Can KETOCONAZOLE cause a false positive on Drug test

I gave my son a drug test to checking for THC and cocaine. The test was administered approximately 3 hours after taking a Dr prescribed dose of 2 200mg tablets/week for a fungil rash.

Upon taking the test he showed negative for THC but positive for the cocaine. We repeated the test about a hour later to insure we had administered the test properly and got the same result. It wasn.t till later I remembered I had seen him take 2 tablet dose of ketoconazole. He also too 2 Aleve for headache.

Could this drug or combinstion be causing us to get a false positive? Your most urgent reply is requested.

Thank You