Estimation of the Half Maximal Inhibitory Concentration

The half maximal inhibitory concentration (IC50) is a measure of the effectiveness of a compound in inhibiting biological or biochemical function. This quantitative measure indicates how much of a particular drug or other substance (inhibitor) is needed to inhibit a given biological process (or component of a process) by half.

See reference(s).

In this version of the function the maximal occupancy (rmax) is estimated automatically. This should be optional.

hillEquation(conc, occ, guess = c(1, 100),
  control = minpack.lm::nls.lm.control())

Arguments

conc	a vector of drug concentrations in plasma (example units are ng/mL).
occ	a vector of PET occupancy values that correspond to the measured drug concentrations in plasma.
guess	a length-two vector of starting values for the nonlinear optimization.
control	is a list of parameters used by nls.lm.control that are set by default, but may be customized by the user.

Value

List with the following elements

• IC50Half maximal inhibitory concentration

• rmaxEstimated maximal occupancy

• IC50SEApproximate standard error for IC50

• rmaxSEApproximate standard erorr for rmax

• hessianHessian matrix from the Levenburg-Marquardt procedure

• infoReturn value from the Levenburg-Marquardt procedure

• devianceDeviance from the Levenburg-Marquardt procedure

• messageText message from the Levenburg-Marquardt procedure

Author

Brandon Whitcher bwhitcher@gmail.com

References

Hill Equation IC50

See also

nls.lm