Determination of Concentration of Zolmitriptan in Solid Dosage Form by UV Spectroscopic Method

 

Shubhangi C. Daswadkar^1*, Jyoti D Gaikwad²

¹Department of Pharmaceutical Chemistry, Dr. D. Y. Patil College of Pharmacy, Akurdi, Pune – 411044 India.

²Department of Pharmaceutical Quality Assurance Techniques, Dr. D. Y. Patil College of Pharmacy, Akurdi, Pune- 411044 India.

 

ABSTRACT:

Zolmitriptan (ZMT) is a drug used in the treatment of migraines and cluster headaches.ZMT in bulk and pharmaceutical formulation determined by Zero order, First order derivative, Second order derivative and AUC by using UV-spectroscopic methods. The standard stock solution was prepared of 100 µg/ml for all proposed methods, and working standard solutions were prepared from the stock solution after adequate dilutions (1-10 µg/ml).For zero order derivative, standard solutions were measured at 283nm.For first order derivative spectroscopy the response (dA/dλ) of standard solutions was measured at 216 nm. Calibration curve was constructed by plotting response (dA/dλ) values against concentrations. Regression equation of linear calibration graph was calculated as (r²=0.994). The response for second order derivative spectroscopy was measured at 237nm,and the regression equation was calculated as (r²=0.992).The AUC-spectroscopic method was based on calculation of area under curve (AUC) for analysis of zolmitriptan in the wavelength range of278-283nm,regression equation of linear calibration graph was calculated as (r²=0.993). All Developed methods were validated as per ICH guidelines. Hence the developed methods are used for routine analysis of solid dosage form containing Zolmitriptan.

 

 

 

 

INTRODUCTION:

Zolmitriptan (ZMT), (Figure1) the antimigraine drug, is a selective agonist of serotonin (5-hydroxytryptamine; 5-HT) type 1B and 1D receptors and chemically known as (4S) - 4-[[3-[2-(dimethylamino) ethyl]-1H-indol-5-yl] methyl]-2- oxazolidinone. ZMT having high affinity to binds with human receptors 5-HT1B and 5HT1D causes cranial blood vessel constriction¹. For the treatment of migraine headache the therapeutic activity of ZMT can most likely be recognized to the agonist effects at the 5HT1B/1D receptors on intracranial blood vessels (including the arteriovenousanastomoses) and sensory nerves of the trigeminal system, which result in cranial vessel constriction and inhibition of proinflammatory neuropeptide release^1,2.

 

Fig. 1: Structure Zolmitriptan (ZMT)

 

Literature survey indicates that few analytical methods have been published for analysis of ZMT in bulk, formulation and human plasma by using various analytical methods like high performance liquid chromatography, coulometric, mass spectrometric detection and liquid chromatography-mass spectrometry, UPLC, voltammetry, and UV-spectroscopic methods^3,4,5,6. As compare to other instrumental analysis methods, spectroscopic methods are better applied for routine analysis because of their economic, rapid, simple and maintenance free advantages without compromising on accuracy and precision.

 

The aim of present study was to develop simple, sensitive, speedy, specific, cost effective and reproducible UV-spectroscopic methods for routine analysis of zolmitriptan in pharmaceutical dosage forms.

 

MATERIAL AND METHODS:

Zolmitriptan:

This was obtained as a gift sample from Glenmark Pharmaceuticals, Goa, India.

 

Chemicals and reagents:

All solvents and reagents were used of analytical grade from Merk India (Mumbai) and double distilled water was used throughout the work.

 

Instrumentation:

A double beam UV-VIS spectrophotometer (UV-1700, Shimadzu,) with 10 mm quartz cells were used. The instrumental parameters responsible for spectra obtained are as follows: wavelength range: 200-400 nm.

 

Spectroscopic procedures:

a) Preparation of standard stock and working standard solution:

The standard stock solution of zolmitriptan was prepared by dissolving accurately weighed 10 mg of the drug in distilled water and diluted to 100mL with same solvent to obtain a final concentration of 100μg/mL. This stock solution was further diluted to get working standard solutions (1-10μg/mL).

 

Method 1: Zero Order method:

The highest concentration of working standard solution was scanned over the range of 400nm to 200nm against blank. The λmax was found to be at 283nm. The calibration curve was constructed by plotting concentration versus absorbance by using various working standard solutions (1-10μg/mL).

 

Method 2: First- derivative method:

The spectrum obtained in Method I was derivatised to get first order derivative spectra and the response (dA /dλ) of the spectra were measured at 216 nm and then calibration curve was constructed by plotting working standard concentrations (1-10μg/mL) versus response (dA/dλ) at 216nm.

 

Method 3: Second- derivative method:

To get second order derivative spectra and the response (dA/dλ) of the spectra were measured at 237nm and then calibration curve was constructed by plotting working standard concentrations (1-10μg/mL) versus response (dA/dλ) at 237nm.

