1. INTRODUCTION:

Early in the 1960s, amantadine hydrochloride (Figure 1) was invented as an anti-influenza medication. A few years later, amantadine hydrochloride was discovered to be effective in the treatment of Parkinson's disease. In the year 1968, a case was observed of a woman who was experiencing Parkinson's symptoms responded better after receiving amantadine, which was being used as an antiviral medication. Schwab in the year 1969 and his associates were the ones who originally proposed this therapeutic approach^1-4.

A synthetic and stable quasi-spherical aliphatic cyclic primary amine, amantadine (1-aminoadamantane or 1-adamantanamine hydrochloride) is generated from adamantane^5-7. The crystalline or powdered form of amantadine hydrochloride is almost completely white. Amantadine is clinically administered at a dose of 100 mg/two times a day, which may be increased up to 400 mg/day depending on the patient's clinical condition. It is rapidly absorbed when taken orally and is quickly and safely excreted about 90% through urine. Parkinson's disease is treated with it in both monotherapy and combination with levodopa^8-10.

Amantadine blocks M2 protein mediated ion channels, which prevents influenza virus life cycle reproduction into the cell. When amantadine is used to treat Parkinsonism, a symptomatic control that affects dopaminergic¹¹ function by amplifying dopamine synthesis, release, or reuptake takes place. However, amantadine may also cause N-methyl D-aspartate (NMDA) receptor blockage¹², which functions as a weak non-competitive NMDA antagonist receptor and indirectly encourages the release of dopamine^13,14. Parkinson's patients are typically treated with levodopa as a first line choice, although about 10% of PD patients experience levodopa induced dyskinesia (LID). Due to ongoing levodopa-dependent treatment, dyskinesia symptoms worsen as Parkinson's disease (PD) advances. Amantadine successfully treats the LID symptoms that cause PD and so prevents this progression and therapy-related problems^15,16.

Amantadine hydrochloride's chemical structure lacks chromophoric groups, making it difficult to analyze it by spectrophotometric method. As reported in various literature, several derivatizing agents, including (2-Naphthoxy) acetyl chloride^17-20, disodium tetraborate decahydrate²¹, 9-fluoroenylmethyl chloroformate²², 1,2-naphthoquinone-4-sulphonate (NQS)^23-30, Fe(III)-o-phenanthroline reagent, Fe(III)-bipyridyl reagent ³¹, anthraquinone-2-sulfonyl chloride^32-3], sulphonphthalein acid dyes (bromocresol green, bromophenol blue, bromothymol blue)^35-38, etc. were reported for the execution of spectrophotometric determination of amine group containing drugs. Out of all the identified derivatizing agents, 1,2-naphthoquinone-4-sulphonate was the most effective at forming a complex with amantadine hydrochloride because it had a stronger affinity for amine groups, the fundamental functional group of the drug's molecular structure. A lack of chromophoric group precluded any spectroscopic method from providing a conclusive measurement of amantadine hydrochloride solubility. The development, validation and application of UV spectrophotometric method^39-41 in solubility studies of solid lipids, liquid lipids and surfactants were the major objectives of the research work.

Figure 1. Chemical structure of amantadine hydrochloride.

2. EXPERIMENTAL:

2.1. Chemical and reagents:

Amantadine hydrochloride was purchased from Sigma-Aldrich Mumbai, India. 1,2-Naphthoquinone-4-sulfonate was purchased from Sisco Research Laboratories Pvt. Ltd., Navi Mumbai, Maharashtra. In addition, analytical grade reagents and solvents were used throughout the study. Double distilled purified water was used for the preparation of samples.

2.2. Instrumentation:

All spectrophotometric measurements were analysed using an ultraviolet-visible spectrophotometer (Shimadzu UV-1800), with 1 cm quartz cuvette, a digital balance (Shimadzu AUX220), pH meter (Electronics India 611E), an ultrasonic water bath with thermostatic monitoring (Labman LMUC-2), vortex mixer (Decibel), and a refrigerated centrifuge (Remi CM-12 PLUS).

