Pfizer and US pharmacies have linked up to launch a new effort to draw attention to the risks associated with counterfeit drugs.

The drugs giant and the National Association of Boards of Pharmacy (NABP) note that worldwide sales of counterfeit medicines were estimated to exceed $75 billion last year, an increase of 90% since 2005. Last year, one in six Americans purchased medicines on the internet, "potentially exposing them to harmful counterfeits".

Patrick Ford, senior director for global security in the Americas for Pfizer, noted that counterfeit medicines "are often produced in unsanitary conditions by people without any medical or scientific background". He noted that “law-enforcement officials have found fake medicines being made in bathrooms and outdoors in the vicinity of farm animals.”

Pfizer has confirmed the presence of counterfeit versions of its drugs in "at least 101 countries", notably its erectile dysfunction drug Viagra (sildenafil). In one project, the company purchased and tested Viagra from 26 pharmacy websites that appeared in the top results for “buy Viagra” on two major search engines and found that all of them were operating illegally and 81% were selling counterfeit Viagra.

Carmen Catizone, the NABP's executive director, said that "counterfeiters who sell fake medicines online prey on ingrained online buying behaviour, in which consumers disregard warning signs, and prioritise price and convenience". Among their response to the problem, Pfizer and NABP have set up a new YouTube channel dedicated to protecting consumers online, while takeovers of websites once used by counterfeiters to sell fake versions of its medicines will be implemented by Pfizer Global Security.