Any experience with "Zanfel"? (poison ivy cure)

Saw a comment on this elsewhere. First I'd heard of it. Anyone tried it? Does it work?
Zanfel

One ounce is $40, but it claims to have a 10 year shelf life.

Worked really great for me. One thing I did notice though (I think) is that its effectiveness tapered off. Probably close to 7-8 years later I needed to use maybe 3 applications for it to work from the original purchase time. Still worked though.

Poison Ivy doesn't effect me, but my father used to get it pretty bad when he used to clear land to put pipe in the ground. The only thing that ever worked for him was washing the effected part with kerosene. That worked better then anything I have ever seen on the market. Good to know.