Triptans and CGRP blockade - impact on the cranial vasculature

The preclinical discovery and development of atogepant for migraine prophylaxis

INTRODUCTION

Atogepant is a selective calcitonin gene-related peptide (CGRP) receptor antagonist that is utilized in adults for the prevention of episodic and chronic migraine. Cumulative findings support the involvement of CGRP in migraine pathophysiology, and atogepant functions by competitively antagonizing CGRP receptors, which results in the inhibition of trigeminovascular nociception. The mechanism of action addresses the cause of migraine pain, providing an effective preventive treatment option.

AREAS COVERED

The key milestones in its development, including preclinical achievements, phase I, II, and III clinical trials, and regulatory approvals are reviewed. Additionally, clinical efficacy, safety profile, and tolerability of atogepant are discussed. The literature review is based on a comprehensive search of English peer-reviewed articles from various electronic databases, including PubMed and ClinicalTrials.gov.

EXPERT OPINION

The development of atogepant represents a significant breakthrough in migraine prevention, particularly due to its improved safety profile that reduces the risk of liver injury, which was a major limitation of first-generation gepants. Drug-drug interaction studies with atogepant highlight the necessity for more inclusive study populations. Given that migraine disproportionately affects females, future clinical development programs should include diverse patient demographics to ensure the findings are generalizable to all individuals suffering from migraine.

The putative proton-coupled organic cation antiporter is involved in uptake of triptans into human brain capillary endothelial cells

BACKGROUND

Triptans are anti-migraine drugs with a potential central site of action. However, it is not known to what extent triptans cross the blood-brain barrier (BBB). The aim of this study was therefore to determine if triptans pass the brain capillary endothelium and investigate the possible underlying mechanisms with focus on the involvement of the putative proton-coupled organic cation (H+/OC) antiporter. Additionally, we evaluated whether triptans interacted with the efflux transporter, P-glycoprotein (P-gp).

METHODS

We investigated the cellular uptake characteristics of the prototypical H+/OC antiporter substrates, pyrilamine and oxycodone, and seven different triptans in the human brain microvascular endothelial cell line, hCMEC/D3. Triptan interactions with P-gp were studied using the IPEC-J2 MDR1 cell line. Lastly, in vivo neuropharmacokinetic assessment of the unbound brain-to-plasma disposition of eletriptan was conducted in wild type and mdr1a/1b knockout mice.

RESULTS

We demonstrated that most triptans were able to inhibit uptake of the H+/OC antiporter substrate, pyrilamine, with eletriptan emerging as the strongest inhibitor. Eletriptan, almotriptan, and sumatriptan exhibited a pH-dependent uptake into hCMEC/D3 cells. Eletriptan demonstrated saturable uptake kinetics with an apparent Km of 89 ± 38 µM and a Jmax of 2.2 ± 0.7 nmol·min-1·mg protein-1 (n = 3). Bidirectional transport experiments across IPEC-J2 MDR1 monolayers showed that eletriptan is transported by P-gp, thus indicating that eletriptan is both a substrate of the H+/OC antiporter and P-gp. This was further confirmed in vivo, where the unbound brain-to-unbound plasma concentration ratio (Kp,uu) was 0.04 in wild type mice while the ratio rose to 1.32 in mdr1a/1b knockout mice.

CONCLUSIONS

We have demonstrated that the triptan family of compounds possesses affinity for the H+/OC antiporter proposing that the putative H+/OC antiporter plays a role in the BBB transport of triptans, particularly eletriptan. Our in vivo studies indicate that eletriptan is subjected to simultaneous brain uptake and efflux, possibly facilitated by the putative H+/OC antiporter and P-gp, respectively. Our findings offer novel insights into the potential central site of action involved in migraine treatment with triptans and highlight the significance of potential transporter related drug-drug interactions.

The transition of medication overuse status by acute medication categories in episodic or chronic migraine patients to non-overuse status after receiving anti-CGRP monoclonal antibodies: a systematic review and meta-analysis of phase 3 randomized control trial

OBJECTIVE

The objective of this systematic review and meta-analysis was to determine whether patients with episodic (EM) or chronic migraine (CM), who were treated with anti-CGRP antibodies, showed a reversal from medication overuse (MO) or medication overuse headache (MOH) status at their baseline to non-overuse status. Furthermore, this study aimed to establish which acute headache medication (AHM) categories responded more effectively to anti-CGRP antibodies.

METHODS

A systematic search was conducted in the PubMed database for relevant studies from January 2013 to September 2023. We included phase three randomized controlled trials to examine the role of anti-CGRP antibodies in patients with EM or CM and their MO status. A meta-analysis was conducted to find the association between anti-CGRP antibodies and the number of EM and CM patients with MO or MOH at baseline that reverted to non-MO status or below the MOH threshold.

RESULTS

The initial search yielded a total of 345 studies. After removing duplicates and screening with inclusion criteria, 5 studies fulfilled our conditions. Each study reviewed the response to changes in the MO status of patients after receiving anti-CGRP antibodies, including eptinezumab, fremanezumab, galcanezumab, and erenumab, compared to placebo. Our study analyzed three AHM categories: triptans, simple analgesics, and multiple drugs. The overall relative risk (RR) was 1.44 (95% CI, 1.31 to 1.59; p < 0.001). The RRs for triptans, simple analgesics, and multi-drug groups were 1.71 (95% CI, 1.53 to 1.91; p < 0.001), 1.10 (95% CI, 0.83 to 1.47; p = 0.5), and 1.29 (95%CI 1.14 to 1.46; p < 0.001) respectively.

CONCLUSION

The meta-analysis has shown that anti-CGRP antibodies were statistically significant in transitioning from MO or MOH status to non-MO status or below the MOH threshold (RR = 1.44) for all included studies and all AHM categories except for simple analgesics. Patients from the triptan group had the highest RR of 1.71 with a p-value < 0.001, while the simple analgesics group had an RR of 1.10, however, with a p-value > 0.05. Interestingly, this analysis can be interpreted as that anti-CGRP antibodies might not be effective in reducing simple analgesics use in EM or CM patients. Further studies are needed to investigate these matters.

Rizatriptan benzoate-loaded dissolving microneedle patch for management of acute migraine therapy

In this study, dissolving microneedles (MNs) using polyvinyl alcohol (PVA) and poly (1-vinylpyrrolidone-co-vinyl acetate) (P(VP-co-VA)) as matrix materials were developed for transdermal delivery of rizatriptan benzoate (RB) for acute migraine treatment. In-vitro permeation studies were conducted to assess the feasibility of the as-fabricated dissolving MNs to release RB. Drug skin penetration were tested by Franz diffusion cells, showing an increase of the transdermal flux compared to passive diffusion due to the as-fabricated dissolving MNs having a sufficient mechanical strength to penetrate the skin and form microchannels. The pharmacological study in vivo showed that RB-loaded dissolving MNs significantly alleviated migraine-related response by up-regulating the level of 5-hydroxytryptamine (5-HT) and down-regulating the levels of calcitonin gene-related peptide (CGRP) and substance P (SP). In conclusion, the RB-loaded dissolving MNs have advantages of safety, convenience, and high efficacy over conventional administrations, laying a foundation for the transdermal drug delivery system treatment for acute migraine.

