Simultaneous Detection of Three Phosphodiesterase Type 5 Inhibitors and Eight of Their Analogs in Lifestyle Products and Screening for Adulterants by High-Performance Thin-Layer Chromatography

Abstract

An HPTLC method is proposed to permit effective screening for the presence of three phosphodiesterase type 5 inhibitors (PDE5-Is; sildenafil, vardenafil, and tadalafil) and eight of their analogs (hydroxyacetildenafil, homosildenafil, thiohomosildenafil, acetildenafil, acetaminotadalafil, propoxyphenyl hydroxyhomosildenafil, hydroxyhomosildenafil, and hydroxythiohomosildenafil) in finished products, including tablets, capsules, chocolate, instant coffee, syrup, and chewing gum. For all the finished products, the same simple sample preparation may be applied: ultrasound-assisted extraction in 10 mL methanol for 30 min followed by centrifugation. The Rf values of individual HPTLC bands afford preliminary identification of potential PDE5-Is. Scanning densitometry capabilities enable comparison of the unknown UV spectra with those of known standard compounds and allow further structural insight. Mass spectrometric analysis of the material derived from individual zones supplies an additional degree of confidence. Significantly, the proposed screening technique allows focus on the already known PDE5 Is and provides a platform for isolation and chemical categorization of the newly-synthesized analogs. Furthermore, the scope could be expanded to other therapeutic categories (e.g., analgesics, antidiabetics, and anorexiants) that are occasionally coadulterated along with the PDE5-Is. The method was successfully applied to screening of 45 commercial lifestyle products. Of those, 31 products tested positive for at least one illegal component (sildenafil, tadalafil, propoxyphenyl hydroxyhomosildenafil, or dimethylsildenafil).

Stability assessment of tamsulosin and tadalafil co‐formulated in capsules by two validated chromatographic methods

“…On reviewing literature, TMS was quantified by several methods, namely; TLC [16][17][18], HPLC in different matrices [18][19][20][21], capillary electrophoresis [16], spectrophotometry [16,[22][23][24], and electrochemical methods [16,25]. For TAD, several methods were reported for its determination includ-ing TLC [26][27][28][29], HPLC [26,[30][31][32][33][34][35][36], gas chromatography [26,37], capillary electrophoresis [26], spectrophotometry [26,[38][39][40][41], and electrochemical methods [42][43][44].…”

Acute poisoning by dexmedetomidine-containing chewing gum in a child

“…Analyses on lifestyle products revealed sildenafil in a brand of chewing gum called Super Lover, available on the internet. 4 Stimulant ('energy') chewing gum containing caffeine has been reported to cause acute intoxication when consumed in substantial amounts. 5 Dexmedetomidine-adulterated chewing gum is a rare cause of intoxication.…”

Rapid Spectrophotometric Methods for the Determination of Moxifloxacin and Sildenafil in Pharmaceutical Preparations Based on Reaction with 4-Aminoantipyrine

“…USP describes HPLC method for the examine sildenafil citrate [16]. Sildenafil citrate was determined by different methods including HPLC in pharmaceutical products [17,18], HPLC in Pharmaceutical products with other drugs [19,20], HPLC in dietary supplements [21], CGC in pharmaceutical formulations and dietary supplements [22,23], HPTLC in commercial lifestyle products [24], electroanalytical methods in pharmaceutical preparations [25][26][27] and flow injection analysis in tablets using UV-detection [28] and amperometric detection [29]. Spectrophotometric methods, such as spectrophotometry through ion-associate formation reactions [30,31], ion-pair reactions [30,32], charge-transfer complexes [33], extractive spectrophotometry [34] and direct UV-spectrophotometry [35] were also communicated for the analysis of sildenafil citrate in pharmaceuticals.…”