Evidence for contamination of herbal erectile dysfunction products with phosphodiesterase type 5 inhibitors.
OBJECTIVE
We determined if pharmacological dosages of phosphodiesterase type 5 inhibitors (PDE5) inhibitors were present within a group of natural products marketed for the treatment of erectile dysfunction.


METHODS
Seven herbal products marketed for the treatment of erectile dysfunction were purchased via the Internet or at local health food stores. Specimens were batched, relabeled and blindly analyzed for contamination with PDE5 inhibitors. High performance liquid chromatography and mass spectrometry were used to detect evidence of contamination with sildenafil, tadalafil or vardenafil.


RESULTS
Of the 7 tested products 2 contained pharmacological dosages of sildenafil and tadalafil. Contamination with vardenafil was not identified. Mean dosages of sildenafil and tadalafil were 30.2 and 19.7 mg, respectively.


CONCLUSIONS
A significant proportion of natural products marketed for erectile dysfunction contains PDE5 inhibitors. Although marketed as natural products devoid of adverse effects, these agents are known to have potentially fatal drug interactions with nitrates. Better regulation of the natural health products industry is urged.
Fleshner
Neil
N
Princess Margaret Hospital, University of Toronto, Toronto, Ontario, Canada. neil.Fleshner@utoronto.ca
Harvey
Melissa
M
Adomat
Hans
H
Wood
Catherine
C
Eberding
Andy
A
Hersey
Karen
K
Guns
Emma
E
D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D002243:Carbolines / Q000008:administration & dosage; D002851:Chromatography, High Pressure Liquid; D004340:Drug Contamination / Q000706:statistics & numerical data*; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D007093:Imidazoles / Q000008:administration & dosage; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage*; D008517:Phytotherapy / Q000706:statistics & numerical data*; D010879:Piperazines / Q000008:administration & dosage; D011687:Purines; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000008:administration & dosage; D000068581:Tadalafil; D014227:Triazines / Q000008:administration & dosage; D000069058:Vardenafil Dihydrochloride
D002243:Carbolines; D007093:Imidazoles; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014227:Triazines; D000069058:Vardenafil Dihydrochloride; D000068581:Tadalafil; D000068677:Sildenafil Citrate; D015106:3',5'-Cyclic-GMP Phosphodiesterases