Calcitonin gene-related peptide receptor antagonism reduces motion sickness indicators in mouse migraine models

BACKGROUND

Migraine and vestibular migraine are disorders associated with a heightened motion sensitivity that provoke symptoms of motion-induced nausea and motion sickness. VM affects ∼3% of adults in the USA and affects three-fold more women than men. Triptans (selective serotonin receptor agonists) relieve migraine pain but lack efficacy for vertigo. Murine models of photophobia and allodynia have used injections of calcitonin gene-related peptide (CGRP) or other migraine triggers, such as sodium nitroprusside (SNP), to induce migraine sensitivities in mice to touch and light. Yet, there is limited research on whether these triggers affect motion-induced nausea in mice, and whether migraine blockers can reduce these migraine symptoms. We hypothesized that systemic delivery of CGRP or SNP will increase motion sickness susceptibility and motion-induced nausea in mouse models, and that migraine blockers can block these changes induced by systemically delivered CGRP or SNP.

METHODS

We investigated two measures of motion sickness assessment [motion sickness index (MSI) scoring and motion-induced thermoregulation] after intraperitoneal injections of either CGRP or SNP in C57BL/6J mice. The drugs olcegepant, sumatriptan and rizatriptan were used to assess the efficacy of migraine blockers.

RESULTS

MSI measures were confounded by CGRP's effect on gastric distress. However, analysis of tail vasodilatations as a surrogate for motion-induced nausea was robust for both migraine triggers. Only olcegepant treatment rescued tail vasodilatations.

CONCLUSIONS

These preclinical findings support the use of small molecule CGRP receptor antagonists for the treatment of motion-induced nausea of migraine, and show that triptan therapeutics are ineffective against motion-induced nausea of migraine.Trial Registration: Not Applicable.

Post-stroke Headache

PURPOSE OF REVIEW

Stroke is a major health concern and a leading cause of long-term disability. Persistent post-stroke headache (PPSH) is a common complication of stroke yet little is known about its specific characteristics or optimal management. The purpose of this review is to discuss the epidemiology, presentation, and hypothesized pathophysiology of PPSH. Acute and preventive treatment options, as well as specific concerns regarding triptans and the newer CGRP antagonists, will be discussed in detail as well.

RECENT FINDINGS

The 2018 International Classification of Headache Disorders, 3rd edition (ICHD-3) was the first headache diagnostic manual to include criteria for PPSH and defines this disorder as an acute headache that develops in close temporal relation to stroke and persists beyond 3 months. Recent literature estimates the prevalence of PPSH to be somewhere between 1 and 23% of patients post-stroke. Presentation is variable, but most often mimics tension-type headache. There are no evidence-based guidelines on the optimal treatment of PPSH. PPSH is a common but poorly understood complication of stroke. Given the significant disability burden that PPSH carries, the epidemiology and pathophysiology of PPSH, as well as the efficacy and safety of potential treatment options, warrant further investigation.

Duality in response of intracranial vessels to nitroglycerin revealed in rats by imaging photoplethysmography

Among numerous approaches to the study of migraine, the nitroglycerin (NTG) model occupies a prominent place, but there is relatively insufficient information about how NTG affects intracranial vessels. In this study we aim to assess the effects of NTG on blood-flow parameters in meningeal vessels measured by imaging photoplethysmography (iPPG) in animal experiments. An amplitude of the pulsatile component (APC) of iPPG waveform was assessed before and within 2.5 h after the NTG administration in saline (n = 13) or sumatriptan (n = 12) pretreatment anesthetized rats in conditions of a closed cranial window. In animals of both groups, NTG caused a steady decrease in blood pressure. In 7 rats of the saline group, NTG resulted in progressive increase in APC, whereas decrease in APC was observed in other 6 rats. In all animals in the sumatriptan group, NTG administration was accompanied exclusively by an increase in APC. Diametrically opposite changes in APC due to NTG indicate a dual effect of this drug on meningeal vasomotor activity. Sumatriptan acts as a synergist of the NTG vasodilating action. The results we obtained contribute to understanding the interaction of vasoactive drugs in the study of the headache pathophysiology and methods of its therapy.

Serotonergic Modulation of Neurovascular Transmission: A Focus on Prejunctional 5-HT Receptors/Mechanisms

5-Hydroxytryptamine (5-HT), or serotonin, plays a crucial role as a neuromodulator and/or neurotransmitter of several nervous system functions. Its actions are complex, and depend on multiple factors, including the type of effector or receptor activated. Briefly, 5-HT can activate: (i) metabotropic (G-protein-coupled) receptors to promote inhibition (5-HT₁, 5-HT₅) or activation (5-HT₄, 5-HT₆, 5-HT₇) of adenylate cyclase, as well as activation (5-HT₂) of phospholipase C; and (ii) ionotropic receptor (5-HT₃), a ligand-gated Na⁺/K⁺ channel. Regarding blood pressure regulation (and beyond the intricacy of central 5-HT effects), this monoamine also exerts direct postjunctional (on vascular smooth muscle and endothelium) or indirect prejunctional (on autonomic and sensory perivascular nerves) effects. At the prejunctional level, 5-HT can facilitate or preclude the release of autonomic (e.g., noradrenaline and acetylcholine) or sensory (e.g., calcitonin gene-related peptide) neurotransmitters facilitating hypertensive or hypotensive effects. Hence, we cannot formulate a specific impact of 5-HT on blood pressure level, since an increase or decrease in neurotransmitter release would be favoured, depending on the type of prejunctional receptor involved. This review summarizes and discusses the current knowledge on the prejunctional mechanisms involved in blood pressure regulation by 5-HT and its impact on some vascular-related diseases.

Semi-Automated Recording of Facial Sensitivity in Rat Demonstrates Antinociceptive Effects of the Anti-CGRP Antibody Fremanezumab

Migraine pain is frequently accompanied by cranial hyperalgesia and allodynia. Calcitonin gene-related peptide (CGRP) is implicated in migraine pathophysiology but its role in facial hypersensitivity is not entirely clear. In this study, we investigated if the anti-CGRP monoclonal antibody fremanezumab, which is therapeutically used in chronic and episodic migraines, can modify facial sensitivity recorded by a semi-automatic system. Rats of both sexes primed to drink from a sweet source had to pass a noxious mechanical or heat barrier to reach the source. Under these experimental conditions, animals of all groups tended to drink longer and more when they had received a subcutaneous injection of 30 mg/kg fremanezumab compared to control animals injected with an isotype control antibody 12-13 days prior to testing, but this was significant only for females. In conclusion, anti-CGRP antibody, fremanezumab, reduces facial sensitivity to noxious mechanical and thermal stimulation for more than one week, especially in female rats. Anti-CGRP antibodies may reduce not only headache but also cranial sensitivity in migraineurs.

Clinical evaluation of super-responders vs. non-responders to CGRP(-receptor) monoclonal antibodies: a real-world experience

BACKGROUND

Clinical trials and real-world studies revealed a spectrum of response to CGRP(-receptor) monoclonal antibodies (mAbs) in migraine prophylaxis, ranging from no effect at all to total migraine freedom. In this study, we aimed to compare clinical characteristics between super-responders (SR) and non-responders (NR) to CGRP(-receptor) mAbs.

METHODS

We performed a retrospective cohort study at the Headache Center, Charité - Universitätsmedizin Berlin. The definition of super-response was a ≥ 75% reduction in monthly headache days (MHD) in the third month after treatment initiation compared to the month prior to treatment begin (baseline). Non-response was defined as ≤ 25% reduction in MHD after three months of treatment with a CGRP-receptor mAb and subsequent three months of treatment with CGRP mAb, or vice versa. We collected demographic data, migraine disease characteristics, migraine symptoms during the attacks in both study groups (SR/NR) as well as the general medical history. SR and NR were compared using Chi-square test for categorical variables, and t-test for continuous variables.

