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P J Lago

Publications and source records attributed to P J Lago.

8 recordsLinked to original sources
PubMed1992

Open-loop stochastic control of pharmacokinetic systems: a new method for design of dosing regimens.

On the basis stochastic control techniques, an algorithm for the design of dosing regimens is developed. The essence of the method relies on a constrained model for the population and on a first-order approximation in the evaluation of the performance cost function. Since it does not require detailed information on the probability distribution of the model parameters, the method can be used in a wide range of practical applications. The application of the design technique is illustrated in two typical situations: lacking a probability model for the pharmacokinetic parameters (etomidate) and having a probability model for the pharmacokinetic parameters (theophylline).

Algorithms↗
PubMed1989

Covariance density estimation for autoregressive spectral modelling of point processes.

The use of autoregressive modelling has acquired great importance in time series analysis and in principle it may also be applicable in the spectral analysis of point processes with similar advantages over the nonparametric approach. Most of the methods used for autoregressive spectral analysis require positive semidefinite estimates for the covariance function, while current methods for the estimation of the covariance density function of a point process given a realization over the interval [0, T] do not guarantee a positive semidefinite estimate. This paper discusses methods for the estimation of the covariance density and conditional intensity function of point processes and present alternative computational efficient estimation algorithms leading always to positive semidefinite estimates, therefore adequate for autoregressive spectral analysis. Autoregressive spectral modelling of point processes from Yule-Walker type equations and Levinson recursion combined with the minimum AIC or CAT principle is illustrated with neurobiological data.

Animals↗
PubMed1989

Approximate maximum likelihood population pharmacokinetic models for the design of dosage regimens.

One of the applications of pharmacokinetics and pharmacodynamics is the design of improved drug administration regimens. In its simplest form only global descriptors of the response to a bolus are used to obtain the dosing scheme leading to the desired drug plasma concentration level. For further improvement on these simple administration regimens it is necessary to have additional information on the drug kinetics in terms of either a disposition equation model or a compartmental model. Due to the high variability of individual responses to the same dosing scheme the design of drug administration regimens is often based on the average pharmacokinetic parameters of a data base of individuals. Although widely used, this approach presents some problems since the average disposition equation model and the average compartmental model are inconsistent between themselves and with the global descriptors of the average response. In this paper methods and algorithms for the estimation of alternative population pharmacokinetic models are developed and their use is illustrated using pharmacokinetic data available from the literature.

Algorithms↗
PubMed1987

A fast algorithm for the computation of the plasma concentration time curve and confidence limits in linear pharmacokinetics.

An algorithm is developed for the computation of the plasma concentration time curve for a drug administration regime involving fast injection (bolus) and/or continuous infusion. The effect of the pharmacokinetic model parameter variations on the plasma concentration time curve is analyzed and efficient algorithms for the computation of the parameter-induced first-order variation and confidence bounds of the plasma concentration time curve are also presented. The application of the method is illustrated with pharmacokinetic data for the etomidate.

Algorithms↗