2.3. Method Development:

2.3.1 Preparation of reagent and buffer solution:

2.3.1.1. 1,2-Naphthoquinone-4-sulfonate (0.5%w/v):

To achieve a concentration of 0.5% w/v, accurately weighed NQS reagent (0.25g), transferred it to a 50ml calibrated volumetric flask, initially dissolved the reagent in 10ml of distilled water, and sonicated the mixture for 10minutes, if necessary to produced NQS solution. This mixture was then diluted with distilled water to produce the desired concentration (0.5% w/v). Reagent must be prepared fresh and protected from light before use.

2.3.1.2. Preparation of buffer solution (pH 9):

12.368 g of boric acid and 14.90 g of potassium chloride are mixed together to produce 1litre of 0.2M solution. Buffer solution of pH 9 was prepared by mixing 21.3ml of 0.2M sodium hydroxide and 50ml of 0.2M boric acid and potassium chloride and make volume up to 200ml in a calibrated volumetric flask.

2.3.2. Derivatization method:

A number of techniques using NQS reagent in various concentrations were used to evaluate and determine amantadine hydrochloride using UV spectrophotometer. As the drug's λmax varies depending on the derivatizing agent and procedure used, there was no predetermined or standard reported value. The following procedure was used to develop the final screened method. One ml of sample solution to be tested was taken and mixed it thoroughly with 1 ml of buffer solution of pH 9, to this add 1 ml of NQS solution (0.5% w/v). The treated sample solution was kept and protected from light at room temperature for 30 mins. Finally, the desired volume was made up with purified water and determined its absorbance²¹.

2.3.3. Determination of maximum absorption wavelength:

Dilutions of 10µg/ml was prepared from the stock solution (100µg/ml) of amantadine hydrochloride and consecutively derivatized as per the above discussed procedure, which was further diluted with distilled water. Finally, scanned the wavelength in UV-Visible range from 200-800nm. The maximum absorbance (Fig. 2) for amantadine hydrochloride was obtained at 433nm (λmax)⁴².

2.4. Method Validation:

2.4.1. Linearity :

Different aliquots of amantadine hydrochloride were prepared in calibrated volumetric flask (of 10ml volume) with distilled water. Dilutions of 2, 4, 6, 8, 10, 12, 16, 20 µg/ml were prepared by withdrawing volume from stock solution and consecutively derivatized as per the above discussed procedure, with volume made up with distilled water⁴³.

2.4.2. Accuracy:

The proposed UV-Vis method's accuracy was assessed following the usual addition of the desired analyte. Recovery method/studies are well known as the accuracy determination method. Three separate drug solutions were prepared in triplicate at specified concentrations of 80%, 100% and 120%. Based on percent recovery in predefined concentrations when amantadine hydrochloride was added using the standard addition method, the accuracy of the method was determined⁴⁴.

2.4.3. Precision:

The precision of the proposed analytical method was analysed at different levels of intra-day precision and inter-day precision at different concentration levels of analyte covering the concentration range of 6, 8, 10 µg/ml. The aliquots underwent three separate intra-day analyses in triplicate on the same day and three consecutive days for inter-day precision analysis in triplicate⁴⁵.

2.4.4. Robustness:

The study's robustness was assessed by analysing the effects of small modifications in each of the process variables, such as the change in wavelength and the reaction duration, on the effectiveness of the proposed method on specified concentration of 16 µg/ml. During each observation, the alterations were taken into account and computed⁴⁶.

2.4.5. Ruggedness

The proposed method's ruggedness was tested by carrying out the procedure under the same conditions of operation using two distinct instruments at two different labs and at two separate times. The study's findings were based on differences from lab-to-lab and day-to-day. Each parameter was estimated by preparing the sample of 12µg/ml concentration sextuple times ⁴⁷.

2.4.6. Repeatability:

The study was done by taking 8 µg/ml concentration of amantadine hydrochloride solution. The repeatability analysis was repeated and computed six times of the respective concentration sample ⁴⁸.

