INTRODUCTION:

Methdilazine hydrochloride, is chemically, 10-[(1-methylpyrrolidin-3-yl) methyl] phenothiazine; hydrochloride. Molecular formula as C₁₈H₂₀N₂S.HCl (molecular weight 332.9 g/mol). The drug is official in United States Pharmacopeia¹, which describes UV-spectrophotometric assay in aqueous medium. The literature survey revealed the availability of few methods for the assay of MDH in pharmaceutical formulations.

Quantification of MDH has been achieved by high-performance liquid chromatography (HPLC) ^2–4, liquid chromatography⁵, spectrofluorimetry⁶, differential fluorimetry, and differential UV-spectrophotometry⁷. Some visible spectrophotometric methods are also reported for the assay of on pharmaceuticals ^8–20.

In recent years, there has been an increasing tendency towards development of stability-indicating assays ^21–²⁴, using the approach to stress testing enshrined in International Conference on Harmonisation (ICH) guideline Q2A(R2) ²⁵miscellanous^26-30. This approach is being extended to pharmaceuticals to enable accurate and precise quantification of drugs in the presence of their degradation products.

MATERIALS AND METHODS:

A Shimadzu -160 A double beam UV-Visible recording spectrophotometer with pair of 10mm matched quartz cell was used to measure absorbance of solutions. A Shimadzu analytical balance was used.

Congo red, picric acid, methyl orange, hydrochloric acid, potassium hydrogen phthalate and chloroform of A.R. grade were used in the study.

Preparation of standard solution and reagents:

Stock solution of methdilazine hydrochloride, (100 μg/ml) was prepared in ethanol. From this stock solution working standard (10 μg/ml) was prepared by diluting 10 ml stock solution to 100 ml with ethanol. A 0.05 % w/v Congo red, 0.25 % picric acid and 0.02 % methyl orange solutions were prepared in distilled water respectively.

Potassium hydrogen phthalate buffer solution of pH 4.01was prepared in distilled water. Dilute hydrochloric acid was used to adjust desired pH of buffer solution.

EXPERIMENTAL:

Method 1 (with Congo red):

Into a series of separating funnels appropriate amount of the working standard drug solutions were pipetted out. To each funnel 1.0 ml of buffer (pH= 3.7) and 5.0 ml of 0.05%w/v congo red were added. 10 ml of chloroform was added to each funnel. The solutions were shaken for thorough mixing of the two phases and were allowed to stand for clear separation of the layers.

The absorbance values of the chloroform layers were measured against their respective reagent blank at the wavelength of the maximum absorbance (λ max =490 nm.)

Method 2 (Picric acid):

Into a series of separating funnels appropriate amount of the working standard drug solutions were pipetted out. To each funnel 4.0 ml of buffer (pH = 3.7) and 3.5 ml of 0.25% w/v picric acid were added. 10ml of chloroform was added to each funnel. The solutions were shaken for thorough mixing of the two phases and were allowed to stand for clear separation of the layers. The absorbance values of the chloroform layers were measured against their respective reagent blank at the wavelength of the maximum absorbance (λ max= 400 nm).

Method 3(with methyl orange):

Into a series of separating funnels appropriate amount of the working standard drug solutions were pipetted out.To each funnel 1.0ml of buffer (pH= 3.7) and 5.5 ml of 0.02% w/v methyl orange were added. 10ml of chloroform was added to each funnel. The solutions were shaken for thorough mixing of the two phases and were allowed to stand for clear separation of the layers. The absorbance values of the chloroform layers were measured against their respective reagent blank at the wavelength of the maximum absorbance (λ max =430 nm).

Estimation from tablets:

Twenty tablets of labelled claim 8 mg of methdilazine hydrochloride were weighed accurately. Average weight of each tablet was determined. Tablets were crushed into fine powder. An accurately weighed quantity of powder equivalent to 10 mg of methdilazine hydrochloride was transferred into a beaker and it was shaken with 50 ml of ethanol and filtered. The filtrate and the washing were collected in a 100.0 ml volumetric flask. This filtrate and the washing were diluted up to the mark with ethanol to obtain final concentration as 100 μg/ml. This solution was further diluted to give 10 μg/ml. Such solution was used for methods respectively.

Appropriate aliquots of drug solution were taken and the individual assay procedures were followed for the estimation of drug contents in tablets. The concentration of the drug in the tablets was calculated using calibration curve. The recovery experiment was carried out by standard addition method. Results of analysis of optical and regression of drug are given in table 1.

