in pharmaceutical manufacturing, using transmission Fourier Transform Infrared (FTIR) spectroscopy.

BACKGROUND OF THE INVENTION
Diclofenac is a widely used non-steroidal anti-inflammatory drug (NSAID) which is commonly prescribed for pain and inflammation relief, while paracetamol, an analgesic and antipyretic, is well known for addressing pain and fever. Therefore, a combination of these two drugs in a single tablet formulation is common, as they complement each other therapeutically. However, ensuring the precise dosage of each component is also crucial, as any variation in concentration can directly impact the safety, efficacy, and regulatory compliance of a final product. An accurate and simultaneous quantification of active pharmaceutical ingredients (APIs), such as diclofenac and paracetamol, in combination tablet formulations is essential for pharmaceutical quality control.
Traditionally, analytical methods like High-Performance Liquid Chromatography (HPLC) and Ultraviolet-Visible (UV-Vis) Spectrophotometry are employed to determine the concentrations of APIs in such formulations. While effective, these techniques involve complex, time-intensive sample preparation steps, often requiring solvent extraction, derivatization, or chromatographic separation. Furthermore, HPLC and other traditional methods demand advanced instrumentation, substantial chemical reagents, and skilled personnel, making the process resource-intensive and increasing operational costs. Such limitations can be a significant challenge in a high-throughput pharmaceutical environment where a rapid and reliable quality control is paramount.
Further, the complexity of separating diclofenac and paracetamol through conventional methods projects an additional analytical challenge due to their overlapping properties. This may complicate detection, separation, and accurate quantification. In such cases, the development of an analytical method that can simultaneously identify and quantify both APIs without necessitating extensive separation steps is a compelling advancement. This need for efficiency is further underscored by Good Manufacturing Practices (cGMP) guidelines by World Health Organization (WHO), which stress the importance of reliable and repeatable analytical methods for consistent quality assurance.
Fourier Transform Infrared (FTIR) spectroscopy is emerging as a valuable tool for pharmaceutical analysis, particularly for APIs, due to its capability to rapidly acquire detailed spectral information. FTIR provides a unique fingerprint of molecular vibrations, enabling the detection of distinct functional groups in organic compounds. In transmission mode, FTIR spectroscopy can analyze samples with minimal interference, capturing the absorption peaks corresponding to specific chemical bonds within the molecular structure. However, traditional FTIR applications have been limited to qualitative analysis or single-component quantification, with limited attempts to apply FTIR in complex, multi-component mixtures.
The inventive use of FTIR spectroscopy in the present invention enables simultaneous, non-destructive quantification of both diclofenac and paracetamol in tablet formulations, which is especially beneficial for pharmaceutical quality control. Unlike conventional techniques, FTIR-based method in the present invention requires minimal sample preparation, as the tablet formulation can be ground, pelletized, and directly analyzed without a need for solvents or chemical reagents. This not only simplifies the analysis process but also reduces the potential for contamination or analyte degradation, making FTIR a cleaner and more environmentally friendly analytical option.
The present invention provides an innovative approach to pharmaceutical quality control by leveraging the strengths of FTIR spectroscopy and multivariate calibration for simultaneous multi-component analysis. By addressing the limitations of traditional methods and reducing the time and resources required for accurate API quantification, the method of the present invention advances current pharmaceutical quality control practices, meeting both operational and regulatory demands in a highly efficient manner.

OBJECTIVES OF THE INVENTION
The primary objective of the present invention is to present an efficient and reproducible technique to ensure that diclofenac and paracetamol are accurately quantified in combination formulations, meeting regulatory standards without extensive preparation or high operational costs. It is also an objective of the present invention to provide a method that supports industry need to reduce time and resources required in quality control, allowing for more streamlined and consistent testing across production batches.
To develop a non-destructive and rapid FTIR spectroscopy-based method for the simultaneous quantification of diclofenac and paracetamol in tablet formulations.
To eliminate extensive sample preparation steps and reduce dependency on costly analytical setups.
To offer a reliable and cost-effective alternative to traditional analysis methods for ensuring pharmaceutical quality standards.
To enable routine quality control with a method that delivers high specificity, accuracy, and precision without complex instrumentation or procedures.