2.5. Application to solubility studies:

2.5.1 Solubility of drug in liquid lipids and surfactants:

To determine the solubility of Amantadine Hydrochloride in liquid lipids and surfactants, 5ml of each excipient were taken and added excess amount of drug in several portions (1-2mg) till the mixture attains saturation. Heated the excipients on water bath at 50ºC with occasional stirring on vortex mixture, the process continues for not less than 48hours. Centrifuged the samples for 20minutes at 5000rpm at room temperature. Collected the supernatant and extracted it with equal amount of distilled water. Again, centrifuge the samples for 20minutes at 5000rpm at room temperature. Collected the aqueous layer and derivatized the sample for further analysis by UV spectrophotometer at 433nm. The experiment was performed in triplicate⁴⁹.

2.5.2. Solubility of drug in solid lipids:

To determine the solubility of amantadine hydrochloride, solid lipids (1gm) were melted above its melting point in a suitable glass vial on water bath and the drug was gradually added. The addition of drug to the melted lipid was proceeded till the amount of drug remain undissolved at point of its saturation solubility. The amount of solid lipids required to solubilize the drug in the molten form was analyzed by UV spectroscopy. The study was performed in triplicate^50,51.

3. RESULTS:

3.1. Method development:

Amantadine hydrochloride's UV spectrophotometric analysis method was created due to the drug's lack of chromophoric group. In contrast to buffer solution of pH 9, 0.5% w/v NQS solution was employed for derivatization. The λmax of resulted sample prepared as per the previously discussed procedure was found to be at 433 nm (Figure 2). For future use, the novel approach of UV-Vis spectrophotometric technique was further validated.

Figure 2. UV-Vis spectra of amantadine hydrochloride showing maximum absorbance.

3.2. Method validation:

3.2.1 Linearity:

The correlation coefficient was used to assess the linearity curve. The aliquots were examined at 433nm using UV-Vis spectrophotometer. In the experimental concentrations, the drug's response was found to be linear, and the linear regression equation was found to be y= 0.0038x+0.0017 with correlation coefficient of 0.9983 (Figure 3).

Figure 3: Linearity curve of amantadine hydrochloride.

3.2.2 Accuracy:

Three different percentage levels were used in triplicate to evaluate the method's accuracy. The best recoveries of the spiked samples are shown in the results, which ranged from 98.55 to 100.34%, and showed the method's accuracy. The results are presented in the Table 1.

Table 1. Recovery percentage of amantadine hydrochloride.

% Recovery Level	Samples	Mean % Recovery (n=3)	SD	% RSD
80%	1	99.35	0.6918	0.6963
	2	99.36	0.6616	0.6658
	3	99.52	0.5101	0.5125
100%	1	99.65	0.1212	0.1217
	2	100.34	0.2103	0.2096
	3	98.55	0.2950	0.2994
120%	1	99.92	0.1801	0.1802
	2	99.50	0.0902	0.0901
	3	99.00	0.0513	0.0518

3.2.3 Precision:

By performing the analysis in accordance with the process and using the standard weight used for analysis, the precision of the developed analytical method was determined. The analysis was evaluated for day duration variance in inter and intra-day precision, among days. The absorbance of each aliquot was represented as a percentage relative standard deviation to help distinguish differences. The generated approach was found to be accurate because the stated %RSD values are under 2%. The resulted values of precision are reported in Table 2 (intra-day precision) and Table 3 (inter-day precision).

Table 2. Evaluation data of intra-day precision study.

Intraday precision	Concentration (µg/ml)	Mean absorbance (n=3)	% RSD
Morning precision	6	0.0259	1.35
	8	0.0315	1.43
	10	0.040	1.58
Afternoon precision	6	0.0265	1.64
	8	0.0305	1.63
	10	0.0395	1.26
Evening precision	6	0.0254	1.58
	8	0.0316	1.67
	10	0.0402	0.72

Table 3. Evaluation data of inter-day precision study.

