Viagra is about to face some stiff competition.
A new drug to treat erectile dysfunction has been approved by Health Canada. The makers of the prescription medication, sold under the trade name Cialis, say its effects last up to 36 hours. Viagra works for about four or five.
"What this does is allow men to have more flexibility and spontaneity . . . in their sexual relations," said Loren Grossman, vice-president of research and development for Eli Lilly Canada. "A man can take it on a Saturday morning and know it will be effective for a good part, if not all, of the weekend."
In Europe, where Cialis has been available for months, the new drug was quickly dubbed "le weekender."
Cialis (pronounced see-al-iss) is the first oral medication to compete directly against Viagra since the "little blue pill" made its Canadian debut in March of 1999.
And another rival is looming on the horizon. GlaxoSmithKline and its partner Bayer HealthCare are seeking government approval for their drug, Levitra.
The makers of Viagra put on a brave front yesterday in the face of the growing challenge.
"Our market research shows that most men are satisfied with Viagra. . . . There is no reason for them to switch," said Sophia McCann, a spokeswoman for Pfizer Canada Inc.
A Toronto man who took part in a six-month clinical trial of Cialis seemed pleased with what the new drug did for him.
"Because it lasts for 36 hours, [sex]doesn't have to be a planned event, which is very attractive. It leads you back to a much more normal life," said Gareth Davis, 54, who developed problems with achieving an erection after undergoing an operation for prostate cancer in 2000.
Viagra, Cialis and Levitra work in a similar fashion, said Sidney Radomski, a urologist at Toronto Western Hospital and a specialist in erectile dysfunction.
They all block the action of phosphodiesterase type 5, a naturally-occurring enzyme that can interfere with getting and maintaining erections. The drugs essentially allow more blood to flow into the penis when a man is sexually stimulated.
Although Cialis can remain effective for up to 36 hours, "it doesn't mean that you have an erection for 24 to 36 hours," Dr. Grossman said. "The medication only works in the presence of usual sexual stimulation."
Another advantage of Cialis is that it can be taken with a rich fatty meal. Viagra works best when it is taken on an empty stomach; Levitra is still effective after a low-fat meal.
None of these drugs should be used by men taking nitrate-based heart medications, such as nitroglycerin, often use to treat angina.