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Alzheimer's Disease (AD)
Published in Charles Theisler, Adjuvant Medical Care, 2023
Sindenafil (Viagra): A new study at the Cleveland Clinic revealed that patients prescribed sindenafil had a 69% reduced risk of Alzheimer’s. It was further found that sildenafil promoted the growth of new nerve projections in nerve cells from patients with the disease. Although further studies are needed, this study supports the concept that sildenafil may be a potential breakthrough preventive treatment.29
The twentieth century
Published in Michael J. O’Dowd, The History of Medications for Women, 2020
Early reports revealed than sildenafil citrate was contraindicated in men on medication with organic nitrates, and there were a number of deaths among men at risk of heart disease. The main adverse effects of sildenafil were headache, flushing, dyspepsia, and visual disturbances (a blue tingeing of vision) and they were usually mild. Although Viagra was licensed for use in impotence it was said not to have aphrodisiac properties — it helped in the achievement and maintenance of erection in patients with erectile dysfunction, in the presence of sexual stimulation.
Substrates of Human CYP2D6
Published in Shufeng Zhou, Cytochrome P450 2D6, 2018
There are currently three available oral phosphodiesterase type 5 inhibitors: sildenafil, vardenafil, and tadalafil (Gupta et al. 2005). Vardenafil is mainly metabolized by CYP3A4 and 3A5 (Ku et al. 2008), while tadalafil is a mechanism-based inhibitor of CYP3A4 (Ring et al. 2005). Sildenafil is used to treat erectile dysfunction and pulmonary arterial hypertension (Briganti et al. 2005; Cartledge and Eardley 1999; Francis and Corbin 2005; Leibovitch et al. 2007; Moreland et al. 1999; Supuran et al. 2006). It is eliminated predominantly by hepatic metabolism and is converted to an active metabolite, N-desmethylsildenafil (UK-103,320, Figure 3.98), with properties similar to the parent, sildenafil. Plasma concentrations of this metabolite are approximately 40% of those seen for sildenafil. The formation of UK-103,320 is mainly by CYP2C9, 3A4, and 3A5, with lesser contribution from CYP2C19 and 2D6 (Ku et al. 2008; Warrington et al. 2000). Both sildenafil and its metabolite have an elimination half-life of approximately 2.5 h. The concomitant use of potent CYP3A4 inhibitors such as erythromycin, ketoconazole, itraconazole, and the nonspecific CYP inhibitor, cimetidine, increases the plasma level of sildenafil (Gupta et al. 2005; Zusman et al. 1999).
A review on pharmacological options for the treatment of erectile dysfunction: state of the art and new strategies
Published in Expert Opinion on Pharmacotherapy, 2023
Mattia Longoni, Alessandro Bertini, Nicolò Schifano, Emanuele Zaffuto, Paolo Maggio, Rossi Piercarlo, Sara Baldini, Giulio Carcano, Gabriele Antonini, Andrea Salonia, Francesco Montorsi, Federico Dehò, Paolo Capogrosso
Administered orally, at doses of 25, 50, or 100 mg, sildenafil is rapidly absorbed with a half-life of 3–5 hours; it reaches the maximum plasma concentrations after 60 minutes, when the onset of action typically occurs [31]. It is advised to take sildenafil without a meal at least 30 minutes before sexual intercourse. Recently, a new oro-dispersible formulation (at doses of 25, 50, and 75 mg) has been introduced in several countries [11]. It is metabolized by the liver, mainly by the cytochrome isoenzymes CYP3A4 (primary route) and CYP2C9 (secondary route), to an active metabolite; avoiding the association with strong inhibitors of these cytochromes (e.g. ritonavir, erythromycin, ketoconazole) is fundamental [32]. The administration of sildenafil should be avoided in case of severe cardiovascular disorders. It is also strictly contraindicated in the following conditions: hypotension (blood pressure < 90/50 mmHg), severe hepatic impairment, retinitis pigmentosa, recent myocardial infarction, or stroke.
Pharmacological strategies for sexual recovery in men undergoing antipsychotic treatment
Published in Expert Opinion on Pharmacotherapy, 2022
Tommaso B. Jannini, Andrea Sansone, Rodolfo Rossi, Giorgio Di Lorenzo, Massimiliano Toscano, Alberto Siracusano, Emmanuele A. Jannini
Adjuvants, instead, are thought as other molecules, outside the antipsychotic spectrum, that have proven to be effective in the treatment of AP-induced TEAEs. To that end, type 5 phosphodiesterase inhibitors (PDE5-i) are widely regarded as the best treatment for ED [177], which frequently occurs among patients treated with APs. Two open-label studies and one randomized controlled trial on sildenafil have shown positive results. The study protocols consisted of the administration of sildenafil 25–75 mg daily, for an average time of 4 weeks, in patients taking different APs [178–180]. Although the study populations were exiguous, with a maximum of 32 individuals, all sexual domains measured with different psychometric tools were reported to be improved. Similar findings were also reported for different molecules, such as tadalafil and vardenafil [181,182].
Adjuvants in IVF—evidence for what works and what does not work
Published in Upsala Journal of Medical Sciences, 2020
Luciano Nardo, Spyridon Chouliaras
Sildenafil. Sildenafil citrate acts as a vasodilator by potentiating the effect of nitric oxide on vascular smooth muscle. It was therefore speculated that improving the blood supply and oxygenation of the uterus could enhance implantation rates. Vaginal sildenafil citrate (Viagra) is predominantly being used for treating cases with thin endometrium. A retrospective study suggested enhancement of endometrial development in 70% of patients, while high implantation and pregnancy rates were achieved in a cohort of poor-prognosis patients (14). In contrast, another study, where sildenafil supplementation was given in women undergoing fresh IVF or frozen embryo transfer, failed to demonstrate an increase in endometrial thickness or blood supply (15). In general, studies which examine sildenafil’s use are underpowered, heterogeneous, and often its use is combined with other medications. Its routine use cannot be recommended outside a research setting.