Methylene blue and ifosfamide-induced encephalopathy: Myth or reality?

BACKGROUND

Ifosfamide-induced encephalopathy (IIE) is a rare and serious adverse reaction. Thus far, no standard medication has been documentedto be efficient in the reversal of IIE, and while ifosfamide infusion interruption and hydration are recommended, methylene blue (MB) administration remains controversial.

METHODS

We retrospectively reviewed medical records to assess cases with IIE after ifosfamide infusion. We included all patients having received an ifosfamide infusion during their hospitalization in the medical oncology unit of the National Institute of Oncology in Rabat, Morocco, between September 2016 and September 2017. We subsequently conducted a literature review to determine the role of MB in IIE by searching PubMed using the terms "Methylene Blue" and "Ifosfamide".

RESULTS

A total of 88 patients received ifosfamide, and four patients had IIE. Ifosfamide infusion was stopped immediately after the IIE occurrence, and patients underwent renal function correction with hydration. All patients received MB infusion, and three patients had an improvement of their neurological status. As regards the literature review, 34 articles were reviewed and 16 items were included in the review. Overall, 38 (65.5%) patients received MB infusion and 28 (75.6%) patients responded favorably to the treatment.

CONCLUSIONS

Methylene blue can be used as a treatment for IIE owing to the severity of the IIE as well as absence of standard medication. Nonetheless, side effects such as serotonergic syndrome should be investigated. More broadly, prospective studies and controlled trials are needed to explore the contribution of MB in IIE management and encourage its use.

Neurotoxicity of antineoplastic drugs: Mechanisms, susceptibility, and neuroprotective strategies

This review summarizes the adverse effects on the central and/or peripheral nervous systems that may occur in response to antineoplastic drugs. In particular, we describe the neurotoxic side effects of the most commonly used drugs, such as platinum compounds, doxorubicin, ifosfamide, 5-fluorouracil, vinca alkaloids, taxanes, methotrexate, bortezomib and thalidomide. Neurotoxicity may result from direct action of compounds on the nervous system or from metabolic alterations produced indirectly by these drugs, and either the central nervous system or the peripheral nervous system, or both, may be affected. The incidence and severity of neurotoxicity are principally related to the dose, to the duration of treatment, and to the dose intensity, though other factors, such as age, concurrent pathologies, and genetic predisposition may enhance the occurrence of side effects. To avoid or reduce the onset and severity of these neurotoxic effects, the use of neuroprotective compounds and/or strategies may be helpful, thereby enhancing the therapeutic effectiveness of antineoplastic drug.

Methylene blue for distributive shock: a potential new use of an old antidote

Methylene blue is used primarily in the treatment of patients with methemoglobinemia. Most recently, methylene blue has been used as a treatment for refractory distributive shock from a variety of causes such as sepsis and anaphylaxis. Many studies suggest that the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway plays a significant role in the pathophysiology of distributive shock. There are some experimental and clinical experiences with the use of methylene blue as a selective inhibitor of the NO-cGMP pathway. Methylene blue may play a role in the treatment of distributive shock when standard treatment fails.

An assessment of risk factors associated with ifosfamide-induced encephalopathy in a large academic cancer center

PURPOSE

Ifosfamide-induced encephalopathy is a neurotoxic adverse effect of ifosfamide chemotherapy. The objective of this study was to determine the incidence of encephalopathy in patients with lymphoma and sarcoma receiving ifosfamide chemotherapy and assess for potential risk factors that influence the incidence of encephalopathy.

METHODS

A retrospective study of sarcoma and lymphoma patients receiving ifosfamide chemotherapy was performed at the participating institutions. Enrollment began 1 July 2011 and continued chronologically backwards until 100 sarcoma and 100 lymphoma patients were enrolled. Identification of ifosfamide-induced encephalopathy events was performed by reviewing provider documentation of ifosfamide infusions. Logistic regression was employed to determine associations between risk factors and ifosfamide-induced encephalopathy events.

RESULTS

Of the 200 patients enrolled, 29 (14.5%) patients experienced encephalopathy. Ifosfamide-induced encephalopathy occurred more frequently in the sarcoma population than the lymphoma population (24 vs. 5 patients, p < 0.001). In addition to cancer type, prior use of cisplatin, concomitant opioids, and use of CYP2B6 inhibitors remained as significant variables in the multivariate model conferring a 12.47, 2.81, and 5.17 increased odds of experiencing encephalopathy, respectively. The odds of experiencing encephalopathy were 9.0 and 1.37 times higher for a one-unit increase in serum creatinine and hemoglobin, respectively, and 0.15 times lower for a one-unit increase in albumin.

CONCLUSIONS

This is the first study to demonstrate that patients with sarcoma experienced ifosfamide-induced encephalopathy more often than those with lymphoma. For all patients, predisposing factors for ifosfamide-induced encephalopathy included previous cisplatin exposure, concomitant opioids and CYP2B6 inhibitors. Laboratory values that increased ifosfamide-induced encephalopathy risk included low serum albumin, increased serum creatinine, and increased hemoglobin.

Suspected serotonin syndrome in a patient being treated with methylene blue for ifosfamide encephalopathy

Methylene blue has been used not only as a diagnostic agent, but also as an agent in the treatment of ifosfamide-induced encephalopathy (IIE) for several years. Recently, several cases of suspected serotonin syndrome have been reported in patients who received methylene blue in combination with serotonin active agents. Rodent models have revealed that methylene blue is a potent, reversible inhibitor of monoamine oxidase A. It is well known that serotonin active drugs, in combination with monoamine oxidase inhibitors can produce profound serotonin syndrome. To date, cases of serotonin syndrome, which resulted from concurrent methylene blue and serotonin active agents, have been published in the anesthesia literature. We report the first known case of serotonin syndrome in a patient receiving methylene blue for IIE.