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I would welcome any thoughts on the application of either Tween 80
versus Cremophor RH40 as surfactant to stabilize an emulsion for oral
gavage in proof of principle preclinical studies. I have experience
with Cremophor RH40 but not Tween 80. The formulation I intend to
use describes 5% Tween 80 where I previously would have used
Cremophor RH40.
Thank you for any thoughts or considerations particularly with
respect to potential chronic toxicity following 21 days
administration in mice.
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Dear Stephen,
In my view a concentration of 5% w/v or v/v is too high to be used in
any of the preclinical studies for long-term or chronic
administration. Most of the surfactants stimulate histamine release
and they do it in different orders of magnitude. Moreover, they may
also influence the (git) membrane barrier permeability transiently
(at times permanently) if used in higher concentrations. A small
feasibility study can be performed prior to assess emulsion stability
(in terms of droplet size, coalescence potential etc.) and to me a
1-2% w/v concentration is quite sufficient. The choice of surfactant
again is based on a case by case basis and as long as chronic
toxicity data is available (NOEL and LD50), a judicious choice can be
made.
regards,
Vaibhav
Vaibhav Sihorkar, Ph.D
Senior Scientist
Formulation Research Department
Disocvery Research,
Dr. Reddy's Laboratories Ltd.
Miyapur, Hyderabad 500 049, India
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Copyright 1995-2010 David W. A. Bourne (david@boomer.org)