RESULTS

Between November 2018 and June 2022, n = 260 patients with migraine received preventive treatment with CGRP(-receptor) mAbs and provided complete headache documentation for the baseline phase and the third treatment month. Among those, we identified n = 29 SR (11%) and n = 26 NR (10%). SR reported more often especially vomiting (SR n = 12/25, 48% vs. NR n = 4/22, 18%; p = 0.031) and typical migraine characteristics such as unilateral localization, pulsating character, photophobia and nausea. A subjective good response to triptans was significantly higher in SR (n = 26/29, 90%) than in NR (n = 15/25, 60%, p = 0.010). NR suffered more frequently from chronic migraine (NR n = 24/26, 92% vs. SR n = 15/29, 52%; p = 0.001), medication overuse headache (NR n = 14/24, 58% versus SR n = 8/29, 28%; p = 0.024), and concomitant depression (NR n = 17/26, 65% vs. SR n = 8/29, 28%; p = 0.005).

CONCLUSION

Several clinical parameters differ between SR and NR to prophylactic CGRP(-R) mAbs. A thorough clinical evaluation prior to treatment initiation might help to achieve a more personalized management in patients with migraine.

Treating Vestibular Migraine When Pregnant and Postpartum: Progress, Challenges and Innovations

Vestibular migraine is a leading cause of vertigo in pregnancy and, although not a distinct migraine subtype, is an episodic syndrome associated with migraine. Vestibular migraine is associated with diverse symptoms such as vertigo, aura, allodynia, osmophobia, nausea, vomiting and tinnitus, many of which may be exacerbated by, masked or even dismissed in pregnancy. Vestibular migraine is likely an underdiagnosed and undertreated condition in pregnancy. The aetiology of vestibular migraine remains incompletely understood, although various theories have been proposed, including genetic predisposition, neurochemical dysregulation and pro-inflammatory mechanisms, all of which are derived from the pathophysiology of classical migraine. Physiologic changes to the endocrine, haematologic and vascular systems in pregnancy may affect pathophysiological processes in vestibular migraine, and can alter the course of symptoms experienced in pregnancy. These changes also predispose to secondary headache disorders, which may have similar presentations. There has been considerable progress in therapeutic advances in vestibular migraine prophylaxis and treatment outside of pregnancy. There is currently no significant evidence base for acute treatment or prophylaxis for pregnant patients, with treatment recommendations extrapolated from studies on classical migraine, and offered on a benefit versus risk basis. Challenges commonly encountered include difficulty establishing a diagnosis, in addition to recognising and treating neuropsychiatric and gestational co-morbidities. Anxiety, depression, hypertensive disorders and cardiovascular disease are closely associated with migraine, and important contributors to morbidity and mortality during pregnancy. Identifying and treating vestibular migraine during pregnancy offers a unique opportunity to impact future patient health through screening and early treatment of associated co-morbidities. There have been innovations in classical migraine therapy that may confer benefit in vestibular migraine in pregnancy, with emphasis on lifestyle modification, effective prophylaxis, abortive therapies, cognitive behaviour therapy and management of vestibular migraine-related comorbidities.

Advances in CGRP Monoclonal Antibodies as Migraine Therapy: A Narrative Review

Migraine is a potentially disabling disorder, yet it remains underdiagnosed and undertreated. The release of the neuropeptide calcitonin gene-related peptide (CGRP) in the trigemino-cerebrovascular system plays a vital role in the evolution of migraine. It enhances peripheral sensitization by mediating neurogenic inflammation and also influences central sensitization. The majority of the drug classes available for migraine prophylaxis are nonspecific and associated with numerous side effects and drug interactions. Anti-CGRP monoclonal antibodies (mAb) are an innovative therapeutic class that fulfills the need for more efficacious and tolerable preventive therapy. While erenumab is a mAb to the CGRP receptor, eptinezumab, fremanezumab, and galcanezumab bind to the CGRP molecule. They decrease the number of headache days and improve disability. Upper respiratory tract infection, nausea, constipation, pain at the site of injection, and fatigue are the associated side effects. CGRP mAbs are an excellent advancement in translational research and are a promising addition in migraine therapy. This article discusses the recent advances in the development of the CGRP mAbs.

Monoclonal Antibodies against Calcitonin Gene-Related Peptide for Migraine Prophylaxis: A Systematic Review of Real-World Data

OBJECTIVE

To perform a systematic review of real-world outcomes for anti-CGRP-mAbs.

METHODS

Following the PRISMA guidelines, we searched PubMed for real-world data of erenumab, galcanezumab, fremanezumab, or eptinezumab in patients with migraines.

RESULTS

We identified 134 publications (89 retrospective), comprising 10 pharmaco-epidemiologic and 83 clinic-based studies, 38 case reports, and 3 other articles. None of the clinic-based studies provided follow-up data over more than one year in more than 200 patients. Findings suggest that there are reductions in health insurance claims and days with sick-leave as well as better treatment adherence with anti-CGRP-mAbs. Effectiveness, reported in 77 clinic-based studies, was comparable to randomized controlled trials. A treatment pause was associated with an increase in migraine frequency, and switching to another antibody resulted in a better response in some of the patients. Adverse events and safety issues were addressed in 86 papers, including 24 single case reports.

CONCLUSION

Real-world data on anti-CGRP-mAbs are limited by retrospective data collection, small patient numbers, and short follow-up periods. The majority of papers seem to support good effectiveness and tolerability of anti-CGRP-mAbs in the real-world setting. There is an unmet need for large prospective real-world studies providing long-term follow-ups of patients treated with anti-CGRP-mAbs.

Migraine Pharmacological Treatment and Cognitive Impairment: Risks and Benefits

Migraine is a common neurological disorder impairing the quality of life of patients. The condition requires, as an acute or prophylactic line of intervention, the frequent use of drugs acting on the central nervous system (CNS). The long-term impact of these medications on cognition and neurodegeneration has never been consistently assessed. The paper reviews pharmacological migraine treatments and discusses their biological and clinical effects on the CNS. The different anti-migraine drugs show distinct profiles concerning neurodegeneration and the risk of cognitive deficits. These features should be carefully evaluated when prescribing a pharmacological treatment as many migraineurs are of scholar or working age and their performances may be affected by drug misuse. Thus, a reconsideration of therapy guidelines is warranted. Furthermore, since conflicting results have emerged in the relationship between migraine and dementia, future studies must consider present and past pharmacological regimens as potential confounding factors.

Recently approved and emerging drug options for migraine prophylaxis

INTRODUCTION

: Migraine occupies the first position regarding to the disability caused in female working population (15-49 years). Research in the field of prophylaxis of this pathology has made enormous strides in recent years.

AREAS COVERED

In this narrative review we retrace the most important scientific evidence regarding recently approved and emerging drug for prophylactic treatment of migraine. The purpose of this article is in fact to evaluate currently approved or emerging pharmacological agents for migraine prophylaxis. This review is based on literature published in peer review journal obtained through PubMed, Cochrane library, Clinicaltrials.gov and US FDA.

EXPERT OPINION

: Monoclonal antibodies (mAbs) that target the calcitonin gene-related peptide signalling pathway (CGRP) have marked an innovation in prophylactic migraine therapy. The combination of Onabotulinumtoxin-A (OBTA) and mAbs appears to be an effective, but costly, therapeutic option for resistant cases. New classes of molecules like gepants and ditans seem to give exceptional results. In addition, new prophylactic drugs are emerging with several targets: the pituitary adenylate cyclase-activating polypeptide (PACAP), ion channels, several receptors coupled to G proteins, orexin, and glutamate. All these therapies will implement and improve migraine management, as well as personalized medicine for each patient.

