Natalie Grover, Tassilo Humel

PARIS/LONDON – A U.S. regulator put on hold a trial that aimed to switch Cialis (prescription-only erectile disfunction drug) to an OTC (over-the-counter) alternative. The French drugmaker Sanofi (NASDAQ: ) Monday.

Company stated that the pause was due to concern about how the protocol for trial design has been constructed, and added that the company had not yet recruited patients.

Cialis (also known as tadalafil) was approved first by the European Medicines Agency (2002, and later by the U.S. Food and Drug Administration [FDA] in 2003, as a prescription only therapy.

It has a time release formula which allows men to take the treatment anywhere they want up to 36hrs before using it. This made Eli Lilly, a U.S.-based drugmaker (NYSE:), billions ahead of generic competition.

After obtaining regulatory approvals in each country, Sanofi was granted the 2014 license to Cialis for non-prescription in America, Europe, Canada, and Australia.

Executives at Sanofi stated last year that the OTC Cialis will be an important contributor to the company’s goal of achieving above-market sales growth in 2024.

Wimal Kapadia from Bernstein said delays are not helpful and that it is unclear what this delay will mean for 2024.

Stocks of Sanofi were down by more than 3 percent on Monday morning.

FDA evaluates whether or not prescription drugs may be available over-the counter. They also consider whether patients can understand the complexities of their condition.

Cialis may cause dangerous drops in blood pressure, just like Viagra and other anti-impotence medications, especially if it is taken along with nitrates (a group of heart drugs which includes nitroglycerine).

According to Coherant Market Insights market intelligence firm, the global market for erectile dysfunction treatments was valued at $3.7 billion in 2013. It is projected to rise to $5.9billion by 2028. However, it wasn’t clear what portion of this market would be owned by OTC drugs.