According to a report in PharmaTimes:
“A study has found that over 80% of on-line advertisements for Internet pharmacies accepted by the search engine Yahoo were in violation of US federal and state laws.The researchers were able to buy prescription drugs without a prescription from Yahoo Internet pharmacy advertisements, and in one case the drugs were imported from India, which is prohibited by US law, says the survey, which was conducted by research firms LegitScript.com and KnujOn.com.”
“Moreover, the researchers acquired prescription drugs without a prescription from an Internet pharmacy approved by PharmacyChecker – the service by which Yahoo, Google and Microsoft require their Internet pharmacy advertisers to be verified as legitimate - and listed on PharmacyChecker.com. Those drugs were also imported from India."
The complete report can be found here.