SUMMARY OF THE INVENTION
The present invention discloses a method that employs transmission mode FTIR spectroscopy for the simultaneous quantification of diclofenac and paracetamol in tablet formulations. The method involves sample preparation, FTIR spectral acquisition, and data processing using multivariate calibration techniques to correlate spectral characteristics with the concentration of each API. The method provides a reliable, precise, and rapid alternative to traditional analytical techniques, suited to the needs of pharmaceutical quality control by providing accurate measurements with minimal sample handling.

BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying figures illustrate several embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. One of ordinary skill in the art readily recognizes that the embodiments illustrated in the figures are merely exemplary, and are not intended to limit the scope of the present disclosure.
FIG. 1 illustrates chemical structure of (a) paracetamol (b) diclofenac used in an embodiment of the present disclosure.
FIG. 2 illustrates transmission spectra of paracetamol (PCM) and diclofenac (DICLO) alone and a mixture of 1:1 of them.
FIG. 3 discloses a group of transmission FT-IR spectra of the PCM and Diclofenac mixing standard with chosen bands for quantitative examination.
FIG. 4 discloses FT-IR spectra of pure Paracetamol in transmission mode.
FIG. 5 discloses a FT-IR spectrum of pure Diclofenac in transmission mode.
Further areas of applicability of the present disclosure will become apparent from the complete description provided hereinafter.
It should be understood that the complete description of exemplary embodiments is intended for illustration purposes only and is, therefore, not intended to necessarily limit the scope of the present disclosure.

DETAILED DESCRIPTION
The present invention is more particularly described in the following present specification that is intended as illustrative only since numerous modifications and variations therein will be apparent to those skilled in the art. Various embodiments of the present disclosure are now described in detail. Referring to the drawings, like numbers, if any, indicate like components throughout the views. As used in the description herein and throughout the claims that follow, the meaning of "a", "an", and "the" includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of "in" includes "in" and "on" unless the context clearly dictates otherwise. Moreover, titles or subtitles may be used in the specification for the convenience of a reader, which shall have no influence on the scope of the present disclosure. Additionally, some terms used in this specification are more specifically defined below.
The terms used in this specification generally have their ordinary meanings in the art, within the context of the present disclosure, and in the specific context where each term is used. Certain terms that are used to describe the present disclosure are discussed below, or elsewhere in the specification, to provide additional guidance to the practitioner regarding the description of the disclosure.
For convenience, certain terms may be highlighted, for example using italics and/or quotation marks. The use of highlighting has no influence on the scope and meaning of a term; the scope and meaning of a term are the same, in the same context, whether or not it is highlighted. It will be appreciated that the same thing can be said in more than one way. Consequently, alternative language and synonyms may be used for any one or more of the terms discussed herein, nor is any special significance to be placed upon whether or not a term is elaborated or discussed herein. Synonyms for certain terms are provided. A recital of one or more synonyms does not exclude the use of other synonyms.
The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only, and in no way limits the scope and meaning of the disclosure or of any exemplified term. Likewise, the disclosure is not limited to various embodiments given in this specification.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. In the case of conflict, the present document, including definitions will control.
As used herein, "around", "about" or "approximately" shall generally mean within 20 percent, preferably within 10 percent, and more preferably within 5 percent of a given value or range. Numerical quantities given herein are approximate, meaning that the term "around", "about" or "approximately" can be inferred if not expressly stated.
As used herein, "plurality" means two or more.
As used herein, the terms "comprising," "including," "carrying," "having," "containing," "involving," and the like are to be understood to be open-ended, i.e., to mean including but not limited to.
As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical OR. It should be understood that one or more steps within a method may be executed in a different order (or concurrently) without altering the principles of the present disclosure.
The present specification provides a comprehensive disclosure of a method for the simultaneous quantification of diclofenac and paracetamol in tablet formulations using Transmission Fourier Transform Infrared (FTIR) spectroscopy.
The innovative analytical approach of the present invention addresses the pressing need for efficient quality control in the pharmaceutical industry, particularly for combination therapies that contain the two widely used active pharmaceutical ingredients (APIs) i.e. diclofenac and paracetamol. The method enhances the accuracy and reliability of quantitative assessments, ensuring that each tablet formulation contains the correct dosages of diclofenac and paracetamol to maximize therapeutic efficacy while maintaining patient safety.
Specifically, the method employs a minimal sample preparation technique that involves grinding the tablet formulation, forming a compressed pellet, and acquiring FTIR spectra in transmission mode. By utilizing multivariate calibration techniques, including Partial Least Squares (PLS) regression, the method establishes a robust correlation between spectral data and API concentrations. It allows for precise, simultaneous quantification of diclofenac and paracetamol, thus facilitating rapid analysis without the complications associated with traditional chromatographic methods. The reliability and specificity of the method of the present invention not only streamline the quality assurance processes but also support compliance with regulatory standards in pharmaceutical manufacturing, ultimately contributing to improved product consistency and patient outcomes.
Moreover, the FTIR-based inventive method provides several advantages over conventional analytical techniques, including reduced operational costs, decreased reliance on hazardous solvents, and enhanced throughput. By offering a reliable and efficient alternative for routine quality control, the present invention supports pharmaceutical manufacturers in meeting the challenges of high-volume production while ensuring that their products remain effective and safe for consumer use. The ability to analyze complex formulations rapidly and accurately positions this method as a valuable tool in the ongoing quest for innovation and excellence in pharmaceutical quality control.
Materials and Reagents
The diclofenac and paracetamol standards used for calibration in the present invention may be obtained from a certified pharmaceutical laboratory. Each standard having an assay purity of 99.9%, ensuring high accuracy in the calibration process. For sample preparation, spectroscopic-grade Potassium Bromide (KBr) may be utilized to create uniform pellets with the active ingredients. A plurality of solid pharmaceutical formulations containing diclofenac and paracetamol as active medicinal ingredients may be sourced from local pharmacies and pharmaceutical laboratories to represent typical commercial samples in the analysis.

