to develop uv spectrophotometric method for the estimation of sildenafil citrate in bulk and tablet

8/3/2019 To Develop Uv Spectrophotometric Method for the Estimation of Sildenafil Citrate in Bulk and Tablet

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Publication Ref No.: IJPRD/2010/PUB/ARTI/VOV-2/ISSUE-7/SEP/012 ISSN 0974 – 9446

International Journal of Pharma Research and Development – Online

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TO DEVELOP UV SPECTROPHOTOMETRIC METHOD FOR THE ESTIMATION OF SILDENAFILCITRATE IN BULK AND TABLET

Ashok Kumar1*,Gaurav Kumar Rajput2

Gaurav Srivastava3,Atul Kumar Singh4

1

Department of Biotechnology,HNBGU (A Central University),

Srinagar- Garhwal-246174 (UK) INDIA2Department of Quality Control,Cooper Pharma Ltd.

Selaqui, Dehradun-248002 (UK) INDIA3Uttarakhand Technical University,Suddhowala Dehradun-248007 (Uttarakhand)

4H. N. B. Garhwal University Srinagar Garhwal-246174 (Uttarakhand), IndiaEmail: [email protected]

ABSTRACT

A simple, sensitive, highly accurate UV spectrophotometric method has been developed for thedetermination of Sildenafil citrate in bulk and tablet dosage form. Solution of sildenafil citrate inmethanol shows maximum absorbance at 291 nm. Beer’s law was obeyed in the concentration rangeof 5-30 µg mL-1 correlation coefficients, detection and quantitation limits were also calculated. Theproposed method has been applied successfully for the analysis of the drug in pure and in its tabletsdosage forms. Result of percentage recovery and placebo interference showed that the method wasnot affected by the presence of common excipients. The percentages assay of sildenafil citrate in tabletwas 100 mg of 99.87% and 50 mg of 99.84%. The method was validated by determining its sensitivity,accuracy and precision which proves suitability of the developed method for the routine estimation ofSildenafil in bulk and tablets.

Key Words: Sildenafil citrate, UV spectroscopy, Estimation, Tablets.

INTRODUCTION

Sildenafil citrate (SC) is designated chemicallyas 1-[[3-(6, 7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazole [4, 3-d] pyromidine-5-yl)-4-

ethoxyphenyl] sulfonyl]-4 methylpiperazinecitrate. The physiological mechanism of erectionof the penis involves release of nitric oxide (NO)in the corpus cavernosum during sexualstimulation. Then, NO activates the enzyme

Ashok Kumar





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guanylate cyclase, which results in increasedlevels of cyclic guanosine monophosphate(cGMP), production of smooth muscle

relaxation in the corpus cavernosum and inflowof blood. SC has no direct relaxant effect onisolated human corpus cavernosum, butenhances the effect of NO by inhibitingphosphodiesterase type 5 (PDES), which isresponsible for degradation of cGMP in thecorpus cavernosum (1, 2, and 3). When sexualstimulation causes local release of NO,inhibition of PDES by SC causes increasedlevels of cGMP in the corpus cavernosum,resulting in smooth muscle relaxation and inflow

to the corpus cavernosum

(2, 4, and 5)

.

Figure 1. Structure of Sildenafil Citrate.objective of the present work was to develop asimple, rapid, accurate and sensitive UV

spectrophotometric method for thedetermination of sildenafil in pharmaceuticalformulation.

MATERIAL AND METHODS

Pharmaceutical grade of sildenafil citrate wasprocured from Cooper Pharma Limited,Dehradun. All the chemicals were of analyticalreagent grade of Merck (Germany) unlessotherwise specified. Doubly distilled water was

used to prepare all solutions. Freshly preparedsolutions were always employed. Differentbrands of tablets of sildenafil were suppliedfrom local stores.

1. Instrumentation:

Spectro Scan 80DV UV-Visible double beamspectrophotometer with 1 cm matched quartzcell (7).

2. Sildenafil stock solution:Standard stock solution was prepared bydissolving 70.25 mg of Sildenafil in 100 mL ofmethanol to get concentration of 500 µg/mLsolution (7).

3. Method development:Aliquots of stock solution were further dilutedwith methanol to get working solution of 5, 10,15, 20, 25 and 30µg mL-1. The working

standards were scanned between 200-400 nm.The same λ max was used for the furthermeasurement of the drug.

4. Procedure for calibration curve:Aliquots of stock solution were further dilutedwith Methanol to get working solution of 5, 10,15, 20, 25 and 30 µg mL-1. Finally, the preparedstandards were measured after standing for 5.0min at λ max as recorded in each case againsta solvent blank similarly prepared. A calibration

graph of the absorbance versus theconcentration of the drug was plotted.

Procedure for dosage forms:For analysis of commercial formulations, twentytablets were taken and powdered. Tabletpowder equivalent to 140.5 mg of sildenafilcitrate was transferred to 100 mL volumetricflask and dissolved in methanol. Then thesolution was sonicated for 15 min and filteredand it was for further diluted to get the requiredconcentration. The absorbance of the preparedsample solution was measure against methanolblank at 291±2 nm. A standard additions technique was also used to confirm theaccuracy and precisions (7, 8).





