A woman uses a spike ring to puncture a mans spinal fluid and mixes it with a powder to stay young and beautiful
I think you are looking for The Leech Woman. It’s a B&W Universal Horror film from 1960. (This movie scared the heck out of me when I was a little kid. Pretty gruesome stuff for the time.) Coleen Gray plays the aging wife of a vile cosmetic manufacturer. They travel to Africa to witness a voodoo ritual that can proportedly make a woman young and beautiful. But it turns out to be a violent blood rite. To make the youth formula, a woman must kill a man by stabbing him in the back of the neck with a spiked sacrificial ring, extract fluid from his pineal gland, and mix the fluid with the polen of a rare orchid. This cocktail makes the woman young and beautiful, but the effect wears off in a day, and leaves her much older than she was before her last transformation. Gray sacrafices her husband and is transformed. She steals the ring and plant, returns to the USA, and starts picking up strange men every night, killing them with the ring to make the magic elixire.
“The Corpse Vanishes” (1942)?
Quote from an IMDb user review:
“old-fashioned horror story about a doctor who kidnaps “dead” brides only to remove spinal fluid in them to inject in his wife who is really 70 some odd years but looks thirtyish.”
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