Course of Preexisting Migraine Following Spontaneous Subarachnoid Hemorrhage

Background

Our objective was to observe the course of preexisting migraine following subarachnoid hemorrhage (SAH) in patients with and without craniotomy.

Methods

We designed an exploratory analysis and hypothesis-generating study of prospectively collected data starting by recruiting patients suffering from SAH with the Hunt and Hess scale score of ≤ 4. Out of 994 cases, we identified 46 patients with preexisting active migraine defined by at least four attacks in the year before SAH. According to the treatment, we subdivided the patients into two groups: the first group included patients with surgical aneurysm clipping with transection of the middle meningeal artery (MMA) and accompanying trigeminal nerve branches and the second group included patients with endovascular aneurysm coiling or without any interventional treatment. During the follow-up, we recorded the course of migraine frequency, duration, intensity, and character.

Results

For both groups (craniotomy n = 31, without craniotomy n = 15), a significant improvement regarding the preexisting migraine during a mean follow-up of 46 months (min. 12 months, max. 114 months) was seen regarding complete remission or at least &gt;50% reduction in migraine attacks (p &lt; 0.001 and p = 0.01). On comparing the groups, this effect was significantly more pronounced in patients with craniotomy (for no recurrence of migraine: p = 0.049). After craniotomy, 77.4% of the patients had no further attacks of migraine headache and 19.4% showed a reduction of &gt;50% while only 2.2% did not report any relevant change. In the non-surgical group, 46.7% had no further migraine attacks, 20% had a reduction of &gt;50%, while no change was noted in 33.3%.

Conclusions

Our study provides evidence that the dura mater might be related to migraine headaches and that transection of the MMA and accompanying trigeminal dural nerve branches might disrupt the pathway leading to a reduction of migraine attacks. However, coiling alone ameliorated migraine complaints.

Functionality, satisfaction, and global impression of change with ubrogepant for the acute treatment of migraine in triptan insufficient responders: a post hoc analysis of the ACHIEVE I and ACHIEVE II randomized trials

Background

Triptans are the first-line option for the acute treatment of migraine attacks; however, triptans are contraindicated in people with certain underlying cardiovascular risk factors and are associated with inadequate efficacy or poor tolerability in some individuals. Ubrogepant is an oral calcitonin gene–related peptide receptor antagonist approved for the acute treatment of migraine.

Methods

This post hoc analysis of the phase 3 ACHIEVE trials examined the impact of ubrogepant on the Functional Disability Scale (FDS), satisfaction with medication, and Patient Global Impression of Change (PGIC) in participants who were self-reported triptan insufficient responders (TIRs), defined as those who are unable to take triptans due to contraindications, tolerability issues, or insufficient efficacy. Responder definitions for the FDS, satisfaction measures, and PGIC were based on qualitative interpretation of the respective response options for the pooled ubrogepant 50 mg and placebo groups.

Results

In the pooled analysis population (n = 1799), 451 (25%) participants were TIRs, with most (80%) reporting insufficient efficacy with triptan use. A significantly higher proportion of TIRs treated with ubrogepant vs placebo reported being able to function normally from 2 to 8 h post dose (P < 0.05). Notably, significance was demonstrated at the time of the primary outcome assessments (2 h post dose), where rates of normal function were 38% for ubrogepant vs 29% for placebo (P = 0.048). A greater proportion of TIRs in the ubrogepant arm vs the placebo arm were satisfied with treatment at 2 (33% vs 21%, P = 0.006) and 24 h (58% vs 28%, P < 0.001) and indicated that their migraine improved at 2 h vs placebo (30% vs 18%, P = 0.006). Results were generally similar in the insufficient efficacy subpopulation of TIRs as in the overall TIRs group. Ubrogepant was safe and well tolerated in TIRs, with no new safety signals identified.

Conclusions

In people with migraine who are TIRs, individuals treated with ubrogepant had favorable 2-h outcomes, as measured by the FDS, satisfaction with medication, and PGIC, compared with placebo.

Trial registration

ClinicalTrials.gov: NCT02828020 (ACHIEVE I), registered July 11, 2016; NCT02867709 (ACHIEVE II), registered August 16, 2016.

The implementation of transcranial Doppler ultrasonography for preclinical study of migraine

Transcranial Doppler ultrasonography is used to study intracranial blood flow changes associated with migraine in humans, but whether this method is helpful in preclinical settings is yet unknown. In order to identify changes in rat intracranial blood flow specific to the trigeminovascular activation - a key process in migraine pathophysiology, we measured Doppler indices in the middle cerebral artery and basilar artery before, during, and after dural or somatosensory electrical stimulation. Haemodynamic changes specific to dural stimulation were tested further in separate experiments. After baseline recordings, the animals received cumulative infusions of valproate (100 mg/kg, trice), sumatriptan (0.3, 1, and 3 mg/kg) or saline, and dural stimulation with the measurement of Doppler indices was repeated every 10 min for 1 hour. Several parameters of blood flow in the rat middle cerebral artery underwent alterations specific to the trigeminovascular activation. These changes, however, were insensitive to valproate and sumatriptan and diminished over time. These findings question the reliability of blood flow velocity variations in large intracranial vessels as biological markers of migraine-related processes and do not support the idea of using transcranial Doppler ultrasonography for preclinical screening of anti-migraine treatments, at least in the model of acute trigeminovascular activation in rats.

Advantages of imaging photoplethysmography for migraine modeling: new optical markers of trigemino-vascular activation in rats

Background

Existent animal models of migraine are not without drawbacks and limitations. The aim of our study was to evaluate imaging photoplethysmography (PPG) as a method of assessing intracranial blood flow in rats and its changes in response to electrical stimulation of dural trigeminal afferents.

Methods

Experiments were carried out with 32 anesthetized adult male Wistar rats. Trigeminovascular system (TVS) was activated by means of electrical stimulation of dural afferents through a closed cranial window (CCW). Parameters of meningeal blood flow were monitored using a PPG imaging system under green illumination with synchronous recording of an electrocardiogram (ECG) and systemic arterial blood pressure (ABP). Two indicators related to blood-flow parameters were assessed: intrinsic optical signals (OIS) and the amplitude of pulsatile component (APC) of the PPG waveform. Moreover, we carried out pharmacological validation of these indicators by determining their sensitivity to anti-migraine drugs: valproic acid and sumatriptan. For statistical analysis the non-parametric tests with post-hoc Bonferroni correction was used.

Results

Significant increase of both APC and OIS was observed due to CCW electrical stimulation. Compared to saline (n = 11), intravenous administration of both the sumatriptan (n = 11) and valproate (n = 10) by using a cumulative infusion regimen (three steps performed 30 min apart) lead to significant inhibitory effect on the APC response to the stimulation. In contrast, intravenous infusion of any substance or saline did not affect the OIS response to the stimulation. It was found that infusion of either sumatriptan or valproate did not affect the response of ABP or heart rate to the stimulation.

Conclusions

Imaging PPG can be used in an animal migraine model as a method for contactless assessment of intracranial blood flow. We have identified two new markers of TVS activation, one of which (APC) was pharmacologically confirmed to be associated with migraine. Monitoring of changes in APC caused by CCW electrical stimulation (controlling efficiency of stimulation by OIS) can be considered as a new way to assess the peripheral mechanism of action of anti-migraine interventions.

