Nephrotoxicity of Select Rheumatologic Drugs

Methotrexate overdose in clinical practice

BACKGROUND

A folic-acid antagonist, methotrexate, is one of the most commonly prescribed drugs with its expanding use in clinical practice. The drug requires regular monitoring given its wide range of adverse effects including bone marrow suppression, hepatic or renal dysfunction, gastrointestinal distress, mucocutaneous damage, and neurotoxicity. The toxicity usually occurs rapidly and leads to severe neutropenia, sepsis, and advanced renal failure that are difficult to manage.

METHODS

This review is an update for the clinicians to understand the pharmacology, clinical features, laboratory evaluation, and treatment of patients with methotrexate overdose. High-quality literature of the past six decades was collected and reviewed in this article. Several landmark articles were reviewed using PubMed, EMBASE Ovid, and the Cochrane Library, that have important implications in current clinical practice.

RESULTS

Methotrexate overdose has complex toxicokinetic and produces myriad clinical features mimicking conditions of lesser severity. Organ dysfunction related to bone marrow, kidney or central nervous system is lifethreatening. The management should focus on high-quality supportive care, antidotal therapy (folinic acid and carboxypeptidase- G2) and plasma alkalization.

CONCLUSION

In accordance with the dictum "prevention is better than cure", the author emphasizes on the role of patient education, regular clinical observation, and laboratory monitoring for prompt recognition and diagnosis of methotrexate overdosing at the earliest stage.

Sika deer antler protein against acetaminophen-induced oxidative stress and apoptosis in HK-2 cells via activating Nrf2/keap1/HO-1 pathway

Nf-E2-related transcription factor 2 (Nrf2) helps cells fight oxidative stress events in vivo and in vitro by promoting the expression of antioxidants and detoxification enzymes. The necessary factors regulating Nrf2 activity and stability during analgesic nephropathy are not fully understood. Our results suggest that acetaminophen produces nephrotoxicity in HK-2 cells by inhibiting keap1 degradation. APAP subsided Nrf2 nuclear accumulation by inhibition of keap1 degradation, thereby reducing the binding of Nrf2 to ARE, leading to the loss of expression of antioxidant proteins such as HO-1, inducing a series of oxidative stress and apoptosis events. Therefore, Nrf2/keap1/HO-1 signal transduction pathway has a poor prognosis during analgesic nephrotoxicity. Sika deer antler protein (SDAPR) significantly prevented APAP-induced HK-2 cell damage by constitutively stabilized Nrf2 nuclear retention. Excess APAP leads to a decrease in Nrf2 nuclear translocation, leading to severe oxidative stress, increasing the levels of GSH and MDA in HK-2 cells, and reducing the enzyme activities of SOD and CAT in HK-2 cells. Increased biomarker levels of acute kidney injury (AKI) in HK-2 cells, including kidney injury molecule-1, neutrophil gelatinase-associated lipocalin and cystatin C, decrease the mitochondrial membrane potential in HK-2 cells, and cause mitochondrial dysfunction, it also reduced the ratio of mitochondria-associated apoptotic protein Bax/Bcl-2, leading to cell apoptosis. SDAPR dose dependently accorded protection against acetaminophen-induced nephrotoxicity, oxidative damage, and cell apoptosis by its molecular intervention with Nrf2/keap1/HO-1 pathway via keap1 degradation. PRACTICAL APPLICATIONS: In this paper, we investigated the protective effect of SDAPR on APAP-induced AKI in HK-2 cells, and briefly explained its possible mechanism of action, providing a basis for future clinical trials and the development of anti-APAP AKI drugs.