5-HT(1D) receptor immunoreactivity in the sphenopalatine ganglion: implications for the efficacy of triptans in the treatment of autonomic signs associated with cluster headache

PACAP-38 related modulation of the cranial parasympathetic projection: A novel mechanism and therapeutic target in severe primary headache

BACKGROUND AND PURPOSE

Little is known of how cranial autonomic symptoms (CAS) in cluster headache and migraine may contribute to their severe headache phenotype. This strong association suggests the involvement of the cranial parasympathetic efferent pathway. To investigate its contribution, we studied the role of pituitary adenylate cyclase activating polypeptide-38 (PACAP-38), a potent sensory and parasympathetic neuropeptide, in modulating pre- and post-ganglionic cranial parasympathetic projection neurons, and their influence on headache-related trigeminal-autonomic responses.

EXPERIMENTAL APPROACH

Using PACAP-38 and PACAP-38 responsive receptor antagonists, electrophysiological, behavioural and facial neurovascular-blood flow was measured in rats to probe trigeminal- and parasympathetic-neuronal, periorbital thresholds and cranial-autonomic outcomes, as they relate to primary headaches.

KEY RESULTS

Sumatriptan attenuated the development of PACAP-38 mediated activation and sensitization of trigeminocervical neurons and related periorbital allodynia. PACAP-38 also caused activation and enhanced responses of dural-responsive pre-ganglionic pontine-superior salivatory parasympathetic neurons. Further, the PACAP-38 responsive receptor antagonists dissected a role of VPAC1 and PAC1 receptors in attenuating cranial-autonomic and trigeminal-neuronal responses to activation of the cranial parasympathetic projection, which requires post-ganglionic parasympathetic neurotransmission.

CONCLUSION AND IMPLICATIONS

Given the prevailing view that sumatriptan acts to some degree via a peripheral mechanism, our data support that PACAP-38 mediated receptor activation modulates headache-related cranial-autonomic and trigeminovascular responses via peripheral and central components of the cranial parasympathetic projection. This provides a mechanistic rationale for the association of CAS with more severe headache phenotypes in cluster headache and migraine, and supports the cranial parasympathetic projection as a potential novel locus for treatment by selectively targeting PACAP-38 or PACAP-38 responsive VPAC1 /PAC1 receptors.

Management of cluster headache: Treatments and their mechanisms

BACKGROUND

The management of cluster headache is similar to that of other primary headache disorders and can be broadly divided into acute and preventive treatments. Acute treatments for cluster headache are primarily delivered via rapid, non-oral routes (such as inhalation, nasal, or subcutaneous) while preventives include a variety of unrelated treatments such as corticosteroids, verapamil, and galcanezumab. Neuromodulation is becoming an increasingly popular option, both non-invasively such as vagus nerve stimulation when medical treatment is contraindicated or side effects are intolerable, and invasively such as occipital nerve stimulation when medical treatment is ineffective. Clinically, this collection of treatment types provides a range of options for the informed clinician. Scientifically, this collection provides important insights into disease mechanisms.

METHODS

Two authors performed independent narrative reviews of the literature on guideline recommendations, clinical trials, real-world data, and mechanistic studies.

RESULTS

Cluster headache is treated with acute treatments, bridge treatments, and preventive treatments. Common first-line treatments include subcutaneous sumatriptan and high-flow oxygen as acute treatments, corticosteroids (oral or suboccipital injections) as bridge treatments, and verapamil as a preventive treatment. Some newer acute (non-invasive vagus nerve stimulation) and preventive (galcanezumab) treatments have excellent clinical trial data for episodic cluster headache, while other newer treatments (occipital nerve stimulation) have been specifically tested in treatment-refractory chronic cluster headache. Most treatments are suspected to act on the trigeminovascular system, the autonomic system, or the hypothalamus.

CONCLUSIONS

The first-line treatments have not changed in recent years, but new treatments have provided additional options for patients.

