Dataset Information

PKQuest: volatile solutes - application to enflurane, nitrous oxide, halothane, methoxyflurane and toluene pharmacokinetics.

ABSTRACT: BACKGROUND: The application of physiologically based pharmacokinetic models (PBPK) to human studies has been limited by the lack of the detailed organ information that is required for this analysis. PKQuest is a new generic PBPK that is designed to avoid this problem by using a set of "standard human" default parameters that are applicable to most solutes. RESULTS: PKQuest is used to model the human pharmacokinetics of the volatile solutes. A "standard human" value for the lipid content of the blood and each organ (klip) was chosen. This set of klip and the oil/water partition coefficient then specifies the organ/blood partition for each organ. Using this approach, the pharmacokinetics of inert volatile solute is completely specified by just 2 parameters: the water/air and oil/water partition coefficients. The model predictions of PKQuest were in good agreement with the experimental data for the inert solutes enflurane and nitrous oxide and the metabolized solutes halothane and toluene. METHODS: The experimental data that was modeled was taken from previous publications. CONCLUSIONS: This approach greatly increases the predictive power of the PBPK. For inert volatile solutes the pharmacokinetics are determined just from the water/air and oil/water partition coefficient. Methoxyflurane cannot be modeled by this PBPK because the arterial and end tidal partial pressures are not equal (as assumed in the PBPK). This inequality results from the "washin-washout" artifact in the large airways that is established for solutes with large water/air partition coefficients.PKQuest and the worked examples are available on the web www.pkquest.com.

SUBMITTER: Levitt DG

PROVIDER: S-EPMC122062 | biostudies-literature | 2002 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

PKQuest: volatile solutes - application to enflurane, nitrous oxide, halothane, methoxyflurane and toluene pharmacokinetics.

Levitt David G DG

BMC anesthesiology 20020815 1

BACKGROUND: The application of physiologically based pharmacokinetic models (PBPK) to human studies has been limited by the lack of the detailed organ information that is required for this analysis. PKQuest is a new generic PBPK that is designed to avoid this problem by using a set of "standard human" default parameters that are applicable to most solutes. RESULTS: PKQuest is used to model the human pharmacokinetics of the volatile solutes. A "standard human" value for the lipid content of the b ...[more]

PMID: 12182764

Similar Datasets

Project description:The structural modifications of the dipalmitoylphosphatidylcholine (DPPC) organization induced by increasing concentration of the volatile anesthetic enflurane have been studied by differential scanning calorimetry, small-angle, and wide-angle x-ray scattering. The interaction of enflurane with DPPC depends on at least two factors: the enflurane-to-lipid concentration ratio and the initial organization of the lipids. At 25 degrees C (gel state), the penetration of enflurane within the lipids induces the apparition of two different mixed lipid phases. At low anesthetic-to-lipid molar ratio, the smectic distance increases whereas the direction of the chain tilt changes from a tilt toward next-neighbors to a tilt between next-neighbors creating a new gel phase called L(beta')(2NNN). At high ratio, the smectic distance is much smaller than for the pure L(beta') DPPC phase, i.e., 50 A compared to 65 A, the aliphatic chains are perpendicular to the membrane and the fusion temperature of the phase is 33 degrees C. The electron profile of this phase that has been called L(beta)(i), indicates that the lipids are fully interdigitated. At 45 degrees C (fluid state), a new melted phase, called L(alpha)(2), was found, in which the smectic distance decreased compared to the initial pure L(alpha)(1) DPPC phase. The thermotropic behavior of the mixed phases has also been characterized by simultaneous x-ray scattering and differential scanning calorimetry measurements using the Microcalix calorimeter of our own. Finally, titration curves of enflurane effect in the mixed lipidic phase has been obtained by using the fluorescent lipid probe Laurdan. Measurements as a function of temperature or at constant temperature, i.e., 25 degrees C and 45 degrees C give, for the maximal effect, an enflurane-to-lipid ratio (M/M), within the membrane, of 1 and 2 for the L(alpha)(2) and the L(beta)(i) lamellar phase respectively. All the results taken together allowed to draw a pseudo-binary phase diagram of enflurane-dipalmitoylphosphatidylcholine in excess water.

Dataset Information

PKQuest: volatile solutes - application to enflurane, nitrous oxide, halothane, methoxyflurane and toluene pharmacokinetics.

Publications

PKQuest: volatile solutes - application to enflurane, nitrous oxide, halothane, methoxyflurane and toluene pharmacokinetics.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets