Understanding toxidromes: serotonin toxicity: a commentary on Montanes-Rada et al

Catatonia secondary to anti-N-methyl-D-aspartate receptor (NMDAr) encephalitis: a review

Anti-N-methyl-D-aspartate receptor (NMDAr) encephalitis is a relatively recent autoimmune entity, as it was first described in 2007. Given that it is a condition with neuropsychiatric symptoms, its initial symptom is frequently psychiatric in nature. Hence, psychiatrists are often the first physicians to assess these patients and, as so, must recognize this type of encephalitis as a possible cause. Catatonia may be inaugural or develop throughout the course of the disease. Management of patients with anti-NMDAr encephalitis is based on etiologic treatment with immunotherapy and removal of the associated tumor, if any. However, these catatonic patients may have variable responses to etiologic treatment, sometimes with refractory catatonic symptoms, which attests to the necessary urgency to know how to manage these patients. In the clinical setting, physicians appear to be using guidelines originally created to the management of catatonia due to primary psychiatric conditions. In this literature review, catatonia was historically contextualized and anti-NMDAr encephalitis overall described. Finally, catatonia secondary to this type of encephalitis was discussed.

CNS toxicity involving methylene blue: the exemplar for understanding and predicting drug interactions that precipitate serotonin toxicity

Methylene blue has only recently been noted to cause severe central nervous system toxicity. Methylene blue is used for various conditions, including, intravenously, in methemoglobinemia, vasoplegia and as an aid to parathyroidectomy (at doses of 1-7.5 mg kg(-1)). This review of the current evidence concludes that 13 of 14 of the reported cases of CNS toxicity were serotonin toxicity that met the Hunter Serotonin Toxicity Criteria. That has important preventative and treatment implications. Serotonin toxicity is precipitated by the monoamine oxidase inhibitor (MAOI) property of methylene blue interacting with serotonin reuptake inhibitors. Serotonin toxicity is reviewed, using the lessons inherent in the methylene blue story and experience, to illustrate how the mechanisms and potency of serotonergic drugs interact to determine severity. Recent human data showed that an intravenous dose of only 0.75 mg kg(-1) of methylene blue produced a peak plasma concentration of 500 ng ml(-1) (1.6 µM), indicating that the concentration in the central nervous system reaches a level that inhibits monoamine oxidase A. That is consonant with the actual occurrence of severe serotonin toxicity in humans at the dose of only 1 mg kg(-1). It seems that all proposed uses of methylene blue entail levels that block monoamine oxidase, so cessation of serotonin reuptake inhibitors should be very carefully considered before using methylene blue.

Monoamine oxidase inhibitors: a modern guide to an unrequited class of antidepressants

Monoamine oxidase inhibitors (MAOIs) currently have a "bad rap" and are thus infrequently used in psychopharmacology, even by experienced clinicians. Misinformation about the dietary and drug interactions of MAOIs is widespread, whereas pragmatic tips for utilizing MAOIs to minimize risks and to maximize therapeutic actions are largely lacking in the contemporary literature. While clearly not first-line treatments, MAOIs, in the hands of experienced and well-informed clinicians, can be a powerful therapeutic intervention for patients with depression, panic disorder, and other anxiety disorders who have failed first-line treatments. This article focuses on the pharmacologic mechanisms of MAOIs, since an understanding of these mechanisms may provide a rationale to empower experts to expand their use of these agents. Discussed here are not only the mechanisms of therapeutic action of MAOIs, but also the mechanisms explaining their side effects, including hypertensive interactions with dietary tyramine (so-called "cheese reactions") and drug interactions that can lead to hypertensive reactions with some drugs and serotonin toxicities with others. This article also provides practical tips on how to use MAOIs, including debunking certain myths and giving specific guidance about which foods and drugs to avoid. Those with no previous interest in MAOIs may discover in this article a new "secret weapon" to add to their therapeutic armamentarium for patients who fail to respond to the better-known agents.