As one of the posters points out, the evidence is mixed. I think there are other factors which depend on its absorbency, skin type, diaphoresis etc. Also I was once told that it is carried in a pleuronic agent, so it should for maximum effect, be applied to the same area, therefore, when I ever apply it, I always signs where I have applied it, i.e. left wrist.
As there is no firm evidence, I often wonder how much of the actual drug is absorbed.
If the patient has no or limited absorption from the gut, it may be the best choice for the patient. Our hospice has used it for years with good results and we apply to wrists alernating wrists with each dose. P.S. It needs to be rubbed in to the skin.