Dihydroergotamine, Ergotamine, Methysergide and Sumatriptan - Basic Science in Relation to Migraine Treatment

Indole-containing pharmaceuticals: targets, pharmacological activities, and SAR studies

Indole is a prestigious heterocyclic skeleton widely found in both naturally-occurring and biologically-active compounds. Pharmaceutical agents containing an indole skeleton in their framework possess a wide range of pharmacological properties, including antiviral, antitumor, analgesic, and other therapeutic activities, and many indole-containing drugs have been proven to have excellent pharmacokinetic and pharmacological effects. Over the past few decades, the FDA has approved over 40 indole-containing drugs for the treatment of various clinical conditions, and the development of indole-related drugs has attracted significant attention from medicinal chemists. This review aims to provide an overview of all the approved drugs that contain an indole nucleus, focusing on their targets, pharmacological activities, and SAR studies.

A randomized, open-label, 5-period crossover study evaluating the pharmacokinetics and safety of a single dose of intranasal dihydroergotamine (DHE) powder (STS101), intramuscular DHE mesylate, and liquid nasal spray DHE in healthy adults

OBJECTIVE

To compare the safety and pharmacokinetics (PK) of dihydroergotamine (DHE) after administration of intranasal DHE powder (STS101), liquid nasal spray (LNS) DHE mesylate, and intramuscular (IM) DHE mesylate injection in healthy participants.

BACKGROUND

DHE is an effective acute migraine treatment; however, self-administration difficulties have prevented its broader role in the management of migraine.

METHODS

This randomized, active-controlled, five-period crossover study was conducted over 5 weeks separated by 1-week washout periods. Three STS101 dosage strengths (5.2, 7.0, 8.6 mg), and one dose each of LNS DHE 2.0 mg, and IM DHE 1.0 mg, were administered to 36 healthy participants. Liquid chromatography, tandem mass spectrometry was used to determine DHE (including its 8'OH-DHE metabolite) plasma levels and to calculate PK parameters (Cmax , Tmax , AUC0-2h , AUC0-last , AUC0-inf , and t1/2 ). Safety was evaluated by monitoring adverse events (AEs), vital signs, electrocardiograms, nasal examinations, and laboratory parameters.

RESULTS

Thirty-six participants (mean age 36 years; 19% Hispanic Black and 81% Hispanic White) were enrolled. DHE plasma concentrations rose rapidly after STS101 5.2, 7.0, and 8.6 mg and IM DHE injection, with mean concentrations greater than 2000 pg/mL for all STS101 dose strengths at 20 min. All STS101 dose strengths showed approximately 3-fold higher Cmax , AUC0-2h , and AUC0-inf , than the LNS DHE. The mean AUC0-inf of STS101 7.0 and 8.6 mg were comparable to IM DHE (12,600 and 13,200 vs. 13,400 h × pg/mL). All STS101 dose strengths showed substantially lower variability (CV%) compared to LNS DHE for Cmax (35%-41% vs. 87%), and AUC0-inf (37%-46% vs. 65%). STS101 was well tolerated, and all treatment-emergent AEs were mild and transient.

CONCLUSION

STS101 showed rapid absorption and was well tolerated with mild and transient treatment-emergent AEs. Achieving effective DHE plasma concentrations within 10 min, STS101 displayed a favorable PK profile relative to the LNS with higher Cmax , AUC0-2h , and AUC0inf , and with greater response consistency. The AUC0-inf was comparable to IM DHE.

Mesenchymal stem cell-derived conditioned medium and Methysergide give rise to crosstalk inhibition of 5-HT2A and 5-HT7 receptors in neuroblastoma cells

OBJECTIVE

(s): We aimed to investigate the effects of mesenchymal stem cell secretome and methysergide combination on 5-hydroxytryptamine 2A, (5-HT2AR), 5-hydroxytryptamine 7 (5-HT7R), adenosine 2A (A2AR) receptors and CD73 on neuroblastoma cell line and how they affect biological characteristics. Methysergide was used as a serotonin antagonist on the neuroblastoma cells.

MATERIALS AND METHODS

Human dental pulp-derived stem cells (hDPSCs) used to obtain conditioned medium (CM). Methysergide drug was prepared in CM and applied to neuroblastoma cells. Analysis of 5-HT7R, 5-HT2AR, A2AR and CD73 expressions was performed by western blot and immunofluorescence staining. Total apoptosis, mitochondrial membrane depolarization, Ki-67 proliferation test, viability analysis, DNA damage and cell cycle analysis were performed in accordance with the product procedure by using biological activity test kits.

RESULTS

Our results showed that neuroblastoma cancer cells are normally on the Gs signaling axis via the serotonin 7 receptor and the adenosine 2A receptor. CM and Methysergide inhibited the 5-HT7 and A2A receptor levels in neuroblastoma cells. We found that CM and methysergide formed crosstalk inhibition between 5-HT2AR, 5-HT7R, A2AR and CD73. CM and Methysergide increased the total apoptosis in neuroblastoma cells and induced the mitochondrial membrane depolarization. CM and Methysergide induced the DNA damage and arrested in G0/G1 phase of cell cycle of the neuroblastoma cells.

CONCLUSION

These findings suggest that the combination of CM and methysergite may exert a therapeutic effect on neuroblastoma cancer cells, and future in vivo studies may be important in area of neuroblastoma research to support the findings.

New Approaches to Shifting the Migraine Treatment Paradigm

The standard of care paradigm for migraine treatment has been based almost exclusively on approaches that grew out of the happenstance use of market pharmaceuticals. Only methysergide, which has long since been removed from use for safety concerns, the ergotamine family of drugs, and the triptans were explicitly developed with migraine and other vascular headaches in mind. While the forward and innovative thinking to utilize the broad array of agents to treat migraine served millions well, their therapeutic efficacy was often low, and adverse event profiles were troublesome in the least. Advances in biochemical and molecular biology and the application of advanced "designing drugs" methods have brought about a potentially significant shift in treatment. The gepants have efficacies similar to the triptans but without vascular safety or medication overuse concerns. Preventative gepants offer innovative approaches to prevention and efficacy that exceed even the CGRP monoclonal antibodies. Those monoclonal antibodies brought rapid and highly effective outcomes across the spectrum of migraine. They outpaced older oral medication efficacy and eliminated most adverse events while potentially improving compliance with monthly or quarterly dosing. Other serotonin receptors beyond the 5HT1B and1D receptors have been targeted for decades. They now lead us to better formulations of dihydroergotamine for efficacy, convenience, and tolerability, and a 5HT1F-specific acute treatment like the gepants opens new options for acute management. Neuromodulation goes back to the mid-1800's. Our improved understanding of applied biomedical engineering has brought forward several tantalizing devices, including the application of currents distant from the target and patient regulated. Whether these advances change the paradigm of migraine treatment and standards of care remains to be seen, and issues such as cost and patient acceptance will help mold it.

Ditans: a new prospective for the therapy of migraine attack?

INTRODUCTION

Migraine attack is characterized by disabling pain and associated symptoms. Triptans represent the "gold standard" therapy, but cardiac subjects have significant limitations for this approach. New drug families are under consideration to expand therapeutic offerings, especially in the presence of contraindications or for non-responsive patients. This review aimed to analyze studies related to the category of "ditans," with a focus on lasmiditan, which is available for human use.

MATERIALS AND METHODS

We consulted PubMed/MEDLINE, Web of Science, and www.

CLINICALTRIALS

gov to find both original and review articles on the mechanism of action of 5-HT1F agonists in migraine, and for randomized, double-blind, placebo-controlled trials (RCTs) on the family of drugs called "ditans," with a focus on "lasmiditan," published in the time frame of 01-Jan-2010 to 31-Mar-2022. Only studies conducted in human subjects and published in English were included in this review.

RESULTS

We retrieved four RCTs (named SAMURAI, SPARTAN, GLADIATOR, and CENTURION) and several studies that analyzed the efficacy and safety of lasmiditan. Lasmiditan at increasing doses showed significant improvement in pain and most other troublesome symptoms at 2 h. Adverse events were mild and mainly represented by dizziness, vertigo, drowsiness, and fatigue. No vasoconstrictive effects were described, suggesting the use of ditans as a safe option in chronic cardio- and cerebro-vascular disease.

DISCUSSION

Lasmiditan could be a viable alternative to triptans, although further RCT studies and real-world evidence are needed to better understand its potential and possible adverse events in a larger population.

Self-Reported Efficacy of Treatments in Cluster Headache: a Systematic Review of Survey Studies

PURPOSE OF REVIEW

The use and efficacy of various substances in the treatment of CH have been studied in several retrospective surveys. The aim of the study is to systematically review published survey studies to evaluate the reported efficacies of both established and unconventional substances in abortive and prophylactic treatment of both episodic and chronic CH, specifically assessing the consistency of the results.

RECENT FINDINGS

No systematic review have been conducted of these studies previously. A systematic literature search with a set of search terms was conducted on PubMed. Retrospective surveys that quantified the self-reported efficacy of two or more CH treatments, published in English during 2000-2020, were included. Several key characteristics and results of the studies were extracted. A total of 994 articles were identified of which 9 were found to be eligible based on the selection criteria. In total, 5419 respondents were included. Oxygen and subcutaneous triptan injections were most reported as effective abortive treatments, while psilocybin and lysergic acid diethylamide were most commonly reported as effective prophylactic treatments. The reported efficacy of most substances was consistent across different studies, and there were marked differences in the reported efficacies of different substances. The reported order of efficacy is generally in agreement with clinical studies. The findings suggest that retrospective surveys can be used to obtain supporting information on the effects of various substances used in the treatment of CH and to form hypotheses about novel treatment methods. The consistently reported efficacy of psilocybin and LSD in prophylactic treatment indicates need for clinical studies.

Drug Safety in Episodic Migraine Management in Adults Part 1: Acute Treatments

PURPOSE OF REVIEW

The aim of this review is to aid in choosing safe options when assessing potential risks of acute migraine treatments based on known mechanisms of action and anticipated safety concerns.

RECENT FINDINGS

Part 1 highlights safety issues associated with commonly used medications to treat acute migraine attacks. Strategies to mitigate cardiovascular and gastrointestinal risks of nonsteroidal anti-inflammatory drugs, evaluation of cardiovascular risks of triptan and ergot alkaloids, and precautions with use of antiemetics and the novel drugs gepants and ditans are discussed to help practitioners in clinical decision-making. When available, we included recommendations from professional societies and data from pharmacovigilance systems. While guidelines on efficacy are available, one must also consider the possible risks and adverse effects of a drug when creating treatment plans.

Migraine cure: a patients' perspective

Objective To conduct a web-based survey concerning patient’s perspective in the migraine cure. Material and Methods A total of 1,102 patients fitting the International Classification of Headache Disorders (ICHD-3) migraine criteria, seeking medical care at the Brain Research Institute at Albert Einstein Hospital in Sao Paulo, Brazil, from January to December 2015, participated in the survey. The online-based survey was accessed via the institute’s website and consisted of demographic data, a description of migraine symptoms, diagnosis and treatment, and the patient’s opinion of migraine cure and which treatment they would consider taking. Results Migraine intensity was significantly higher in female participants than male participants. Chronic migraine tended to affect female participants more than male participants. There was a significant difference in the rate of migraine cure belief between patients with episodic and chronic migraine. Conclusion Some points that were important to migraineurs have been identified in this study. Ultimately, the findings of this study may facilitate the migraine treatment decision process, by providing a better understanding of patients’ perspectives and beliefs, thus creating a more friendly communication between migraineurs and care providers and hopefully, improving the quality of life of patients.

Using the Intranasal Route to Administer Drugs to Treat Neurological and Psychiatric Illnesses: Rationale, Successes, and Future Needs

While the intranasal administration of drugs to the brain has been gaining both research attention and regulatory success over the past several years, key fundamental and translational challenges remain to fully leveraging the promise of this drug delivery pathway for improving the treatment of various neurological and psychiatric illnesses. In response, this review highlights the current state of understanding of the nose-to-brain drug delivery pathway and how both biological and clinical barriers to drug transport using the pathway can been addressed, as illustrated by demonstrations of how currently approved intranasal sprays leverage these pathways to enable the design of successful therapies. Moving forward, aiming to better exploit the understanding of this fundamental pathway, we also outline the development of nanoparticle systems that show improvement in delivering approved drugs to the brain and how engineered nanoparticle formulations could aid in breakthroughs in terms of delivering emerging drugs and therapeutics while avoiding systemic adverse effects.

Dihydroergotamine and triptan use to treat migraine during pregnancy and the risk of adverse pregnancy outcomes

Migraine is prevalent during pregnancy. Antimigraine medications such as dihydroergotamine (DHE) and triptans have been associated with adverse pregnancy outcomes in individual studies but lack of consensus remains. We compared the risk of prematurity, low birth weight (LBW), major congenital malformations (MCM), and spontaneous abortions (SA) associated with gestational use of DHE or triptans. Three cohort and one nested-case–control analyses were conducted within the Quebec Pregnancy Cohort to assess the risk of prematurity, LBW, MCM, and SA. Exposure was defined dichotomously as use of DHE or triptan during pregnancy. Generalized estimation equations were built to quantify the associations, adjusting for potential confounders. 233,900 eligible pregnancies were included in the analyses on prematurity, LBW, and MCM; 29,104 cases of SA were identified. Seventy-eight subjects (0.03%) were exposed to DHE and 526 (0.22%) to triptans. Adjusting for potential confounders, DHE and triptans were associated with increased risks of prematurity, LBW, MCM, and SA but not all estimates were statistically significant. DHE was associated with the risk of prematurity (aRR: 4.12, 95% CI 1.21–13.99); triptans were associated with the risk of SA (aOR: 1.63, 95% CI 1.34–1.98). After considering maternal migraine, all antimigraine specific medications increased the risk of some adverse pregnancy outcomes, but estimates were unstable.

A critical review of the neurovascular nature of migraine and the main mechanisms of action of prophylactic antimigraine medications

INTRODUCTION

Migraine involves neurovascular, functional, and anatomical alterations. Migraineurs experience an intense unilateral and pulsatile headache frequently accompanied with vomiting, nausea, photophobia, etc. Although there is no ideal preventive medication, frequency in migraine days may be partially decreased by some prophylactics, including antihypertensives, antidepressants, antiepileptics, and CGRPergic inhibitors. However, the mechanisms of action involved in antimigraine prophylaxis remain elusive.

AREAS COVERED

This review recaps some of the main neurovascular phenomena related to migraine and currently available preventive medications. Moreover, it discusses the major mechanisms of action of the recommended prophylactic medications.

EXPERT OPINION

In the last three years, migraine prophylaxis has evolved from nonspecific to specific antimigraine treatments. Overall, nonspecific treatments  mainly involve neural actions, whereas specific pharmacotherapy (represented by CGRP receptor antagonists and CGRPergic monoclonal antibodies) is predominantly mediated by neurovascular mechanisms that may include, among others: (i) reduction in the cortical spreading depression (CSD)-associated events; (ii) inhibition of pain sensitization; (iii) blockade of neurogenic inflammation; and/or (iv) increase in cranial vascular tone. Accordingly, the novel antimigraine prophylaxis promises to be more effective, devoid of significant adverse effects (unlike nonspecific treatments), and more beneficial for the quality of life of migraineurs.

Therapeutic Advances in Diabetes, Autoimmune, and Neurological Diseases

Since 2015, 170 small molecules, 60 antibody-based entities, 12 peptides, and 15 gene- or cell-therapies have been approved by FDA for diverse disease indications. Recent advancement in medicine is facilitated by identification of new targets and mechanisms of actions, advancement in discovery and development platforms, and the emergence of novel technologies. Early disease detection, precision intervention, and personalized treatments have revolutionized patient care in the last decade. In this review, we provide a comprehensive overview of current and emerging therapeutic modalities developed in the recent years. We focus on nine diseases in three major therapeutics areas, diabetes, autoimmune, and neurological disorders. The pathogenesis of each disease at physiological and molecular levels is discussed and recently approved drugs as well as drugs in the clinic are presented.

Migraine and Ischemic Stroke: Deciphering the Bidirectional Pathway

Migraine and stroke are common, disabling neurological conditions with several theories being proposed to explain this bidirectional relationship. Migraine is considered as a benign neurological disorder, but research has revealed a connection between migraine and stroke, predominantly those having migraine with aura (MA). Among migraineurs, females with MA are more susceptible to ischemic stroke and may have a migrainous infarction. Migrainous infarction mostly occurs in the posterior circulation of young women. Although there are several theories about the potential relationship between MA and stroke, the precise pathological process of migrainous infarction is not clear. It is assumed that cortical spreading depression (CSD) might be one of the essential factors for migrainous infarction. Other factors that may contribute to migrainous infarction may be genetic, hormonal fluctuation, hypercoagulation, and right to left cardiac shunts. Antimigraine drugs, such as ergot alkaloids and triptans, are widely used in migraine care. Still, they have been found to cause severe vasoconstriction, which may result in the development of ischemia. It is reported that patients with stroke develop migraines during the recovery phase. Both experimental and clinical data suggest that cerebral microembolism can act as a potential trigger for MA. Further studies are warranted for the treatment of migraine, which may lead to a decline in migraine-related stroke. In this present article, we have outlined various potential pathways that link migraine and stroke.

