Pfizer has won its fight to keep the exclusive rights to sell Viagra (sildenafil citrate) through to 2019.

The US District Court for the Eastern District of Virginia backed the patent protecting the erectile dysfunction drug, preventing generic drug manufacturer Teva Pharmaceuticals from receiving approval for its version of the pill until October 2019.

Pfizer executive vice-president and general counsel Amy Schulman said, “We are pleased that the court recognised the validity and enforceability of our Viagra patent for the treatment of erectile dysfunction.”

Pfizer sued Teva in June this year to block a copycat version of Viagra, which brings in sales of $1bn per year in the US.

Litigation on the same patent remains pending against other generic companies, but no other trials are scheduled.