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.
— 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."