UPLC-ESI-Q-TOF-MS/MS analysis of anticancer fractions from Ophiocordyceps xuefengensis and Ophiocordyceps sinensis

Ophiocordyceps xuefengensis (O. xuefengensis), a new species of caterpillar fungus, has been identified as the sister taxon of Ophiocordyceps sinensis (O. sinensis). The aims of the present study are to evaluate the anticancer activity and to qualitatively analyze the potential bioactive chemical constituents of O. xuefengensis and O. sinensis, comparatively. An MTT assay was used to evaluate the in vitro anticancer activities of different fractions from O. xuefengensis and O. sinensis. The results show that ethyl acetate fractions of O. xuefengensis and O. sinensis have significant in vitro anticancer activity. These two bioactive fractions were analyzed by ultra-performance liquid chromatography-electrospray ionization with quadrupole-time of flight tandem mass spectrometry technology. A total of 82 compounds and 101 compounds were identified or tentatively characterized in the bioactive fractions of O. xuefengensis and O. sinensis, respectively. Among these compounds, 68 existed in both O. xuefengensis and O. sinensis. A total of 67 compounds were reported in O. xuefengensis and 8 compounds were reported in caterpillar fungus for the first time. This is the first detailed comparative analysis of the in vitro anticancer activity and chemical ingredients between O. xuefengensis and O. sinensis. The application of this work will provide reliable fundamental pharmacological substances for the use of O. xuefengensis by Yao people.

Secukinumab-induced Raynaud's phenomenon: first report in the literature

Secukinumab is an IL-17A antagonist that has proven efficacy in the treatment of patients with ankylosing spondylitis (AS) and psoriatic arthritis. Side effects of the drug include infections, skin rashes, and allergic reactions. Raynaud’s phenomenon (RP), a vasospastic syndrome and an important feature of different connective tissue diseases, is not an expected finding in AS patients. This article reports the development of secukinumab-related RP in a 35-year-old female patient with AS. Treatment with secukinumab was continued and RP was treated with low-dose aspirin and a calcium-channel blocker.

A Phase 1, Randomized, Open-Label, Safety, Tolerability, and Comparative Bioavailability Study of Intranasal Dihydroergotamine Powder (STS101), Intramuscular Dihydroergotamine Mesylate, and Intranasal DHE Mesylate Spray in Healthy Adult Subjects

Objective

To investigate and compare the safety and the pharmacokinetics of dihydroergotamine (DHE) after administration of intranasal DHE powder (STS101), intranasal DHE spray (Migranal^®), and intramuscular (IM) DHE injection in healthy subjects.

Methods

This was a 2‐part, active‐controlled, 3‐period crossover study over 3 weeks, separated by 1‐week washout periods. In part 1, 3 ascending dosage strengths of STS101 (1.3, 2.6, and 5.2 mg) were administered to 15 healthy subjects with no history of migraine. In part 2, 27 healthy subjects were administered 1 dose each of STS101 5.2 mg, Migranal DHE Mesylate Liquid Nasal Spray 2.0 mg, and IM DHE Mesylate 1.0 mg in a randomized order. Liquid chromatography, tandem mass spectrometry was used to determine plasma levels of DHE and its major metabolite, 8′OH‐DHE. Pharmacokinetic parameters (C_max, T_max, AUC_0‐2 h, AUC_0‐48 h, AUC_0‐inf, and t_1/2) for DHE and metabolite were calculated. Geometric means and 90% confidence intervals of log‐transformed data were calculated and the ratio of means compared. Safety was evaluated by monitoring adverse events, vital signs, electrocardiograms, subjective and objective assessments of nasal signs and symptoms, and changes in laboratory parameters. The study is registered as NCT03874832.

Results

Forty‐three subjects were enrolled and received study medication. Forty completed all study activities, 14 in part 1 and 26 in part 2. In part 1, DHE plasma levels showed a dose‐dependent increase, with STS101 5.2 mg reaching a mean C_max of 1870 pg/mL with a T_max of 23 minutes. In part 2, STS101 5.2 mg showed rapid absorption, achieving mean DHE plasma concentrations of 1230 and 1850 pg/mL at 10 and 15 minutes after administration, respectively. In comparison to Migranal, STS101 5.2 mg showed approximately 2‐fold higher C_max (2175 vs 961 pg/mL), AUC_0‐2 h (2979 vs 1316 h × pg/mL), and AUC_0‐inf (12,030 vs 6498 h × pg/mL), respectively. The mean AUC_0‐inf of STS101 5.2 mg was comparable to IM DHE (12,030 vs 13,650 h × pg/mL). STS101 5.2 mg showed substantially lower variability compared to Migranal for C_max (41% vs 76%), AUC_0‐2 h (39% vs 75%), and AUC_0‐inf (39% vs 55%). The incidence of treatment emergent AEs (TEAEs), all mild and transient, reported in parts 1 and 2 combined was 9/15 (60%), 5/15 (33%), and 16/41 (39%) of the subjects after 1.3, 2.6, and 5.2 mg STS101, respectively, and 4/26 (15%) and 5/27 (19%) of the subjects after IM DHE and Migranal, respectively.

Conclusion

STS101 showed rapid absorption, achieving effective DHE plasma concentrations within 10 minutes. It achieved substantially higher C_max, AUC_0‐2 h and AUC_0‐inf, compared to Migranal suggesting potentially better efficacy than Migranal. Its variability was better than Migranal, thus offering improved consistency of response. AUC_0‐inf was comparable to IM DHE, suggesting prolonged action and low recurrence. Additionally, the C_max was sufficiently low to avoid any significant nausea reported with IV DHE. Thus, STS101 is an easy to administer, non‐injected, acute treatment for migraine, with a favorable tolerability profile and is expected to provide rapid and consistent freedom from pain and associated migraine symptoms without recurrence.

Triptan and ergotamine overdoses in the United States

Objective

To examine the clinical outcomes of intentional overdoses involving triptans and ergotamines with a retrospective review of the National Poison Data System (NPDS).

Methods

This was a 5-year retrospective cross-sectional study (2014–2018) using the NPDS. Demographics, exposure characteristics, and outcomes were described. Univariate logistic regression was used to estimate the odds ratio (OR) for major effect or death. A multivariable logistic regression model with inclusion criteria ofp< 0.1 in univariate analysis was implemented with backwards selection.

Results

In this population (n = 1,489), multiple exposure was most common (n = 1,145). The mean age was 31.2 years and 1,197 (80.4%) participants were female. Major effects from a single exposure were seen in <1% with no recorded deaths. Triptan ingestion (n = 328) resulted in hypertension (14%), tachycardia (10.7%), drowsiness (11%), nausea (6.4%), vomiting (4.6%), vertigo (4%), chest pain (3.7%), and diaphoresis (2.4%). Ergotamine ingestion (n = 16) resulted in abdominal pain (16%), vomiting (12.5%), numbness (12.5%), nausea (6.3%), diarrhea (6.3%), and vertigo (6.3%). No clinical effect was seen in 90 (26.2%). No cases met Hunter criteria for serotonin syndrome. There is risk of major event or death due to age (OR 1.02; 95% confidence interval [CI] 1.01–1.04;p= 0.004), multiple product exposure (OR 9.50; 95% CI 2.29–39.48;p= 0.002), and concomitant overdose with benzodiazepines (OR 1.71; 95% CI 1.05–2.78;p= 0.032) or tricyclic antidepressants (OR 3.16; 95% CI 1.88–5.31;p< 0.001).

Conclusion

The risk of major effect or death was low and predicted by age, multiple product exposure, and concomitant benzodiazepine or tricyclic antidepressant. The triptan toxidrome consists of hypertension, tachycardia, and drowsiness. The toxic effects of ergotamine are acute gastrointestinal syndrome with vertigo and numbness. No cases of serotonin syndrome were seen.