 

Method 4: Area under curve (AUC) method:

The AUC (area under curve) method is applicable when there is no sharp peak or when broad spectra are obtained. It involves the calculation of integrated value of absorbance with respect to the wavelength between the two selected wavelengths λ₁ and λ₂ (278-288). Area calculation processing calculates the area bound by the curve and the horizontal axis. The horizontal axis is selected by the wavelength range over which area has to be calculated. On the basis of repeated observation, this wavelength range is selected on, so as to get the linearity between area under curve and concentration. The spectrum obtained in Method I was used to calculate AUC. The calibration curve was constructed by plotting concentration (1-10μg/mL) verses AUC.

 

Assay of Formulation:

Twenty tablets of ZMT each containing 5mg were weighed, transferred to a clean dry mortar and ground into a fine powder using a pestle. Tablet powder equivalent to 5mg of drug was accurately weighted and transferred to a 50mL volumetric flask and 20mL distilled water was added. Ultrasonicated for 30min, after that the mixture was diluted to remaining volume with distilled water and filtered through Whatman filter paper (No. 41). From the filtrate an appropriate aliquot was taken in such a way that the final concentration in 10mL lies within the linearity range tested. The responses were measured and concentration in the sample was determined by comparing the response of sample with that of the standard.

 

UV Method Validation:

UV method was developed for ZMT was carried out as per ICH (Q2B) guidelines^{7,8,9,10,11,12,13}.

 

 

 

Range:

The range was calculated by preparing different working standard solutions and by plotting respective responses verses theoretical concentrations in order to get linear response i.e., increase in response with increasing concentration.

 

Linearity:

For all the proposed methods linearity was calculated with working standard solution (1-10μg/mL). The calibration curve were constructed by plotting response (absorbance) verses theoretical concentrations of working standards. (Figure 2, and table 2). Linearity was expressed in the term of correlation coefficient.

 

Accuracy (Recovery Study):

The accuracy of the method was determined by calculating recoveries of ZMT by the method of standard additions. Recovery studies were carried, to determine the suitability and reproducibility of the proposed method, by adding known quantities of standard ZMT (80,100,120%) to the pre-quantified working standard solution (10μg/mL). Three samples were prepared at each of these concentrations, and the mixtures were analyzed by the proposed method.

 

Precision:

The both intra-day and inter-day precisions of the proposed spectroscopic methods were determined by estimating the corresponding response 3 times on the same day and on different day for concentration of working standard solution (4μg/mL) and the results are reported in terms of percent relative standard deviation.

 

Limit of Detection:

Its calculation was based on the Standard Deviation of the response and the slope, and estimated as three times the signal-to-noise ratio.

 

LOD=3.3σ/s

 

Limit of Quantitation:

It is estimated as 10 times the signal-to-noise ratio.

 

LOQ=10σ/s

 

 

Robustness:

It was carried out by changing parameters like, varying ±2nm in working λmax, change in solvent (methanol), and by different analyst as per respective methods. Robustness of the method was studied using three replicates at a concentration level of 4μg/ml of ZMT.

 

RESULTS AND DISCUSSION:

Distilled water was selected as solvent because ZMT was completely soluble in distilled water and shows UV absorbance without interference. Results showed that, zero order, first derivative, Second derivative and area under curve method measurements are feasible for the analysis of ZMT without interference. Optical characteristics of ZMT were calculated by the above methods and presented in (Table No.1).

 

 

Fig. 2(a): Absorption spectra of ZMT

 

Fig.2 (b): Graph of Linearity of ZMT by UV

Table 1: Optical Chracteristics Of Zmt

Parameters	Method 1	Method 2	Method 3	Method 4
Beer-Lambert’s range(µg/ml)	1-10	1-10	1-10	1-10
λ max (nm)/ wavelength range (nm)	283	216	237	278-288
Equation of line	0.024x +0.013	0.003x-0.002	0.001x+ 0.00	0.196x+0.048
Slope+SD	0.024+0.0022	0.003+ 0.0009	0.001+ 0.0001	0.196+ 0.0278
Intercept±SD	0.013±0.0082	0.002±0.0014	0.0004± 0.0006	0.048± 0.0511
Correlation Coefficient±SD	0.9916± 0.0031	0.994± 0.0095	0.9926± 0.0067	0.9933± 0.0035
LOD(µg/ml)	0.288	0.94	0.36	0.45
LOQ(µg/ml)	0.87	2.86	1.1	1.42

 

 

 

From the calibration curve Figure 2(a, b), it was observed that with the increase in ZMT concentration, the responses are increased. In Method 1, the λmax was found to be at 283nm, Figure 2(a). The study was carried out at 283 nm, because at this wavelength the Beer- Lambert’s law was following properly with good linearity range. For Method 2 and Method 3, 216nm and 237nm wavelength was selected respectively. For Method 4, study was carried out at two wavelength ranges i.e. 278nm-288nm and good linearity range was obtained at the selected wavelength range.