Shared and independent roles of CGRP and PACAP in migraine pathophysiology

The neuropeptides calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating polypeptide (PACAP) have emerged as mediators of migraine pathogenesis. Both are vasodilatory peptides that can cause migraine-like attacks when infused into people and migraine-like symptoms when injected into rodents. In this narrative review, we compare the similarities and differences between the peptides in both their clinical and preclinical migraine actions. A notable clinical difference is that PACAP, but not CGRP, causes premonitory-like symptoms in patients. Both peptides are found in distinct, but overlapping areas relevant to migraine, most notably with the prevalence of CGRP in trigeminal ganglia and PACAP in sphenopalatine ganglia. In rodents, the two peptides share activities, including vasodilation, neurogenic inflammation, and nociception. Most strikingly, CGRP and PACAP cause similar migraine-like symptoms in rodents that are manifested as light aversion and tactile allodynia. Yet, the peptides appear to act by independent mechanisms possibly by distinct intracellular signaling pathways. The complexity of these signaling pathways is magnified by the existence of multiple CGRP and PACAP receptors that may contribute to migraine pathogenesis. Based on these differences, we suggest PACAP and its receptors provide a rich set of targets to complement and augment the current CGRP-based migraine therapeutics.

Occipital Nerve Stimulation: An Alternative Treatment of Chronic Migraine

PURPOSE OF REVIEW

This paper will examine the efficacy and safety of occipital nerve stimulation as a non-pharmacological alternative treatment for migraine.

RECENT FINDINGS

Migraine is characterized as a primary headache disorder with possible premonitory and aura phases, both of which vary greatly in symptomatology. The most common treatments for chronic migraine are pharmacological and are aimed at both acute relief (e.g., nonsteroidal anti-inflammatory drugs, triptans, and ergots) and prophylaxis (e.g., propranolol, valproic acid, and topiramate). For patients with medically refractory migraine, acute relief medication overuse can increase the risk of developing more severe and more frequent migraine attacks. Occipital nerve stimulation is a non-pharmacological alternative treatment for chronic migraine, which could eliminate the risk of adverse effects from acute relief medication overuse. Neurostimulation is thought to prevent pain by blocking signal transduction from small nociceptive fibers with non-painful signaling in larger adjacent fibers. Existing data from clinical trials support the overall safety and efficacy of occipital nerve stimulation for the treatment of chronic migraine. However, few large controlled, double-blinded studies have been conducted, due to both practical and ethical concerns. Currently, occipital nerve stimulation is available as an off-label use of neurostimulation for pain prevention but is not approved by the FDA specifically for the treatment of chronic migraine.

New Insights on Metabolic and Genetic Basis of Migraine: Novel Impact on Management and Therapeutical Approach

Migraine is a hereditary disease, usually one-sided, sometimes bilateral. It is characterized by moderate to severe pain, which worsens with physical activity and may be associated with nausea and vomiting, may be accompanied by photophobia and phonophobia. The disorder can occur at any time of the day and can last from 4 to 72 h, with and without aura. The pathogenic mechanism is unclear, but extensive preclinical and clinical studies are ongoing. According to electrophysiology and imaging studies, many brain areas are involved, such as cerebral cortex, thalamus, hypothalamus, and brainstem. The activation of the trigeminovascular system has a key role in the headache phase. There also appears to be a genetic basis behind the development of migraine. Numerous alterations have been identified, and in addition to the genetic cause, there is also a close association with the surrounding environment, as if on the one hand, the genetic alterations may be responsible for the onset of migraine, on the other, the environmental factors seem to be more strongly associated with exacerbations. This review is an analysis of neurophysiological mechanisms, neuropeptide activity, and genetic alterations that play a fundamental role in choosing the best therapeutic strategy. To date, the goal is to create a therapy that is as personalized as possible, and for this reason, steps forward have been made in the pharmacological field in order to identify new therapeutic strategies for both acute treatment and prophylaxis.

Modulation of brain networks by sumatriptan-naproxen in the inflammatory soup migraine model

Migraine is a debilitating condition; however, the pharmacological effects on central nervous system networks after successful therapy are poorly understood. Defining this neurocircuitry is critical to our understanding of the disorder and for the development of antimigraine drugs. Using an established inflammatory soup model of migraine-like pathophysiology (N = 12) compared with sham synthetic interstitial fluid migraine induction (N = 12), our aim was to evaluate changes in network-level functional connectivity after sumatriptan-naproxen infusion in awake, conscious rodents (Sprague-Dawley rats). Sumatriptan-naproxen infusion functional magnetic resonance imaging data were analyzed using an independent component analysis approach. Whole-brain analysis yielded significant between-group (inflammatory soup vs synthetic interstitial fluid) alterations in functional connectivity across the cerebellar, default mode, basal ganglia, autonomic, and salience networks. These results demonstrate the large-scale antimigraine effects of sumatriptan-naproxen co-administration after dural sensitization.

