Fatal disseminated intravascular coagulation following a monoamine oxidase inhibitor/tricyclic interaction

Metabolomics and computational analysis of the role of monoamine oxidase activity in delirium and SARS-COV-2 infection

Delirium is an acute change in attention and cognition occurring in ~ 65% of severe SARS-CoV-2 cases. It is also common following surgery and an indicator of brain vulnerability and risk for the development of dementia. In this work we analyzed the underlying role of metabolism in delirium-susceptibility in the postoperative setting using metabolomic profiling of cerebrospinal fluid and blood taken from the same patients prior to planned orthopaedic surgery. Distance correlation analysis and Random Forest (RF) feature selection were used to determine changes in metabolic networks. We found significant concentration differences in several amino acids, acylcarnitines and polyamines linking delirium-prone patients to known factors in Alzheimer's disease such as monoamine oxidase B (MAOB) protein. Subsequent computational structural comparison between MAOB and angiotensin converting enzyme 2 as well as protein-protein docking analysis showed that there potentially is strong binding of SARS-CoV-2 spike protein to MAOB. The possibility that SARS-CoV-2 influences MAOB activity leading to the observed neurological and platelet-based complications of SARS-CoV-2 infection requires further investigation.

Tranylcypromine in mind (Part I): Review of pharmacology

It has been over 50 years since a review has focused exclusively on the monoamine oxidase (MAO) inhibitor tranylcypromine (TCP). A new review has therefore been conducted for TCP in two parts which are written to be read preferably in close conjunction: Part I - pharmacodynamics, pharmacokinetics, drug interactions, toxicology; and Part II - clinical studies with meta-analysis of controlled studies in depression, practice of TCP treatment, place in therapy. Pharmacological data of this review part I characterize TCP as an irreversible and nonselective MAO-A/B inhibitor at low therapeutic doses of 20mg/day with supplementary norepinephrine reuptake inhibition at higher doses of 40-60mg/day. Serotonin, norepinephrine, dopamine, and trace amines, such as the "endogenous amphetamine" phenylethylamine, are increased in brain, which leads to changes in neuroplasticity by e.g. increased neurotrophic growth factors and translates to reduced stress-induced hypersecretion of corticotropin releasing factor (CRF) and positive testing in animal studies of depression. TCP has a pharmacokinetic half-life (t_1/2) of only 2h which is considerably lower than for most other antidepressant drugs. However, a very long pharmacodynamic half-life of about one week is found because of the irreversible MAO inhibition. New studies show that, except for cytochrome P450 (CYP) 2A6, no other drug metabolizing CYP-enzymes are inhibited by TCP at therapeutic doses which defines a low potential of pharmacokinetic interactions in the direction from TCP to other drugs. Insufficient information is available, however, for plasma concentrations of TCP influenced by comedication. More quantitative data are also needed for TCP metabolites such as p-hydroxytranylcypromine and N-acetyltranylcypromine. Pharmacodynamic drug interactions comprise for instance severe serotonin toxicity (SST) with serotonergic drugs and hypertensive crisis with indirect sympathomimetics. Because of the risk of severe food interaction, TCP treatment remains beset with the need for a mandatory tyramine-restricted diet. Toxicity in overdose is similar to amitriptyline and imipramine according to the distance of therapeutic to toxic doses. In conclusion, TCP is characterized by an exceptional pharmacology which is different to most other antidepressant drugs, and a more special evaluation of clinical efficacy and safety may therefore be needed.

Nonmotor symptoms of Parkinson’s disease

Nonmotor symptoms occur commonly in Parkinson's disease (PD) patients and are frequently under-recognized and undertreated. Symptoms include sleep abnormalities, fatigue, autonomic disturbances, mood disorders and cognitive dysfunction. Early recognition and treatment of nonmotor symptoms in PD is critical to providing optimal management. A new screening questionnaire and the revised Unified PD Rating Scale should assist healthcare providers to better identify and evaluate these symptoms. This article reviews the identification and treatment of nonmotor symptoms in PD.