 

 

 

A correlation coefficient of 0.9916, 0.994, 0.9926, 0.9933 were observed for all methods 1,2,3,4, respectively, Table (1) suggests that the developed methods had an excellent linearity over the selected concentration range; there was no interference from the any external factors. It was also observed that there was no significant difference in the content of ZMT obtained by using the different proposed spectroscopic methods.

 

Assay of Formulation:

The absorbance of the solutions was measured at 283nm against blank. The concentrations drug in sample was determined by using simultaneous equations. The results are reported in the (Table 2).

 

Table 2: Assay of Marketed Formulation

Method	Formulation	Taken Amount(mg)*	Amount Estimated(mg)*	%Estimated*	SD*	%RSD*
1	Zomig	5	4.94	98.8	0.8226	0.8253
2		5	4.98	99.6
3		5	5.02	100.4
4		5	4.93	98.6

*Indicates mean of three replicates, SD is standard deviation, RSD is relative standard deviation.

 

Table 3: Recovery Study by Standard Addition Method

Method	Level of Recovery	Amount of working standard (5μg/ml)* Tablet	Amount of standard (Drug)* μg/ml	Amount of Drug Recoverd (μg/ml)*	Percentage recovery*	Mean*	SD*	%RSD*
1	80 100 120	5 5 5	4 5 6	3.98 4.89 5.96	99.5 97.8 99.4	98.88	0.93	0.94
2	80 100 120	5 5 5	4 5 6	3.96 5.01 5.87	99 100.2 97.83	99.01	1.18	1.19
3	80 100 120	5 5 5	4 5 6	4.01 5.05 5.98	100.25 101 99.67	100.3	0.66	0.65
4	80 100 120	5 5 5	4 5 6	3.96 4.90 5.94	99 98 98.68	98.55	0.50	0.50

 

Accuracy (Recovery Study):

The accuracy of all the proposed methods at 80%,100% and 120% level was performed and shows the mean range of percentage recovery 98.88,99.01,100.3,98.5 and 0.94,1.19,0.65,0.50 % RSD (Table 3).

 

Precision:

ZMT shows results of intraday and inter day precision, RSD =0.14, 1.47, 0.45, 0.48 and 1.26, 1.57, 0.55,1.20 respectively for proposed methods; indicating repeatability of method (Table 4).

 

Robustness:

The Robustness of developed methods were checked by changing parameters such as λ max ±2 nm, solvent(methanol), and analyst and result was found to be satisfactory with SD and % RSD (Table 5).

 

 

Table 4: Inyer- Day and Intra-Day Precision Study

		Intra-day precision			Inter-day precision
Method	Concentration*(μg/mL)	Absorbance*	SD*	%RSD*	Absorbance*	SD*	%RSD*
1	4	0.0789	0.00011	0.14	0.079	0.0010	1.26
2	4	0.0198	0.00028	1.47	0.019	0.0003	1.57
3	4	0.024	0.00011	0.45	0.020	0.00011	0.55
4	4	0.8389	0.0041	0.48	0.8310	0.010	1.20

 

 

Table 5: Robustness Study By Change In Parameters

Method	Concentration (μg/mL)	λ max	Absorbance*			Mean*	SD*	% RSD*
			Wavelength (nm)	Solvent (methanol)	Analyst
			n=3	n=3	n=3
1	4 4	281 285	0.080 0.078	0.789	0.080	0.079	0.0014	1.77
2	4 4	214 218	0.0195 0.020	0.0198 0.019	0.0192 0.019	0.019	0.0003	1.57
3	4 4	235 239	0.8021 0.8212	0.7986 0.8096	0.8041 0.8169	0.8116	0.013	1.60
4	4 4 4 4	276 280 286 300	0.8512 0.830 0.8214 0.8442	0.8231 0.8196 0.8231 0.8363	0.8483 0.8410 0.8210 0.8399	0.83	0.013	1.56

 

The limit of detection and limit of quantification were found to be 0.28, 0.94, 0.36, 0.45μg/ml and 0.87, 2.86, 1.1, 1.42μg /ml for methods 1, 2, 3, 4 respectively which indicate sensitivity of the method (Table 1).

 

CONCLUSION:

Proposed methods that were developed for the determination of ZMT are based on different analytical techniques, zero order, first-derivative, second derivative and AUC method. All the methods were found to be simple, sensitive, accurate, speedy and precise. Hence, all the methods can be used successfully for routine analysis of pharmaceutical dosage forms of ZMT.

 

ACKNOWLEDGEMENT:

The authors like to acknowledge Dr. D.Y. Patil College of Pharmacy Akurdi, Pune, for providing all necessary facilities to successfully carry out these research work.

 

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Received on 23.08.2019            Accepted on 16.10.2019           

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