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I have a further query for oral nitroglycerin sustained release
prepration
to conduct Bioavailabilty study:
To conduct Bioavailabilty study for Glyceryl Trinitrate we have to
quantify along with its active metabolites like 1,2 glyceryl
dinitrate and
1,3- Glyceryl dinitrate by using GCMS-MS.
what is the acceptable LLOQ of each them we should look for and Is it
impotant
to measure both the metabolites or nitroglycerin and one matabolite is
sufficient.
Dr yuvraj
Senior clinical research scientist
[Please no long discussion about the significance of LLOQ, maybe more
a suggestion about how low the concentrations of these metabolites
might be ;-) - db]
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GTN and Metabolites
You need to measure both of the dinitrate metabolites and GTN to
decribe the pK of the formulation. The plasma concentrations for the
1, 2 metabolite will be higher than GTN.
The lower ( and indeed upper limit of quantitation ) for the
dinitrates will have to be established as appropriate for the dose
level and unique formulation under consideration. Recommend
propecting some pilot PK profiles prior to establishing the
validated assay range to be implemented for the study.
Angus McLean Ph.D.
8125 Langport Terrace,
Gaithersburg,
MD 20877
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Dear Angus,
thanks for your valuable information.
yes indeed, the plasma concentrations for the 1, 2 metabolite are
higher than GTN.
I have a reference paper of the said formulation which gives Peak
plasma Glyceryl Trinitrate concentrations of 2.8 +/- 0.6 ng/ml with
GLC apparatus.
Also peak plasma NO3 concentrations were 0.48 +/- 0.03 ug/ml at 4hr
(range 4 - 14 hr) and 0.45 +/- 0.02 ug/ml at 6 hr (range 4 - 10hr)
And peak plasma No2 concentration was 0.48 +/- 0.04 ug/ml at 2 hr
(range 1-2hr)
Now kindly help, can we reach any figure for LLOQ for GTN as well as
1,2 dinitrate from above values.
Regards,
Dr yuvraj
M.D. Pharmacology
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