The company that manufactures Viagra mounted a tiny study of some of the products called “Viagra” that are sold via some web sites:
“Internet-Ordered Viagra (Sildenafil Citrate) Is Rarely Genuine,” Neil Campbell, John P. Clark, Vera J. Stecher, Irwin Goldstein, Journal of Sexual Medicine, volume 9, issue 11, November 2012, pp. 2943–2951. The authors, at Pfizer Inc and Alvarado Hospital in San Diego, California, explain:
Counterfeit medication is a growing problem. This study assessed the requirement for prescription, cost, origin, and content of medications sold via the Internet and purporting to be the phosphodiesterase type 5 inhibitor Viagra (sildenafil citrate).
METHODS. Pfizer monitored top search results for the query “buy Viagra” on the two leading Internet search engines in March 2011. Orders were placed from 22 unique Web sites claiming to sell Viagra manufactured by Pfizer. Tablets received were assessed for chemical composition.
RESULTS. No Web site examined required a prescription for purchase or a health screening survey; 90% offered illegal “generic Viagra.” Cost per tablet ranged from $3.28–$33.00. Shipment origins of purchases were Hong Kong (N = 11), the United States (N = 6), and the United Kingdom (N = 2) as well as Canada, China, and India (N = 1 each)…. Of 22 sample tablets examined, 17 (77%) were counterfeit, 4 (18%) were authentic, and 1 (5%) was an illegal generic. Counterfeit tablets were analyzed for sildenafil citrate, the active pharmaceutical ingredient (API) of Viagra, and contents varied between 30% and 50% of the label claim….
CONCLUSION. Internet sites claiming to sell authentic Viagra shipped counterfeit medication 77% of the time; counterfeits usually came from non-U.S. addresses and had 30% to 50% of the labeled API claim.
Detail from the study:
(Thanks to investigator Erwin Kompanje for bringing this to our attention.)