WEBVTT
Kind: captions
Language: en
00:00:10.670 --> 00:00:14.680
So moving on to step number three
00:00:14.680 --> 00:00:18.820
Find the volume diffusion based on the first IV load
00:00:18.820 --> 00:00:22.120
120 mg over one hour
00:00:22.120 --> 00:00:26.000
And this is the equation that we can use
00:00:26.000 --> 00:00:30.520
where T or small T is one hour.
00:00:30.520 --> 00:00:33.840
So we have K, 0.231
00:00:33.840 --> 00:00:37.280
we have T is one hour.
00:00:37.280 --> 00:00:43.860
we have peak concentration of eleven
point two after the first loading
00:00:43.860 --> 00:00:50.200
and we knew the infusion rate was a hundred
twenty million per hour
00:00:50.200 --> 00:00:53.300
so solve for only unknown here
00:00:53.300 --> 00:00:54.420
which is V
00:00:54.420 --> 00:00:58.060
and a V turns out to be nine point five liter
00:00:58.060 --> 00:00:59.740
for gentamicin
00:00:59.740 --> 00:01:02.460
Calculation step number four
00:01:02.460 --> 00:01:05.260
find the patient's clearance for gentamicin.
00:01:05.260 --> 00:01:09.760
We know clearance is K times V
00:01:09.760 --> 00:01:15.620
You ought to have remember this
formula or equation by now
00:01:15.620 --> 00:01:23.140
So clearance is equal to K times V is equal to 0.231 times nine point five
00:01:23.140 --> 00:01:28.840
and that would give us an answer of
two point two liter per hour
00:01:28.840 --> 00:01:34.920
and that's gentamicin clearance for
this particular patient.
00:01:34.920 --> 00:01:40.660
So again that is a formula to
memorize if you don't memorize
00:01:40.660 --> 00:01:42.420
many other equations.
00:01:42.420 --> 00:01:45.120
Calculation step number five
00:01:45.120 --> 00:01:50.920
calculate the dosing interval to constrain gentamicin concentration00:01:50.920 --> 00:01:55.560
between the peak of eight and a trough of one.
00:01:55.560 --> 00:02:00.620
So remember this equation defines the tau or the dosing interval
00:02:00.620 --> 00:02:05.400
based on peak concentration and trough concentration.
00:02:05.400 --> 00:02:09.720
So we have here k point two three one
00:02:09.720 --> 00:02:17.140
the peak concentration is eight as
decided by the infection specialist
00:02:17.140 --> 00:02:22.040
and the trough concentration is one with
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infusion time at one hour
00:02:25.800 --> 00:02:27.200
and as a result
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tau turn out to be 10 hours.
00:02:30.980 --> 00:02:35.320
We've run it up to 12 hours.
00:02:35.320 --> 00:02:39.740
Okay continue on to calculation
step number 6
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Find the appropriate infusion rate at the above calculated dosing interval
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by this equation:
00:02:48.000 --> 00:02:52.180
the peak concentration is equal to k zero
00:02:52.180 --> 00:02:54.640
which is the zero order in infusion rate
00:02:54.640 --> 00:02:58.980
times 1 minus e to the minus K cap T
00:02:58.980 --> 00:03:03.760
divided by K elimination rate constant
00:03:03.760 --> 00:03:10.160
times the volume tribution
times 1 minus e to the minus K tau.
00:03:10.160 --> 00:03:14.760
Here the peak concentration is 8 mg/L
00:03:14.760 --> 00:03:18.560
As decided by the infection specialist
00:03:18.560 --> 00:03:22.060
we know K is point 231
00:03:22.060 --> 00:03:24.410
and the infusion time is 1 hour
00:03:24.410 --> 00:03:28.200
volume distribution is 9.5
00:03:28.200 --> 00:03:34.280
and the Tau based on our previous
calculation is 12 hours
00:03:34.280 --> 00:03:43.300
and therefore the zero the infusion rate
turn out to be 79.7 mg
00:03:43.300 --> 00:03:48.780
We'll rounded it up to 80 milligram Q12 hour.
00:03:48.780 --> 00:03:53.920
So here we realize that the initial maintenance infusion
00:03:53.920 --> 00:03:58.720
at 80 million QAh was undesirable
00:03:58.720 --> 00:04:02.980
because it could lead to toxicity
00:04:02.980 --> 00:04:05.900
here I have one additional question
00:04:05.900 --> 00:04:11.960
if this patient was obese, then would the
dosage of recommendation be any different?
00:04:11.960 --> 00:04:15.140
The answer is not really.
00:04:15.140 --> 00:04:22.560
Because here we use the patient specific
data from the two plasma concentration
00:04:22.560 --> 00:04:24.480
that we obtained.
00:04:24.480 --> 00:04:29.560
So this is the power of individualized medicine
00:04:29.560 --> 00:04:33.060
or individualized dosing regimen
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by applying patience specific kinetic information
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We are able to take advantage of the
individualized dosing regimen