Inter day precision	Concentration (µg/ml)	Mean absorbance (n=3)	% RSD
Day 1	6	0.0276	1.71
	8	0.0326	1.69
	10	0.0408	0.99
Day 2	6	0.0248	0.81
	8	0.0323	1.17
	10	0.0406	1.30
Day 3	6	0.0256	1.19
	8	0.034	0.90
	10	0.0396	1.15

3.2.4. Robustness:

Robustness evaluation depends on the type of technique being studied and should be taken into account during the development phase. It should demonstrate the accuracy of an analysis in context of intentional changes to the method parameters. Thus, the appropriateness of the analytical process was controlled by the susceptibility to minute changes in analytical circumstances. The findings of the method's robustness analysis were established in Table 4. The final outcome showed that the values obtained were unaffected and consistent with the actual value for all variance situations. Thus, the proposed method is applicable for the analysis of amantadine hydrochloride in the future.

Table 4. Robustness studies data.

Condition	Value	Mean absorbance (n=3)	%RSD
Change in wavelength	433 nm	0.061	0.941
	434 nm	0.062
	432 nm	0.061
Change in reaction duration	30 min	0.062	1.613
	29 min	0.063
	31 min	0.061

3.2.5. Ruggedness:

The sample's robustness was evaluated in order to estimate the effectiveness of the proposed approach by executing the analysis on various instruments and with various analysts. The findings demonstrated that the corresponding process consistently produced identical results, and the %RSD was under 2%. Table 5 provides a summary of the study's multiple variables.

Table 5. Results of ruggedness study.

Condition	Trials	Absorbance	Mean absorbance	% RSD
Analyst - I	1	0.047	0.047	1.903
	2	0.048
	3	0.046
	4	0.048
	5	0.047
	6	0.046
Analyst – II	1	0.048	0.0471	1.596
	2	0.046
	3	0.047
	4	0.048
	5	0.047
	6	0.047
Equipment – I	1	0.049	0.0483	1.689
	2	0.047
	3	0.049
	4	0.048
	5	0.048
	6	0.049
Equipment – II	1	0.046	0.0458	1.642
	2	0.046
	3	0.045
	4	0.047
	5	0.045
	6	0.046

3.2.6. Repeatability:

By repeatedly analysing the same concentration six times (8 µg/ml), the newly developed method's repeatability was tested. The resulting absorbance was found to be within the expected range, and the %RSD was obtained below 2%.

3.3. Solubility studies:

An initial approach for the assessment of amantadine hydrochloride solubility profile is to develop a procedure for spectroscopic identification of the moiety. The drug's solubility was tested in a number of phases, including solid lipid, liquid lipid and surfactants (Figure 4). Amantadine hydrochloride showed its maximum solubilities in tween-20 (3.48 mg/ml) in surfactant. The drug further showed its lowest solubility in liquid lipid namely, isopropyl myristate (0.2 mg/ml).

Figure 4. Solubility data of amantadine hydrochloride in different excipients.

4. DISCUSSION:

An unfortunate approach led to the discovery of the usage of amantadine hydrochloride, a repurposed anti-viral substance, in the treatment of Parkinson's disease. The molecule cannot be identified directly using any spectrophotometric method since there are no chromophoric groups present in its chemical structure. Numerous derivatizing agents were screened and examined in accordance with study of the literature so as to choose the most appropriate one. The developed method was analyzed and validated by UV-Vis spectrophotometric technique. The produced aliquots were derivatized as per the predefined derivatization technique before analysis. The amine group is a component of the drug's chemical structure, hence the derivatizing agent was chosen based on which molecule has a higher affinity for the amine group for derivatization. During the technique development process, the buffer solution of pH 9 and NQS derivative were selected as the medium and derivatizing agents, respectively that were found to be most suited. All of the parameters that were evaluated for validation had suitable ranges and %RSD values under 2, which indicated that the method was appropriate for the particular experimental circumstances. As a result, the designed process was effectively employed to determine the solubility status of amantadine hydrochloride in various excipients, including solid lipids, liquid lipids, and surfactants. The developed and investigated method demonstrated a successful platform for future drug estimation by different spectrophotometric analytical procedures for other non-chromophoric drugs also.

