This document details the development and validation of a simple RP-HPLC method for the estimation of sildenafil citrate, a drug used primarily for treating erectile dysfunction, in pharmaceutical formulations. The method was validated according to ICH guidelines, showing high linearity, accuracy, and specificity with no interference from excipients. Results indicate that this method can be accurately used for routine analysis of sildenafil citrate in both bulk and tablet forms.

1. SABYA SACHI DAS
PhD Scholar
Dept. Of Pharm. Sci. & Tech.
Birla Institute Of Technology
Mesra,Ranchi-835215,Jharkhand

2. INTRODUCTION
Sildenafil Citrate is 5-[2-ethoxy-5- (4-
methylpiperazin-1-ylsulfonyl)phenyl]-1methyl-3-
propyl-1, 6-dihydro-7H-pyrazolo [4, 3-d] pyrimidin-
7-one citrate .
 It is used as a smooth muscle relaxtant by enhancing
the effect of NO by inhibiting phosphodiesterase
type 5 (responsible for degradation of cGMP in
corpus cavernosum).
 It is used mainly for the treatment of erectile
dysfunction.
11/30/2017 sabya2049@gmail.com 2

3. OBJECTIVE
There is always a requirement of an accurate
and precise analytical method for determination of
drugs in bulk and pharmaceutical dosage form.
So, the objectives of this work are :
Develop a simple and novel RP-HPLC method
for estimation of Sildenafil citrate in bulk and
pharmaceutical dosage forms.
 Optimization of chromatographic (LC)
conditions.
 Validation of the developed method as per ICH
guidelines.
11/30/2017 sabya2049@gmail.com 3

4. MATERIALS AND METHODS
• 1] Instrumentation: Quantitative HPLC was
performed on Shimadzu HPLC with LC- 20AT pumps
besides SPD- 20A UV-Visible detector. Shimadzu
Spinchrom-CFR software is used along with inertsil
shield RP-C8 (150 mm × 3.9 mm), 5 µm column for the
separation. A calibrated electronic single pan of Mettler
Toledo was used.
• 2] Reagents Used: HPLC grade acetonitrile,triple
distilled water, pure drug & marketed formulation of
Sildenafil Citrate.
11/30/2017 sabya2049@gmail.com 4

5. HPLC conditions:
 Column : LiChroCART®LiChrospher® 100;C18(250 x 4 mm,5μm)
 Mobile phase : Acetonitrile: water at 50:50 (v/v)
 Flow Rate : 1 mL/min.
 Temperature : 300c
 Injection volume : 20 µL.
 Run time : 15min.
 Retention Time : 11.625 min.
 UV Détection Wavelength : 290nm
Fig.-1. Representative Chromatogram of Sildenafil Citrate in acetonitrile: water at 50:50; v/v 10μg/ml)
11/30/2017 sabya2049@gmail.com 5

6. DRUGPROFILE
SILDENAFIL
CITRATE
Pharmacokinetics data:
Bioavailability : Approximately 25%
Metabolism : Does not undergo metabolism , it is
excreted unchanged entirely in urine.
Half- life : 10-12 hours
Excretion : Renal
11/30/2017 sabya2049@gmail.com 6

7. validation
 The developed method was validated for linearity, accuracy,
intraday & interday precision,specificity,LOD,LOQ. The
results are shown in detail in the results and discussion section.
Results and discussion:
 Linearity: The method was found to be linear over a range
of 25-150μg/mL with a correlation coefficient of 0.9999.
 Analysis of commercial Sildenafil Citrate Tablet:
11/30/2017 sabya2049@gmail.com 7

8.  Accuracy:
 Precision:
 Specificity : No interference was observed from the excipients
present in tablet.
11/30/2017 sabya2049@gmail.com 8

9.  System Suitability:
 Stability: Bench top stability studies for 48hr of the sample
solution revealed no significant change in the concentration of
analyte. (% Recovery= 99.48-99.992%;n=5)
11/30/2017 sabya2049@gmail.com 9

10. Chemical data:
Chemical name : 5-[2-ethoxy-5- (4-methylpiperazin-1-
ylsulfonyl)phenyl]-1-methyl-3-propyl-1,6-
dihydro-7H-pyrazolo[4,3-d] pyrimidin-7-one
citrate
Empirical formula : C22H30N6O4S, C6H8O7
Molecular weight : 666.7 gm/mole
Physical stability:
Colour : White to off-white.
Solubility : Soluble in dimethylformamide, sparingly
soluble in acetic acid, slightly soluble in methanol.
Form : Crystalline powder
Usual strengths : 25mg;50mg;100mg
11/30/2017 sabya2049@gmail.com 10

11. Pharmacological action:
This Methylpiperazine compound inhibits the enzyme PDE 5 in
corpora caverosa of the penis,thereby prolonging the life of cGMP at
that site. This leads to better erection.
ADVERSE REACTION:
 The drug potentiates the hypotensive effects to nitrates, and hence its
administration to persons who are currently using nitrates in any
form is dangerous.
 There is also a degree of cardiac risk associated with sexual activity,
especially in elderly persons over the age of 60 years.
 The plasma levels of sildenafil increases in subjects over age
65,those with renal/hepatic impairment and in those who are being
concurrently treated with cytochrome P 450 inhibitors such as
erythromycin and ketoconazole.Hence,its adverse effects are likely
to be more frequent in these situations.
 Category : PDE 5 INHIBITOR (TREATMENT FOR SEXUAL IMPOTENCE)
11/30/2017 sabya2049@gmail.com 11

