- On 30 Apr 2000 at 23:01:36, Jean Debord (JDebord.aaa.compuserve.com) sent the message

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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 - On 2 May 2000 at 21:37:13, "Prof. Michael Weiss" (michael.weiss.-a-.medizin.uni-halle.de) sent the message

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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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