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The following message was posted to: PharmPK
Does anyone know how to calculate for EC90 (or IC90), that isn't through
iteration or observed data? Is there an equation available that is
similar to that of Sigmoid Emax models?
Thank you!
Glenn Whelan, Pharm.D.
Adjunct Clinical Pharmacologist/Clinical Coordinator
National Jewish Medical and Research Center
1400 Jackson Street
Office J329
Denver, CO 80206
phone: 303-398-1448
fax: 303-270-2189
pager: 303-281-1375
Email: whelang.aaa.njc.org
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The following message was posted to: PharmPK
Dear Glenn,
At EC50 the effect (E) equals 0.5 (for Emax=1).
At EC90: E=0.9=c^n/(c^n+EC50^n).
Rearrangement gives: c^n=9*EC50^n.
Thus when n=1 the concentration at which the effect is 90% of the maximum
equals 9 times EC50.
For n=2 this is 3 times EC50 (nice rule of thumb to keep in mind).
Best regards,
Kees
Kees Bol, PhD
Director Clinical Pharmacokinetics
Kinesis Holding
Consultants in Drug Development
Lage Mosten 29
4822 NK Breda
The Netherlands
tel: +31 (0) 76 54 80 621
gsm: +31 (0) 65 31 26 153
fax: +31 (0) 76 54 21 777
kees.bol.-at-.kinesis-pharma.com
www.kinesis-pharma.com
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