Today, 5/22/2018; all under control now after returning five days earlier to the original four grams daily of thiamin HCI.
Initial success was at 4g daily several months ago. Moved to 6g daily for two weeks trying to reduce tremor. Did not affect tremor. Failure was in fine motor control and constipation return. Moved to 2g daily finding improved motor control but still constipated. I returned to the dose 4 g daily. Now no constipation and suppressed Parkinson's symptoms.
Everyone must determine what dose works for them. Doctor Costantini, as appears in my observation and reading, chooses a standard therapeutic dose of 4g, just as he started me with. Others have found adjustments necessary.