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Dear to all,
If we are giving drug orally and if we are estimating drug other than
plasma, urine or serum biological fluid then how the LLOQ and
calibration range for std plot has to decide ?
Please suggest the answer for the same.
Thanking you
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The following message was posted to: PharmPK
Dear Prashant,
Kindly specify the matrix in which you want to estimate your drug. If
the concentration of your analyte is known in the matrix, in which you
want to estimete your drug, then you can apply the same principles for
deciding the calibration range as for plasma.
Generally (not necessary), the LLOQ is 1/20th of the Cmax and you cover
a range of 100-500 folds in your calibration curve. Hope this clarifies.
Regards
Dr. Tausif Ahmed
Ranbaxy research Lab., India
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The following message was posted to: PharmPK
I suggest making some tries to evaluate the concentration of your
drug in
the different matrices. You may need to have a lower LLOQ in plasma for
example and a higher in urine.
If not possible, I think you could validate a LLOQ as low as possible
and a
calibration range as large as possible (7 or 8 points)
With a low LLOQ you will have the possibility to dilute samples which
are
higher than the ULOQ (that is obviously not possible with a LLOQ
higher than
the sample value)
Fabrice Guillet
Biopredic
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Dear Prashant,
As a rule of thumb, we normally use the following index in selecting
a calibration range:
Upper range : 2 times the estimated Cmax
LOQ : divide Cmax by 32 or 16 which would give either 6 or 5 half-
lives.
Regards,
Sylvain Mandeville, Ph.D.
LAB Research Inc.
www.labinc.ca
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Hi Sylvain,
I think that dividing the Cmax by 32 and 16 corresponds to 5 and 4
half-lives.
radu
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