Combination therapy with topical alprostadil and phosphodiesterase 5 inhibitors after failure of oral therapy in patients with erectile dysfunction: a prospective, two arm, open label, non randomized study International Journal of Impotence Research L Carnitine CAM Cancer Do nutraceuticals work in erectile dysfunction? Although nutraceutical based treatments are often offered for erectile dysfunction (ED), their efficacy remains doubtful. In a recent meta analysis, the efficacy of available nutraceutical Propionyl L carnitine induces eNOS activation and nitric oxide synthesis in endothelial cells via PI3 and Akt kinases ScienceDirect