Dihydroergotamine (DHE) - Then and Now: A Narrative Review

OBJECTIVE

To provide a narrative review of clinical development programs for non-oral, non-injectable formulations of dihydroergotamine (DHE) for the treatment of migraine.

BACKGROUND

Dihydroergotamine was one of the first "synthetic drugs" developed in the 20th century for treating migraine. It is effective and recommended for acute migraine treatment. Since oral DHE is extensively metabolized, it must be given by a non-oral route. Intravenous DHE requires healthcare personnel to administer, subcutaneous/intramuscular injection is challenging to self-administer, and the approved nasal spray formulation exhibits low bioavailability and high variability that limits its efficacy. Currently there are several attempts underway to develop non-oral, non-injected formulations of DHE.

METHOD

A systematic search of MEDLINE/PubMed and ClinicalTrials.gov databases, then narrative review of identified reports, focusing on those published in the last 10 years.

RESULTS

Of 1881 references to DHE from a MEDLINE/PubMed search, 164 were from the last 10 years and were the focus of this review. Further cross reference was made to ClinicalTrials.gov for 19 clinical studies, of which some results have not yet been published, or are studies that are currently underway. Three nasal DHE products are in clinical development, reawakening interest in this route of delivery for migraine. Other routes of DHE administration have been, or are being, explored.

CONCLUSION

There is renewed appreciation for DHE and the need for non-oral, non-injected delivery is now being addressed.

Functional Characterization of the Prejunctional Receptors Mediating the Inhibition by Ergotamine of the Rat Perivascular Sensory Peptidergic Drive

Calcitonin gene-related peptide (α-CGRP) released from perivascular sensory nerves induces decreases in diastolic blood pressure (DBP). Experimentally, this can be shown by spinal thoracic (T₉-T₁₂) electrical stimulation of these afferent fibers. Because ergotamine inhibits these neurogenic vascular responses and displays affinity for monoaminergic receptors that inhibit neurotransmitter release, we investigated whether this ergotamine-induced inhibition results from activation of serotonin 5-HT_1B/1D, dopamine D₂-like, and α₂-adrenergic receptors. Wistar rats were pithed and, under autonomic ganglion blockade, received intravenous infusions of methoxamine followed by ergotamine (0.1-3.1 μg kg^-1 min^-1). Thoracic T₉-T₁₂ electrical stimulation or an intravenous bolus of α-CGRP resulted in decreases in DBP. Ergotamine inhibited the electrically induced, but not α-CGRP-induced, responses. The vasodilator sensory inhibition by 3.1 μg of ergotamine kg^-1 min^-1 was resistant to simultaneous blockade of 5-HT_1B/1D, D₂-like, and α₂-adrenergic receptors upon addition of antagonists GR127935, haloperidol, and rauwolscine. Moreover, the inhibition by 0.31 μg of ergotamine kg^-1 min^-1 was unaltered by GR127935 and haloperidol, partly blocked by GR127935 and rauwolscine or rauwolscine and haloperidol, and abolished by GR127935, haloperidol, and rauwolscine. These findings imply that prejunctional 5-HT_1B/1D, D₂-like, and α₂-adrenergic receptors mediate the sensory inhibition induced by 0.31 μg of ergotamine kg^-1 min^-1, whereas larger doses may involve other receptors. Thus, ergotamine's ability to inhibit the perivascular sensory peptidergic drive may result in facilitation of its systemic vasoconstrictor properties.

Alkaloids from the rhizomes of Ligusticum striatum exert antimigraine effects through regulating 5-HT1B receptor and c-Jun

ETHNOPHARMACOLOGICAL RELEVANCE

Migraine is a prevalent, complex, painful, and disabling neurovascular disorder that places an enormous social and economic burden on patients. Rhizome Chuanxiong (RCX), the dried rhizomes of Ligusticum striatum DC., has been widely used in the clinic for the treatment of migraine for centuries in China. Total alkaloids (TAs) are considered to be important effective ingredients of L. striatum, especially for cardiovascular and cerebrovascular diseases. However, there has been no study published, to date, reporting the antimigraine effects of TAs from RCX (RCXTAs).

AIM OF THE STUDY

The present study was designed to evaluate the antimigraine effects of RCXTAs and explore the underlying mechanisms in an experimental migraine rat model.

MATERIALS AND METHODS

RCXTAs were prepared in accordance with our previous optimized preparation process. A nitroglycerin-induced migraine model in rats and a reserpine-induced migraine model in mice were established to investigate the effects of RCXTAs on monoamine neurotransmitters in brain tissue, including 5-hydroxytryptamine (5-HT) and its metabolite (5-HIAA). Migraine rats or mice were divided into six groups as follows: control; model; zolmitriptan (1.67 mg/kg); and low-, medium-, and high-dose RCXTAs (12.5, 25, and 50 mg/kg, respectively). The levels of 5-HT and 5-HIAA in the brains of rats and mice were determined by using the enzyme-linked immunosorbent assay method. Pathological changes in the brains of migraine rats were examined by immunohistochemistry. The protein expression of 5-HT_1B receptor, c-Fos, and c-Jun in the periaqueductal gray (PAG) of migraine rats was measured by Western blot.

RESULTS

After preventive administration of RCXTAs to the nitroglycerin-induced migraine rats, the levels of 5-HT and 5-HIAA in the brain tissue were generally upregulated in all three RCXTA dose groups, a finding that was similar to that observed in the control group. Additionally, the 5-HT and 5-HIAA levels were significantly increased in the medium- and high-dose RCXTA groups when compared with the model group (p < 0.01). Therapeutical administration of RCXTAs to reserpine-induced migraine mice also inhibited the reduction of 5-HT and 5-HIAA in the brain (p < 0.01). Both immunohistochemistry and Western blot tests showed that RCXTAs pretreatment has significantly upregulated 5-HT_1B receptor expression and downregulated c-Jun expression in the nitroglycerin-induced migraine rats.

CONCLUSIONS

RCXTAs exerted significant preventive and therapeutic effects on migraine via increasing the levels of 5-HT and 5-HIAA. Upregulation of the expression of monoamine neurotransmitter 5-HT_1B receptor and downregulation of the expression of c-Jun were the possible mechanisms.

The need for new acutely acting antimigraine drugs: moving safely outside acute medication overuse

Background

The treatment of migraine is impeded by several difficulties, among which insufficient headache relief, side effects, and risk for developing medication overuse headache (MOH). Thus, new acutely acting antimigraine drugs are currently being developed, among which the small molecule CGRP receptor antagonists, gepants, and the 5-HT_1F receptor agonist lasmiditan. Whether treatment with these drugs carries the same risk for developing MOH is currently unknown.

Main body

Pathophysiological studies on MOH in animal models have suggested that decreased 5-hydroxytryptamine (5-HT, serotonin) levels, increased calcitonin-gene related peptide (CGRP) expression and changes in 5-HT receptor expression (lower 5-HT_1B/D and higher 5-HT_2A expression) may be involved in MOH. The decreased 5-HT may increase cortical spreading depression frequency and induce central sensitization in the cerebral cortex and caudal nucleus of the trigeminal tract. Additionally, low concentrations of 5-HT, a feature often observed in MOH patients, could increase CGRP expression. This provides a possible link between the pathways of 5-HT and CGRP, targets of lasmiditan and gepants, respectively. Since lasmiditan is a 5-HT_1F receptor agonist and gepants are CGRP receptor antagonists, they could have different risks for developing MOH because of the different (over) compensation mechanisms following prolonged agonist versus antagonist treatment.

Conclusion

The acute treatment of migraine will certainly improve with the advent of two novel classes of drugs, i.e., the 5-HT_1F receptor agonists (lasmiditan) and the small molecule CGRP receptor antagonists (gepants). Data on the effects of 5-HT_1F receptor agonism in relation to MOH, as well as the effects of chronic CGRP receptor blockade, are awaited with interest.

STOP 101: A Phase 1, Randomized, Open-Label, Comparative Bioavailability Study of INP104, Dihydroergotamine Mesylate (DHE) Administered Intranasally by a I123 Precision Olfactory Delivery (POD® ) Device, in Healthy Adult Subjects

OBJECTIVE

Investigate the safety and pharmacokinetics (PK) of INP104, intranasal dihydroergotamine mesylate (DHE) administered via a Precision Olfactory Delivery (POD^® ) device, (Impel NeuroPharma, Seattle, WA) vs intravenous (IV) DHE and DHE nasal spray (Migranal^® ) in healthy adult subjects.

