Pfizer has filed with the WIPO Arbitration and Mediation Center claims rights over the domain name viagra.biz .
Also,the domain name redirect visitors to another web site that contains pay-per-click links to other websites ,including one which sells Levitra,a product that competes with Pfizer's Viagra.
By all means,viagra.biz is confusingly similar to their Viagra mark and could cause confusion among their costumers.They also think the domain name was registered in bad faith.
"Pfizer’s VIAGRA mark is an invented and coined mark that has a strong worldwide reputation, of which the Respondent was undoubtedly aware at the time the subject domain name was registered. The Respondent’s repeated references to erectile dysfunction and products that compete with VIAGRA confirm Respondent’s awareness of Pfizer’s VIAGRA mark. Moreover, by virtue of Pfizer’s registration of the VIAGRA mark in the United States and other jurisdictions, the Respondent had constructive knowledge of Pfizer’s rights in the mark at the time the domains were registered."
Therefore,the right thing to do was to transferr the domain name to Pfizer.