In a landmark legal decision Pfizer the manufacturer of the erectile dysfunction medicine Viagra has lost in its attempt to stop the sales of Cialis made by the company Eli Lilly. The High Court ruled that Pfizer claim to exclusivity in certain sections of its patent were unfounded and ruled in favour of Eli Lilly. The fight began some years back when Eli Lilly took Pfizer to court saying that some of the parts of the Viagra and sildenafil patent were not valid and that the patent should be modified or even cancelled.

Pfizer responded on the attack by claiming that the drug tadalafil or Cialis actually was an infringment of the Viagra patent nd was not an original compound. The advantage of Cialis is that it can last for as much as 36 hours compared to the 4 hours that Viagra traditionally lasts for. For this reason Cialis is increasing popular for those wanting to be in a position to have sex all weekend and who don't want to have to remember to quickly take a pill before sex.

The Court by throwing out Pfizer's request has cast further doubt on some aspects of the Viagra patent and has ruled that the active ingredient in Viagra  namely sildenafil citrate was not an original invention. Pfizer immediately made to appeal the decision but this was thrown out too. The ruling could have serious commercial implications for the drug giant Pfizer and its wonder drug Viagra.

Most of the claims made by Eli Lilly were false according to the rulling however the fact that they scored a minor victory by getting a judge to declare that the sildenafil citrate was not completely original was seen to be important for Eli Lilly and for the drug Cialis and has undermined the Pfizer patent to a small extent.

The drugs Cialis and Viagra are the best 2 selling erectile dysfunction medicines in the world and between them they have over 50% of the erectile dyfunction market. Cialis has stolen market share from Viagra since its introduction and works in the same way as Viagra by being a PDE-5 inhibitor. Cialis is often referred to as the weekend pill due to its longer lasting effects. Viagra is nicknamed the little blue pill.