METHODS

This was a Phase 1, open-label, randomized, single-dose, 3-period, 3-way crossover study. Subjects received a single dose of A) INP104 1.45 mg (a drug-device combination product composed of DHE and the I123 POD device); B) DHE 45^® Injection (IV) 1.0 mg; and C) DHE by Migranal^® Nasal Spray 2.0 mg. Plasma levels of DHE and the major bioactive metabolite, 8'OH-DHE, were measured, and PK parameters were determined for both. Comparative bioavailability (BA) was assessed by calculating the ratio of the geometric means between treatments for C_max and AUC_0-inf on the ln-transformed data. Safety was assessed from adverse events, vital signs, electrocardiograms, and clinical laboratory values.

RESULTS

Thirty-eight subjects were enrolled, 36 were dosed with at least 1 IP and 27 were included in the evaluation of PK and comparative BA. DHE plasma levels following INP104 1.45 mg administration reached 93% of C_max by 20 minutes and were comparable to IV DHE 1.0 mg by 30 minutes (1219 ng/mL for INP104 vs 1224 ng/mL for IV DHE), which was the T_max for INP104. From 30 minutes onward, DHE levels for INP104 closely matched those of IV DHE to 48 hours, the last time point measured. In comparison, the C_max for Migranal was 299.6 pg/mL (approximately 4-fold less than INP104) and occurred at 47 minutes, 17 minutes later than INP104. Plasma DHE AUC_0-inf were 6275, 7490, and 2199 h*pg/mL for INP104, IV DHE, and Migranal, respectively. Variability (coefficient of variation [CV%]) for C_max and AUC_0-inf for INP104 compared to Migranal indicated more consistent delivery with INP104. In the BA comparison using the PK population (subjects who had received all 3 treatments), the ratios of geometric means (percent) for C_max and AUC_0-inf were 7.9% and 74.2%, respectively, for INP104: IV DHE, and 445% and 308% for INP104: Migranal. Mean plasma concentration profiles for 8'-OH-DHE were proportionately lower and followed a similar profile to the parent compound, regardless of route of administration (IN vs IV) or delivery system (Migranal vs INP104). Treatment emergent AEs (TEAEs), of mostly mild intensity, were reported by 15/31 (48.4%), 21/32 (65.6%), and 14/34 (41.2%) subjects after INP104, IV DHE, and Migranal, respectively. Treatment-related TEAEs occurred in 6/31 (19.4%), 16/32 (50.0%), and 4/34 (11.8%) subjects after INP104, IV DHE, and Migranal, respectively.

CONCLUSION

INP104 met the predefined statistical criteria for comparative bioavailability with IV DHE and Migranal. The shorter time to reach C_max and at 4 times the plasma concentration of DHE in comparison to Migranal combined with a favorable tolerability profile support further investigation of INP104 as an effective, well tolerated, and non-invasive treatment for acute episodic migraine.

5-HT1D receptors inhibit the monosynaptic stretch reflex by modulating C-fiber activity

The monosynaptic stretch reflex (MSR) plays an important role in feedback control of movement and posture but can also lead to unstable oscillations associated with tremor and clonus, especially when increased with spinal cord injury (SCI). To control the MSR and clonus after SCI, we examined how serotonin regulates the MSR in the sacrocaudal spinal cord of rats with and without a chronic spinal transection. In chronic spinal rats, numerous 5-HT receptor agonists, including zolmitriptan, methylergonovine, and 5-HT, inhibited the MSR with a potency highly correlated to their binding affinity to 5-HT_1D receptors and not other 5-HT receptors. Selective 5-HT_1D receptor antagonists blocked this agonist-induced inhibition, although antagonists alone had no action, indicating a lack of endogenous or constitutive receptor activity. In normal uninjured rats, the MSR was likewise inhibited by 5-HT, but at much higher doses, indicating a supersensitivity after SCI. This supersensitivity resulted from the loss of the serotonin transporter SERT with spinal transection, because normal and injured rats were equally sensitive to 5-HT after SERT was blocked or to agonists not transported by SERT (zolmitriptan). Immunolabeling revealed that the 5-HT_1D receptor was confined to superficial lamina of the dorsal horn, colocalized with CGRP-positive C-fibers, and eliminated by dorsal rhizotomy. 5-HT_1D receptor labeling was not found on large proprioceptive afferents or α-motoneurons of the MSR. Thus serotonergic inhibition of the MSR acts indirectly by modulating C-fiber activity, opening up new possibilities for modulating reflex function and clonus via pain-related pathways. NEW & NOTEWORTHY Brain stem-derived serotonin potently inhibits afferent transmission in the monosynaptic stretch reflex. We show that serotonin produces this inhibition exclusively via 5-HT_1D receptors, and yet these receptors are paradoxically mostly confined to C-fibers. This suggests that serotonin acts by gating of C-fiber activity, which in turn modulates afferent transmission to motoneurons. We also show that the classic supersensitivity to 5-HT after spinal cord injury results from a loss of SERT, and not 5-HT_1D receptor plasticity.

DHE-Induced Peripheral Arterial Vasospasm in Primary Raynaud Phenomenon: Case Report

Dihydroergotamine (DHE) is primarily a serotonin 5HT1B and 5HT1D receptor agonist used for acute migraine treatment. It is associated with acute vasoconstriction mediated through the 5HT1B receptor and is contraindicated in patients with history of cardiac disease and peripheral vascular disease. We present a case of acute peripheral arterial vasospasm in a patient with primary Raynaud phenomenon while receiving inpatient treatment for status migrainosus with intravenous (IV) DHE. The patient is a 35-year-old female with a history of chronic migraine and primary Raynaud phenomenon. After 15 doses of IV DHE, the patient reported paresthesias of the right hand and was noted to have absent right radial and ulnar pulses to palpation. Portable arterial Doppler study demonstrated abnormal flat line pulse volume recordings (PVRs) in the right second, third, and fourth digits, with markedly dampened PVR in the right thumb and fifth finger along with no ulnar PVR detectable at the wrist. Duplex revealed bilateral severely diminished flow in the right ulnar and radial arteries without acute occlusions. Computed tomography angiogram of right upper extremity visualized arteries through the mid-forearm but not distally. Dihydroergotamine was discontinued, and the patient was started on oral amlodipine and aspirin. Repeat Doppler ultrasound 3 days later revealed normal arm and digital waveforms bilaterally consistent with resolution of vasospasm. This case highlights a potential complication of IV DHE therapy. Risk may be increased in patients with primary Raynaud phenomenon. We suggest cautious use of IV DHE in this population.

Dihydroergotamine inhibits the vasodepressor sensory CGRPergic outflow by prejunctional activation of α2-adrenoceptors and 5-HT1 receptors

BACKGROUND

Dihydroergotamine (DHE) is an antimigraine drug that produces cranial vasoconstriction and inhibits trigeminal CGRP release; furthermore, it inhibits the vasodepressor sensory CGRPergic outflow, but the receptors involved remain unknown. Prejunctional activation of α_2A/2C-adrenergic, serotonin 5-HT_1B/1F, or dopamine D₂-like receptors results in inhibition of this CGRPergic outflow. Since DHE displays affinity for these receptors, this study investigated the pharmacological profile of DHE-induced inhibition of the vasodepressor sensory CGRPergic outflow.

METHODS

Pithed rats were pretreated i.v. with hexamethonium (2 mg/kg·min) followed by continuous infusions of methoxamine (20 μg/kg·min) and DHE (3.1 μg/kg·min). Then, stimulus-response curves (spinal electrical stimulation; T₉-T₁₂) or dose-response curves (i.v. injections of α-CGRP) resulted in frequency-dependent or dose-dependent decreases in diastolic blood pressure.

RESULTS

DHE inhibited the vasodepressor responses to electrical stimulation (0.56-5.6 Hz), without affecting those to i.v. α-CGRP (0.1-1 μg/kg). This inhibition by DHE (not produced by the methoxamine infusions): (i) was abolished by pretreatment with the combination of the antagonists rauwolscine (α₂-adrenoceptor; 310 μg/kg) plus GR127935 (5-HT_1B/1D; 31 μg/kg); and (ii) remained unaffected after rauwolscine (310 μg/kg), GR127935 (31 μg/kg) or haloperidol (D₂-like; 310 μg/kg) given alone, or after the combination of rauwolscine plus haloperidol or GR127935 plus haloperidol at the aforementioned doses.