The potential of lasmiditan in migraine

Lasmiditan, a highly selective 5-hydroxytryptamine receptor 1F (5-HT_1F) agonist, is the first drug in its class and is lacking triptan-like vasoactive properties. The US Food and Drug Administration (FDA) has recently approved lasmiditan for the acute treatment of migraine in adults based on positive results of two pivotal phase III trials, which showed a significant difference to placebo in the proportion of patients achieving total migraine freedom within 2 h. More patients with lasmiditan achieved headache freedom and, in addition, freedom from the most bothersome symptom, that is, photophobia, than with placebo. Treatment-related side effects seem to be related to the rapid penetration of the drug into the brain and include dizziness, paresthesia and drowsiness, mostly of mild to moderate intensity. Interim results from an ongoing long-term phase III trial suggest a decrease in the frequency of adverse events after multiple lasmiditan use. Lasmiditan is a promising acute anti-migraine therapy, in particular for patients with cardiovascular risk factors, contraindications, or unwanted side effects to triptans.

Associations between adherence to MIND diet and severity, duration and frequency of migraine headaches among migraine patients

OBJECTIVES

Migraine is a neurological disorder causing unbearable pain. Dietary approach is proposed as a preventive way of reducing the severity of migraine headaches. The present study aimed to examine the association between MIND diet and migraine headaches.

RESULTS

We found that participants with higher score of MIND diet compared to those with lower score, were less likely to have severe headaches (OR = 0.64; 95% CI 0.45, 0.91; P = 0.01). Moreover, our results showed an inversed correlation between mind diet score and duration (β = - 0.14, 95% CI - 1.42, - 0.14, P = 0.04) and frequency of headaches (β = - 0.13, 95% CI - 0.99, - 0.07, P = 0.03).

Persistent Post-Traumatic Headache and Migraine: Pre-Clinical Comparisons

Background: Oftentimes, persistent post traumatic headache (PPTH) and migraine are phenotypically similar and the only clinical feature that differentiate them is the presence of a mild or moderate traumatic brain injury (mTBI). The aim of this study is to describe the differences in brain area and in biochemical cascade after concussion and to define the efficacy and safety of treatments in use. Methods: Sources were chosen in according to the International Classification of Headache Disorder (ICHD) criteria. Results: The articles demonstrated a significant difference between PPTH and migraine regarding static functional connectivity (sFC) and dynamic functional connectivity (dFC) in brain structure that could be used for exploring the pathophysiological mechanisms in PPTH. Many studies described a cascade of neuro-metabolic changes that occur after traumatic brain injury. These variations are associated to the mechanism occurring when developing a PPTH. Conclusions: The state of art of this important topic show how although the mechanisms underlying the development of the two different diseases are different, the treatment of common migraine is efficacious in patients that have developed a post traumatic form.

Tibetan medicine Ru-yi-Zhen-bao Pills exhibits anti-migraine effect through mediating PAG anti-nociceptive channel

ETHNOPHARMACOLOGICAL RELEVANCE

Migraine is a disabling neurovascular disorder, which increases risk of cardiovascular events and is a social burden worldwide. The present first-line anti-migraine medications can cause overwhelming side-effects, of which one includes the onset of cardiovascular disease. As one of the marketed Tibetan drugs, Ru-yi-Zhen-bao Pills (RYZBP) have been clinically used to treat cardiovascular disorders and as anti-migraine medication. However, there is currently no research exploring the anti-migraine actions of RYZBP.

AIM OF THE STUDY

The current research was designed to assess the anti-migraine roles of RYZBP and explore the underlying mechanisms in a nitroglycerin (NTG)-induced migraine rat model trial.

MATERIALS AND METHODS

120 rats were randomly divided into the following six groups of 20 rats each: normal control group, model control group, positive control group, and RYZBP high/medium/low-dose groups (Ru-yi-Zhen-bao Pills; TH 1.00 g/kg, TM 0.50 g/kg and TL 0.25 g/kg). All rats were administered intragastrically for 7 consecutive days, which were subcutaneously injected with the NTG (10 mg/kg) after the last gavage (except in the normal control group). 3min after NTG treatment, 30 rats (5 rats from each group) were anesthetized and devoted to electroencephalogram(EEG) testing, which was used to evaluate the analgesic effect of RYZBP. One hour after NTG treatment, the rest of the 90 rats (15 rats from each group) were anesthetized and midbrain tissue sample was dissected. The dissection was then washed with physiological saline and collected. The histopathological changes in the periaqueductal gray(PAG) of 5 tissue samples were determined by aematoxylin-eosin (H&E) staining, as well as an estimation of substance P (SP) and neurokinin 1 receptor (NK1R) expression through immunohistochemically staining(IHC). Another 5 midbrain preparations were carried out to evaluate calcitonin gene-related peptide (CGRP), proenkephalin (PENK), SP, and cholecystokinin (CCK) expressions by real-time quantitative polymerase chain reaction (RT-qPCR). The rest of the 5 brainstem tissues were then used to measure CCK, CGRP, and opioid peptide receptor (DORR) levels by western blotting(WB).

RESULTS

In the EEG test, RYZBP (TM 0.50 g / kg) treatment transformed the EEG pain-wave of the NTG-induced migraine model rats in different time period. In the mechanism assay, compared with the model control group, RYZBP pretreatment reduced inflammatory cell infiltration, fibrosis and vacuolation of neuronal cells of PAG tissue seen by HE staining. IHC experiments further showed that RYZBPTM up-regulated SP expression levels and enhanced NK1R levels in the NTG-induced migraine rats (P < 0.05). Therapeutic administration of RYZBP also increased PENK mRNA expression and DORR protein level. Both RT-qPCR and western blotting trials indicated that RYZBP treatment significantly decreased CCK and CGRP expression levels (P < 0.01 or P < 0.05) in the NTG-induced migraine rats.

CONCLUSIONS

RYZBP has the potential to be an effective anti-migraine treatment through suppressing the EEG pain-wave, increasing the levels of SP, PENK, DORR and reducing expression of CCK and CGRP. Mediating the PAG anti-nociceptive channel and inhibiting central sensitization were the two potential mechanisms, which offers further evidence for clinical therapy.

TRP Channels in the Focus of Trigeminal Nociceptor Sensitization Contributing to Primary Headaches

Pain in trigeminal areas is driven by nociceptive trigeminal afferents. Transduction molecules, among them the nonspecific cation channels transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1), which are activated by endogenous and exogenous ligands, are expressed by a significant population of trigeminal nociceptors innervating meningeal tissues. Many of these nociceptors also contain vasoactive neuropeptides such as calcitonin gene-related peptide (CGRP) and substance P. Release of neuropeptides and other functional properties are frequently examined using the cell bodies of trigeminal neurons as models of their sensory endings. Pathophysiological conditions cause phosphorylation, increased expression and trafficking of transient receptor potential (TRP) channels, neuropeptides and other mediators, which accelerate activation of nociceptive pathways. Since nociceptor activation may be a significant pathophysiological mechanism involved in both peripheral and central sensitization of the trigeminal nociceptive pathway, its contribution to the pathophysiology of primary headaches is more than likely. Metabolic disorders and medication-induced painful states are frequently associated with TRP receptor activation and may increase the risk for primary headaches.

Characterization of binding, functional activity, and contractile responses of the selective 5-HT1F receptor agonist lasmiditan

BACKGROUND AND PURPOSE

Triptans are 5-HT1B/1D receptor agonists (that also display 5-HT1F receptor affinity) with antimigraine action, contraindicated in patients with coronary artery disease due to their vasoconstrictor properties. Conversely, lasmiditan was developed as an antimigraine 5-HT1F receptor agonist. To assess the selectivity and cardiovascular effects of lasmiditan, we investigated the binding, functional activity, and in vitro/in vivo vascular effects of lasmiditan and compared it to sumatriptan.

