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Background Sildenafil is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specifil phophodiesterase type 5 (PDE5). Sildenafil enhances the effect of nitric oxide by inhibiting phosphodiesterase type 5, which is responsible for the degradation of cGMP in the corpus cavernosum. The possible genotoxic impurities of sildenafil were synthesized, i.e., sildenafil sulfonyl methyl ester, sildenafil sulfonyl ethyl ester, and sildenafil sulfonyl isopropyl ester. The present work describes the synthesis and characterization of these sulfonyl ester compounds related to sildenafil. Results All the synthesized sildenafil sulfonyl esters have proved to be beneficial for the pharmaceutical industry in view of the regulatory importance. Conclusion A simple, efficient, and repeatable method was developed for the preparation of sildenafil sulfonyl esters in view of the regulatory importance of the potential genotoxic impurities in the active pharmaceutical ingredient. A detailed study of various impurities in sildenafil was conducted. Different process-related sulfonyl esters in sildenafil were identified, synthesized, and characterized by using various spectroscopic techniques like liquid chromatography-mass spectrometry (LCMS), mass, 1H NMR, and FT-IR. These efforts to synthesize and characterize them effectively have proved to be beneficial.

The present work describes the origin, identification, synthesis, characterization and control of four novel analogues of cefpodoxime proxetil, which are ethyl, methyl, propyl and N-propyl analogues of cefpodoxime proxetil.

The present work describes the identification, origin, synthesis, characterization and control of four novel analogues of lopinavir viz. leucine analogue of lopinavir, isoleucine analogue of lopinavir, methyl analogue of lopinavir and dihydroxy analogue of lopinavir.

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