CONCLUSION

DHE-induced inhibition of the vasodepressor sensory CGRPergic outflow is mainly mediated by prejunctional rauwolscine-sensitive α₂-adrenoceptors and GR127935-sensitive 5-HT_1B/1D receptors, which correlate with α_2A/2C-adrenoceptors and 5-HT_1B receptors, respectively. These findings suggest that DHE-induced inhibition of the perivascular sensory CGRPergic outflow may facilitate DHE's vasoconstrictor properties resulting in an increased vascular resistance.

Dihydroergotamine Complicating Reversible Cerebral Vasoconstriction Syndrome in Status Migrainosus

Reversible cerebral vasoconstriction syndrome (RCVS) is a clinicoradiological syndrome that occurs due to dysfunction of cerebrovascular autoregulation. It is characterized by recurrent thunderclap headache from cerebral vasoconstriction which can cause ischemic infarction, spontaneous intraparenchymal and subarachnoid hemorrhage. This syndrome can be triggered by a variety of etiologies including medications, infectious, and inflammatory conditions. The diagnosis is often delayed due to unawareness among the health-care providers and delayed neuroimaging evidence of vasoconstriction with or without ischemic and/or hemorrhagic infarction. Status migrainosus is a prevalent condition requiring emergency room visits and inpatient admission. Thus, patients with RCVS can be easily misdiagnosed with migraine. We report a patient with RCVS misdiagnosed as status migrainosus with visual aura, treated with intravenous dihydroergotamine with worsening of cerebral vasoconstriction and lead to ischemic and hemorrhagic complications. We discuss this complication and provide guidance on differentiating between migraine and RCVS.

Targeted 5-HT1F Therapies for Migraine

Migraine is a common neurological disease characterised by the presence of attacks of unilateral, severe head pain accompanied by other symptoms. Although it has been classified as the sixth most disabling disorder, the available therapeutic options to treat this condition have not progressed accordingly. The advance in the development of 5-HT1 receptor agonists for migraine, including 5-HT1B/D and 5-HT1F receptor agonists, has meant a major step forward towards the progression of a better treatment for migraine. Triptans have a limited efficacy, and their effect on vasoconstriction makes them unsafe for patients with cardiovascular and/or cerebrovascular diseases. Therefore, novel effective antimigraine treatments without cardiovascular effects are required, such as selective 5-HT1F receptor agonists (ditans). Lasmiditan has much higher affinity for the 5-HT1F receptor than for the vasoconstrictor 5-HT1B receptor. This has been confirmed in preclinical studies performed to date, where lasmiditan showed no effect on vasoconstriction, and in clinical trials, where healthy individuals and patients did not report cardiac events due to treatment with lasmiditan, although it should be confirmed in larger cohorts. Lasmiditan crosses the blood-brain barrier and may act both centrally and peripherally on 5-HT1F receptors expressed on trigeminal neurons. It is a well-tolerated compound that does not induce major adverse events. Although ongoing phase III clinical trials are needed to confirm its efficacy and safety, lasmiditan might offer an alternative to treat acute migraine with no associated cardiovascular risk. This review will focus on the characterisation of 5-HT1 receptor agonists and their effects as migraine therapies.

Side effects associated with current and prospective antimigraine pharmacotherapies

INTRODUCTION

Migraine is a neurovascular disorder. Current acute specific antimigraine pharmacotherapies target trigeminovascular 5-HT1B/1D, 5-HT1F and CGRP receptors but, unfortunately, they induce some cardiovascular and central side effects that lead to poor treatment adherence/compliance. Therefore, new antimigraine drugs are being explored. Areas covered: This review considers the adverse (or potential) side effects produced by current and prospective antimigraine drugs, including medication overuse headache (MOH) produced by ergots and triptans, the side effects observed in clinical trials for the new gepants and CGRP antibodies, and a section discussing the potential effects resulting from disruption of the cardiovascular CGRPergic neurotransmission. Expert opinion: The last decades have witnessed remarkable developments in antimigraine therapy, which includes acute (e.g. triptans) and prophylactic (e.g. β-adrenoceptor blockers) antimigraine drugs. Indeed, the triptans represent a considerable advance, but their side effects (including nausea, dizziness and coronary vasoconstriction) preclude some patients from using triptans. This has led to the development of the ditans (5-HT1F receptor agonists), the gepants (CGRP receptor antagonists) and the monoclonal antibodies against CGRP or its receptor. The latter drugs represent a new hope in the antimigraine armamentarium, but as CGRP plays a role in cardiovascular homeostasis, the potential for adverse cardiovascular side effects remains latent.

Allodynia Is Associated With Initial and Sustained Response to Acute Migraine Treatment: Results from the American Migraine Prevalence and Prevention Study

OBJECTIVE

In a population sample of persons with migraine treating with a single category of acute migraine medication, to identify rates and factors associated with acute treatment outcomes, including 2-hour pain freedom (2hPF), 24-hour pain response (24hPR), and 24-hour sustained pain response (24hSPR). Key predictors include acute treatment type (triptans and other medication categories), the influence of allodynia on response to medication, and the interaction between medication category and presence of allodynia in response to treatment among people with migraine.

BACKGROUND

Cutaneous allodynia was previously associated with inadequate 2hPF, 24hPR, and 24hSPR (sustained response at 24 hours among those with adequate 2hPF) among people with migraine in the American Migraine Prevalence and Prevention (AMPP) Study.

METHODS

The AMPP Study obtained data from a representative US sample of persons with migraine by mailed questionnaire. The 2006 survey included 8233 people with migraine aged 18 or over who completed the Migraine Treatment Optimization Questionnaire (mTOQ). mTOQ was used to assess acute treatment outcomes including 2hPF, 24hPR, and 24hSPR. Eligible individuals used only a single category of acute prescription migraine treatments (n  =  5236, 63.6%). This sample was stratified into 5 categories of type of acute prescription headache medication used (triptans, nonsteroidal anti-inflammatory drugs, barbiturate-combinations, opioids, and opioid combinations and ergot alkaloids). Separate binary logistic regression models evaluated: (1) triptans vs other medication types; (2) presence of allodynia vs no allodynia; and (3) the interaction of medication category with allodynia. Sociodemographic variables, health insurance status, over-the-counter and preventive medication use were included as covariates. Odds ratios (OR) and 95% confidence intervals (CI) were generated for each acute treatment outcome.

RESULTS

Among eligible participants, the mean age was 46 years, and 82.5% were women. The triptan use group had better outcomes than other medication groups for 2hPF (OR range: 2.00-2.63, all significant except ergot alkaloids) and 24hPR (OR range: 2.10-6.22, all significant). No significant medication effects were found for the 24hSPR outcome. The presence of allodynia was associated with significantly worse outcomes for both 2hPF (OR range: 1.42-1.55, all significant) and 24hPR (OR range: 1.30-1.32, all significant, except for ergot alkaloids, P  =  .051). Allodynia effects were not significant for the 24hSPR. The interaction between medication and allodynia was also not significant (OR range for 2hPF: .68-2.02; OR range for 2hPR: .35-1.34; OR range for 24hSPR: 1.21-2.72) in any of the models, suggesting allodynia is an important predictor of treatment response regardless of the medication group prescribed.

CONCLUSIONS

The use of triptan medication was associated with significantly better 2hPF (except vs ergot alkaloids) and significantly better 24hPR outcomes compared with other acute medication categories. The presence of allodynia significantly increased the likelihood of an inadequate treatment response for both of these outcomes. Triptan use was generally associated with the best outcomes. Because allodynia was associated with inadequate outcomes for all medication groups, we suggest that allodynia is an area of unmet treatment need.

Drug-induced Raynaud's phenomenon: beyond β-adrenoceptor blockers

AIM

Drug-induced Raynaud's phenomenon (RP) has long been associated with the use of different drugs, including cancer chemotherapy or β-adrenoceptor blockers. However, sources report extremely variable prevalence and the level of evidence for each class is heterogeneous. Moreover, new signals are emerging from case reports and small series. Our objective was therefore to review available evidence about this adverse drug effect and to propose a mechanistic approach of drug-induced RP.

METHODS

A systematic review of English and French language articles was performed through Medline (1946-2015) and Embase (1974-2015). Further relevant papers were identified from the reference lists of retrieved articles.

RESULTS

We identified 12 classes of drugs responsible for RP, with a variety of underlying mechanisms such as increased sympathetic activation, endothelial dysfunction, neurotoxicity or decreased red blood cell deformability. Cisplatin and bleomycin were associated with the highest risk, followed by β-adrenoceptor blockers. Recent data suggest a possible involvement of tyrosine kinase inhibitors (TKI), through an unknown mechanism.