5. CONCLUSION:

The outcomes and statistical analysis showed that the developed UV-Vis spectrophotometric approach satisfies particular acceptance criteria and was found to be simple, quick, sensitive, highly accurate, reproducible, and cost-effective. As a result, the established and validated method herein can be used to estimate the amantadine hydrochloride in different excipients (solid lipids, liquid lipids and surfactants) using UV-Vis spectrophotometric technique.

6. CONFLICT OF INTEREST:

The authors declare no conflict of interest.

7. ACKNOWLEDGMENTS:

The authors would like to acknowledge the Faculty of Pharmacy and Research Cell, Integral University for continuous support and guidance during all stages of this research work. Manuscript Communication Number: IU/R&D/2023-MCN0002161.

8. REFERENCES:

1. Danysz W. Dekundy A. Scheschonka A. Riederer P. Amantadine: reappraisal of the timeless diamond—target updates and novel therapeutic potentials. J Neural Transm. 2021; 128: 127-169. https://doi.org/10.1007/s00702-021-02306-2

2. Parkes JD. Curzon G. Knott PJ. Tattersall R. Baxter RC. Knill-Jones RP. Marsden CD. Vollum D. Treatment of Parkinson's disease with amantadine and levodopa: a one-year study. The Lancet. 1971; 297(7709): 1083-7. https://doi.org/10.1016/S0140-6736(71)91834-4

3. Tseng ZH. Lee HL. Wu SY. Yeh KL. Lee T. Development of sustainable reaction and separation processes for amantadine and amantadine hydrochloride. Chem Eng Res Des. 2022; 188: 393-405. https://doi.org/10.1016/j.cherd.2022.09.049

4. Lee PY. Lai YH. Liu PL. Liu CC. Su CC. Chiu FY. Cheng WC. Hsu SL. Cheng KC. Chiu LY. Kao TE. Toxicity of amantadine hydrochloride on cultured bovine cornea endothelial cells. Sci Rep. 2021; 11(1): 18514.| https://doi.org/10.1038/s41598-021-98005-9

5. Suwalsky M. Jemiola-Rzeminska M. Altamirano M. Villena F. Dukes N. Strzalka K. Interactions of the antiviral and antiparkinson agent amantadine with lipid membranes and human erythrocytes. Biophys Chem. 2015; 202: 13-20. https://doi.org/10.1016/j.bpc.2015.04.002

6. Caroff SN. Jain R. Morley JF. Revisiting amantadine as a treatment for drug-induced movement disorders. Ann Clin Psychiatry. 2020; 32(3): 198-208.

7. Vu BD. Phan TPD. Van Tran T. Dang AT. Nguyen PL. Phan DC. A simple method for synthesis of amantadine hydrochloride. Int J Pharm Sci Res. 2021; 13(2): 763-775. 10.13040/IJPSR.0975-8232.13(2).763-75

8. Raupp-Barcaro IF. Vital MA. Galduróz JC. Andreatini R. Potential antidepressant effect of amantadine: a review of preclinical studies and clinical trials. Braz J Psychiatry. 2018; 40: 449-58. https://doi.org/10.1590/1516-4446-2017-2393

9. Li Y. Jiang Y. Lin T. Wan Q. Yang X. Xu G. Huang J. Li Z. Amantadine hydrochloride monitoring by dried plasma spot technique: High‐performance liquid chromatography–tandem mass spectrometry based clinical assay. J Sep Sci. 2020; 43(12): 2264-2269. https://doi.org/10.1002/jssc.201901298

10. Bodnar W. Aranda-Abreu G. Slabon-Willand M. Kotecka S. Farnik M. Bodnar J. The efficacy of amantadine hydrochloride in the treatment of COVID-19-a single-center observation study. Res Sq. 2021; 1-14. https://doi.org/10.21203/rs.3.rs-493154/v1

11. Imran M. Mishra A. Usmani A. Eqbal A. Experimental Animal Models of Parkinson’s Disease: An Overview. Asian J Pharm Clin Res. 2020; 13(11): 12-17.10.22159/AJPCR.2020.V13I11.39131

12. Ansari AJ. Khushtar M. Fatima N. Monawwar M. Tanveer A. Khan MF. An Overview on the Diagnosis and Approaches in Pharmacological Management of Parkinson’s Disease. Res Rev: J Neurosci. 2021; 11(1): 10-13.