EXPERIMENTAL APPROACH

Binding and second messenger activity assays of lasmiditan and other serotoninergic agonists were performed for human 5-HT1A , 5-HT1B , 5-HT1D , 5-ht1E , 5-HT1F , 5-HT2A , 5-HT2B , and 5-HT7 receptors, and the results were correlated with their potency to constrict isolated human coronary arteries (HCAs). Furthermore, concentration-response curves to lasmiditan and sumatriptan were performed in proximal and distal HCA, internal mammary, and middle meningeal arteries. Finally, anaesthetized female beagle dogs received i.v. infusions of lasmiditan or sumatriptan in escalating cumulative doses, and carotid and coronary artery diameters were measured.

KEY RESULTS

Lasmiditan showed high selectivity for 5-HT1F receptors. Moreover, the functional potency of the analysed compounds to inhibit cAMP increase through 5-HT1B receptor activation positively correlated with their potency to contract HCA. In isolated human arteries, sumatriptan, but not lasmiditan, induced contractions. Likewise, in vivo, sumatriptan decreased coronary and carotid artery diameters at clinically relevant doses, while lasmiditan was devoid of vasoconstrictor activity at all doses tested.

CONCLUSIONS AND IMPLICATIONS

Lasmiditan is a selective 5-HT1F receptor agonist devoid of vasoconstrictor activity. This may represent a cardiovascular safety advantage when compared to the triptans.

Characterisation of the calcitonin gene-related peptide receptor antagonists ubrogepant and atogepant in human isolated coronary, cerebral and middle meningeal arteries

BACKGROUND

Migraine has been associated with a dysfunctional activation of the trigeminovascular system. Calcitonin gene-related peptide, a neuropeptide released from the trigeminal nerve fibres, has an important role in the pathophysiology of migraine and is a current therapeutic target for migraine treatment.

METHODS

We examined the effects of two novel calcitonin gene-related peptide receptor antagonists, ubrogepant and atogepant, on the relaxations induced by α calcitonin gene-related peptide in human isolated middle meningeal, cerebral and coronary arteries. Furthermore, the contractile responses to atogepant and ubrogepant per se were studied and compared to the responses elicited by zolmitriptan in proximal and distal human coronary arteries.

RESULTS

In intracranial arteries, both blockers antagonized the calcitonin gene-related peptide-induced relaxations more potently when compared to the inhibition observed in distal human coronary arteries, with atogepant showing a higher potency. When analysing their antagonistic profile in HCA, ubrogepant showed a competitive antagonist profile, while atogepant showed a non-competitive one. Neither of the gepants had vasoconstrictor effect at any of the concentrations studied in human coronary arteries, whereas zolmitriptan elicited concentration-dependent contractions.

CONCLUSION

ubrogepant and atogepant differentially inhibit the calcitonin gene-related peptide-dependent vasodilatory responses in intracranial arteries when compared to distal human coronary arteries. Also, both gepants are devoid of vasoconstrictive properties in human coronary arteries.

CGRP-dependent and independent mechanisms of acute and persistent post-traumatic headache following mild traumatic brain injury in mice

Background

Acute and persistent post-traumatic headache are often debilitating consequences of traumatic brain injury. Underlying physiological mechanisms of post-traumatic headache and its persistence remain unknown, and there are currently no approved therapies for these conditions. Post-traumatic headache often presents with a migraine-like phenotype. As calcitonin-gene related peptide promotes migraine headache, we explored the efficacy and timing of intervention with an anti- calcitonin-gene related peptide monoclonal antibody in novel preclinical models of acute post-traumatic headache and persistent post-traumatic headache following a mild traumatic brain injury event in mice.

Methods

Male, C57Bl/6 J mice received a sham procedure or mild traumatic brain injury resulting from a weight drop that allowed free head rotation while under minimal anesthesia. Periorbital and hindpaw tactile stimulation were used to assess mild traumatic brain injury-induced cutaneous allodynia. Two weeks after the injury, mice were challenged with stress, a common aggravator of migraine and post-traumatic headache, by exposure to bright lights (i.e. bright light stress) and cutaneous allodynia was measured hourly for 5 hours. A murine anti- calcitonin-gene related peptide monoclonal antibody was administered after mild traumatic brain injury at different time points to allow evaluation of the consequences of either early and sustained calcitonin-gene related peptide sequestration or late administration only prior to bright light stress.

Results

Mice with mild traumatic brain injury, but not a sham procedure, exhibited both periorbital and hindpaw cutaneous allodynia that resolved by post-injury day 13. Following resolution of injury-induced cutaneous allodynia, exposure to bright light stress re-instated periorbital and hindpaw cutaneous allodynia in injured, but not sham mice. Repeated administration of anti-calcitonin-gene related peptide monoclonal antibody at 2 hours, 7 and 14 days post mild traumatic brain injury significantly attenuated the expression of cutaneous allodynia when evaluated over the 14-day post injury time course and also prevented bright light stress-induced cutaneous allodynia in injured mice. Administration of anti-calcitonin-gene related peptide monoclonal antibody only at 2 hours and 7 days after mild traumatic brain injury blocked injury-induced cutaneous allodynia and partially prevented bright light stress-induced cutaneous allodynia. A single administration of anti-calcitonin-gene related peptide monoclonal antibody after the resolution of the peak injury-induced cutaneous allodynia, but prior to bright light stress challenge, did not prevent bright light stress-induced cutaneous allodynia.

Conclusions

We used a clinically relevant mild traumatic brain injury event in mice along with a provocative stimulus as novel models of acute post-traumatic headache and persistent post-traumatic headache. Following mild traumatic brain injury, mice demonstrated transient periorbital and hindpaw cutaneous allodynia suggestive of post-traumatic headache-related pain and establishment of central sensitization. Following resolution of injury-induced cutaneous allodynia, exposure to bright light stress re-established cutaneous allodynia, suggestive of persistent post-traumatic headache-related pain. Continuous early sequestration of calcitonin-gene related peptide prevented both acute post-traumatic headache and persistent post-traumatic headache. In contrast, delayed anti-calcitonin-gene related peptide monoclonal antibody treatment following establishment of central sensitization was ineffective in preventing persistent post-traumatic headache. These observations suggest that mechanisms involving calcitonin-gene related peptide underlie the expression of acute post-traumatic headache, and drive the development of central sensitization, increasing vulnerability to headache triggers and promoting persistent post-traumatic headache. Early and continuous calcitonin-gene related peptide blockade following mild traumatic brain injury may represent a viable treatment option for post-traumatic headache and for the prevention of post-traumatic headache persistence.

Abbreviations

CA Cutaneous allodynia CGRP Calcitonin gene-related peptide mTBI Mild traumatic brain injury PTH Post-traumatic headache APTH Acute post-traumatic headache PPTH Persistent post-traumatic headache

Emerging Novel Pharmacological Non-opioid Therapies in Headache Management: a Comprehensive Review

PURPOSE OF REVIEW

Chronic headache is a significant worldwide problem despite advances in treatment options. Chronic headaches can have significant a detrimental impact on the activities of daily living.

RECENT FINDINGS

Patients who do not obtain relief from chronic head and neck pain from conservative treatments are commonly being managed with interventional treatments. These interventional treatment options include botulinum toxin A, injections, local occipital nerve anesthetic and corticosteroid infiltration, occipital nerve subcutaneous stimulation and occipital nerve pulsed radiofrequency (PRF), sphenopalatine ganglion block, and radiofrequency techniques. Recently, evidence has emerged to support non-opioid-based drug and interventional approaches. Overall, more research is necessary to clarify the safety and efficacy of interventional treatments and to better understand the pathogenesis of chronic headache pain.