Table 1: Values of results of optical and regression of drug

Parameter	Congo Red	Picric acid	Methyl orange
Detection Wavelength (nm)	490	400	430
Beer Law Limits (µg/ml)	1-10	2-12	1-14
Correlation coefficient(r²)	0.9999	0.9999	0.9999
Regression equation (y=b+ac) Slope (a) Intercept (b)	0.025 0.0002	0.0405 0.0004	0.008 -7x 10^-17

RESULTS:

The extractive spectrophotometric methods are popular due to their sensitivity in assay of the drug and hence ion pair extractive spectrophotometric methods have gain considerable attention for quantitative determination of many pharmaceutical preparations. These proposed methods are extractive spectrophotometric methods for the determination of methdilazine hydrochloride, by using chloroform as solvent from its formulations. The colour ion pair complexes formed are very stable. The working conditions of these methods were established by varying one parameter at time and keeping the other parameters fixed by observing the effect produced on the absorbance of the colour species. The various parameters involved for maximum colour development for these methods were optimized. The proposed methods were validated statistically and by recovery studies. The molar absorptivity values showed the sensitivity of methods while the precision was confirmed by %RSD (relative standard deviation). The optical characteristics such as absorption maxima (nm), co-relation coefficient (r) were calculated and are also summarized in table 1. Assay results of recovery studies are given in table 2 A,B,C.

Table no 2: A (Congo red)

Amount of Sample Added In (µg/ml)	Amount of Standard Added in (µg/ml)	Total amount recovered	Percentage recovery (%)	Standard deviation	Percentage of relative standard deviation (C.O.V.)
1	0	1.002857	100.2857	0.004451	0.443811
1	1	2.031429	101.5714	0.021594	1.062979
1	2	3.001143	100.0381	0.005014	0.167079
1	3	4.074286	101.8571	0.053807	1.320659
				Mean= 0.021217	Mean= 0.748632

Table no 2: B (Picric acid)

Amount of Sample Added in (µg/ml)	Amount of Standard Added in (µg/ml)	Total amount recovered	Percentage recovery (%)	Standard deviation	Percentage of relative standard deviation (C.O.V.)
2	0	2.007055	100.3527	0.027474	1.368872
2	2	4.003527	100.0882	0.038854	0.970497
2	4	5.975309	99.58848	0.031876	0.533469
2	6	7.978836	99.73545	0.038854	0.486965
				Mean= 0.034265	Mean=0.839951

Table no 2:C (methyl orange)

Amount of Sample Added in (µg/ml)	Amount of Standard Added in (µg/ml)	Total amount recovered	Percentage recovery (%)	Standard deviation	Percentage of relative standard deviation (C.O.V.)
2	0	2.014286	100.7143	0.013363	0.663414
2	2	4.014286	100.3571	0.015187	0.378332
2	4	6.019643	100.3274	0.015905	0.264222
2	6	8.0125	100.1563	0.0125	0.156006
				Mean= 0.014239	Mean= 0.365494

Results are in good in agreement with labelled value.

DISCUSSION:

The percent recovery obtained indicates non interference from the common excipients used in the formulation. The reproducibility, repeatability and accuracy of these methods were found to be good, which is evidenced by low standard deviation. The proposed methods are simple, sensitive, accurate, precise and reproducible. They are directly applied to drug to form chromogen. Hence they can be successfully applied for the routine estimation of methdilazine hydrochloride, in bulk and pharmaceutical dosage form even at very low concentration and determination of stability of drug in formulation. The strong recommendation is made here for the proposed methods for determination of Methdilazine hydrochloride, from its formulation.

ACKNOWLEDGMENTS:

Authors express sincere thanks to the Principal of D.G. Ruparel College, for providing necessary facility for research work.

REFERENCES:

1. The United States Pharmacopoeia XXIV Revision. The National Formulary XIX Rockville, USP Convention, 2000.

2. R. T. Sane, L. S. Joshi, R. M. Kothurkar, K. D. Ladage, R. V. Tendolkar, and D. P. Gangal, “HPLC determination of methdilazine HCl in pharmaceutical dosage forms,” Indian Journal of Pharmaceutical Sciences. 52(3); 1990: 160–161.

3. K. Croes, P. T. McCarthy, and R. J. Flanagan, “HPLC of basic drugs and quaternary ammonium compounds on microparticulate strong cation-exchange materials using methanolic or aqueous methanol eluents containing an ionic modifier,” Journal of Chromatography A. 693(2); 1995: 289–306.

4. N. W. Smith and M. B. Evans. The efficient analysis of neutral and highly polar pharmaceutical compounds using reversed-phase and ion-exchange electrochromatography. Chromatographia. 1995; 41(3): 197–203.

5. H. Y. Mohammed and F. F. Cantwell. Liquid chromatographie analysis of pharmaceutical syrups using pre-columns and salt-adsorption on amberlite XAD-2. Analytical Chemistry. 1978; 50(3): 491–496.

6. C. S. P. Sastry, A. S. R. Prasad Tipirneni, M. V. Suryanarayana, T. Thirupathi Rao, and T. Satyanarayana. Spectrofluorimetric determination of trimeprazine tartrate and methdilazine hydrochloride in formulations. Indian Journal of Pharmaceutical Sciences. 1990; 52(2): 115–117.

7. D. F. Gurka, R. E. Kolinski, J. W. Myrick, and C. E. Wells. Scope of differential UV and differential fluorescence assays for phenothiazines: comparison with official methods. Journal of Pharmaceutical Sciences. 1980; 69 (9): 1069– 1074.

