INTRODUCTION:

Meloxicam is a nonsteroidal anti-inflammatory drug (NSAID) used to relieve the symptoms of arthritis. Meloxicam is chemically (4-Hydroxy-2-methyl-N-(5-methyl-2-thiazolyl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide). Meloxicam acts by inhibiting prostaglandin synthetase (cyclooxygenase 1 and 2) enzymes leading to a decreased synthesis of prostaglandins, which normally mediate painful inflammatory symptoms¹.

Hydrotropy is a solubilization process in which the addition of a large amount of the hydrotropic agent results in an increase in the aqueous solubility of poorly soluble solute. Mixed hydrotropic solubilization includes the use of blends of hydrotropic agents for solubilisation, this reduces the concentration of individual hydrotropic agents required for solubilisation². The various hydrotropic agents include urea, sodium acetate, sodium caprylate, sodium benzoate, trisodium citrate, niacinamide etc. These agents are been used to solubilize poorly soluble drugs and developing their UV Spectrophotometric methods^3-7.

Meloxicam is a poorly soluble drug, conventionally poorly soluble drugs are estimated by solubilising them in organic solvents. The drawbacks of organic solvents include higher cost, toxicity, pollution and error due to volatility. Literature survey reveals only few HPLC, HPTLC and UV spectrophotometric methods are reported for the estimation of Meloxicam^8-13. By using blend of 10% sodium benzoate and 10% sodium caprylate there was more than 40 fold enhancement in solubility of Meloxicam.The motto of this study is to estimate Meloxicam from tablet dosage form using hydrotropic solubilization and preclude the use of organic solvent.

Fig. 1: Structure of Meloxicam¹⁴

MATERIALS AND METHODS:

INSTRUMENTS:

The spectrophotometric analysis was carried out using double beam UV–Visible Spectrophotometer (Hitachi UH5300 double beam Spectrophotometer) with quartz cells and Shimadzu ATX 224 as weighing balance.

Reagents and Chemicals:

Meloxicam was supplied from Microlabs Ltd (Tamil Nadu) as gift sample. Sodium caprylate AR from Lobachemie Pvt Ltd and Sodium benzoate AR from Central Drug House Pvt Ltd. Tablets of Meloxicam (Muvera-15 (Meloxicam BP 15mg) Sun Pharma laboratories Ltd) was purchased from drug store.

METHOD:

Selection of Hydrotropic Agent:

Selection of suitable hydrotropic agent was done by trial and error method. Various hydrotropic agents of different concentration were used to enhance the solubility of Meloxicam. Hydrotropic agents employed were Sodium benzoate, Sodium Salicylate, Sodium ascorbate, Tri Sodium citrate, Sodium acetate, Niacinamide etc. It was found that Meloxicam has enhanced solubility in Mixed hydrotropic solution of 10% sodium caprylate and 10% sodium benzoate.

Enhancement of Solubility:

The solubility enhancement of Meloxicam was determined by addition of excess amount of drug into screw capped glass vials of 30ml capacity each containing distilled water and hydrotropic solution. Vials are shaken mechanically for more than 24hours in a mechanical shaker.

Vials are allowed to equilibrate and then centrifuged and supernatant liquid is filtered through whatmann filter paper no. 41. Filtrate is diluted suitably and analysed spectrophotometrically andestimation was done by using UV visible spectrophotometer. The enhancement of solubility was determined by

Solubility in hydrotropic solution

Solubility Enhancement ratio = ---------------------------

Solubility in distilled water.

Estimation Methodology:

UV Spectrophotometric Estimation:

Meloxicam is dissolved in mixed hydrotropic solution of 10% sodium benzoate and 10% sodium caprylate. The peak absorbance (λ-max) of this solution was determined and was found to be 364nm. The mixed hydrotropic solution was also scanned and it was found that there is no significant peak above 300nm and it shows thenon interference of hydrotropic solution during estimation of Meloxicam.

Fig-2: Spectral scan of Meloxicam with peak absorbance at 364nm

Fig-3: Spectral scan of 10% Sodium benzoate and 10% Sodium caprylate solution

Preparation of Calibration Curve:

50mg of Meloxicam was weighed and dissolved in 10 ml of 10% sodium benzoate and 10% sodium caprylate (mixed hydrotropic) solution. This solution is sonicated for 15minutes to dissolve the drug and was further diluted to 50ml with distilled water (Stock solution-1). 10ml of stock solution-1 is made up to 100ml with distilled water. This solution was further diluted to obtain concentration of 2, 4, 6, 8 and 10µg/ml. The absorbance of these solutions was determined at 364nm against blank prepared in same method by excluding the drug. The calibration curve is prepared by plotting absorbance against concentration.