13. Ma HM. Zafonte RD. Amantadine and memantine: a comprehensive review for acquired brain injury. Brain Inj. 2020; 34(3): 299-315. https://doi.org/10.1080/02699052.2020.1723697

14. Sharma VD. Lyons KE. Pahwa R. Amantadine extended-release capsules for levodopa-induced dyskinesia in patients with Parkinson’s disease. Ther Clin Risk Manag. 2018; 12: 665-73.

15. Hauser RA. Walsh RR. Pahwa R. Chernick D. Formella AE. Amantadine ER (Gocovri®) significantly increases ON time without any dyskinesia: pooled analyses from pivotal trials in Parkinson's disease. Front Neurol. 2021; 12: 645706. https://doi.org/10.3389/fneur.2021.645706

16. Dashtipour K. Tafreshi AR. Pahwa R. Lyons KE. Extended-release amantadine for levodopa-induced dyskinesia. Expert Rev Neurother. 2019; 19(4): 293-9. https://doi.org/10.1080/14737175.2019.1592677

17. Yanamadala G. Praveen Srikumar P. A pre-column derivatization technique for the development and validation of a stability indicating HPLCUV method for the determination of memantine hydrochloride in bulk and formulations by using (2-napthoxy) acetyl chloride. Der Pharma Chem. 2014; 6(4): 169-80.

18. Duh TH. Wu HL. Kou HS. Lu CY. (2-Naphthoxy) acetyl chloride, a simple fluorescent reagent. J Chromatogr A. 2003; 987(1-2): 205-9. https://doi.org/10.1016/S0021-9673(02)01904-0

19. Duh TH. Wu HL. Pan CW. Kou HS. Fluorimetric liquid chromatographic analysis of amantadine in urine and pharmaceutical formulation. J Chromatogr A. 2005; 1088(1-2): 175-81. https://doi.org/10.1016/j.chroma.2005.04.011

20. Chung TC. Tai CT. Wu HL. Simple and sensitive liquid chromatographic method with fluorimetric detection for the analysis of gabapentin in human plasma. J Chromatogr A. 2006; 1119(1-2): 294-298. https://doi.org/10.1016/j.chroma.2005.12.081

21. Kunjir N. Dube A. Sahu S. Development and validation of assay method of estimation of amantadine hydrochloride by HPLC. Int J Discov Herb Res. 2011; 1(3): 117-120.

22. El-Enany NM. Abdelal A. Belal F. Spectrofluorimetric determination of sertraline in dosage forms and human plasma through derivatization with 9-fluorenylmethyl chloroformate. Chem Cent J. 2011; 5(1): 1-8. http://journal.chemistrycentral.com/content/5/1/56

23. Chaudhari SR. Shirkhedkar AA. Exploration of 1, 2-naphthoquinone-4-sulfonate derivatizing reagent for determination of chlorthalidone in tablets: a spectrophotometric investigation. Future J Pharm Sci. 2021; 7(1): 1-9. https://doi.org/10.1186/s43094-021-00180-z

24. Osman RA. Elbashir AA. A high-performance liquid chromatographic (HPLC) method for the determination of amlodipine drug in dosage form using 1, 2-naphthoquine-4-sulfonate (NQS). J Anal Pharm Res. 2017; 6(1): 00163.