An Update: Pathophysiology of Migraine

Migraine is the most common disabling primary headache globally. Attacks typically present with unilateral throbbing headache and associated symptoms including, nausea, multisensory hypersensitivity, and marked fatigue. In this article, the authors address the underlying neuroanatomical basis for migraine-related headache, associated symptomatology, and discuss key clinical and preclinical findings that indicate that migraine likely results from dysfunctional homeostatic mechanisms. Whereby, abnormal central nervous system responses to extrinsic and intrinsic cues may lead to increased attack susceptibility.

Fluorescently-labeled fremanezumab is distributed to sensory and autonomic ganglia and the dura but not to the brain of rats with uncompromised blood brain barrier

Background

The presence of calcitonin gene-related peptide and its receptors in multiple brain areas and peripheral tissues previously implicated in migraine initiation and its many associated symptoms raises the possibility that humanized monoclonal anti-calcitonin gene-related peptide antibodies (CGRP-mAbs) can prevent migraine by modulating neuronal behavior inside and outside the brain. Critical to our ability to conduct a fair discussion over the mechanisms of action of CGRP-mAbs in migraine prevention is data generation that determines which of the many possible peripheral and central sites are accessible to these antibodies – a question raised frequently due to their large size.

Material and methods

Rats with uncompromised and compromised blood-brain barrier (BBB) were injected with Alexa Fluor 594-conjugated fremanezumab (Frema594), sacrificed 4 h or 7 d later, and relevant tissues were examined for the presence of Frema594.

Results

In rats with uncompromised BBB, Frema594 was similarly observed at 4 h and 7 d in the dura, dural blood vessels, trigeminal ganglion, C2 dorsal root ganglion, the parasympathetic sphenopalatine ganglion and the sympathetic superior cervical ganglion but not in the spinal trigeminal nucleus, thalamus, hypothalamus or cortex. In rats with compromised BBB, Frema594 was detected in the cortex (100 µm surrounding the compromised BBB site) 4 h but not 7 d after injections.

Discussion

Our inability to detect fluorescent (CGRP-mAbs) in the brain supports the conclusion that CGRP-mAbs prevent the headache phase of migraine by acting mostly, if not exclusively, outside the brain as the amount of CGRP-mAbs that enters the brain (if any) is too small to be physiologically meaningful.

CSD-Induced Arterial Dilatation and Plasma Protein Extravasation Are Unaffected by Fremanezumab: Implications for CGRP's Role in Migraine with Aura

Cortical spreading depression (CSD) is a wave of neuronal depolarization thought to underlie migraine aura. Calcitonin gene-related peptide (CGRP) is a potent vasodilator involved in migraine pathophysiology. Evidence for functional connectivity between CSD and CGRP has triggered scientific interest in the possibility that CGRP antagonism may disrupt vascular responses to CSD and the ensuing plasma protein extravasation (PPE). Using imaging tools that allow us to generate continuous, live, high-resolution views of spatial and temporal changes that affect arteries and veins in the dura and pia, we determined the extent to which CGRP contributes to the induction of arterial dilatation or PPE by CSD in female rats, and how these events are affected by the anti-CGRP monoclonal antibody (anti-CGRP-mAb) fremanezumab. We found that the CSD-induced brief dilatation and prolonged constriction of pial arteries, prolonged dilatation of dural arteries and PPE are all unaffected by fremanezumab, whereas the brief constriction and prolonged dilatation of pial veins are affected. In comparison, although CGRP infusion gave rise to the expected dilatation of dural arteries, which was effectively blocked by fremanezumab, it did not induce dilatation in pial arteries, pial veins, or dural veins. It also failed to induce PPE. Regardless of whether the nociceptors become active before or after the induction of arterial dilatation or PPE by CSD, the inability of fremanezumab to prevent them suggests that these events are not mediated by CGRP, a conclusion with important implications for our understanding of the mechanism of action of anti-CGRP-mAbs in migraine prevention.SIGNIFICANCE STATEMENT The current study identifies fundamental differences between two commonly used models of migraine, CSD induction and systemic CGRP infusion. It raises the possibility that conclusions drawn from one model may not be true or relevant to the other. It sharpens the need to accept the view that there is more than one truth to migraine pathophysiology and that it is unlikely that one theory will explain all types of migraine headache or the mechanisms of action of drugs that prevent it. Regarding the latter, it is concluded that not all vascular responses in the meninges are born alike and, consequently, that drugs that prevent vascular dilatation through different molecular pathways may have different therapeutic outcomes in different types of migraine.