Fig. 4: Calibration curve of Meloxicam

Table-1. Linearity of Meloxicam at 364nm in mixed hydrotropic solution

Standard concentration (µg/ml)	Rep-1	Rep-2	Rep-3	Rep-4	Rep-5	Rep-6
2	0.109	0.107	0.106	0.104	0.108	0.107
4	0.191	0.189	0.193	0.192	0.191	0.188
6	0.285	0.282	0.283	0.284	0.281	0.286
8	0.377	0.379	0.375	0.374	0.380	0.377
10	0.466	0.465	0.466	0.461	0.468	0.467

Table-2: Optical characteristics and linearity data of Meloxicam in mixed hydrotropic solution

Sl No.	Parameter	Values
1	Working λ	364nm
2	Beers law limit (µg/ml)	2-10
3	Correlation coefficient (R²)	0.9996
4	Slope (m)	0.045
5	Intercept (c)	0.0156

Table-3: Result of tablet analysis

Sl No.	Amount present in label claim mg/tablet	Amount obtained mg/ tablet	Percentage label claim
Sl No.	Meloxicam	Meloxicam	Meloxicam
1	15	14.82	98.80
2	15	14.67	97.80
3	15	14.94	99.60
4	15	14.62	97.46
5	15	14.72	98.13
6	15	14.89	99.26

Analysis of Tablet Formulation:

Muvera-15 (Meloxicam BP 15mg) manufactured by Sun Pharma laboratories Ltd was selected for the tablet analysis. 20 tablets of Muvera-15 was weighed and average weight was determined and ground to fine powder. Accurately weighed powder equivalent to 50 mg of Meloxicam and transferred to 50ml volumetric flask containing 10ml mixed hydrotropic solution of 10% sodium benzoate and 10% sodium caprylate. This solution was sonicated for 15 minutes to solubilize drug and volume was made upto 50ml. This solution was filtered through whatman filter paper no #41. This solution was further diluted appropriately using distilled water and the solution was analysed using UV spectrophotometer at 364nm against corresponding reagent blank. The drug content was estimated from the calibration data.

Method Validation:

The developed method for estimation of Meloxicam was validated according to ICH guidelines. The method was validated using following parameters [ICH. Q2A 1994]¹⁵.

1. Accuracy

2. Precision

3. Linearity

4. Sensitivity

5. Robustness

6. Ruggedness

The accuracy of the proposed method was found by standard addition method and calculate the percentage recovery. Varying concentration of 80%, 100% and 120% of standard drug was added to the tablet solution. The percentage std Meloxicam recovered was calculated and the data is shown below.

Table-4: Data of recovery studies

Sl No	Level of recovery	Absorbance at 364nm	Percentage recovered %
1	80%	0.482	97.70
2		0.485	99.16
3		0.483	98.12
1	100%	0.535	97.88
2		0.538	98.83
3		0.536	98.16
1	120%	0.593	99.44
2		0.589	98.19
3		0.591	98.75

The precision of an analytical procedure expresses the closeness of agreement with a series of measurement. The precision was considered at 3 levels

· Repeatability

· Intermediate precision

· Reproducibility

Repeatability expresses the precision under the same operating conditions over a short interval of time.

The intermediate precision was carried out both intra-day and inter-day and three measurements were taken both on same day and different days. The concentration of Meloxicam taken were 2,4,6µg/ml and the results are shown below.

Table-6: Intra-day precision

Sl No.	Concentration (µg/ml)	Absorbance at 364nm			% RSD
Sl No.	Concentration (µg/ml)	0hr	1.5hr	3hr	% RSD
1	2	0.107	0.106	0.108	0.934579
2	4	0.190	0.188	0.191	0.805374
3	6	0.286	0.284	0.287	0.534723

Table-7: Inter-day precision

Sl No.	Concentration (µg/ml)	Absorbance at 364nm			% RSD
Sl No.	Concentration (µg/ml)	1^st day	2^nd day	5^th day	% RSD
1	2	0.108	0.107	0.109	0.925926
2	4	0.192	0.189	0.190	0.802553
4	6	0.287	0.286	0.288	0.348432

Limit of Detection [LOD]:

The detection limit of an analytical procedure is the lowest amount of analyte in a sample which can be detected but not necessarily quantitated as an exact value. The LOD of Meloxicam by the developed method was found to be 0.2634µg/ml.