Step 1: Sample Preparation
Tablet samples containing diclofenac and paracetamol may be prepared by grinding the tablets into a fine powder, ensuring a homogeneous mixture. The powdered sample is then compacted into a thin, uniform pellet, which serves as the test sample for FTIR transmission analysis.

Step 2: FTIR Spectral Data Acquisition
The prepared sample pellet is subjected to FTIR analysis in transmission mode. Spectra are typically collected in the mid-infrared range, specifically from 4000 cm?¹ to 400 cm?¹. This range is selected as it captures the characteristic absorption bands associated with the molecular structures of diclofenac and paracetamol, enabling clear distinction between the two compounds within the spectrum.
In an embodiment, for the FTIR-based analysis, a Shimadzu FTIR spectrometer equipped with Potassium Bromide (KBr) optics and a Deuterated Lanthanum a Alanine doped Tri-Glycine Sulfate (DLaTGS) detector may be utilized, along with detachable KBr lenses. Each tablet sample may be finely ground, pressed into a pellet, and subject to spectral analysis. Every spectrum may be recorded within the Mid-Infrared range of 4000 to 400 cm?¹, capturing 20-40, preferably 30, scans per spectrum at a nominal resolution of 4 cm?¹ to ensure a high-quality data. Prior to recording the standard and sample spectra, a fresh background spectrum may be acquired under identical instrument settings to maintain accuracy and minimize background interference.
Further, the transmission mode is preferred due to its capacity to provide strong and clear absorption signals with minimal interference from scattering or baseline variations. This setup allows direct light passage through the sample pellet, enhancing the detection sensitivity and spectral clarity required for accurate analysis.