Recent Advances in Pharmacotherapy for Migraine Prevention: From Pathophysiology to New Drugs

Migraine is a common and disabling neurological disorder, with a significant socioeconomic burden. Its pathophysiology involves abnormalities in complex neuronal networks, interacting at different levels of the central and peripheral nervous system, resulting in the constellation of symptoms characteristic of a migraine attack. Management of migraine is individualised and often necessitates the commencement of preventive medication. Recent advancements in the understanding of the neurobiology of migraine have begun to account for some parts of the symptomatology, which has led to the development of novel target-based therapies that may revolutionise how migraine is treated in the future. This review will explore recent advances in the understanding of migraine pathophysiology, and pharmacotherapeutic developments for migraine prevention, with particular emphasis on novel treatments targeted at the calcitonin gene-related peptide (CGRP) pathway.

Alterations of structural connectivity in episodic cluster headache: A graph theoretical analysis

We evaluated structural volumes and connectivity using graph theoretical analysis in patients with cluster headache. Ten patients with episodic cluster headache were recruited, who had a normal brain MRI on visual inspection. We also enrolled a control group of 20 healthy volunteers. All of the participants underwent 3-D volumetric T1-weighted imaging. We obtained the structural volumes using FreeSurfer image analysis and performed structural global and local connectivity analysis using BRAPH. The volumes of the left caudal anterior cingulate and postcentral gyrus were decreased in the patients with cluster headache compared to healthy individuals. In addition, in the measures of local structural connectivity, there was significant hub re-organization in the patients with cluster headache; the strength of the right frontopolar, left pericalcarine, and left posterior cingulate gyrus, the betweenness centrality of the right precentral and left pericalcarine gyrus, and the closeness centrality of the left pericalcarine and left posterior cingulate gyrus were decreased. Whereas the betweenness centrality of the right rostral middle frontal and left inferior temporal gyrus were increased in the patients with cluster headache. However, the measures of global structural connectivity were not different between the patients with cluster headache and healthy individuals. We demonstrate that the structural volumes and connectivity in patients with cluster headache are significantly different from those in healthy controls, especially revealing hub re-organization. These alterations are implicated in the pathogenesis of cluster headache and suggest that cluster headache is a network disease.

Sphenopalatine ganglion block: an external gate to modulate cardiac autonomic tone and suppress premature ventricular beats?

Background

Autonomic modulation is used for treating various cardiovascular diseases, such as cardiac arrhythmias. Sphenopalatine ganglion (SPG) block is an easy, non-invasive therapy for migraine with a potential cardiovascular impact that remains unclear. In this study, we sought to assess the effect of SPG block on cardiac autonomic tone, as expressed by heart rate variability (HRV), and on ventricular arrhythmogenesis.

Methods

Forty patients (14 male and 26 female) suffering from migraine were randomized by 1:1 to SPG block or placebo (controls) and HRV parameters were evaluated 1 hour before and hourly after the intervention. Twenty-four additional patients (11 men and 13 women) with premature ventricular contractions (PVCs) from the right ventricular outflow tract underwent the same randomization and the number of PVCs was assessed during 1 hour before and every hour after treatment. Values were summarized as median (1st-3rd quartile).

