The effects of CYP3A4 induction and inhibition on the pharmacokinetics of alisporivir in humans

Cyclophilin inhibition as a strategy for the treatment of human disease

Cyclophilins (Cyps), characterized as peptidyl-prolyl cis-trans isomerases (PPIases), are highly conserved and ubiquitous, playing a crucial role in protein folding and cellular signaling. This review summarizes the biochemical pathways mediated by Cyps, including their involvement in pathological states such as viral replication, inflammation, and cancer progression, to underscore the therapeutic potential of Cyp inhibition. The exploration of Cyp inhibitors (CypI) in this review, particularly non-immunosuppressive cyclosporine A (CsA) derivatives, highlights their significance as therapeutic agents. The structural and functional nuances of CsA derivatives are examined, including their efficacy, mechanism of action, and the balance between therapeutic benefits and off-target effects. The landscape of CypI is evaluated to emphasize the clinical need for targeted approaches to exploit the complex biology of Cyps and to propose future directions for research that may enhance the utility of non-immunosuppressive CsA derivatives in treating diseases where Cyps play a key pathological role.

Pharmacokinetics and Bioequivalence of 2 Azithromycin Tablet Formulations: A Randomized, Open-Label, 2-Stage Crossover Study in Healthy Volunteers

The current study aimed to assess the bioequivalence of a new branded azithromycin with the reference formulation. An open-label, randomized, 2-stage, crossover study design was implemented involving 77 healthy volunteers under fasting conditions. Each volunteer received a single dose of 250-mg azithromycin tablets test and reference formulations separated by a 21-day washout period. Twenty-two samples were collected at pre-dose and until 72 hours post-dose. Azithromycin concentrations were analyzed using a high-performance liquid chromatography-mass spectrometry validated method following a solid-phase plasma extraction. Noncompartmental analysis was carried out to estimate the pharmacokinetic parameters, which were compared between the test and reference products using a multivariate analysis of variance. The difference between C_max and AUC_0-72 of the test and reference formulation was not significant. The 94.1% confidence intervals of ln-transformed C_max and AUC_0-72 of azithromycin were within the bioequivalence acceptance limits of 80%-125%, therefore it can be concluded that the tested formulation is bioequivalent to the reference formulation.

The detoxification effect of cytochrome P450 3A4 on gelsemine-induced toxicity

Gelsemine (GA), the principal alkaloid in Gelsemium elegans Benth, exhibits potent and specific antinociception in chronic pain without the induction of apparent tolerance. However, GA also exerts neurotoxicity and hepatotoxicity when overdosed, and potential detoxification pathways are urgently needed. Cytochrome P450 enzymes (CYPs) are important phase I enzymes involved in the detoxification of xenobiotic compounds. The study aimed to investigate the role of CYPs-mediated metabolism in GA-induced toxicity. Microsomes, chemical special inhibitors and human recombinant CYPs indicated that GA was mainly metabolized by CYP3A4/5. The major metabolite of GA was isolated and identified as 4-N-demethyl-GA by high-resolution mass spectrometry and nuclear magnetic resonance technology. The CYP3A4 inhibitor ketoconazole significantly inhibited the metabolism of GA. This drastically increased GA toxicity which is caused by increasing the level of malondialdehyde and decreasing the level of the superoxide dismutase in mice. In contrast, the CYP3A4 inducer dexamethasone significantly increased GA metabolism and markedly decreased GA toxicity in mice. Notably, in CYP3A4-humanized mice, the toxicity of GA was significantly reduced compared to normal mice. These findings demonstrated that CYP3A4-mediated metabolism is a robust detoxification pathway for GA-induced toxicity.