RP-HPLC Method Development for Estimation of Sildenafil Citrate in Tablets and in Seminal Fluid

Abstract

A RP HPLC method for estimation of sildenafil citrate (SC) in tablet dosage form and seminal fluid was developed and validated. Best resolution was obtained with column Waters Spherisorb® C 18 bonded silica, (5 µm, 4.6 x 250 mm) at 230 nm with retention time of 5.01 min. The mobile phase used was TEA (0.2%) pH adjusted at 3 with OPA and ACN (60:40) with flow rate of 1.0 mL/min. The method for estimation of sildenafil citrate in tablet dosage form was found to be linear, accurate, precise, sensitive and selective. Whereas the bioanalytical estimation of SC in seminal fluid was found to be in the range of 100 ng/mL to 10µg/mL. Method was found to be highly sensitive as LOD and LOQ were found to 0.3 µg/ml and 0.9µg/ml. The repeatability and reproducibility were within the range i.e. less than 2%.The accuracy of the method was 99.3%. The percentage purity was calculated for market formulation was 102.8%. The internal standard used for bioanalytical methods was Diclofenac sodium. The drug was extracted from seminal fluid by protein precipitation using ACN as precipitating agent. The linearity range was from 100.0ng/mL to 2.0µg/mL. The LOD and LOQ were found to 0.03µg/mL and 0.1µg/mL. The repeatability and reproducibility were within the range i.e. % RSD less than 15%. The accuracy of the method was 90.36%.and the extraction efficiency was found to be 98.25%. The stability of drug was found to be within the range i.e. less the 15%. INTRODUCTIONSildenafil citrate marketed as Viagra TM (Pfizer) was approved as a drug for treating male erectile dysfunction (ED) by the US Food and Drug Administration on 27 March 1998 (Anonymous, 1998). SC is 1- [[3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H pyrazolo[4,3-d] pyrimidin-5-yl) -4-ethoxyphenyl] sulfonyl]-4-methyl piperazine citrate is a PDE5 inhibitor used for treatment of ED (Anonymous, 2010). Nitric Oxide (NO) is released with sexual stimulation from nerve endings and endothelial cells in the spongy erectile tissue, the corpus cavernosum of the penis. This release of NO activates the enzyme guanylate cyclase. The enzyme guanylate cyclase then converts guanosine triphosphate (GTP) into cGMP causing the smooth muscle to relax, which causes an inflow of blood, which then leads to an erection. Cyclic guanosine monophosphate (cGMP) is then hydrolysed back to the inactive GMP by phosphodiesterase type 5 (PDE5). The level of cGMP is therefore controlled by the activation of cyclic nucleotide cyclase and the breakdown by PDE5.

HPLC Determination of Sildenafil in Tablets

“…A linear correlation was obtained and the regression equation was y = 126217.2x-29536.0 with correlation coefficient (R 2 ) 0.9998. Limit of Detection (LOD) and Limit of Quantitation (LOQ) were evaluated based on signal-to-noise ratio and were found to be 0.7 and 2.2 μg/ml, respectively, which are similar to earlier reported [16,23]. The precision was determined by six successive injections of a sample at the 100% concentration level of the Sildenafil.…”

“…Various analytical techniques like spectrophotometry [9,11], Raman spectroscopy [11,12], thin layer chromatography [13], high performance liquid chromatography [14][15][16][17][18][19][20][21][22][23], high performance liquid chromatography-mass spectrometry [24][25][26][27] are reported for Sildenafil determination in pharmaceutical preparations [10, 12, 18-20, 22, 23, 25], biological samples [16,20,21,[24][25][26][27], dietary supplements [3,5,13], herbal products [15] and drinks [11].…”

Sildenafil 4.0—Integrated Synthetic Chemistry, Formulation and Analytical Strategies Effecting Immense Therapeutic and Societal Impact in the Fourth Industrial Era

“…Simple, fast and sensitive high-performance liquid chromatography (HPLC) methods have been developed and validated for the determination of sildenafil citrate in pharmaceutical preparations. The methods refer to reverse phase chromatography and their conditions are summarized in Table 4 [ 152 , 153 , 154 , 155 , 156 , 157 , 158 ]. The parameters evaluated were the detection wavelength, the type and amount of the organic modifier, the salt concentration and the pH of the mobile phase.…”

Simultaneous quantification of sildenafil and N‐desmethyl sildenafil in human plasma by UFLC coupled with ESI‐MS/MS and pharmacokinetic and bioequivalence studies in Malay population

“…1(a). Hence cGMP accumulates in corpus cavernosum and causes the erection to be maintained (Sharma et al, 2012). This release of NO activates the enzyme guanylate cyclase.…”

“…Sildenafil citrate acts to inhibit PDE5. Hence cGMP accumulates in corpus cavernosum and causes the erection to be maintained (Sharma et al, 2012). N-Desmethyl sildenafil (NDS), 1- [4-ethoxy-3-(6,7-di-hydro-lmethyl-7-oxo-3-propyl-lH-pyrazolo[4,3-d]pyrimidin-5-yl)phenylsulfonylpiperazine, is the active metabolite of SIL; is potent and exhibits 50% of the potency of parent drug, which contributes to the pharmacological action (Jeong et al, 2001).…”