If you are still with me, here is part 5
7.0 Selecting the Best Tablet Dosage.
There is no magic to finding the optimum dosage, but because there are
so many factors affecting the outcome it can be difficult to hold all the
relevant factors in mind at one time. The sketch below shows the four areas
which chiefly define the shape of the characteristic.
____________________________________________________________
|
|
|
|
L |- - - - - ******************
| *| |*
| *
| * |
| * | *
| * | *
|****************** | * **********
0 A B C D
Considering the interval from points 0 to A, we cannot influence this
part of the trace, apart from using Sinemet or Sinemet CR (about 1 hour)
or madopar dispersible (20 -30 minutes).
The most important region is between points B and C. The level L is
related to the size of the tablet. By setting up an escalating series of
test levels in the form of steps, it is possible to locate the level L
which produces that tantalising target known as 'feeling normal'.
The sketch below shows one method of setting up 4 steps
_____
| 4/1 |
_____|_____|_____
| 3/1 3/2 | 4/2 |
_____|___________|_____|_____
| 2/1 2/2 2/3 | 3/3 | 4/3 |
_____|_________________|_____|_____|_____
| 1/1 1/2 1/3 1/4 | 2/4 | 3/4 | 4/4 |
__zero_________|_______________________|_____|_____|_____|
The zero level need not necessarily be truly zero level of levodopa. It
could be a baseline set to get nearer to the target.
The duration of each element of the steps i.e. from 1/1 to 1/4 must be
discovered by testing: You have no control over the duration, so the rest
of the experiment must be tailored to suit it.
The height of each step will depend on the size of the input as each level
is initiated at time length/4.
An example may be helpful: Using Sinemet25/100, we may choose to make
each step equivalent to 50 mg of Sinemet. For me, Sinemet lasts for 2
hours,so I would take half a Sinemet at time 0 hr,0.5 hr, 1.0 hr, 1.5 hr.
i.e. 1/2 hour intervals.
That is, if you are using Sinemet25/100 tablets, which for me last 2 hours
break them in half, and take 1/2 a Sinemet at time 0, 30 mins, 1hour, and
1.5 hrs. This will give a result where the levels are related to 50,100,
150,200 mg of levodopa. (This is a rather coarse step size, which is why I
referred to that tablet as a blunt instrument. If you are able to use
Madopar dispersibles, then 1/2 a tablet will be worth 25 mg instead of 50mg.
So far, we have discussed the size of each dose. Having done that, we can
decide how frequently to take the tablets. If you imagine 2 tablets
spaced apart, and you gradually slide them together, you will reach a
point where the decreasing flow from one tablet, is made up by the
increasing flow from the next tablet. Done carefully, you can define a
time interval which gives constant On and no Off time at all. If that
sounds unlikely, I can assure you that I used to get such performance,
from the point where I developed this technique ( 1991) When I was 12
years from diagnosis, to present day, where I still get mainly Ons, but
find it difficult to cover the effect of meals completely, so that about
2 hrs per day in the Off condition after meals is about the norm.
--
Brian Collins <[log in to unmask]>
