N Alpha Methyl Histamine Versus Propranolol in Migraine Prophylaxis

Migraine, Allergy, and Histamine: Is There a Link?

The relationship between migraines and allergies is controversial. Though they are epidemiologically linked, the underlying pathophysiological connection between them remains unclear. Migraines and allergic disorders have various underlying genetic and biological causes. As per the literature, these conditions are epidemiologically linked, and some common pathophysiological pathways have been hypothesized. The histaminergic system may be the clue to understanding the correlation among these diseases. As a neurotransmitter in the central nervous system with a vasodilatory effect, histamine has a well-documented influence on the allergic response and could be involved in the pathophysiology of migraines. Histamine may influence hypothalamic activity, which may play a major role in migraines or may simply influence their severity. In both cases, antihistamine drugs could prove useful. This review examines whether the histaminergic system, particularly H3 and H4 receptors, may provide a mechanistic link between the pathophysiology of migraines and allergic disorders, two common and debilitating conditions. Identifying their connection could help identify novel therapeutic strategies.

Untargeted Metabolomics Identify a Panel of Urinary Biomarkers for the Diagnosis of Urothelial Carcinoma of the Bladder, as Compared to Urolithiasis with or without Urinary Tract Infection in Dogs

Urothelial carcinoma (UC), the most common urologic cancer in dogs, is often diagnosed late because the clinical signs are shared by other non-malignant lower urinary tract disorders (LUTD). The urine-based BRAFV595E test for UC is highly effective only in certain breeds; hence additional non-invasive biomarkers of UC are needed. Here, urine from dogs with UC (n = 27), urolithiasis (n = 8), or urolithiasis with urinary tract infection (UTI) (n = 8) were subjected to untargeted metabolomics analyses, using GC-TOF-MS for primary metabolites, QTOF-MS for complex lipids, and HILIC-QTOF MS for secondary and charged metabolites. After adjusting for age and sex, we identified 1123 known metabolites that were differentially expressed between UC and LUTD. Twenty-seven metabolites were significant (1.5 ≤ log2FC ≤ −1.5, adjusted p-value < 0.05); however, 10 of these could be attributed to treatment-related changes. Of the remaining 17, 6 (hippuric acid, N-Acetylphenylalanine, sarcosine, octanoylcarnitine, N-alpha-methylhistamine, glycerol-3-galactoside) discriminated between UC and LUTD (area under the ROC curve > 0.85). Of the 6 metabolites, only hippuric acid and N-alpha-methylhistamine were discriminatory in both male (n = 20) and female (n = 23) dogs, while sarcosine was an effective discriminator in several breeds, but only in females. Further investigation of these metabolites is warranted for potential use as non-invasive diagnostic biomarkers of dogs with UC that present with LUTD-related clinical signs.

Low-dose sodium valproate versus low-dose propranolol in prophylaxis of common migraine headache: A randomized, prospective, parallel, open-label study

CONTEXT:

Migraine is the second most common headache disorder. However, prophylactic therapy remains underutilized.

AIMS:

The objective of the study was to compare the efficacy and safety of low-dose sodium valproate and low-dose propranolol sustained release (SR) in the prophylaxis of common migraine headache.

SETTINGS AND DESIGN:

The study was conducted in a tertiary care teaching institute. It was a randomized, prospective, parallel, open-label, clinical study.

SUBJECTS AND METHODS:

The study included 60 patients with common migraine headaches (≥2 attacks/month) treated for 12 weeks. The patients were randomly divided into two treatment groups treated by sodium valproate 500 mg/day and propranolol SR 40 mg/day, respectively. The primary outcome measures were the percentage of responders (i.e., >50% decrease in mean headache frequency) at the end of 12 weeks and decrease in mean headache frequency (per 4 weeks) at the end of 12 weeks. The patients were assessed at 0, 4, 8, and 12 weeks of the study.

STATISTICAL ANALYSIS USED:

Intention-to-treat analysis was used for all the statistical analysis.

RESULTS:

Fifty-five patients completed the study. At the end of the treatment, both sodium valproate and propranolol caused a significant (P < 0.0001) reduction in frequency, severity, and duration of migraine headache. Propranolol caused significantly greater reduction in the severity of headache (P = 0.0410) than sodium valproate. The percentage of responders was 60% in sodium valproate group and 70% in propranolol group. Drowsiness was the most common adverse effect noted in both the groups.

CONCLUSION:

Both sodium valproate and propranolol significantly reduced frequency, severity, and duration of migraine headache, but propranolol caused significantly greater reduction in the severity of headache compared to sodium valproate. Both the medications were well tolerated and did not result in discontinuation.

Evaluating the reporting of adverse events in controlled clinical trials conducted in 2010–2015 on migraine drug treatments

Background

In 2008, the International Headache Society published guidelines on the “evaluation and registration of adverse events in clinical drug trials on migraine”. They listed seven recommendations for reporting adverse events in randomized controlled trials on migraine. The present study aimed to evaluate adherence to these recommendations, and based on the results, to recommend improvements.

Methods

We searched the PubMed/MEDLINE database to identify controlled trials on migraine drugs published from 2010 to 2015. For each trial, we noted whether five of the recommended parameters were presented. In addition, we noted whether adverse events were reported in abstracts.

Results

We identified 73 trials; 51 studied acutely administered drugs and 22 studied prophylactic drugs for migraine. The number of patients with any adverse events were reported in 74% of acute-administration and 86% of prophylactic drug trials. Only 30 (41%) of the 73 studies reported adverse events with data in the abstracts, and 27 (37%) abstracts did not mention adverse events.

Conclusion

Adverse events, both frequency and symptoms, should be reported to allow a fair judgement of benefit/tolerability ratio when randomized controlled trials in migraine treatment are published. Clinically significant adverse events should be included in the abstract of every randomized controlled trial in migraine treatment.

Histamine and Migraine

BACKGROUND

Histamine is an ancient "tissue amine" preceding multicellular organisms. In the central nervous system (CNS), its fibers originate solely from the tuberomammillary nucleus and travel throughout the brain. It is mainly responsible for wakefulness, energy homeostasis, and memory consolidation. Recently, several studies suggest a potential role of histamine in migraine pathogenesis and management.

METHODS

Narrative review of current literature regarding histamine and migraine.

RESULTS

Histamine plays a crucial role in migraine pathogenesis: sustaining the neurogenic inflammation pathway. Interaction between mast cells (MC) and calcitonin-gene related protein (CGRP) results in sensitization of trigeminal afferents and trigeminal ganglia (TG). Histamine binds with differing affinities to four different histaminergic G-protein coupled receptors, activating protein kinases, or triggering calcium release with subsequent mode of actions. Histamine 1 receptor (H₁ R) and histamine 2 receptor (H₂ R) antagonists are frequently used for the treatment of allergy and gastric acid secretion, respectively, but their antagonism is probably ineffective for migraine. Histamine 3 receptor (H₃ R) and histamine 4 receptor (H₄ R) have a threefold higher affinity than H₁ R/H₂ R for histamine and are found almost exclusively on neurons and immune tissues, respectively. H₃ R acts as an autoreceptor or as a heteroreceptor, lowering the release of histamine and other neurotransmitters. This is a potential target for anti-nociception and anti-neurogenic inflammation. To date, several small clinical trials using low dose histamine or N^α -methylhistamine have demonstrated migraine prophylactic efficacy, probably via H₃ R or other undetermined pathways.

CONCLUSION

The histamine system interacts with multiple regions in the CNS and may hypothetically modulate the migraine response. Low dose histamine may be a promising option for migraine prevention.