Older than people think
From The Lost Media Wiki
This is a 1970 film originally called "The Sex Serum of Dr. Blake". It debuted under that title on the last day of the 1970 Cannes Film Festival but didn't make it to general release until 1972 (as "Voodoo Heartbeat"). It was later rereleased under its original title in 1976, often with an X rating. Belfilm has a 35mm print in English with Dutch subtitles under the original moniker.