CONCLUSION

Drug-induced RP is a probably underestimated adverse drug event, with limited available evidence regarding its prevalence. Although rare, serious complications like critical digital ischaemia have been reported. When these treatments are started in patients with a history of RP, careful monitoring must be made and, if possible, alternative therapies that do not alter peripheral blood flow should be considered.

Role of 5-HT5A and 5-HT1B/1D receptors in the antinociception produced by ergotamine and valerenic acid in the rat formalin test

Sumatriptan, dihydroergotamine and methysergide inhibit 1% formalin-induced nociception by activation of peripheral 5-HT1B/1D receptors. This study set out to investigate the pharmacological profile of the antinociception produced by intrathecal and intraplantar administration of ergotamine (a 5-HT1B/1D and 5-HT5A/5B receptor agonist) and valerenic acid (a partial agonist at 5-HT5A receptors). Intraplantar injection of 1% formalin in the right hind paw resulted in spontaneous flinching behavior of the injected hindpaw of female Wistar rats. Intrathecal ergotamine (15nmol) or valerenic acid (1 nmol) blocked in a dose dependent manner formalin-induced nociception. The antinociception by intrathecal ergotamine (15nmol) or valerenic acid (1nmol) was partly or completely blocked by intrathecal administration of the antagonists: (i) methiothepin (non-selective 5-HT5A/5B; 0.01-0.1nmol); (ii) SB-699551 (selective 5-HT5A; up to 10nmol); (iii) anti-5-HT5A antibody; (iv) SB-224289 (selective 5-HT1B; 0.1-1nmol); or (v) BRL-15572 (selective 5-HT1D; 0.1-1nmol). Likewise, antinociception by intraplantar ergotamine (15nmol) and valerenic acid (10nmol) was: (i) partially blocked by methiothepin (1nmol), SB-699551 (10nmol) or SB-224289 (1nmol); and (ii) abolished by BRL-15572 (1nmol). The above doses of antagonists (which did not affect per se the formalin-induced nociception) were high enough to completely block their respective receptors. Our results suggest that ergotamine and valerenic acid produce antinociception via 5-HT5A and 5-HT1B/1D receptors located at both spinal and peripheral sites. This provides new evidence for understanding the modulation of nociceptive pathways in inflammatory pain.

Diagnosis and Management of Childhood Headache

Headache is one of the most common chief complaints seen in the pediatrician's office. Oftentimes, identifying the etiology of headache and differentiating primary and secondary causes can present a diagnostic conundrum. Understanding the most common causes of primary and secondary headache is vital to making a correct diagnosis. Here we review the typical presentations of the most common primary headache disorders and the approach to evaluation of the pediatric patient presenting with headache. Diagnostic workup, including the key features to elicit on physical examination, when to order head imaging, and the use of other ancillary tests, is discussed. Current treatment modalities and their indications are reviewed. We will also describe some of the new, emerging therapies that may alter the way we manage headache in the pediatric population. Headache can, at times, be a frustrating symptom seen in the pediatrician's office, but here we hope to better elucidate the approach to evaluation, management, and treatment as well as provide some hope in regards to more effective upcoming therapies.

Ergot Alkaloids (Re)generate New Leads as Antiparasitics

Praziquantel (PZQ) is a key therapy for treatment of parasitic flatworm infections of humans and livestock, but the mechanism of action of this drug is unresolved. Resolving PZQ-engaged targets and effectors is important for identifying new druggable pathways that may yield novel antiparasitic agents. Here we use functional, genetic and pharmacological approaches to reveal that serotonergic signals antagonize PZQ action in vivo. Exogenous 5-hydroxytryptamine (5-HT) rescued PZQ-evoked polarity and mobility defects in free-living planarian flatworms. In contrast, knockdown of a prevalently expressed planarian 5-HT receptor potentiated or phenocopied PZQ action in different functional assays. Subsequent screening of serotonergic ligands revealed that several ergot alkaloids possessed broad efficacy at modulating regenerative outcomes and the mobility of both free living and parasitic flatworms. Ergot alkaloids that phenocopied PZQ in regenerative assays to cause bipolar regeneration exhibited structural modifications consistent with serotonergic blockade. These data suggest that serotonergic activation blocks PZQ action in vivo, while serotonergic antagonists phenocopy PZQ action. Importantly these studies identify the ergot alkaloid scaffold as a promising structural framework for designing potent agents targeting parasitic bioaminergic G protein coupled receptors.

The parasitic infection schistosomiasis afflicts millions of people worldwide and is clinically treated using a single drug, praziquantel (PZQ). Despite the fact that PZQ has served as a stalwart anthelmintic for decades, the molecular basis of action of this clinical agent is poorly understood. This lack of mechanistic information impedes the rational design of alternative therapies and highlights the need for new approaches for studying the target(s) and effectors engaged by PZQ in vivo. Here, we exploit the predictive phenology between free-living planarian regenerative screens and parasitic neuromuscular physiology to reveal a broad efficacy of ergot alkaloids in phenocopying the action of PZQ. In planarian regenerative screens, data highlight structural features of the ergoline scaffold that yield specific regenerative effects to promote or inhibit head regeneration. Ergot alkaloids with efficacy in regenerative assays were also found to modulate the contractility of schistosomules. Overall, these data highlight a possible therapeutic potential of ergot alkaloids as antischistosomals and the action of PZQ as an ergomimetic.

Dihydroergotamine and sumatriptan in isolated human coronary artery, middle meningeal artery and saphenous vein

BACKGROUND

Dihydroergotamine (DHE) and sumatriptan are contraindicated in patients with cardiovascular disease because of their vasoconstricting properties, which have originally been explored in proximal coronary arteries. Our aim was to investigate DHE and sumatriptan in the proximal and distal coronary artery, middle meningeal artery and saphenous vein.

METHODS

Blood vessel segments were mounted in organ baths and concentration response curves for DHE and sumatriptan were constructed.

RESULTS

In the proximal coronary artery, meningeal artery and saphenous vein, maximal contractions to DHE (proximal: 8 ± 4%; meningeal: 32 ± 7%; saphenous: 52 ± 11%) and sumatriptan (proximal: 17 ± 7%; meningeal: 61 ± 18%, saphenous: 37 ± 8%) were not significantly different. In the distal coronary artery, contractions to DHE (5 ± 2%) were significantly smaller than those to sumatriptan (17 ± 9%). At clinically relevant concentrations, mean contractions to DHE and sumatriptan were below 3% in proximal coronary arteries and below 6% in distal coronary arteries. Contractions in the meningeal artery and saphenous vein were higher (7%-38%).

CONCLUSIONS

Contractions to DHE in distal coronary arteries are smaller than those to sumatriptan, while at clinical concentrations they both induce only slight contractions. In meningeal arteries contractions to DHE and sumatriptan are significantly larger, showing their cranioselectivity. Contractions to DHE in the saphenous vein are higher than those in the arteries, confirming its venous contractile properties.

[Current state of knowledge and developments in the prophylaxis and acute treatment of migraine]

For the acute treatment of the headache phase of a migraine attack, a variety of different pharmacotherapeutic treatment options exist. These range from nonspecifically acting non-opioid analgesics (e.g., paracetamol) and nonsteroidal anti-inflammatory substances (e.g., acetylsalicylic acid, ibuprofen, naproxen, diclofenac) to agents specifically interfering with the serotonin system (ergot alkaloids such as ergotamine and its derivatives, triptans). In patients with significant emesis co-occurring during an attack, additional antiemetics such as metoclopramide or domperidone may be administered. In migraine prophylaxis, largely divergent agents, e.g., β-adrenoceptor antagonists, Ca-antagonists, or anticonvulsants, are commonly used. The diversity of these compounds may help the treating physician to tailor prophylactic treatment to the patient's individual needs. The treatment success of the individual patient is difficult to predict both in acute and prophylactic migraine treatment. Apart from contraindications or associated side effects of a particular substance, the individual patient's response to treatment is therefore a major determinant in selecting the suitable medication.

Original article. Potential risk of dihydroergotamine causing medicationoveruse headache: preclinical evidence

Background: Overuse of abortive medication is a common factor contributing to an increase in headache frequency in patients with migraine. Whether or not chronic exposure to dihydroergotamine (DHE) can lead to this transformation remains uncertain.