25. Muszalska I. Sobczak A. Kiaszewicz I. Rabiega K. Lesniewska MA. Jelińska A. 1, 2-Naphthoquinone-4-sulfonic acid sodium salt as a reagent for spectrophotometric determination of rimantadine and memantine. J Anal Chem. 2015; 70: 320-7. 10.1134/S1061934815030120

26. Darwish IA. Al-Shehri MM. El-Gendy MA. Novel spectrophotometric method for determination of cinacalcet hydrochloride in its tablets via derivatization with 1, 2-naphthoquinone-4-sulphonate. Chem Cent J. 2012; 6(1): 1-8. http://journal.chemistrycentral.com/content/6/1/1

27. Elbashir AA. Ahmed AA. Ali Ahmed SM, Aboul-Enein HY. 1, 2-Naphthoquinone-4-sulphonic acid sodium salt (NQS) as an analytical reagent for the determination of pharmaceutical amine by spectrophotometry. Appl Spectrosc Rev. 2012; 47(3): 219-32. https://doi.org/10.1080/05704928.2011.639107

28. Mahmoud AM. Khalil NY. Darwish IA. Aboul-Fadl T. Selective spectrophotometric and spectrofluorometric methods for the determination of amantadine hydrochloride in capsules and plasma via derivatization with 1, 2-naphthoquinone-4-sulphonate. Int J Anal Chem. 2009, 1-9. https://doi.org/10.1155/2009/810104

29. Darwish IA. Abdine HH. Amer SM. Al-Rayes LI. Simple spectrophotometric method for determination of Paroxetine in tablets using 1, 2-naphthoquinone-4-sulphonate as a chromogenic reagent. Int J Anal Chem. 2009, 1-9. https://doi.org/10.1155/2009/237601

30. Ashour S. Bayram R. Novel spectrophotometric method for determination of some macrolide antibiotics in pharmaceutical formulations using 1, 2-naphthoquinone-4-sulphonate. Spectrochim Acta A: Mol Biomol Spectrosc. 2012; 99: 74-80. https://doi.org/10.1016/j.saa.2012.08.024

31. Omara HA. Amin AS. Spectrophotometric microdetermination of anti-Parkinsonian and antiviral drug amantadine HCl in pure and in dosage forms. Arab J Chem. 2011; 4(3): 287-92. https://doi.org/10.1016/j.arabjc.2010.06.048

32. Shuangjin C. Fang F. Han L. Ming M. New method for high-performance liquid chromatographic determination of amantadine and its analogues in rat plasma. J Pharma Biomed Anal. 2007; 44(5): 1100-5. https://doi.org/10.1016/j.jpba.2007.04.021

33. Feng F. Uno B. Goto M. Zhang Z. An D. Anthraquinone-2-sulfonyl chloride: a new versatile derivatization reagent—synthesis mechanism and application for analysis of amines. Talanta. 2002; 57(3): 481-490. https://doi.org/10.1016/S0039-9140(02)00050-4

34. Liu H. Feng F. Ma M. Cui S. Xie D. Xu S. Pharmacokinetic study of three cardiovascular drugs by high-performance liquid chromatography using pre-column derivatization with 9, 10-anthraquinone-2-sulfonyl chloride. J Chromatogr B. 2007; 858(1-2): 42-48. https://doi.org/10.1016/j.jchromb.2007.08.004

35. Omara HA. Amin AS. Extractive-spectrophotometric methods for determination of anti-Parkinsonian drug in pharmaceutical formulations and in biological samples using sulphonphthalein acid dyes. J Saudi Chem Soc. 2012; 16(1): 75-81. https://doi.org/10.1016/j.jscs.2010.11.001

36. Prashanth KN. Basavaiah K. Vinay KB. Sensitive and selective spectrophotometric assay of rizatriptan benzoate in pharmaceuticals using three sulphonphthalein dyes. Arab J Chem. 2016; 9: S971-S980. https://doi.org/10.1016/j.arabjc.2011.10.006

37. Basavaiah K. Abdulrahman SAM. Vinay KB. Simple and sensitive spectrophotometric determination of olanzapine in pharmaceutical formulations using two sulphonphthalein acid dyes. J Food Drug Anal. 2009; 17(6): 11. https://doi.org/10.38212/2224-6614.2585

38. Sakur AA. Obaydo R. Sensitive spectrophotometric methods for Determination of zolmitriptan in bulk form and in tablets via complex formation with tow sulphonphthalein acid dyes. Int J Acad Sci Res. 2015; 3(4): 106-114.