8. J. Emmanuel and R. Mathew. Spectrophotometric determination of methdilazine hydrochloride in Pharmaceutical Formulations. Indian Drugs. 1985; 22: 602–605.

9. C. S. P. Sastry, A. S. R. P. Tipirneni, and M. V. Suryanarayana. Spectrophotometric determination of trimeprazine and methdilazine with sodium cobaltinitrite. Eastern Pharmacist. 1989; 32: 131–133.

10. C. S. P. Sastry, A. S. R. P. Tipirneni, and M. V. Suryanarayana. Sensitive spectrophotometric determination of some antihistamines with haematoxylin and chloramines-T. Indian Drugs. 1989; 36: 351–357.

11. C. S. P. Sastry, A. S. R. P. Tipirneni, and M. V. Suryanarayana. Spectrophotometric determination of some antiallergic agents with 3-methyl-2-benzothiazolinone hydrazine. Journal of Pharmaceutical and Biomedical Analysis. 1990; 8(3): 287–289.

12. K. Basavaiah and V. S. Charan. Visible spectrophotometric determination of methdilazine in dosage forms using metavanadate and H2O2. Indian Drugs. 2002; 39 (8): 449–451.

13. K. Basavaiah and V. S. Charan. Four new vanadometric methods for the assay of methdilazine in bulk drug and in pharmaceutical formulations. Science Asia. 2003; 29: 37–44.

14. K. Basavaiah and V. S. Charan. Four simple procedures for the assay of methdilazine in bulk drug and in tablets and syrup using potassium iodate. Farmaco. 2003; 58(4):285–292.

15. K. Basavaiah and V. S. Charan. The use of chloranilic acid for the spectrophotometric determination of three antihistamines. Turkish Journal of Chemistry. 2002; 26(5): 653– 661.

16. B. G. Gowda and J. Seetharamappa. Extractive spectrophotometric determination of fluoroquinolones and antiallergic drugs in pure and pharmaceutical formulations. Analytical Sciences.19; 2003: 461–464.

17. K. C. Ramesh, B. G. Gowda, M. B. Melwanki, J. Seetharamappa, and J. Keshavayya. Extractive spectrophotometric determination of antiallergic drugs in pharmaceutical formulations using bromopyrogallol red and bromothymol blue. Analytical Sciences. 2001; 17(9):1101–1103.

18. C. S. P. Sastry, T. A. S. R. Prasad, and M. V. Suryanarayana. Extraction-spectrophotometric determination of some antihistaminic agents with fast green FCF. Mikrochimica Acta. 1999; 100(1-2):107–112.

19. K. Basavaiah and V. S. Charan. Spectrophotometric and turbidimetric determination of methdilazine using bromophenol blue. Indian Pharmacist. 2003; 97–100.

20. C. S. P. Sastry, A. S. R. Prasad Tipirneni, and M. V. Suryanarayana. Spectrophotometric determination of some antihistamines with cobalt thiocyanate. Indian Journal of Pharmaceutical Sciences. 1989; 51(4): 146–148.

21. S. Singh, B. Singh, R. Bahuguna, L. Wadhwa, and R. Saxena. Stress degradation studies on ezetimibe and development of a validated stability-indicating HPLC assay. Journal of Pharmaceutical and Biomedical Analysis. 2006; 41(3); 1037–1040.

22. A. Mohammadi, I. Haririan, N. Rezanour, L. Ghiasi, and R. B. Walker. A stability-indicating high performance liquid chromatographic assay for the determination of orlistat in capsules. Journal of Chromatography A. 2006; 1116(1-2): 153–157.

23. I. Ivana, Z. Ljiljana, and Z. Mira. A stability indicating assay method for cefuroxime axetil and its application to analysis of tablets exposed to accelerated stability test conditions. Journal of Chromatography A. 2006; 1119(1-2): 209–215.

24. K. B. Vinay, H. D. Revanasiddappa, C. M. Xavier, P. J. Ramesh, and M. S. Raghu. A stability indicating UPLC method for the determination of tramadol hydrochloride: application topharmaceutical analysis. Chromatography Research International. 2012, Article ID 870951; 2012: 9.

25. Stability testing of new drug substances and products, in Proceedings of the International Conference on Harmonization Q1A (R2), IFPMA, Geneva, Switzerland, 2006.

26. Rajan V. Rele, S.S. Zarapker Vipul Doshi, V.M. Shah. A simple extractive colorimetric determination of three drug from pharmaceutical preparations. Indian Drug. 1987; 24(12): 560-564.

27. Rajan V. Rele, Pankaj Gurav. A simple extractive spectrophotometric determination of loradatadine desloratadine and Rupatadine from Pharmaceutical Formulation. International Journal of Pharma and Biosciences. 2012; 3(2): 89-92.

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Received on 25.10.2023 Modified on 10.12.2023

Asian J. Research Chem. 2024; 17(2):85-88.

DOI: 10.52711/0974-4150.2024.00017