Objective: To determine the effect of acute and chronic DHE exposure on development of cortical spreading depression (CSD) and trigeminal nociception.

Methods: The study comprised two experiments, namely acute and chronic exposure. In the acute experiment, a single dose of DHE (100 μg/kg) was given to male Wistar rats after successful induction of CSD. In the chronic experiment, DHE was given daily for the period of 0, 7, 14, and 28 days. CSD was induced 30 minutes after the final injection and the cortical field potential was recorded. Expression of c-Fos in caudal brainstem was used as an indicator of trigeminal nociception.

Results: Acute exposure to DHE attenuated the expression of c-Fos in the caudal brainstem without change in CSD response. By contrast, chronic exposure (14 and 28 days) to DHE increased the area under the curve of CSD waveforms. In parallel with the change in the CSD, there was significant increase of c-Fos expression within 14 days exposure to DHE and the expression remained significantly elevated for up to the 28 days examined.

Conclusion: Our study demonstrated that chronic DHE administration can increase cortical excitability and increase c-Fos expression in caudal brainstem. Our preclinical evidence suggests the possible adverse effect of chronic DHE use in causing chronification of headache.

Activation of 5-hydroxytryptamine1B/1D/1F receptors as a mechanism of action of antimigraine drugs

INTRODUCTION

The introduction of the triptans (5-hydroxytryptamine (5-HT)1B/1D receptor agonists) was a great improvement in the acute treatment of migraine. However, shortcomings of the triptans have prompted research on novel serotonergic targets for the treatment of migraine.

AREAS COVERED

In this review the different types of antimigraine drugs acting at 5-HT receptors, their discovery and development are discussed. The first specific antimigraine drugs were the ergot alkaloids, consisting of ergotamine, dihydroergotamine and methysergide, which are agonists at 5-HT receptors, but can also bind α-adrenoceptors and dopamine receptors. In the 1990s, the triptans became available on the market. They are 5-HT1B/1D receptor agonists, showing fewer side effects due to their receptor specificity. In the last years, compounds that bind specifically to 5-HT1D, 5-HT1F and 5-HT7 receptors have been explored for their antimigraine potential. Furthermore, the serotonergic system seems to act in tight connection with the glutamatergic as well as the CGRP-ergic systems, which may open novel therapeutic avenues.

EXPERT OPINION

Although the triptans are very effective in treating migraine attacks, their shortcomings have stimulated the search for novel drugs. Currently, the focus is on 5-HT1F receptor agonists, which seem devoid of vascular side effects. Moreover, novel compounds that affect multiple transmitter and/or neuropeptide systems that are involved in migraine could be of therapeutic relevance.

Effect of methysergide on pudendal inhibition of micturition reflex in cats

The role of 5-HT2 and opioid receptors in pudendal inhibition of bladder activity induced by intravesical infusion of saline or 0.25% acetic acid (AA) was investigated in anesthetized cats using methysergide (a 5-HT2 receptor antagonist) and naloxone (an opioid receptor antagonist). AA irritated the bladder and significantly (P<0.0001) reduced bladder capacity to 27.0 ± 7.4% of saline control capacity. Pudendal nerve stimulation (PNS) at multiples of the threshold (T) intensity for inducing anal sphincter twitching restored bladder capacity to 60.1 ± 8.0% at 1-2T (P<0.0001) and 92.2 ± 14.1% at 3-4T (P=0.001) of the saline control capacity. Methysergide (0.03-1mg/kg, i.v.) suppressed low intensity (1-2T) PNS inhibition but not high intensity (3-4T) inhibition, and also significantly (P<0.05) increased control bladder capacity at the dosage of 0.3-1mg/kg. During saline infusion without AA irritation, PNS significantly increased bladder capacity to 150.8 ± 9.9% at 1-2T (P<0.01) and 180.4 ± 16.6% at 3-4T (P<0.01) of the saline control capacity. Methysergide (0.1-1 mg/kg) significantly (P<0.05) increased saline control bladder capacity and suppressed PNS inhibition at the dosage of 0.03-1mg/kg. After methysergide treatment (1 mg/kg), naloxone significantly (P<0.05) reduced control bladder capacity during AA infusion but had no effect during saline infusion. Naloxone also had no influence on PNS inhibition. These results suggest that 5-HT2 receptors play a role in PNS inhibition of reflex bladder activity and interact with opioid mechanisms in micturition reflex pathway. Understanding neurotransmitter mechanisms underlying pudendal neuromodulation is important for the development of new treatments for bladder disorders.

Dihydroergotamine: a review of formulation approaches for the acute treatment of migraine

Dihydroergotamine (DHE) was first used to treat migraine in 1945 and is currently included among migraine-specific treatments for moderate-severe migraine. DHE may be administered through several routes of delivery, with efficacy and tolerability varying among formulations. We review DHE formulation approaches for the acute treatment of migraine, reviewing pharmacokinetics/dynamics and comparing clinical response among various formulations. Pharmacokinetic properties vary among DHE formulations, with peak concentration occurring in 6 min with intravenous, 34 min with intramuscular, 56 min with intranasal, 12 min with oral inhalation and 75 min with oral administration. DHE is a potent agonist at serotonin 5-HT1B and 5-HT1D receptors. Adverse effects due to binding to select adrenergic and dopaminergic receptors are significantly less with orally inhaled than intravenous DHE when comparing therapeutically effective doses. Among parenteral formulations (including subcutaneous, intramuscular, intravenous and nasal spray), efficacy is superior with injectable dosing. Nasal spray DHE is generally more effective than placebo, but less effective than sumatriptan. Orally inhaled DHE is likewise more effective than placebo, but there are no head-to-head comparisons with triptans available for review. Adverse effects, particularly nausea, may limit use of parenteral DHE. Nausea is generally less frequent with non-injectable dosing.

Serotonin facilitates peripheral pain sensitivity in a manner that depends on the nonproton ligand sensing domain of ASIC3 channel

Tissue acidosis and inflammatory mediators play critical roles in inflammatory pain. Extracellular acidosis activates acid-sensing ion channels (ASICs), which have emerged as key sensors for extracellular protons in the central and peripheral nervous systems and play key roles in pain sensation and transmission. Additionally, inflammatory mediators, such as serotonin (5-HT), are known to enhance pain sensation. However, functional interactions among protons, inflammatory mediators, and ASICs in pain sensation are poorly understood. In the present study, we show that 5-HT, a classical pro-inflammatory mediator, specifically enhances the proton-evoked sustained, but not transient, currents mediated by homomeric ASIC3 channels and heteromeric ASIC3/1a and ASIC3/1b channels. Unexpectedly, the effect of 5-HT on ASIC3 channels does not involve activation of 5-HT receptors, but is mediated via a functional interaction between 5-HT and ASIC3 channels. We further show that the effect of 5-HT on ASIC3 channels depends on the newly identified nonproton ligand sensing domain. Finally, coapplication of 5-HT and acid significantly increased pain-related behaviors as assayed by the paw-licking test in mice, which was largely attenuated in ASIC3 knock-out mice, and inhibited by the nonselective ASIC inhibitor amiloride. Together, these data identify ASIC3 channels as an unexpected molecular target for acute actions of 5-HT in inflammatory pain sensation and reveal an important role of ASIC3 channels in regulating inflammatory pain via coincident detection of extracellular protons and inflammatory mediators.

Relatively slow and long-lasting antimigraine effect of dihydroergotamine is most likely due to basic pharmacological attributes of the drug: A review

Introduction

If a drug has a slow dissociation from the receptor this can result in a long duration of effect and a slow effect. The long duration of the antimigraine effect of dihydroergotamine (DHE) has been reported previously whereas a possible slow onset of DHE’s antimigraine effect, which is the subject of this review, has only rarely been mentioned.

Methods

Eight randomised, controlled trials (RCT) with DHE for acute treatment with migraine were selected from the literature. The speed of the effect of DHE in migraine was evaluated by plotting the effect up to four hours against time.

Findings

Subcutaneous DHE 1 mg was inferior to subcutaneous sumatriptan 6 mg for headache relief for the first two hours but equally effective after three hours. After intranasal DHE 2 mg the mean therapeutic gain increased slowly up to four hours. For orally inhaled DHE 0.5 mg there was a considerable time lag between therapeutic gain (maximum after two hours) and plasma concentrations of DHE (Tmax = 12 min).

Conclusion

DHE has a slow dissociation from the receptor; and this basic attribute of the drug is the most likely cause of the general relatively slow anti-migraine effect of DHE.