Oleander is available in mutlitple forms, but they all use pretty much the same method of obtaining the aqueous extract. I have been taking the home remedy version (you have to follow exact directions in handling and preparation) until this past week when I got two bottles of the capsule version of Sutherlandia OPC, which is my favorite version and is made by a pharmaceutical and supplement manufacturing company to very exact standards.
You can also get a patented medicine version from Honduras and another supplement version from Alpha Omega Labs, the makers of Cansema, which combines oleander with graviola and chaparral.
BTW, the home remedy I was taking was made by the most experienced oleander home remedy maker in the US - the sister of the man who devised the remedy based on the original Ozelle patent for Anvirzel, She makes gallons of it every year and puts on clinics for naturopaths and Mexican clinic operators. And she lives very close to you near Austin. She does not sell it, but if you told her you were a friend . . .