Background: Phosphodiesterase-5 inhibitors (5-PDE-i) are first line treatment for erectile dysfunction, whose incidence will continue growing until affecting 322 million men worldwide. The forensic interest in this drug class is consequently increasing in fatal cases suggestive of recent assumption as well as in fatalities involving cardiac failure related to sexual activity.

Methods: Stability of sildenafil, vardenafil, avanafil and tadalafil in post-mortem blood has been studied over a period of one, three and five weeks of storage at -20 °C by using three quality controls samples at concentration of 400, 200, 50 ng/mL. The analytical procedure, based on a liquid/liquid extraction and UHPLC/MSMS analysis, was applied to two real cases.

Results: Selected drugs presented scarce stability: after one week of storage at -20 °C tadalafil and vardenafil levels sensibly decreased (27.5%-45% for tadalafil and 19.2%-28% for vardenafil) and blood samples from real cases resulted completely negative after two months.

Conclusions: the diffusion of 5-PDE-i assumption without medical prescription makes it appropriate to include phosphodiesterase-5 inhibitors detection in cases of cardiac death related to sexual activity. Toxicological analyses must be performed immediately after autopsy to overcome analytes instability.