Results

During the first four hours after SPG block, an increase in mean RR [883 (IQR, 869-948) vs. 839 (IQR, 806-887) ms at baseline, P<0.01], SDNN [64 (IQR, 59-69) vs. 51 (IQR, 47-55) ms, P<0.01], SDANN [39 (IQR, 36-43) vs. 27 (IQR, 22-29) ms, P<0.01], ASDNN [51 (IQR, 47-53) vs. 40 (IQR, 37-44) ms, P<0.01], rMSSD [30 (IQR, 27-32) vs. 25 (IQR, 23-27) ms, P<0.01], VLF [26 (IQR, 24-29) vs. 23 (IQR, 22-25) ms², P<0.01] and HF [14 (IQR, 11-16) vs. 11 (IQR, 9-12) ms², P<0.01], along with a decrease in LF/HF ratio [1.7 (IQR, 1.4-1.9) vs. 2.0 (IQR, 1.7-2.5), P<0.01] was observed in patients with migraine. In patients with PVCs, the number of ectopic ventricular beats per hour was decreased for the first five hours following SPG block [360 (IQR, 264-850) from 956 (IQR, 545-1,412), P<0.001]. No such differences were observed in controls.

Conclusions

SPG block is associated with a transient increase in those HRV parameters that mainly express parasympathetic activity. It is also followed by a significant decrease in ventricular arrhythmic burden. These findings imply an effect on cardiac autonomic tone with a potential favorable clinical impact on arrhythmogenesis.

Peripheral provocation of cranial autonomic symptoms is not sufficient to trigger cluster headache attacks

Background

Recently it has been suggested that low frequency stimulation of the sphenopalatine ganglion (SPG) may provoke cluster-like attacks in cluster headache (CH) patients. The question arises whether a robust activation of cranial autonomic symptoms is sufficient to trigger CH attacks.

Methods

Kinetic oscillation stimulation (KOS) of the nasal mucosa generates ipsilateral marked autonomic symptoms, among which lacrimation is quantitatively measurable. KOS was applied to 29 CH-patients, including both episodic and chronic course. We measured lacrimation at rest and during stimulation, and assessed CH attacks within 24 hours after the experiment.

Results

Autonomic symptoms including lacrimation were robust and significantly generated, compared to rest. Six patients were lost to follow-up, but did not develop an attack during their stay in the clinic. Of the remaining 23 patients, none developed an attack in the next 4 hours after stimulation, despite marked cranial autonomic symptoms during stimulation.

Discussion

Peripheral stimulation close to the SPG generated a strong parasympathetic response. However, this stimulation was not sufficient to induce CH attacks, which suggests that a central component is crucial to attack generation.

Current and novel insights into the neurophysiology of migraine and its implications for therapeutics

Migraine headache and its associated symptoms have plagued humans for two millennia. It is manifest throughout the world, and affects more than 1/6 of the global population. It is the most common brain disorder, and is characterized by moderate to severe unilateral headache that is accompanied by vomiting, nausea, photophobia, phonophobia, and other hypersensitive symptoms of the senses. While there is still a clear lack of understanding of its neurophysiology, it is beginning to be understood, and it seems to suggest migraine is a disorder of brain sensory processing, characterized by a generalized neuronal hyperexcitability. The complex symptomatology of migraine indicates that multiple neuronal systems are involved, including brainstem and diencephalic systems, which function abnormally, resulting in premonitory symptoms, ultimately evolving to affect the dural trigeminovascular system, and the pain phase of migraine. The migraineur also seems to be particularly sensitive to fluctuations in homeostasis, such as sleep, feeding and stress, reflecting the abnormality of functioning in these brainstem and diencephalic systems. Implications for therapeutic development have grown out of our understanding of migraine neurophysiology, leading to major drug classes, such as triptans, calcitonin gene-related peptide receptor antagonists, and 5-HT1F receptor agonists, as well as neuromodulatory approaches, with the promise of more to come. The present review will discuss the current understanding of the neurophysiology of migraine, particularly migraine headache, and novel insights into the complex neural networks responsible for associated neurological symptoms, and how interaction of these networks with migraine pain pathways has implications for the development of novel therapeutics.

