AbstractThe interaction between the two drugs, warfarin and phenylbutazone, is considered through a previously derived model. A minimum time problem, which involves a state constraint is formulated. This problem is investigated both analytically and numerically. The numerical results are obtained by transforming the state constrained problem to one which is singular and then using a conjugate gradient algorithm to obtain approximations to the optimal control. Further approximations to the control, the rate of infusion of phenylbutazone, are made so that the time profile is feasible for practical implementation.
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