Border authorities discovered about 55,000 suspected Viagra pills hidden in a truck's spare tire in Hidalgo, TX, The Associated Press reported.

U.S. Customs and Border Protection officers found the pills on Dec. 4 in a truck crossing from Mexico into the United States at Hidalgo International Bridge. The 55,181 blue pills were found in 29 packages.

A sample was sent to a lab to confirm that the pills are Viagra, an anti-impotence medication that is available only by prescription.

Viagra sells for about $11 a pill in pharmacies, giving the confiscated cache a value of nearly $607,000 if the pills are real, Customs and Border Protection spokesman Rick Pauza said.

That would be one of the largest seizures of a prescription-only medication in South Texas, Hidalgo Port Director David Higgerson said in a Monday statement. No one was arrested, but U.S. Immigration and Customs Enforcement agents were continuing their investigation.