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Dear Colleagues,
I am working on an absorption model in which the distribution of absorption
times follows a Gamma law rather than an exponential law.
In other words, the rate of absorption at time t is given by:
r(t) = FD b^a . t^(a-1) . exp(-bt) / Gamma(a)
where a and b are model parameters, D the total dose, F the bioavailability
factor and Gamma the Gamma function.
I found this model useful for describing cyclosporine pharmacokinetics.
I was wondering if such a model has been used before. I have found no
reference about it.
Thanks in advance.
Jean Debord
Laboratoire de Pharmacologie, Faculte de Medecine
2 Rue du Docteur Marcland, F-87025 Limoges, France
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It seems that in this case also the Inverse Gaussian density is a suitable
absorption model. (One of its advantages compared to the Gamma function is
the existence of a Laplace transform.)
M. Weiss. A novel extravascular input function for the assessment of drug
absorption in bioavailability studies. Pharm. Res. 13: 1545-1551 (1996)
Michael Weiss
Martin Luther Univ.
Dep of Pharmacology
Section of Pharmacokinetics
D-06097 Halle/Saale
Germany
michael.weiss.aaa.medizin.uni-halle.de
Fax: 49-345-557 1657
Tel: 49-345-557 1835
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