The most potent sex drug is to take out
The ultimate sex drug and tell the lady it's hers if she's horny enough to do u right now.
Otherwise, a senior once taught me another method: put a glass of water before u, concentrate and point 2 fingers to the sky, stomp your feet 3 times and shout "sibeh horny ah"! Let the girl drink it and u will have your way with her.

If it doesn't work, it means u didn't concentrate enough and need more focus. Comes with years of practice.