Pathophysiology of Migraine: A Disorder of Sensory Processing

Plaguing humans for more than two millennia, manifest on every continent studied, and with more than one billion patients having an attack in any year, migraine stands as the sixth most common cause of disability on the planet. The pathophysiology of migraine has emerged from a historical consideration of the "humors" through mid-20th century distraction of the now defunct Vascular Theory to a clear place as a neurological disorder. It could be said there are three questions: why, how, and when? Why: migraine is largely accepted to be an inherited tendency for the brain to lose control of its inputs. How: the now classical trigeminal durovascular afferent pathway has been explored in laboratory and clinic; interrogated with immunohistochemistry to functional brain imaging to offer a roadmap of the attack. When: migraine attacks emerge due to a disorder of brain sensory processing that itself likely cycles, influenced by genetics and the environment. In the first, premonitory, phase that precedes headache, brain stem and diencephalic systems modulating afferent signals, light-photophobia or sound-phonophobia, begin to dysfunction and eventually to evolve to the pain phase and with time the resolution or postdromal phase. Understanding the biology of migraine through careful bench-based research has led to major classes of therapeutics being identified: triptans, serotonin 5-HT1B/1D receptor agonists; gepants, calcitonin gene-related peptide (CGRP) receptor antagonists; ditans, 5-HT1F receptor agonists, CGRP mechanisms monoclonal antibodies; and glurants, mGlu5 modulators; with the promise of more to come. Investment in understanding migraine has been very successful and leaves us at a new dawn, able to transform its impact on a global scale, as well as understand fundamental aspects of human biology.

A novel translational animal model of trigeminal autonomic cephalalgias

OVERVIEW

Trigeminal autonomic cephalalgias (TACs) are highly disabling primary headache disorders that involve severe unilateral head pain coupled with significant lateralized cranial autonomic features. Our understanding of these disorders and the development of novel and more effective treatments has been limited by the lack of a suitable animal model to explore their pathophysiology and screen prospective treatments.

DISCUSSION

This review details the development of a novel preclinical model that demonstrates activation of both the trigeminovascular system and parasympathetic projections, thought to be responsible for the severe head pain and autonomic symptoms.

CONCLUSION

This model demonstrates a unique response to TAC specific treatments and highlights the importance of the cranial parasympathetic pathway to the pathophysiology of TACs and as a potential locus of action for treatments. The development of this model opens up opportunities to understand the pathophysiology of these disorders further, the likely involvement of the hypothalamus, as well as providing a preclinical model with which to screen novel compounds.

AVP-825 breath-powered intranasal delivery system containing 22 mg sumatriptan powder vs 100 mg oral sumatriptan in the acute treatment of migraines (The COMPASS study): a comparative randomized clinical trial across multiple attacks

OBJECTIVE

The objective of this study was to compare the efficacy, tolerability, and safety of AVP-825, an investigational bi-directional breath-powered intranasal delivery system containing low-dose (22 mg) sumatriptan powder, vs 100 mg oral sumatriptan for acute treatment of migraine in a double-dummy, randomized comparative efficacy clinical trial allowing treatment across multiple migraine attacks.

BACKGROUND

In phases 2 and 3, randomized, placebo-controlled trials, AVP-825 provided early and sustained relief of moderate or severe migraine headache in adults, with a low incidence of triptan-related adverse effects.

METHODS

This was a randomized, active-comparator, double-dummy, cross-over, multi-attack study (COMPASS; NCT01667679) with two ≤12-week double-blind periods. Subjects experiencing 2-8 migraines/month in the past year were randomized 1:1 using computer-generated sequences to AVP-825 plus oral placebo tablet or an identical placebo delivery system plus 100 mg oral sumatriptan tablet for the first period; patients switched treatment for the second period in this controlled comparative design. Subjects treated ≤5 qualifying migraines per period within 1 hour of onset, even if pain was mild. The primary end-point was the mean value of the summed pain intensity differences through 30 minutes post-dose (SPID-30) using Headache Severity scores. Secondary outcomes included pain relief, pain freedom, pain reduction, consistency of response across multiple migraines, migraine-associated symptoms, and atypical sensations. Safety was also assessed.

RESULTS

A total of 275 adults were randomized, 174 (63.3%) completed the study (ie, completed the second treatment period), and 185 (67.3%) treated at least one migraine in both periods (1531 migraines assessed). There was significantly greater reduction in migraine pain intensity with AVP-825 vs oral sumatriptan in the first 30 minutes post-dose (least squares mean SPID-30 = 10.80 vs 7.41, adjusted mean difference 3.39 [95% confidence interval 1.76, 5.01]; P < .001). At each time point measured between 15 and 90 minutes, significantly greater rates of pain relief and pain freedom occurred with AVP-825 treatment compared with oral sumatriptan. At 2 hours, rates of pain relief and pain freedom became comparable; rates of sustained pain relief and sustained pain freedom from 2 to 48 hours remained comparable. Nasal discomfort and abnormal taste were more common with AVP-825 vs oral sumatriptan (16% vs 1% and 26% vs 4%, respectively), but ∼90% were mild, leading to only one discontinuation. Atypical sensation rates were significantly lower with AVP-825 than with conventional higher dose 100 mg oral sumatriptan.