Potential Antimigraine Effects of Warfarin: An Exploration of Biological Mechanism with Survey of Patients

Case reports suggest a link between anticoagulant use and improved migraine symptoms, and a role for platelet-induced cerebral vasoconstriction in migraine pathobiology. Hence, we investigated the mechanism by which warfarin may affect migraine symptoms and whether there is a change in migraine symptomology in patients initiating oral anticoagulants, most commonly warfarin. The effects of warfarin on human platelet aggregation and secretion as well as platelet-induced rat cerebral artery vasoconstriction were studied. A survey of migraine and symptom change after starting or stopping oral anticoagulants was also conducted. Warfarin inhibited platelet aggregation and 5-hydroxytryptamine (5-HT) secretion in a concentration-dependent manner. Warfarin-inhibited platelet secretion products constricted middle cerebral arteries from male but not from female rats. For the survey, patient demographic information, migraine and medical history, and Migraine Disability Assessment Score (MIDAS) changes were collected. Out of 175 consenting, 40 respondents met the criteria for migraine and completed the survey. A total of 11 patients reported migraine symptom change, all coinciding with starting warfarin. Of those having symptom and MIDAS improvement, most were female with migraines with aura, whereas those worsening were male with fewer having migraine with aura. Of those reporting migraine symptom change with warfarin, female sex may be associated with improved MIDAS, and those experiencing an aura component are more likely to report a symptom change. Warfarin-mediated symptom improvement in females may occur due to inhibition of platelet 5-HT secretion and a lower sensitivity of female cerebral blood vessels to platelet-derived 5-HT-induced vasoconstriction.

Effects of two isometheptene enantiomers in isolated human blood vessels and rat middle meningeal artery - potential antimigraine efficacy

Background

Racemic isometheptene [(RS)-isometheptene] is an antimigraine drug that due to its cardiovascular side-effects was separated into its enantiomers, (R)- and (S)-isometheptene. This study set out to characterize the contribution of each enantiomer to its vasoactive profile. Moreover, rat neurogenic dural vasodilatation was used to explore their antimigraine mechanism of action.

Methods

Human blood vessel segments (middle meningeal artery, proximal and distal coronary arteries, and saphenous vein) were mounted in organ baths and concentration response curves to isometheptene were constructed. Calcitonin gene-related peptide (CGRP)-induced neurogenic dural vasodilation was elicited in the presence of the enantiomers using a rat closed cranial window model.

Results

The isometheptene enantiomers did not induce any significant contraction in human blood vessels, except in the middle meningeal artery, when they were administered at the highest concentration (100 μM). Interestingly in rats, (S)-isometheptene induced more pronounced vasopressor responses than (R)-isometheptene. However, none of these compounds affected the CGRP-induced vasodilator responses.

Conclusion

The isometheptene enantiomers displayed a relatively safe peripheral vascular profile, as they failed to constrict the human coronary artery. These compounds do not appear to modulate neurogenic dural CGRP release, therefore, their antimigraine site of action remains to be determined.

Mitochondrial Migraine: Disentangling the angiopathy paradigm in m.3243A>G patients

Migraine, characterized by recurrent attacks of predominantly unilateral throbbing headache, affects approximately 15% of the adult population and is an important cause of disability worldwide. Knowledge required for the development of new classes of antimigraine drugs might come from studying rare metabolic diseases associated with migraine. An illustrative example of a monogenetic disorder associated with migraine is the spectrum of disorders caused by the m.3243A>G mutation in the mitochondrial transfer RNA Leucine. Reported migraine prevalence figures in patients with this particular mutation vary considerably, but compared to the general population, m.3243A>G patients have a higher migraine prevalence. This burdensome symptom might sometimes even be the only clinical feature in maternal relatives carrying the m.3243A>G mutation. Although the exact sequence of events and the relative importance of factors underlying migraine in m.3243A>G MELAS spectrum disorders are still enigmatic, substantial evidence in man exist that dysfunctional mitochondria in both the vascular, the smooth muscle cells and the neuronal system and the interaction between these are at the starting point of the migraine developing pathophysiological cascade. Exclusively based on results of studies performed in patients harboring the m.3243A>G mutation, either in vivo or ex vivo, we here summarize our current understanding of mitochondrial angiopathy associated migraine in m.3243A>G patients which knowledge might lead to potential new avenues for migraine drug development.

Enhanced pharmacological efficacy of sumatriptan due to modification of its physicochemical properties by inclusion in selected cyclodextrins

The study focused on the pharmacological action of sumatriptan, in particular its antiallodynic and antihyperalgesic properties, as an effect of cyclodextrinic inclusion of sumatriptan, resulting in changes of its physicochemical qualities such as dissolution and permeability through artificial biological membranes, which had previously been examined in vitro in a gastro-intestinal model. The inclusion of sumatriptan into β-cyclodextrin and 2-hydroxylpropylo-β-cyclodextrin by kneading was confirmed with the use of spectral (fourier-transform infrared spectroscopy (FT-IR); solid state nuclear magnetic resonance spectroscopy with magic angle spinning condition, ¹H and ¹³C MAS NMR) and thermal (differential scanning calorimetry (DSC)) methods. A precise indication of the domains of sumatriptan responsible for its interaction with cyclodextrin cavities was possible due to a theoretical approach to the analysis of experimental spectra. A high-performance liquid chromatography with a diode-array detector method (HPLC-DAD) was employed to determine changes in the concentration of sumatriptan during dissolution and permeability experiments. The inclusion of sumatriptan in complex with cyclodextrins was found to significantly modify its dissolution profiles by increasing the concentration of sumatriptan in complexed form in an acceptor solution compared to in its free form. Following complexation, sumatriptan manifested an enhanced ability to permeate through artificial biological membranes in a gastro-intestinal model for both cyclodextrins at all pH values. As a consequence of the greater permeability of sumatriptan and its increased dissolution from the complexes, an improved pharmacological response was observed when cyclodextrin complexes were applied.

Antigens and Antibodies in Disease With Specifics About CGRP Immunology

Growth in knowledge about calcitonin gene-related peptide (CGRP) in the pathophysiology of migraine brought CGRP antagonism to headache medicine. Failures in development of small molecule CGRP receptor antagonists and increasing knowledge and use of monoclonal antibodies (mAbs) in medicine led to the breakthrough development of large molecule anti-CGRP mAbs: eptinezumab, erenumab, fremanezumab, and galcanezumab. This specifics about CGRP immunology aims to outline: (1) knowledge needed for CGRP antagonism and (2) developmental issues of specific CGRP antagonists for provider use. This clinically oriented review documents IgG structure and function; state of the art of monoclonal IgG production and ligand-antigen-antibodies in migraine therapeutics contributing to immunogenic risks and off-target toxicities. Specifics to CGRP ligand, receptor, antagonism, and molecules, small and large, complete this review. Completion will facilitate assessment of the similarities, differences, and application of the forthcoming anti-CGRP receptor and ligand antagonists for patients.

Pathophysiology of chronic pain in cerebral palsy: implications for pharmacological treatment and research

The high prevalence of chronic pain in individuals with cerebral palsy (CP) across the lifespan has been well documented, as has its negative impact on quality of life. However, without an understanding of the underlying (possibly unique) pathophysiology of pain in CP, identification of more effective management options, such as innovative and individualized pharmacological approaches to non-opioid pain treatment, will be significantly hindered. We review, briefly, what is known about chronic pain in CP and present what we need to know with respect to the neurobiology of pain and new developments in pain treatment research that might be applied to CP.

