CYP3A-Mediated Carbon-Carbon Bond Cleavages in Drug Metabolism

Cytochrome P450 enzymes (P450s) play a critical role in drug metabolism, with the CYP3A subfamily being responsible for the biotransformation of over 50% of marked drugs. While CYP3A enzymes are known for their extensive catalytic versatility, one intriguing and less understood function is the ability to mediate carbon-carbon (C-C) bond cleavage. These uncommon reactions can lead to unusual metabolites and potentially influence drug safety and efficacy. This review focuses on examining examples of C-C bond cleavage catalyzed by CYP3A, exploring the mechanisms, physiological significance, and implications for drug metabolism. Additionally, examples of CYP3A-mediated ring expansion via C-C bond cleavages are included in this review. This work will enhance our understanding of CYP3A-catalyzed C-C bond cleavages and their mechanisms by carefully examining and analyzing these case studies. It may also guide future research in drug metabolism and drug design, improving drug safety and efficacy in clinical practice.

Practical approach to the treatment of NSAID hypersensitivity

INTRODUCTION

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most frequently involved in drug hypersensitivity reactions (DHR). NSAIDs are prescribed for different processes and some NSAIDs can be obtained over the counter. Areas covered: We analyse the practical approaches for managing and treating NSAID-DHR considering the five major groups of entities recognised, divided into two categories: those responding to strong COX-1 inhibitors and possibly weak COX-1 or selective COX-2 inhibitors named cross-intolerant (CI), and those induced by a single drug or drug group with good tolerance to strong COX-1 inhibitors, known as allergic reactions (SR). An analysis of the recent literature indicates that two approaches can be followed for CI: to give acetyl salicylic acid to confirm NSAID hypersensitivity or to give alternative drugs to provide a solution for the treatment of pain, fever, inflammation or other conditions. Desensitisation approaches have been undertaken, but mainly for CI cases with respiratory airway involvement and they are very rarely used for CI with cutaneous involvement or SR. Expert commentary: DHR to NSAIDs are now recognised as one of the most important problems in the evaluation and management of drug allergy. Because no diagnostic tests exist, important resources are needed to evaluate these patients.

Tolerability to nabumetone and meloxicam in patients with nonsteroidal anti-inflammatory drug intolerance

BACKGROUND

Because nonsteroidal anti-inflammatory drug (NSAID) intolerance depends on COX-1 inhibition, preferential or selective COX-2 inhibitors have been thought to be well tolerated by these patients.

OBJECTIVE

The aim of this study is to evaluate tolerability to nabumetone and meloxicam in patients with NSAID intolerance.

METHODS

Seventy patients intolerant to NSAIDs were selected. Thirty subjects were patients with asthma with respiratory (rhinitis-asthma) intolerance to NSAIDs (group A); 40 patients (group B) had cutaneous-mucous (urticaria-angioedema) NSAID intolerance. Diagnosis was based on clinical histories in all patients, and it was confirmed by positive single-blind placebo-controlled oral challenge test in 36 patients. After written informed consent, a single-blind placebo-controlled oral challenge test with nabumetone in all patients (2 g except for 11 patients who reached 1 g) and meloxicam (15 mg) in 51 patients was performed.

RESULTS

Of the total selected, 94.3% tolerated 1 g nabumetone. In those who reached the 2-g dose, the tolerability was 83.6%. With respect to meloxicam, 96.1% of patients, tolerated 15 mg. No significant difference in nabumetone and meloxicam tolerability was observed between groups A and B.

CONCLUSION

The results of this study confirm a high percentage of tolerability to the maximum therapeutic dosage of nabumetone and meloxicam in patients with NSAID intolerance, both in those with cutaneous/mucous manifestations and in those with respiratory disease.

CLINICAL IMPLICATIONS

Nabumetone and meloxicam are safe alternatives in NSAID-intolerant patients.