Serotonin syndrome. Presentation of 2 cases and review of the literature

Serotonin syndrome is an underreported complication of pharmacotherapy that has been relatively ignored in the medical literature. We discuss 2 recent cases seen at our institution and 39 cases described in the English-language literature since 1995. We found that patients with serotonin syndrome most often (74.3%) presented within 24 hours of medication initiation, overdose, or change in dosage. The most common presenting symptoms and signs were confusion, agitation, diaphoresis, tachycardia, myoclonus, and hyperreflexia. The prevalences of hypertension, coma/unresponsiveness, seizures, and death were not as prominent in our study as previously reported, perhaps reflecting earlier recognition and intervention. The most common therapeutic intervention was supportive care alone (48% of patients). The use of 5-hydroxytryptamine (5-HT) antagonists such as cyproheptadine, however, has become more common and might reduce the duration of symptoms. Only 1 death occurred, and most patients (57.5%) had complete resolution of their symptoms within 24 hours of presentation. The increased use of serotonergic agents (alone and in combination) across multiple medical disciplines presents the possibility that the prevalence and clinical significance of this condition will rise in the future. Internists will need to be increasingly aware of and prepared for this pharmacologic complication. Prevention, early recognition of the clinical presentation, identification and removal of the offending agents, supportive care, and specific pharmacologic therapy are all important to the successful management of serotonin syndrome.

The serotonin syndrome and its treatment

Serotonin syndrome is caused by drug induced excess of intrasynaptic 5-hydroxytryptamine. The clinical manifestations are mediated by the action of 5-hydroxytryptamine on various subtypes of serotonin receptors. There is no effective drug treatment established. The history of the treatment of serotonin syndrome with 5-hydroxytryptamine blocking drugs is reviewed. A literature search was undertaken using both Medline and a manual search of the older literature. Reports of cases treated with the 5-HT2 blockers cyproheptadine and chlorpromazine were identified and analysed. There is some evidence suggesting the efficacy of chlorpromazine and cyproheptadine in the treatment of serotonin syndrome. The evidence for cyproheptadine is less substantial, perhaps because the dose of cyproheptadine necessary to ensure blockade of brain 5-HT2 receptors is 20-30 mg, which is higher than that used in the cases reported to date (4-16 mg).

Serotonin syndrome: history and risk

This review focuses on the history of investigations into the behavioural reaction resulting from excess stimulation of post-synaptic 5-hydroxytryptamine receptors and the relative risk of this occurring with different combinations of drugs. Other aspects, particularly treatment with 5-hydroxytryptamine receptor antagonists, are reviewed in a recent separate paper [44]. The first human case was in 1955 and animal work had defined the characteristic features by 1958, and established they were lessened by chlorpromazine. Substantial evidence of a 'dose-effect' relationship existed by 1984. The relative risk with different drug combinations is assessed from available evidence and argued to be strongly associated with the degree of elevation of 5-hydroxytryptamine, which is greatest following combinations of irreversible inhibitors of monoamine oxidase A and B with potent serotonin reuptake inhibitors. The various serotonergic drugs that may be implicated in serotonin syndrome are tabulated and discussed in relation to the relative risk. It is suggested that the proposed 'diagnostic criteria' for serotonin syndrome are inappropriate since there is a continuous spectrum from side effects to toxicity. The term 'serotonin syndrome' may encourage the presumption that it is an idiosyncratic response, as neuroleptic malignant syndrome is usually considered to be. The terms 'toxic serotomimetic reaction' or 'toxic serotonin syndrome' may be preferable alternatives. The differences between serotonin syndrome and neuroleptic malignant syndrome are highlighted with examples from difficult or questionable cases in the recent literature. It is proposed that more systematic national collection of toxicity data is essential in order to quantify the relative risk of serotonin syndrome with various combinations of serotonergic drugs.

Antiparkinsonian Agents : Clinically Significant Drug Interactions and Adverse Effects, and Their Management

The treatment of Parkinson's disease for most patients entails long term exposure to multiple agents, including anticholinergics, levodopa, amantadine, dopamine receptor agonists, catechol-O-methyltransferase inhibitors, selegiline (deprenyl) and clozapine. Patients with Parkinson's disease require medication for the control of the motor symptoms of their condition, for related medical or psychiatric symptoms of the disorder, and for concurrent medical problems, such as hypertension or cardiac disease.All these agents may cause adverse effects. There is a potential for drug-drug interactions between different antiparkinsonian agents and between antiparkinsonian medication and the other drugs a patient may be taking. Clinicians caring for patients with Parkinson's disease must be knowledgable about the potential adverse effects and drug interactions of an expanding array of medications for this condition.