39. Yunus M. Siddiqui HH. Bagga P. Ali MA. Singh K. A Simple UV Spectrophotometric Method for the Determination of Flupenthixol Dihydrochloride in Bulk and Pharmaceutical Formulations. Int J Pharma Sci Res. 2011; 2(8): 2152.

40. Bagga P. Salman M. Siddiqui HH. Ansari AM. Mehmood T. Singh K. A simple UV spectrophotometric method for the determination of febuxostat in bulk and pharmaceutical formulations. Int J Pharma Sci Res. 2011; 2(10): 2655-2659.

41. Singh K. Bagga P. Shakya P. Kumar A. Khalid M. Akhtar J. Arif M. Validated UV spectroscopic method for estimation of montelukast sodium. Int J Pharma Sci Res. 2015; 6: 4728-4732. http://dx.doi.org/10.13040/IJPSR.0975-8232.6(11).4728-31

42. Anusha T. Sri RS. Derivative UV Spectroscopic Cleaning Method Development and Validation of Darunavir API incorporated into Dissolving Oral Film. Res J Sci Technol. 2024; 16(2): 107-4. http://dx.doi.org/10.52711/2349-2988.2024.00016

43. Jain HK. Deore DD. Development and Validation of Spectrophotometric Method for Determination of Trimetazidine Hydrochloride in Bulk and Tablet Dosage Form. Res J Pharm Technol. 2016; 9(9): 1457-1460. http://dx.doi.org/10.5958/0974-360X.2016.00282.1

44. Afroz A. Haque T. Talukder MM. Islam SMA. Spectrophotometric Estimation of Rosuvastatin Calcium and Glimepiride in Tablet Dosage Form. Asian J Pharm Ana. 2011; 1(4): 74-78.

45. Dahiya J. Singh A. Gupta SK. Kumar B. Spectrophotometric Estimation of Dextromethorphan in Bulk Drug using Hydrotropic Solubilization Technique. Asian J Pharm Ana. 2013; 3(3): 90-93.

46. Mali AD. Simultaneous Determination of Carvedilol and Hydrochlorothiazide in Pharmaceutical Dosage Form by Second Order Derivative UV Spectrophotometry. Asian J Pharm Ana. 2015; 5(3): 133-138.

47. Kumar P. Saini B. Dahiya R. Akhtar J. Shrivastav B. Development and Validation of UV Spectrophotometric Method for Simultaneous Estimation of Hydrochlorothiazide and Lisinopril in Bulk Drug and Its Formulations. Res J Pharm Technol. 2013; 6(2): 212-215.

48. Babu KS. P. Kareemulla NV. Reddy M. Ishaq BM. Natarajan NB. Madhu M. Gopinath C. Extractive Spectrophotometric Method for the Determination of Metaxalone in Bulk and its Pharmaceutical Formulation. Res J Pharm Technol. 2013; 6(8): 905-907.

49. Ahamed SS. Khaleel M. Havannavar NT. Miyan SS. Colorimetric Estimation of Nebivolol Hydrochloride in Bulk and Pharmaceutical Dosage Form. Asian J Pharm Technol. 2019; 9(4): 253-259. http://dx.doi.org/10.5958/2231-5713.2019.00042.4

50. Nithisha M. Ashwini P. Swetha R. Implementation of Hydrotropic Solvents for UV Spectrophotometric Assessment of Esomeprazole-Loaded Microspheres: Greenness Evaluation. Asian J Pharm Technol. 2024; 14(2): 123-7. http://dx.doi.org/10.52711/2231-5713.2024.00022

51. Koradia SK. Shah PT. Rana RR. Vaghani SS. Pandey S. Jivani NP. Spectrophotometric Determination of Atomoxetine Hydrochloride from Its Pharmaceutical Dosage Forms. Asian J Res Chem. 2009; 2(3): 258-259.

Received on 25.06.2024 Revised on 24.10.2024

Accepted on 29.01.2025 Published on 02.08.2025

Available online from August 08, 2025

Research J. Pharmacy and Technology. 2025;18(8):3742-3748.

DOI: 10.52711/0974-360X.2025.00539

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