7Li-NMR and FTIR studies of lithium, potassium, rubidium, and cesium complexes with ionophore lasalocid in solution.

Lasalocid metal salts were combined with 1 : 1 lithium and 2:2 potassium, rubidium, and cesium to form complexes. The nature of the lasolocid salt complexes was studied in a solid and chloroform by FTIR spectroscopy in the middle and far IR regions. The process of the complexation of lithium was also studied by (7)Li-NMR. In chloroform a 1 : 1 complex of lasalocid and Li(+) ions was formed. Continuous absorption was observed in the far FTIR spectrum of this complex. It indicated large Li(+) polarizability, which was due to fast fluctuations of the Li(+) ions in the multiminima potentials, in the monomeric structure. In the lasalocid salt with the other monovalent cations (K(+), Rb(+), Cs(+)) 2:2 complexes were formed in which the cations showed cation polarizability, which strongly depended on the mass and the radius of the cations.

Pharmacokinetics of propranolol and atenolol in patients after partial gastric resection: a comparative study.

OBJECTIVE: Partial gastric resection alters the anatomy and secretory activity of the gastrointestinal tract. It might be expected that the consequences of such changes should affect the pharmacokinetics, especially concerning the absorption of orally administered drugs. Propranolol and atenolol, as representatives of lipophilic and hydrophilic beta-adrenoreceptor antagonists, have been studied in order to define their pharmacokinetic characteristics in patients after partial gastrectomy. METHODS: The study was carried out in 29 patients after gastric resection with Billroth I (B1) anastomosis and in 18 healthy volunteers as controls. Pharmacokinetics of propranolol and atenolol was investigated after a single oral dose of 80 mg and 100 mg, respectively, following a cross-over schedule. Blood samples were collected ten times during the 24 h after the drug administration. Pharmacokinetic parameters of propranolol and atenolol were calculated using a one-compartment open model with first-order absorption. RESULTS: The average blood plasma concentrations of propranolol in gastrectomised patients were lower than those in controls, reaching significance between 1.5 h and 6.0 h of the observation period. Pharmacokinetic parameters of propranolol were different in subjects submitted to surgery compared with healthy persons. We observed a significant decrease in the area under the concentration-time curve (32%) and the peak plasma concentration (20%), and an increase in half-life (25%). Mean plasma concentrations and pharmacokinetic parameters of atenolol in patients following partial gastric resection were not significantly different from those in the controls. No relationship between time interval following partial gastrectomy and pharmacokinetic parameters of the investigated drugs was noted. CONCLUSION: Partial gastrectomy with B1 anastomosis affects the pharmacokinetics of propranolol (lipophilic drug) but not atenolol (hydrophilic drug).