CONCLUSIONS

AVP-825 (containing 22 mg sumatriptan nasal powder) provided statistically significantly greater reduction of migraine pain intensity over the first 30 minutes following treatment, and greater rates of pain relief and pain freedom within 15 minutes, compared with 100 mg oral sumatriptan. Sustained pain relief and pain freedom through 24 and 48 hours was achieved in a similar percentage of attacks for both treatments, despite substantially lower total systemic drug exposure with AVP-825. Treatment was well tolerated, with statistically significantly fewer atypical sensations with AVP-825.

Is sinus disease the cause of my headaches? An update on sinus disease and headache

The interplay between head pain caused by sinus disease and primary headaches is complex. Classification of secondary headaches, attributed to disorders of the nose or paranasal sinuses has been recently updated. New treatments including office- based procedures are emerging for patients with chronic sinusitis. This paper briefly reviews sinus disease and headache.

A randomized, double-blind, placebo-controlled study of breath powered nasal delivery of sumatriptan powder (AVP-825) in the treatment of acute migraine (The TARGET Study)

Objective

To evaluate the efficacy and safety of AVP-825, a drug–device combination of low-dose sumatriptan powder (22 mg loaded dose) delivered intranasally through a targeted Breath Powered device vs an identical device containing lactose powder (placebo device) in the treatment of migraine headache.

Background

Early treatment of migraine headaches is associated with improved outcome, but medication absorption after oral delivery may be delayed in migraineurs because of reduced gastric motility. Sumatriptan powder administered with an innovative, closed-palate, Bi-Directional, Breath Powered intranasal delivery mechanism is efficiently absorbed across the nasal mucosa and produces fast absorption into the circulation. Results from a previously conducted placebo-controlled study of AVP-825 showed a high degree of headache relief with an early onset of action (eg, 74% AVP-825 vs 38% placebo device at 1 hour, P < .01).

Methods

In this double-blind, placebo-controlled, parallel-group study in adults with a history of migraine with or without aura, participants were randomized via computer-generated lists to AVP-825 or placebo device to treat a single migraine headache of moderate or severe intensity. The primary endpoint was headache relief (defined as reduction of headache pain intensity from severe or moderate migraine headache to mild or none) at 2 hours post-dose.

Results

Two hundred and thirty patients (116 AVP-825 and 114 placebo device) were randomized, of whom 223 (112 and 111, respectively) experienced a qualifying migraine headache (their next migraine headache that reached moderate or severe intensity). A significantly greater proportion of AVP-825 patients reported headache relief at 2 hours post-dose compared with those using the placebo device (68% vs 45%, P = .002, odds ratio 2.53, 95% confidence interval [1.45, 4.42]). Between-group differences in headache relief were evident as early as 15 minutes, reached statistical significance at 30 minutes post-dose (42% vs 27%, P = .03), and were sustained at 24 hours (44% vs 24%, P = .002) and 48 hours (34% vs 20%, P = .01). Thirty-four percent of patients treated with AVP-825 were pain-free at 2 hours compared with 17% using the placebo device (P = .008). More AVP-825 patients reported meaningful pain relief (patient interpretation) of migraine within 2 hours of treatment vs placebo device (70% vs 45%, P < .001), and fewer required rescue medication (37% vs 52%, P = .02). Total migraine freedom (patients with no headache, nausea, phonophobia, photophobia, or vomiting) reached significance following treatment with AVP-825 at 1 hour (19% vs 9%; P = .04). There were no serious adverse events (AEs), and no systemic AEs occurred in more than one patient. Chest pain or pressure was not reported, and only one patient taking AVP-825 reported mild paresthesia. No other triptan sensations were reported.

Conclusions

Targeted delivery of a low-dose of sumatriptan powder via a novel, closed-palate, Breath Powered, intranasal device (AVP-825) provided fast relief of moderate or severe migraine headache in adults that reached statistical significance over placebo by 30 minutes. The treatment was well tolerated with a low incidence of systemic AEs.

