Sildenafil is a drug used to treat erectile dysfunction commonly known as impotence, in men.Glutathione which sources are some fruits,vegetables,etc, is a vitamin supplement which could remove toxins.There is no documented drug interaction between the two.However in one study, ingestion of 250 ml (approximately one cup) of grapefruit juice one hour before and together with sildenafil increased the total amount of sildenafil absorbed by 23%, but tended to delay the absorption of the drug. The authors of this study recommended that sildenafil and grapefruit juice not be taken together.