Predicting drug-drug interactions by electrochemically driven cytochrome P450 3A4 reactions

OBJECTIVES

Human cytochrome P450 3A4 is the most abundant hepatic and intestinal Phase I enzyme that metabolizes approximately 60% marketed drugs. Simultaneous administration of several drugs may result in appearance of drug-drug interaction. Due to the great interest in the combination therapy, the exploration of the role of drug as "perpetrator" or "victim" is important task in pharmacology. In this work the model systems based on electrochemically driven cytochrome P450 3A4 for the analysis of drug combinations was used. We have shown that the analysis of electrochemical parameters of cytochrome P450 3A4 and especially, potential of the start of catalysis, Eonset, possess predictive properties in the determination of the leading ("perpetrator") properties of drug. Based on these experimental data, we concluded, that the more positive potential of the start of catalysis, Eonset, the more pronounced the role of drug as leading medication.

METHODS

Electrochemically driven cytochrome P450 3A4 was used as probe and measuring tool for the estimation of the role of interacting drugs.

RESULTS

It is shown that the electrochemical non-invasive model systems for monitoring the catalytic activity of cytochrome P450 3A4 can be used as prognostic devise in assessment of drug/drug interacting medications.

CONCLUSIONS

Cytochrome P450 3A4 activity was studied in electrochemically driven system. Method was implemented to monitor drug/drug interactions. Based on the obtained experimental data, we can conclude that electrochemical parameter such as potential of onset of catalysis, Eonset, has predictive efficiency in assessment of drug/drug interacting medications in the case of the co-administration.

Bioanalytical applications of Mössbauer spectroscopy

Data on the applications of Mössbauer spectroscopy in the transmission (mainly on 57Fe nuclei) and emission (on 57Co nuclei) variants for analytical studies at the molecular level of metal-containing components in a wide range of biological objects (from biocomplexes and biomacromolecules to supramolecular structures, cells, tissues and organisms) and of objects that are participants or products of biological processes, published in the last 15 years are discussed and systematized. The prospects of the technique in its biological applications, including the developing fields (emission variant, use of synchrotron radiation), are formulated.

The bibliography includes 248 references.

No effect of lipoic acid on catalytic activity of cytochrome P450 3A4

Objectives α-Lipoic acid is used as an antioxidant in multivitamin formulations to restore the normal level of intracellular glutathione after depletion caused by environmental pollutants or during physiological aging of the body, as a chelating agent, as a dietary supplement, in anti-aging compositions. Lipoic acid (LA) acts as a buffer in cancer therapy and in therapy of diseases associated with oxidative stress. The effect of LA on the catalytic functions of cytochrome P450 3A4 as the main enzyme of the biotransformation of drugs was studied. It was shown that LA in the concentration range of 50-200 μM affects the stage of electron transfer (stage of cytochrome P450 3A4 heme reduction), decreasing the cathodic reduction current by an average of 20 ± 5%. The kinetic parameters (k cat) of the N-demethylation reaction of erythromycin, the antibiotic of the macrolide group, used as a marker substrate for the comparative analysis of the catalytic activity of cytochrome P450 3A4, both in the presence of α-lipoic acid and in the cytochrome P450 3A4-erythromycin complex, amounted to comparable values of 3.5 ± 0.9 and 3.4 ± 0.9 min-1, respectively. Based on these experimental data, we can conclude that there is no significant effect of α-lipoic acid on the catalysis of cytochrome P450 3A4. These results can be projected on the possibility of using α-lipoic acid in complex therapy without negative impact on the enzymatic cytochrome P450 system. Methods The analysis was performed in electrochemical non-invasive model systems for recording the catalytic activity of cytochrome P450 3A4, using screen-printed electrodes, modified with membranous didodecyldimethylammonium bromide. Results It was shown that LA did not affect the N-demethylation of macrolide antibiotic erythromycin. Catalytic constant (k cat) of N-demethylation of erythromycin corresponds to 3.4 ± 0.9 min-1 and in the presence of LA corresponds to 3.5 ± 0.9 min-1. Conclusions Based on the obtained experimental data, we can conclude that there is no significant effect of α-lipoic acid on individual stages and processes of catalysis of cytochrome P450 3A4. LA can be recommended for inclusion in complex therapy as an antioxidant, antitoxic and chelating compound without negative impact on the enzymatic cytochrome P450 3A4 activity of the human body.