12. LITERATURE REVIEW OF SILDENAFIL
The Intraday and Interday precision for sildenafil and its active
metabolite were found to be 0.0946 and 0.1457 respectively.
Correlation co-efficient for sildenafil was found to be 0.9999 .
LOD and LOQ was found to be 0.1224 µg/ml and 0.4014 µg/ml
respectively.
RP-HPLC method was validated according to the guidelines of Food
and Drug Administration, showing to be accurate (bias within
±2.28%)over the concentration range of 25-150 μg/mL for sildenafil.
Λmax.( Abs. Max.) for sildenafil was monitored at 290 nm .
Tablet dosage form was estimated, and percentage recovery was
98.48-99.992%.
11/30/2017 sabya2049@gmail.com 12

13. CONCLUSIONS
 The proposed method was found to be simple, precise,
sensitive and accurate for determination of Sildenafil
Citrate in bulk and tablet dosage forms.
 The mobile phase is simple to prepare.
 The method is also validated as per ICH.
 Hence, this method can be easily and conveniently
adopted for routine analysis of Sildenafil Citrate in bulk,
pharmaceutical dosage forms and dissolution mediums.
11/30/2017 sabya2049@gmail.com 13

14. Precision
Theprecisionoftheproposedmethodwas
ascertainedbyactualdeterminationofsixreplicates
offixedconcentrationofthedrugwithintheBeer’s
rangeandfindingouttheabsorbance'sbythe
proposedmethod.
Fromtheseabsorbance'sMean,Standarddeviation
and%R.S.Dwascalculated.11/30/2017 sabya2049@gmail.com 14

15. RESULTS IN PRECISION
PRECISION
CONCENTRAT
ION
(µg/ml)
METHOD-I
(MEAN ± SD)
METHOD-II
(MEAN ± SD)
RSD(%)
METHOD-I METHOD-II
INTRADAY 20 0.213 ±
0.0028
20.112 ±
0.0121
1.314 0.0601
INTERDAY 20 0.204 ±
0.0019
20.011 ±
0.0221
0.0931 0.1104
11/30/2017 sabya2049@gmail.com 15

16. ACCURACY
Todeterminetheaccuracyoftheproposedmethod,
recoverystudieswerecarriedoutbytakingdifferent
amounts(80%,100%and120%)ofbulksamplesofA
sildenafilwithinthelinearityrangeandaddingto
thepre-analyzedformulationconcentration.
Fromthatpercentagerecoveryvalueswere
calculated.
11/30/2017 sabya2049@gmail.com 16

17. RESULT IN ACCURACY
SAMPLE ID
CONCENTRATION (µg/ml)
%RECOVERY OF PURE DRUG
STATISTICAL ANALYSIS
PURE DRUG FORMULATION METHOD-I METHOD-II METHOD-I METHOD-II
S1: 80% 8 10 98.45 98.69
MEAN= 98.36
SD =0.3286
%RSD = 0.3340
MEAN =99.23
SD =0.6709
%RSD =0.73
S2: 80% 8 10 98 99.89
S3: 80% 8 10 98.64 99.12
S4: 100% 10 10 100.12 101.21
MEAN= 100.45
SD = 0.6715
%RSD= 0.6684
MEAN =101.2
SD =1.014
%RSD= 1.065
S5: 100% 10 10 100.23 99.94
S6: 100% 10 10
100.02 100.25
S7: 120% 12 10 101.23 101.56 MEAN= 100.26
SD = 0.864
%RSD= 0.8617
MEAN = 101.7
SD = 1.214
%RSD = 1.12
S8:
120%
12 10
99.56 100.28
S9:
120%
12 10
100.01 101.8
11/30/2017 sabya2049@gmail.com 17

18. CONCLUSION
Theproposedmethodsaresimple,sensitiveand
reliablewithgoodprecisionandaccuracy.
Theproposedmethodsarespecificwhileestimating
thecommercialformulationswithoutinterference
ofexcipientsandotheradditives.
Hence,thismethodcanbeusedfortheroutine
determinationofsildenafilinbulksamplesand
Pharmaceuticalformulations.11/30/2017 sabya2049@gmail.com 18

19. REFERENCE
GRChatwal, S Anand, Instrumental Methods of Chemical Analysis;
2002:209-217.
 Scottish intercollegiate guidelines network (sign), control of pain in adults with
cancer-anationalclinicalguideline.Scotlandnationalhealthservice(nhs).2008:76-
89.
G. T. Warner and B. Jarvis, Olmesartan medoxomil, Drugs 62 (2002)
1345–1353.
 Sissmann j, bouroudian m, armagnac c, donazollo y, latreille m, and panis r.
Angiotensin ii blockade in healthy volunteers: tolerability and impact on renin
angiotensin system components of single and repeated doses of a new angiotensin
iireceptorantagonistsr47436(bms186295).Jhypertens1994;12:s92.
Metabocardforsildenafilretrieved29april2004:1010-1025.11/30/2017 sabya2049@gmail.com 19

20. 11/30/2017 sabya2049@gmail.com 20