Step 3: Calibration Model Development and Quantitative Analysis
Multivariate Calibration Techniques
After obtaining the FTIR spectra, multivariate calibration techniques, such as Partial Least Squares (PLS) regression, may be applied. PLS is particularly effective in handling spectral data with overlapping signals, as it isolates the distinct spectral characteristics of diclofenac and paracetamol even when these compounds are present together. The calibration model may be developed using known standard samples of varying diclofenac and paracetamol concentrations, allowing the system to establish correlations between spectral intensity at specific wavelengths and the concentration of each analyte.
Further, to establish a reliable calibration model for FTIR analysis, a stock powder mixture may be prepared by combining equal amounts of paracetamol (PCM) and diclofenac with spectroscopic-grade Potassium Chloride (KCl). The stock powder mixture may serve as a basis for generating a series of calibration standards. Specific quantities of the primary powder mixture may be added to KCl to create standards with varying concentrations, ranging from 10% to 100% weight/weight (w/w) relative to KCl.
DICLO


This concentration gradient enables the creation of a robust calibration curve across the full analytical range required for accurate quantification of both PCM and diclofenac.
Further, the calibration models may be evaluated based on several performance parameters:
Correlation Coefficient (R²): A high correlation coefficient (ideally =0.99) indicates a strong linear relationship between spectral intensity and analyte concentration, confirming that the model can accurately predict concentrations within the defined range.
Root Mean Square Error of Calibration (RMSEC): RMSEC assesses the model's ability to predict concentrations of diclofenac and paracetamol accurately within the calibration dataset.
Root Mean Square Error of Prediction (RMSEP): RMSEP evaluates the model's predictive accuracy for unknown samples, serving as an additional validation step to confirm robustness and reliability in real-world applications.
Once validated, the calibration model may be applied to new tablet samples by acquiring FTIR spectra and using the established calibration curves to calculate the concentration of each analyte. The model's reliance on spectral fingerprints specific to diclofenac and paracetamol ensures that the method remains selective and accurate even when other excipients are present.

