I highly suspect there is a lot of trial and error in the dosaging. I take 60 mg 4X daily. I started with 60 mg 2x a day.

I just pulled this off the prescribing information page. I included the link at the bottom of the page.

"Dosage: The size and frequency of the dosage must be
adjusted to the needs of the individual patient.

Syrup and Conventional Tablets — The average dose is ten
60 mg tablets or ten 5 mL teaspoonfuls daily, spaced to
provide maximum relief when maximum strength is needed. In
severe cases as many as 25 tablets or teaspoonfuls a day
may be required, while in mild cases one to six tablets or
teaspoonfuls a day may suffice.

Timespan Tablets — One to three 180 mg tablets, once or
twice daily, will usually be sufficient to control symptoms;
however, the needs of certain individuals may vary markedly
from this average. The interval between doses should be at
least 6 hours. For optimum control, it may be necessary to use
the more rapidly acting regular tablets or syrup in conjunction
with Timespan therapy."

http://mestinon.com/Portals/25/Pdf/p...g_PI_May01.pdf