Serotonin syndrome. A clinical update

Serotonin syndrome is characterized by varied degrees of cognitive, autonomic, and neuromuscular dysfunction and can only be produced by drug therapy that increases central nervous system serotonin neurotransmission. Information gained from a retrospective review of 127 cases of serotonin syndrome is presented. It is not uncommon for severe cases of serotonin syndrome to be confused with neuroleptic malignant syndrome. Treatment is mainly supportive, but specific pharmacologic therapy with serotonin antagonists may be potentially beneficial.

Myoglobinuria, malignant hyperthermia, neuroleptic malignant syndrome and serotonin syndrome

This article presents an overview of the causes and manifestations of myoglobinuria and provides criteria for its diagnosis and management. The article also reviews neuroleptic malignant syndrome, malignant hyperthermia, and serotonin syndrome, all of which could cause rhabdomyolysis and myoglobinuria.

Selective serotonin reuptake inhibitor-induced serotonin syndrome: review

The selective pharmacology of the selective serotonin reuptake inhibitors (SSRIs) results in a lower potential for pharmacodynamic drug interactions relative to other antidepressants such as the tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs). However, the SSRIs have been implicated in the development of the serotonin syndrome--a potentially life-threatening complication of treatment with psychotropic drugs. The syndrome is produced most often by the concurrent use of two or more drugs that enhance central nervous system serotonin activity and often goes unrecognized because of the varied and nonspecific nature of its clinical features. The serotonin syndrome is characterized by alterations in cognition (disorientation, confusion), behavior (agitation, restlessness), autonomic nervous system function (fever, shivering, diaphoresis, diarrhea), and neuromuscular (ataxia, hyperreflexia, myoclonus) activity. The difference between this syndrome and the occurrence of adverse effects caused by serotonin reuptake inhibitors alone is the clustering of the signs and symptoms, their severity, and their duration. There are important pharmacokinetic interactions between SSRIs and other serotonergic drugs due principally to their effects on the cytochrome P450(CYP) isoenzymes, the potential for which varies widely amongst the SSRI group, which may increase the likelihood of a pharmacodynamic interaction. The exceptionally long washout period required after fluoxetine discontinuation may cause additional problems and/or inconvenience. Patients with serotonin syndrome usually respond to discontinuation of drug therapy and supportive care alone, but they may also require treatment with antiserotonergic agent such as cyproheptadine, methysergide, and/or propranolol. To reduce the occurrence, morbidity, and mortality of the serotonin syndrome, it must be both prevented by prudent pharmacotherapy and given prompt recognition when it is present.

[Serotonin syndrome: critical review of the literature]

Since Sternbach's first review, serotonin syndrome has been reported many times. Our purpose was to examine this concept's pertinence, utility and meaning. Its physiopathology remains unclear: 5-HT1A receptors activation is certain, but others mechanisms and individual or family factors could be also involved. Appearance circumstances are more various than first expected. The concept of serotonin syndrome seems to bring together entities that differ in physiopathology and seriousness, and we propose to distinguish between serotonin syndrome and other types of syndromes. Knowing serotonin syndrome is useful both for prevention and for recognizing it as a potentially lethal emergency.

Switch in treatment from tricyclic antidepressants to moclobemide: a new generation monoamine oxidase inhibitor

The combination of classic monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressant drugs (TCAs) has been associated with a variety of adverse events. A switch in treatment from TCAs to moclobemide, a reversible and selective inhibitor of MAO-A, was investigated in a double-blind, placebo-controlled study in healthy volunteers. Two groups of 12 subjects were treated with either amitriptyline (75 mg/day) or clomipramine (100 mg/day) until steady-state conditions had been attained (14 days). Treatment with the TCAs was discontinued abruptly and switched to either a therapeutic dose regimen of moclobemide (300 mg/day) or placebo. The tolerability and safety pattern did not reveal any clinically relevant differences between moclobemide and placebo recipients, nor was there any sign of a pharmacokinetic interaction between the TCAs and moclobemide. In conclusion, the findings of this study suggest that therapeutic doses of moclobemide up to 300 mg daily can be given 24 hours after the last dose of treatment with either amitriptyline or clomipramine without major risks.

A rapidly progressing lethal case of neuroleptic malignant syndrome

A fast progressing lethal case of neuroleptic malignant syndrome (NMS) complicated by disseminated intravascular coagulation (DIC) is presented. The fulminant course is infrequent and relates NMS to malignant hyperthermia. Muscular relaxation in combination with fluid load dramatically decreased the temperature, but the catastrophic course of this case was so advanced that the currently recommended treatment of NMS was impossible.