WHAT THIS PAPER ADDS

Pain conditions in cerebral palsy have differing mechanisms and will not respond to the same treatments. Novel analgesics under development include inhibitors of ion channels, nerve growth factor, and calcitonin gene-related peptide.

Drosophila CaV2 channels harboring human migraine mutations cause synapse hyperexcitability that can be suppressed by inhibition of a Ca2+ store release pathway

Gain-of-function mutations in the human CaV2.1 gene CACNA1A cause familial hemiplegic migraine type 1 (FHM1). To characterize cellular problems potentially triggered by CaV2.1 gains of function, we engineered mutations encoding FHM1 amino-acid substitutions S218L (SL) and R192Q (RQ) into transgenes of Drosophila melanogaster CaV2/cacophony. We expressed the transgenes pan-neuronally. Phenotypes were mild for RQ-expressing animals. By contrast, single mutant SL- and complex allele RQ,SL-expressing animals showed overt phenotypes, including sharply decreased viability. By electrophysiology, SL- and RQ,SL-expressing neuromuscular junctions (NMJs) exhibited enhanced evoked discharges, supernumerary discharges, and an increase in the amplitudes and frequencies of spontaneous events. Some spontaneous events were gigantic (10-40 mV), multi-quantal events. Gigantic spontaneous events were eliminated by application of TTX-or by lowered or chelated Ca2+-suggesting that gigantic events were elicited by spontaneous nerve firing. A follow-up genetic approach revealed that some neuronal hyperexcitability phenotypes were reversed after knockdown or mutation of Drosophila homologs of phospholipase Cβ (PLCβ), IP3 receptor, or ryanodine receptor (RyR)-all factors known to mediate Ca2+ release from intracellular stores. Pharmacological inhibitors of intracellular Ca2+ store release produced similar effects. Interestingly, however, the decreased viability phenotype was not reversed by genetic impairment of intracellular Ca2+ release factors. On a cellular level, our data suggest inhibition of signaling that triggers intracellular Ca2+ release could counteract hyperexcitability induced by gains of CaV2.1 function.

Is selective 5-HT1F receptor agonism an entity apart from that of the triptans in antimigraine therapy?

Migraine is a neurovascular disorder that involves activation of the trigeminovascular system and cranial vasodilation mediated by release of calcitonin gene-related peptide (CGRP). The gold standard for acute migraine treatment are the triptans, 5-HT1B/1D/(1F) receptor agonists. Their actions are thought to be mediated through activation of: (i) 5-HT1B receptors in cranial blood vessels with subsequent cranial vasoconstriction; (ii) prejunctional 5-HT1D receptors on trigeminal fibers that inhibit trigeminal CGRP release; and (iii) 5-HT1B/1D/1F receptors in central nervous system involved in (anti)nociceptive modulation. Unfortunately, coronary arteries also express 5-HT1B receptors whose activation would produce coronary vasoconstriction; hence, triptans are contraindicated in patients with cardiovascular disease. In addition, since migraineurs have an increased cardiovascular risk, it is important to develop antimigraine drugs devoid of vascular (side) effects. Ditans, here defined as selective 5-HT1F receptor agonists, were developed on the basis that most of the triptans activate trigeminal 5-HT1F receptors, which may explain part of the triptans' antimigraine action. Amongst the ditans, lasmiditan: (i) fails to constrict human coronary arteries; and (ii) is effective for the acute treatment of migraine in preliminary Phase III clinical trials. Admittedly, the exact site of action is still unknown, but lasmiditan possess a high lipophilicity, which suggests a direct action on the central descending antinociceptive pathways. Furthermore, since 5-HT1F receptors are located on trigeminal fibers, they could modulate CGRP release. This review will be particularly focussed on the similarities and differences between the triptans and the ditans, their proposed sites of action, side effects and their cardiovascular risk profile.

Serotonin receptor agonists in the acute treatment of migraine: a review on their therapeutic potential

Migraine is an important socioeconomic burden and is ranked the sixth cause of years of life lost because of disability in the general population and the third cause of years of life lost in people younger than 50 years. The cornerstone of pharmacological treatment is represented by the acute therapy. The serotonin (5-hydroxytryptamine [5-HT]) receptor subtype 1_B/1_D agonists, called triptans, are nowadays the first-line acute therapy for patients who experience moderate-to-severe migraine attacks. Unfortunately, a high percentage of patients are not satisfied with this acute treatment, either for lack of response or side effects. Moreover, their mechanism of action based on vasoconstriction makes them unsuitable for patients with previous cardio- and cerebrovascular diseases and for those with uncontrolled hypertension. Since the introduction of triptans, no other acute drug class has passed all developmental stages. The research for a new drug lacking vasoconstrictive effects led to the development of lasmiditan, a highly selective 5-HT1_F receptor agonist with minimized interactions with other 5-HT receptor subtypes. Lasmiditan is considered to be the first member of a new drug category, the neurally acting anti-migraine agent (NAAMA). Phase II and III trials had shown superiority compared to placebo and absence of typical triptan-associated adverse events (AEs). Most of the AEs were related to the central nervous system, depending on the high permeability through the blood–brain barrier and mild to moderate severity. The results of ongoing long-term Phase III trials will determine whether lasmiditan will become available in the market, and then active triptan comparator studies will assess patients’ preference. Future studies could then explore the safety during pregnancy and breastfeeding or the risk that overuse of lasmiditan leads to medication overuse headache.

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.

Calcitonin Gene-Related Peptide Antagonists and Therapeutic Antibodies

The calcitonin gene-related peptide (CGRP) receptor is composed of the calcitonin receptor-like receptor (CLR, a class B GPCR) and a single-pass membrane protein known as receptor activity modifying protein type 1 (RAMP1). The levels of the CGRP peptide increase during a migraine attack and infusion of CGRP can provoke a migraine attack. Consequently, there is much interest in inhibiting the actions of CGRP as a way to control migraine. Here we describe the development of small molecule antagonists designed to bind to the CGRP receptor to block its action by preventing binding of the CGRP peptide. We also describe the development of antibody drugs, designed to bind either to the CGRP receptor to block its action, or to bind directly to the CGRP peptide. The field has been very active, with one antibody drug approved and three antibody drugs in phase III clinical trial. Initial programs on the development CGRP antagonists were frustrated by liver toxicity but the current outlook is very promising with five small molecule antagonists in various stages of clinical trial.

PACAP38 in human models of primary headaches

Background

To review the role of PACAP38 in human models of primary headaches, discuss possible mechanisms of PACAP38-induced migraine, and outline future directions.

Discussion

Experimental studies have established PACAP38 as a potent pharmacological “trigger” molecule of migraine-like attacks. These studies have also revealed a heterogeneous PACAP38 migraine response in migraine without aura patients. In addition, findings from brain imaging studies have demonstrated neuronal and vascular changes in migraine patients both ictally and interictally after PACAP38 infusion.

Conclusion

Human migraine models have shed light on the importance of PACAP38 in the pathophysiology of primary headaches. These studies have also pointed to the PAC₁ receptor and the PACAP38 molecule itself as target sites for drug testing. Future research should seek to understand the mechanisms underlying PACAP38-induced migraine. The results from an ongoing proof of concept randomized clinical trial may reveal the therapeutic potential of anti-PAC₁ receptor antibodies for migraine prevention.