The nasal approach to delivering treatment for brain diseases: an anatomic, physiologic, and delivery technology overview

The intricate pathophysiology of brain disorders, difficult access to the brain, and the complexity and high risks and costs of drug development represent major hurdles for improving therapies. Nose-to-brain drug transport offers an attractive alternative or addition to formulation-only strategies attempting to enhance drug penetration into the CNS. Although still a matter of controversy, many studies in animals claim direct nose-to-brain transport along the olfactory and trigeminal nerves, circumventing the traditional barriers to CNS entry. Some clinical trials in man also suggest nose-to-brain drug delivery, although definitive proof in man is lacking. This review focuses on new nasal delivery technologies designed to overcome inherent anatomical and physiological challenges and facilitate more efficient and targeted drug delivery for CNS disorders.

Neurochemical classification and projection targets of CART peptide immunoreactive neurons in sensory and parasympathetic ganglia of the head

The aims of the present study were to determine if there is neuronal Cocaine and amphetamine regulated transcripts (CART) peptide expression (CART+) in parasympathetic (sphenopalatine (SPG); otic (OG)) and sensory (trigeminal (TG)) ganglia of the head and to examine the neurochemical phenotype (calcitonin gene-related peptide (CGRP), neurofilament 200 (NF200), isolectin B4 (IB4) binding, vasoactive intestinal peptide (VIP), neuropeptide Y (NPY) and enkephalin (ENK) immunoreactivity) and projection targets (lacrimal gland (LG), parotid gland (PG), nasal mucosa (NM), temporomandibular joint (TMJ), middle cerebral artery (MCA) and middle meningeal artery (MMA)) of CART expressing neurons in these ganglia. We found CART+ neurons in both the SPG (5.25±0.07%) and OG (4.32±0.66). A significant proportion of these CART+ neurons contained VIP, NPY or ENK (34%, 26% and 11%, respectively). SPG neurons retrogradely labelled from the lacrimal gland (29%) were CART+, but we were unable to demonstrate CART+ labelling in any of the SPG or OG neurons labelled from other targets. This supports a role for CART peptides in lacrimation or regulation of vascular tone in the lacrimal gland, but not in salivation or nasal congestion. CART+ neurons were also present in the trigeminal ganglion (1.26±0.38%), where their size distribution was confined almost completely to neurons smaller than 800 μm2 (mean=410 μm2; 98%<800 μm2), and were almost always CGRP+, but did not bind IB4. This is consistent with a role for CART peptides in trigeminal pain. However, there were few CART+ neurons amongst any of the trigeminal neurons retrogradely labelled from the targets we investigated and thus we cannot comment on the tissue type where such pain may have originated. Our study shows that some specialization of CART peptide expression (based on neurochemical phenotype and target projection) is evident in sensory and parasympathetic ganglia of the head.

Peripheral targets of 5-HT(1D) receptor immunoreactive trigeminal ganglion neurons

OBJECTIVE

The aim of the current study was to determine the proportion of trigeminal primary afferent neurons that innervate the intracranial vasculature, and other craniofacial tissues, that are also 5 hydroxy triptamine (5-HT)(1D) receptor immunoreactive.

METHODS

Retrograde tracing and immunohistochemistry was used to identify 5-HT(1D) receptor labeled trigeminal primary afferent neurons that innervate the lacrimal gland (n = 3 animals), nasal mucosa (n = 3 animals), and the intracranial vasculature (middle meningeal artery in the dura [n = 3 animals] and middle cerebral artery [n = 3 animals]).

RESULTS

The percentage of neurons that were 5-HT(1D) receptor immunoreactive was greater for primary afferent neurons innervating the middle meningeal artery (41.8 ± 1%) than those innervating the middle cerebral artery (28.4 ± 0.8%), nasal mucosa (25.6 ± 1%), or lacrimal gland (23.5 ± 3%). For each retrograde labeled population, the 5-HT(1D) receptor immunoreactive cells were among the smallest of the retrograde labeled cells.

CONCLUSIONS

These findings provide a basis for understanding the role of 5-HT(1D) receptor agonists (eg, triptans) in the treatment of primary vascular headaches and suggest that the selectivity of triptans in the treatment of these headaches does not appear to result from specific localization of the 5-HT(1D) receptor to trigeminovascular neurons alone.