I have read about this on a PD caregiver forum and according to the members there, it does work. It appears to be used only for end-stage, though, or in situations like the one posted about here, where one cannot take oral meds.

To add to the weirdness: we read somewhere, some time back, about someone snorting their sinemet....before you laugh your butt off like our neuro did when we asked him about it, think about this: snorting a med would bypass the whole digestive/absorption problem, and go direct to the brain. He could not/would not help us with this, which was no surprise really, but I was intrigued. I could not find out any more, though, and we're too afraid to crush up a sinemet and try!