Step 4: Validation of Analytical Method
To ensure regulatory compliance and method reliability, the FTIR-based method may undergo validation based on one or more of the following parameters, with each step directly addressing requirements for pharmaceutical analytical methods:
• Specificity: The method must demonstrate that it can selectively quantify diclofenac and paracetamol without interference from excipients. Specificity testing involves analyzing a formulation with known excipients and confirming that only the spectra for diclofenac and paracetamol are quantified in the output, ensuring accuracy.
• Accuracy: Accuracy validation may be achieved by analyzing standard samples of known concentrations, calculating the recovery percentage for each analyte. An acceptable accuracy range (typically 98-102%) may be maintained, confirming that the method reliably reflects actual concentrations.
• Precision: Precision includes both repeatability (testing within the same day) and intermediate precision (testing on different days). Samples may be analyzed multiple times, and any variations in results may be measured. A standard deviation within 2% across repetitions may be considered acceptable, establishing the method's consistency.
• Robustness: To ensure stability under variable conditions, robustness testing examines the impact of minor changes, such as small variations in temperature or instrument settings. Consistent results across these changes confirm that the method remains reliable under routine operational conditions.
• Linearity: Linearity testing ensures a direct, proportional relationship between concentration and spectral intensity. This is verified by analyzing samples over a concentration range and confirming a correlation coefficient (R²) of at least 0.99, indicative of reliable quantitative performance.
The present invention provides a valuable tool for the pharmaceutical industry, particularly in routine quality control settings. By eliminating complex sample preparation and relying on non-destructive infrared spectroscopy, it enables rapid analysis, reducing both operational time and costs associated with traditional methods.
The inventive method is especially beneficial in high-throughput manufacturing environments where timely quality assessment is critical. It allows quality assurance teams to efficiently verify that diclofenac and paracetamol concentrations in tablet formulations meet specified limits, ensuring regulatory compliance and maintaining high standards of product safety.
Furthermore, the introduction of multivariate calibration techniques, such as Partial Least Squares (PLS) regression, enhance the quantitative capability of FTIR spectroscopy by allowing it to handle overlapping spectral data from multiple components. Multivariate calibration is particularly advantageous in complex formulations, as it can separate the spectral contributions of each API, enabling accurate quantification despite potential interference from excipients or overlapping absorption bands. In the context of diclofenac and paracetamol analysis, PLS regression isolates the characteristic spectral patterns of each API, establishing a robust calibration model that relates spectral intensity to concentration. This model is then applied to new samples, allowing precise concentration estimates without requiring individual calibration curves for each analyte, which is a limitation in many traditional spectroscopic methods.
The proposed FTIR-based method of the present invention aligns well with industry objectives to streamline quality control processes while maintaining compliance with regulatory standards. It offers a high-throughput alternative to chromatographic methods, supporting manufacturers' efforts to reduce time, costs, and reliance on hazardous reagents. By offering a faster, less resource-intensive, and more operator-friendly approach, this method addresses the pharmaceutical industry's growing need for efficient analytical solutions in a competitive, cost-sensitive landscape.
Moreover, in a quality-driven pharmaceutical production environment, routine assessments of multi-component drug formulations are critical to ensuring that each batch meets stringent regulatory standards. The use of FTIR spectroscopy for multi-component quantification, as outlined in this invention, promotes regulatory compliance by offering an accurate, validated approach to determining the concentrations of diclofenac and paracetamol. This is essential for maintaining product consistency, meeting therapeutic standards, and safeguarding patient health. Additionally, the method's adaptability to other combination formulations underscores its potential as a versatile tool for quality assurance in various pharmaceutical applications.
The embodiments described hereinabove are exemplary of the present invention. The disclosure may enable those skilled in the art to make and use embodiments having alternative elements that likewise correspond to the elements of the invention. The intended scope of the invention may thus include other embodiments that do not differ or that insubstantially differ from the literal language of the invention. However, the scope of the present invention is accordingly defined as set forth in the present complete specification.
, Claims:WE CLAIM:
1. A method for simultaneous quantitative estimation of diclofenac and paracetamol in pharmaceutical tablet formulations, the method comprises:
a) grinding the tablet formulation comprising diclofenac and paracetamol to produce a homogeneous powder;
b) forming a uniform pellet from the powdered sample for a spectral analysis;
c) obtaining a Transmission Fourier Transform Infrared (FTIR) spectrum of the sample in a transmission mode within a range of 4000 cm?¹ to 400 cm?¹, capturing distinct absorption peaks of diclofenac and paracetamol; and
d) applying multivariate calibration, including a Partial Least Squares (PLS) regression, to correlate at least one specific spectral feature with concentrations of diclofenac and paracetamol, enabling a simultaneous quantification of diclofenac and paracetamol compounds with a minimal sample preparation,
characterized in that the simultaneous quantification of diclofenac and paracetamol compounds is performed using transmission Fourier Transform Infrared (FTIR) spectroscopy in combination with multivariate calibration.
2. The method as claimed in claim 1, wherein the FTIR spectrum is acquired in transmission mode to provide clear absorption signals with minimal baseline interference, enhancing detection sensitivity, and enabling rapid analysis of diclofenac and paracetamol in combination.
3. The method as claimed in claim 1, wherein a multivariate calibration model is developed for the multivariate calibration using standard concentrations of diclofenac and paracetamol, achieving a correlation coefficient (R²) of at least 0.99 to confirm reliable, linear concentration estimation.
4. The method as claimed in claim 1, further comprising validating the method for pharmaceutical quality control by performing the following steps:
a) assessing specificity to ensure accurate quantification of diclofenac and paracetamol in the presence of excipients;
b) evaluating accuracy by analyzing recovery percentages of each analyte from standard samples;
c) testing precision through repeatability and intermediate precision assessments;
d) examining robustness to confirm reliability under varying operational conditions; and
e) verifying linearity to ensure a proportional relationship between concentration and spectral intensity within the concentration range of interest.
5. The method as claimed in claim 1, further comprising a validation of specificity by verifying that the FTIR spectrum distinctly identifies and quantifies diclofenac and paracetamol without an interference from excipients in the tablet formulation.
6. The method as claimed in claim 1, wherein an accuracy is validated by analyzing standard samples to ensure recovery within 98-102%, confirming the reliability of the FTIR-based method for pharmaceutical quality control.
7. The method as claimed in claim 1, wherein a precision is evaluated by repeatability and intermediate precision tests, demonstrating less than 2% variation across repeated analyses to ensure consistency.
8. The method as claimed in claim 1, wherein robustness is established by consistent results under minor method variations, verifying the method reliability under one or more typical operational conditions in a manufacturing environment.

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