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Abstract. The aim of this study was to develop a drug-specific absorption model for gliclazide (GLK) using mechanistic gastrointestinal simulation technology (GIST) implemented in GastroPlus TM software package. A range of experimentally determined, in silico predicted or literature data were used as input parameters. Experimentally determined pH-solubility profile was used for all simulations. The human jejunum effective permeability (P eff ) value was estimated on the basis of in vitro measured Caco-2 permeability (literature data). The required PK inputs were taken from the literature. The results of the simulations were compared with actual clinical data and revealed that the GIST-model gave accurate prediction of gliclazide oral absorption. The generated absorption model provided the target in vivo dissolution profile for in vitro-in vivo correlation and identification of biorelevant dissolution specification for GLK immediate-release (IR) tablets. A set of virtual in vitro data was used for correlation purposes. The obtained results suggest that dissolution specification of more than 85% GLK dissolved in 60 min may be considered as "biorelevant" dissolution acceptance criteria for GLK IR tablets.

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The influence of symmetrical chemi-ionization and chemi-recombination processes on the helium atom Rydberg states' population in weakly ionized layers of helium-rich DB white dwarfs has been investigated. The ionization processes in He à ðnÞ þ Heð1s 2 Þ collisions and their inverse recombination processes He þ 2 þ e and Heð1s 2 Þ þ He þ þ e have been considered in domains of principal quantum numbers n ! 3 and temperatures 12; 000 K T eff 30; 000 K. These processes have been treated within the frame of the semiclassical theory developed earlier. Their contributions to the Rydberg state populations have been compared with electron-electron-ion recombination, electron-excited atom ionization, and electron-ion photorecombination processes. Results showed that these processes can be dominant ionization/recombination mechanisms in helium-rich DB white dwarf atmosphere layers for log g ¼ 7 and 8 and T eff 20; 000 K and have to be implemented in relevant models of weakly ionized helium plasmas.

On the basis of a semi-classical theory, the rate coefficients of collisional H -H*(n) ionization and recombination during electron scattering on H -H + complexes and H : ions were determined in this paper. The calculations were carried out in the case of non-equilibrium hydrogen plasma with atomic temperature Ts and electronic temperature Te, in the domains 2000 K Q Q 10 000 K and 2000 K 6 To Q 30 000 K, with the principal quantum number 4 C n Q 10. In the paper we have also determined the conditions under which these processes are important for the kinetics of weakly ionized hydrogen plasma.Table I . Calculated values of coefficients KPb) as functions of n, T, and T,, for n = 4-10.T,/[Kl (n = 4) T,