Drug Interactions

CYP3A, a key member of the cytochrome P450 (CYP450) superfamily, is integral to drug metabolism, processing a substantial portion of medications. Their role in drug metabolism is particularly prominent, as CYP3A4 and CYP3A5 metabolize approximately 30-50% of known drugs. The genetic polymorphism of CYP3A4/5 is significant inter-individual variability in enzymatic activity, which can result in different pharmacokinetic profiles in response to the same drug among individuals. These polymorphisms can lead to either increased drug toxicity or reduced therapeutic effects, requiring dosage adjustments based on genetic profiles. Consequently, the study of the enzymatic activity of CYP3A4/5 gene variants is of great importance for the formulation of personalized treatment regimens. This article first reviews the role of CYP3A4/5 in drug metabolism in the human body, including inhibitors and inducers of CYP3A4/5 and drug-drug interactions. In terms of genetic polymorphism, it discusses the detection methods, enzymatic kinetic characteristics, and clinical guidelines for CYP3A5. Finally, the article summarizes the importance of CYP3A4/5 in clinical applications, including personalized therapy, management of drug-drug interactions, and adjustment of drug doses. This review contributes to the understanding of the functions and genetic characteristics of CYP3A4/5, allowing for more effective clinical outcomes through optimized drug therapy.

Antibacterial activity can be classified as either bactericidal or bacteriostatic, using methods such as the MBC/MIC ratio and time-kill curves. However, such categorization has proven challenging in clinical practice, as these definitions only apply under specific laboratory conditions, which may differ from clinical settings. Several factors, such as the specific bacteria or infectious medium, can affect the action of antibiotics, with many antibacterials exerting both activities. These definitions have also led to the belief that bactericidal antibacterials are superior to bacteriostatic, especially in more severe cases, such as endocarditis, neutropenia and bacteraemia. Additionally, current dogma dictates against the combination of bactericidal and bacteriostatic antibacterials in clinical practice, due to potential antagonism. This review aimed to assess the differences in antibacterial activity of bactericidal and bacteriostatic antibacterials based on in vitro and in vivo studies and examine their antagonistic or synergistic effects. Our findings show that specific bacteriostatic agents, such as linezolid and tigecycline, are clinically non-inferior to bactericidals in multiple infections, including pneumonia, intra-abdominal infections, and skin and soft tissue infections. Studies also support using several bacteriostatic agents as salvage therapies in severe infections, such as neutropenic fever and endocarditis. Additionally, not all combinations of bacteriostatic and bactericidal agents appear to be antagonistic, with many combinations, such as linezolid and rifampicin, already being used. The findings should be interpreted with caution, as most evidence is from observational studies and there is a need for randomized controlled trials to assess their effectiveness and combinations, especially within the context of rising antimicrobial resistance.

Current KRASG12C (OFF) inhibitors that target inactive GDP-bound KRASG12C cause responses in less than half of patients and these responses are not durable. A class of RASG12C (ON) inhibitors that targets active GTP-bound KRASG12C blocks ERK signaling more potently than the inactive-state inhibitors. Sensitivity to either class of agents is strongly correlated with inhibition of mTORC1 activity. We have previously shown that PI3K/mTOR and ERK-signaling pathways converge on key cellular processes and that inhibition of both pathways is required for inhibition of these processes and for significant antitumor activity. We find here that the combination of a KRASG12C inhibitor with a selective mTORC1 kinase inhibitor causes synergistic inhibition of Cyclin D1 expression and cap-dependent translation. Moreover, BIM upregulation by KRASG12C inhibition and inhibition of MCL-1 expression by the mTORC1 inhibitor are both required to induce significant cell death. In vivo, this combination causes deep, durable tumor regressions and is well tolerated. This study suggests that the ERK and PI3K/mTOR pathways each mitigate the effects of inhibition of the other and that combinatorial inhibition is a potential strategy for treating KRASG12C-dependent lung cancer.

Grapefruit juice is a well-established inhibitor of cytochrome P450 (CYP) 3A4, but its effects on other CYP enzymes or organic anion transporting polypeptides (OATPs) are not fully characterized in humans. Recently, lingonberry powder was shown to induce murine CYP enzymes. We investigated the effects of lingonberry powder and grapefruit juice on seven CYP enzymes and two OATPs. Eleven healthy volunteers received three pretreatments three times per day: water for 1 day (control), lingonberry powder for 9 days, and grapefruit juice for 3 days. CYP index drugs (caffeine/CYP1A2, bupropion/CYP2B6, repaglinide/CYP2C8, flurbiprofen/CYP2C9, omeprazole/CYP2C19, dextromethorphan/CYP2D6, midazolam/CYP3A4, and simvastatin/CYP3A4) were administered orally on the study day of each pretreatment (day 1, 10, and 3, respectively). Venous blood samples were collected until 23 hours postdose. The concentrations of index drugs, their metabolites and endogenous OATP1B1 and OATP1B3 biomarkers glycochenodeoxycholate 3-O-glucuronide (GCDCA-3G) and glycochenodeoxycholate 3-sulfate (GCDCA-3S), respectively, were quantified. Grapefruit juice expectedly increased the AUC0-23h values of the CYP3A4 index drugs midazolam and simvastatin (P 0-23h ratios to 0.57-fold (90% confidence interval: 0.45-0.74), 0.78-fold (0.69-0.87), 0.43-fold (0.36-0.52), and 0.72-fold (0.63-0.84) of control, respectively (P < 0.01). Lingonberry pretreatment did not change any CYP indices. GCDCA-3G and GCDCA-3S concentrations were unaffected by grapefruit juice or lingonberry pretreatment. Collectively, our findings indicate that in addition to inhibiting CYP3A4, repeated grapefruit juice intake causes clinically relevant inhibition of CYP2B6, CYP2C9, and CYP2C19, revealing previously underappreciated interaction risks. Conversely, lingonberry powder is unlikely to induce CYP enzymes in humans.