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RESULTS AND DISCUSSION

The absorption spectrum of sildenafil was

measured in the range 200–400 nm against theblank methanol [Figure 1]. The workingstandards were scanned between 200-400 nmwhich showed the maximum absorbance at 291nm [Figure 2]. The curve for 10 ppm methanoland 10 ppm HCl was given in figure 3 and 4. Thestandard solution show maximum absorbance atλ max for each three systems as recorded inTable 1. And the method was validated bystudying the following parameters as ICH guidelines for method validation (9). ( Please Refer

Table No. 04 at bottom)

The precision of the method was investigatedwith respect to repeatability. For intra-dayprecision, standard solution of fixedconcentration was analyzed at various timeinterval and %RSD was noted (limit%RSD<2.0%). And the day-to-day precisionwas studied by taken the absorbance of thesame concentration of standard solution atvarious days and the %RSD was calculated

(%RSD<2.0%) as shown in Table 2.( PleaseRefer Table No. 02 at bottom)

The specificity of the method was conducted toprove that the free from determined interferenceof solvent and commonly used tablet excipients.This is evidenced by the lack of absorbance atthe specified λ max for the excipients in theplacebo and blank solutions.

The applicability of the proposed method for theassay of sildenafil in tablet formulation wasexamined by analyzing formulations and theresults were tabulated in Table 2. The resultsobtained were good agreement with the labelclaims. The results were reproducible with low%RSD values. The results of analysis of thecommercial tablets and the recovery study ofdrug suggested that there is no interference

from any excipients (such as starch, lactose,titanium dioxide, and magnesium stearate)which are commonly present in tablets.

CONCLUSION

A method for the determination of sildenafil inthe bulk drug and tablet formulation has beendeveloped. From the spectrum of sildenafilcitrate as shown in Figure 2, it was found thatthe maximum absorbance is at about 291 nm inmethanol. A good linear relationship (0.9998)was observed between the concentrationranges of 5-30 µg/mL. The assay of sildenafil

tablet was found to be 100 mg of 99.87% and50 mg of 99.84%. The high percentagerecovery indicates the high accuracy of themethod. This demonstrates that the developedspectroscopic method is simple, accurate andreproducible. Thus the developed method canbe easily used for the routine quality control ofsildenafil in bulk and tablet dosage form.

ACKNOWLEDGEMENTS

The authors are thankful to Cooper PharmaLimited (Labs), Dehradun for providing giftsample of sildenafil. Authors are also grateful toMrs. K.P. Rathoure for technical support.

REFERENCES:

1. Boolell M, Allen MJ, Ballard SA, Gepi-Attee S, Muirhead GJ, Naylor AM, Osterloh IH,Gingell C (1996). Sildenafil: an orally active type

5 cyclic GMP-specific phosphodiesteraseinhibitor for the treatment of penile erectiledysfunction. Int J Impot Res 8 (2): 47–52.2. Dinesh, N. D., Nagaraja, P., MadeGowda, N. N. and Rangappa, K. S. (2002).Extractive spectrophotometric methods for theassay of sildenafil citrate (Viagra) in pure form





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and in pharmaceutical formulations. Talanta 57:757-764.3. Nicholas K. Terrett, Andrew S. Bell,

David Brown and Peter Ellis. (1996). Sildenafil(Viagra), a potent and selective inhibitor of Type5 cGMP phosphodiesterase with utility for thetreatment of male erectile dysfunction. Bioorg Med Chem Lett 6: 1819–1824.4. Webb, D.J.; Freestone, S.; Allen, M.J.;Muirhead, G.J. (1999), Sildenafil citrate andblood-pressure-lowering drugs: results of druginteraction studies with an organic nitrate and acalcium antagonist. Am. J. Cardiol. 83 (5A):21C–28C.

5. Jean-Paul Richalet, Pierre Gratadour,Paul Robach, Isabelle Pham, Michèle Déchaux,Aude Joncquiert-Latarjet, Pascal Mollard, JulienBrugniaux and Jérémy Cornolo. (2005),Sildenafil inhibits altitude-induced hypoxemia

and pulmonary hypertension. Am. J. Respir.Crit. Care Med. 171 (3): 275–81.6. K. Harikrishna, B. S. Nagaralli and J.

Seetharamappa (2008). ExtractiveSpectrophotometric Determination of SildenafilCitrate (Viagra) in Pure and PharmaceuticalFormulations. J. Food & Drug Anal, 16 (1): 11- 17. 7. Vogel, A. I. (1969). A text book ofquantitave in-organic anlysis. 3rd ed. p. 35.ELBS and Longman.8. Analytical Methods Committee. (1987),Recommendations for the definition, estimationand use of the detection limit. Analyst 112: 199-

2049. ICH draft Guidelines on Validation ofAnalytical Procedures (1995); Definitions andTerminology, Federal Register, 60, IFPMA,Switzerland: 1260.

TABLES AND FIGURES:

Table 1: Parameters for determination of sildenafil citrate against methanol

Parameters ValuesA max (nm) 291 ±2

Beer’s law limit (µg mL-1) 5– 30

Correlation coefficient (r) 0.9999

Table 2: Results of Assay and Precision Studies

Precision**Interday

Sample Labelclaim,mg/tab

Amountfound,mg /tab

(%)* C.V.*

Repeatability

Intraday

Sildenafilcitrate

100mg

99.87±

0.1890

99.87±0.1890

0.1514 0.326 0.511 0.701

Sildenafilcitrate

50 mg 49.92±0.1958

99.84±0.1986

0.1689 0.312 0.507 0.731





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Figure 1. Standard plot of Sildenafil Citrate.

Standard Curve

0.137

0.274

0.411

0.548

0.685

0.822

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

5 10 15 20 25 30Concentration ppm

A b s o r b a n c e

Figure 2. UV spectra of Sildenafil Citrate in Methanol 20 ppm.

Figure 3: UV Spectra for Sildenafil Citrate in Methanol 10 ppm.





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Figure 4. UV spectra of Sildenafil Citrate in HCl 10 ppm.

…End…

to develop uv spectrophotometric method for the estimation of sildenafil citrate in bulk and tablet

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