Limit of Quantification [LOQ]:

The quantitation limit of an individual analytical procedure is the lowest amount of analyte in a sample which can be quantitatively determined with suitable precision and accuracy. The LOQ of Meloxicam by the developed method was found to be 0.7983µg/ml.

Linearity:

The linearity of an analytical procedure is its ability (within a given range) to obtain test results which are directly proportional to the concentration (amount) of analyte in the sample. The calibration curve of Meloxicam was linear over the range of 2-10µg/ml.

Robustness:

The robustness of an analytical procedure is a measure of its capacity to meet the expected performance requirements during normal use. The RSD values obtained for drug was below 2% which indicates that the method gives robust results even after slight change in solvent concentration.

Table 8: Robustness data of Meloxicam

Robustness		Mixed hydrotropic blend	Mixed hydrotropic blend
Replicates	Concentration	Meloxicam	Meloxicam
1	6 µg/ml.	0.286	0.285
2	6 µg/ml.	0.284	0.285
3	6 µg/ml.	0.285	0.283
4	6 µg/ml.	0.283	0.282
5	6 µg/ml.	0.284	0.284
6	6 µg/ml.	0.282	0.284
% RSD		0.497%	0.411%

RUGGEDNESS:

The ruggedness of an analytical procedure is a measure of reproducibility of test results under the variation in conditions normally expected from laboratory to laboratory and from analyst to analyst. The analytical method was found to be rugged as %RSD obtained for absorbance of each replicate of solution was within the acceptance by change in the analyst and instrument.

Table 9: Ruggedness data of Meloxicam

Ruggedness		Change in Analyst	Change in instrument
Replicates	Concentration	Meloxicam	Meloxicam
1	4 µg/ml.	0.191	0.190
2	4 µg/ml.	0.193	0.191
3	4 µg/ml.	0.192	0.194
4	4 µg/ml.	0.191	0.193
5	4 µg/ml.	0.190	0.192
6	4 µg/ml.	0.192	0.194
% RSD		0.547%	0.850%

RESULTS AND DISCUSSION:

Solubility is a major constraint for the estimation of poorly soluble drugs. Organic solvents are employed commonly for estimating poorly soluble drugs. In this study mixed hydrotropic solubilisation method was employed to solubilize poorly soluble NSAID Meloxicam. There was more than 40 times enhancement in aqueous solubility of meloxicam in mixed hydrotropic solution of 10% Sodium benzoate and 10% Sodium caprylate. This mixed hydrotropic solution was used to extract Meloxicam from the fine powder of tablet formulation and solubilize the drug. The drug was scanned in spectrum mode and the peak absorbance was found to be 364nm. The assay result of Meloxicam (Muvera-15 [Meloxicam BP 15mg]) showed mean percentage label claim of 98.50±0.5982. The low values of standard error and standard deviation confirms accuracy of the developed method. The accuracy, precision and reproducibility of developed method was confirmed by mean percentage recovery values. The proposed method was linear over the range of 2-10 µg/ml. The linear regression of absorbance on concentration gives the equation y=0.045x+0.0156 with correlation coefficient R² value of 0.9996.

CONCLUSION:

Analytical method development is a tedious process for poorly soluble drugs, since solubility is limiting factor in its estimation. Most of the poorly soluble drugs are estimated using organic solvents. Organic solvents are toxic, have high cost and cause error due to volatility. Hydrotropic solubilisation can be utilised to solubilise poorly water-soluble drugs. Mixed hydrotropic solubilisation can be used to preclude the use of organic solvents. The hydrotropic solubilisation is novel, simple, precise, cost-effective, eco-friendly and safe. Thus, this method can be used to solubilise and estimate poorly soluble drugs

CONFLICT OF INTEREST:

The authors have no conflicts of interest regarding this investigation.

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Received on 30.03.2023 Modified on 18.04.2023

Asian J. Pharm. Ana. 2023; 13(3):175-179.

DOI: 10.52711/2231-5675.2023.00028

Sl. No.	Concentration µg/ml	Absorbance at 364 nm	Mean	S.D	S.E	C.V
1	2	0.109	0.109	0.00152	0.00458	1.39712
		0.111
		0.108
2	4	0.191	0.191	0.00200	0.00115	1.04712
		0.193
		0.189
3	6	0.285	0.284	0.00251	0.00435	0.88405
		0.282
		0.287