The results of this study show the quantitative importance of the CYP2D6 genotype, especially the presence of multiple functional CYP2D6 genes for the pharmacokinetics of nortriptyline and 10-hydroxynortriptyline. Genotyping of subjects with multiple copies of functional genes may be of great value for differentiating ultrarapid metabolizers from patients who do not comply with the prescription and for assuring adequate drug choice and dosage for these patients.

Complexation of o-phthalate (1,2-benzenedicarboxylate) at the water−boehmite (γ-AlOOH) interface has been studied in 0.1 N NaCl media at 298.2 K within the range 4.0 < pH < 10.0. Equilibrium measurements were performed as potentiometric titrations and adsorption measurements. Attenuated total reflectance IR spectra were recorded to obtain structural information of the phthalate surface complexes. Additional adsorption and IR spectroscopic measurements were performed as a function of ionic strength. Infrared data strongly indicated the formation of two complexes at the surface, one outer-sphere and one inner-sphere complex with a chelating bidentate structure. The relative concentrations of these complexes were shown to vary with ionic strength and pH. The potentiometric and adsorption data were modeled using the extended constant capacitance approach to describe the electrostatics at the water−boehmite interface. Furthermore, constraints from the infrared spectroscopic results were used in the model. The surface complexation model which provided the best fit to all experimental data included the following equilibria:  ⋮AlOH + HL- ↔ ⋮AlOH2 +L2- (outer sphere); ⋮Al(OH)2 + H+ + HL- → ⋮AlL + 2H2O (inner sphere).

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Speciation and equilibria of 1,2,4,5-benzenetetracarboxylate (pyromellitate) at the water−boehmite (γ-AlOOH) interface were studied in 0.1 M Na(Cl) at 298 K. Surface equilibrium analyses were based upon potentiometric and adsorption measurements in the range 4.5 < pH < 10.0. To characterize the surface complexes at the molecular level, attenuated total reflectance infrared spectra were recorded. The IR data provided information on the structure and composition of the complexes. This information could then be used to constrain the thermodynamic surface complexation model. The acid/base properties of pyromellitate in solution and its complexation with Al(III) were also studied by means of potentiometric titrations in 0.1 M Na(Cl) at 298 K. The results of these measurements were primarily used to investigate the effect of pyromellitate on the dissolution of boehmite. In aqueous solution Al(III) forms a series of mononuclear complexes, namely, AlHL, AlL-, and Al(OH)L2-. No indication of polynuclear complexes was found within the concentration ranges studied. IR spectra of pyromellitate sorbed at the water−boehmite interface suggested the existence of one dominating surface complex over a wide pH range (4.4 ≤ pH ≤ 8.1). The IR spectroscopic characteristics of this complex were in agreement with an outer-sphere nonprotonated pyromellitate ion. No evidence was found for protonation of the sorbed ion. Thus, the nonprotonated form is greatly stabilized at the interface as compared to the speciation in the aqueous solution. The IR data also showed some indications of a second minor surface complex. This was tentatively assigned to an inner-sphere species. According to the constraints provided by the IR data, the potentiometric and adsorption data were modeled with two surface complexes, ⋮AlOH2 +L4- (outer-sphere) and ⋮AlL- (inner-sphere). The extended constant capacitance model was used to account for the electrostatic effects at the interface. The agreement between the experimental data and the model was satisfactory. Furthermore, the model was also in agreement with the minor changes observed in the IR spectra as a function of pH.

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