Anett Csáti

Prophylactic Drug Treatment of Migraine in Children and Adolescents: An Update

Migraine as a highly disabling pain condition influences the daily activities of those affected, including children and adolescents. The pathomechanism of migraine is not fully understood, and the different types of prophylactic antimigraine drugs that are applied are not specific for migraine. There is a need for preventive treatment in the event of frequent migraine attacks, an impairment of the quality of life, severe accompanying or aura symptoms, and the failure of acute drug treatment. The following pharmacological classes are recommended: antidepressants, antiepileptics, antihistamines, beta-adrenergic receptor blockers, and calcium ion channel antagonists, besides onabotulinum toxin A and nutraceuticals (butterbur). The most urgent goal as concerns pharmaceutical innovation is the development of pathomechanism-based antimigraine drugs and personalized therapy tailored to the children and adolescents.

Migraine and neuropeptides

Migraine is a common disabling neurovascular primary headache disorder. The pathomechanism is not clear, but extensive preclinical and clinical studies are ongoing. The structural basis of the leading hypothesis is the trigeminovascular system, which includes the trigeminal ganglion, the meningeal vasculature, and the distinct nuclei of the brainstem, the thalamus and the somatosensory cortex. This review covers the effects of sensory (calcitonin gene-related peptide, pituitary adenylate cyclase-activating polypeptide and substance P), sympathetic (neuropeptide Y) and parasympathetic (vasoactive intestinal peptide) migraine-related neuropeptides and the functions of somatostatin, nociceptin and the orexins in the trigeminovascular system. These neuropeptides may take part in neurogenic inflammation (plasma protein extravasation and vasodilatation) of the intracranial vasculature and peripheral and central sensitization of the trigeminal system. The results of human clinical studies are discussed with regard to the alterations in these neuropeptides in the plasma, saliva and cerebrospinal fluid during or between migraine attacks, and the therapeutic possibilities involving migraine-related neuropeptides in the acute and prophylactic treatment of migraine headache are surveyed.

Calcitonin gene-related peptide and its receptor components in the human sphenopalatine ganglion - Interaction with the sensory system.

Clinical studies have suggested a link between the sensory trigeminal system and the parasympathetic ganglia. Calcitonin gene-related peptide (CGRP) is a sensory neuropeptide which plays an important role in vasodilatation and pain transmission in craniocervical structures. The present study was designed to examine if CGRP and CGRP receptor components are present in the human sphenopalatine ganglion (SPG) in order to reveal an interaction between the sensory and parasympathetic systems. Indirect immunofluorescence technique was used for immunohistochemical demonstration of CGRP, the calcitonin receptor-like receptor (CLR) and the receptor activity modifying protein 1 (RAMP1) in human and rat SPG. Cryostat sections were examined and images were obtained using a light- and epifluorescence microscope coupled to a camera to visualize co-labeling by superimposing the digital images. In addition, Western blot technique was used to demonstrate the existence of CGRP receptor components in rat SPG. CGRP immunoreactive fibers were frequently found intraganglionic in the SPG in the vicinity of neurons. CLR immunoreactivity was observed in satellite glial cells (SGCs) as well as in nerve fibers, but not in neurons. RAMP1 immunoreactivity was localized in many neurons and SGCs. Thus, the two CGRP receptor components together were found in the SGCs. In addition, Western blot revealed the presence of RAMP1 and CLR in rat SPG. Our results suggest a possible sensory influence in the parasympathetic cranial ganglia. The sensory CGRP-containing fibers probably originate in the trigeminal ganglion, project to the SPG and act on CGRP receptors on SGCs.

Where does a migraine attack originate? In the brainstem

Migraine is a common, paroxysmal, highly disabling primary headache disorder. The origin of migraine attacks is enigmatic. Numerous clinical and experimental results suggest that the activation of distinct brainstem nuclei is crucial in its pathogenesis, but the primary cause of this activation is not fully understood. We conclude that the initialization of a migraine attack can be explained as an altered function of the neuronal elements of the brainstem nuclei. In light of our findings and the literature data, we can assume that migraine is a subcortical disorder of a specific brainstem area.

Drug safety and tolerability in prophylactic migraine treatment

Introduction: Migraine is a frequent, disabling primary headache disorder, whose pathomechanism is not yet fully understood. Prophylactic treatment is advisable for migraineurs with severe or highly frequent attacks, which impair the quality of life. Areas covered: The different types of prophylactic migraine drugs are discussed, with particular regard to potential adverse effects and safety issues. β-Adrenergic blockers, antiepileptic drugs and calcium-channel blockers are drugs widely used for migraine prevention, whereas complementary medicine and onabotulinumtoxin A can be used in selected cases. Expert opinion: The background of the recurrence and chronification of migraine attacks has not been fully clarified, and causative preventive therapy is therefore not currently available. The tolerability and adverse effects of the currently used medications often limit their use. β-Adrenergic receptor blockers may induce adverse cardiovascular events, whereas flunarizine is frequently associated with a weight gain and depression. As most migraine sufferers are young women of child-bearing age, the use of valproate is limited. Topiramate is associated with central nervous system-related side effects. There is a need for future development of pathomechanism-based preventive drugs, and personalized therapy tailored to the patient.

CGRP antagonists and antibodies for the treatment of migraine

Introduction: Migraine is a highly devastating neurovascular disorder that affects up to 16% of the population worldwide. In spite of intensive research, its origin remains enigmatic with no therapeutic option appropriate for all migraine patients. One of the leading hypotheses is related to the function of the calcitonin gene-related peptide (CGRP). Regardless, the pharmaceutical options currently applied for the acute and prophylactic treatment of migraine are not appropriate for all migraine patients. Areas covered: This article is based on a literature review using the PubMed database and highlights the CGRP theory of the pathomechanism of migraine. Expert opinion: Since migraine is a CGRP-related disorder, it appeared obvious to develop CGRP receptor antagonists that exert high efficacy, both intravenously and orally. Unfortunately, the frequent use of these antagonists results in an elevated liver transaminase level. In an attempt to bypass these harmful side effects, efforts should be made to modify these pharmacons. The use of fully humanized monoclonal antibodies (mAbs) that target CGRP and its receptors may also be possible. However, while Phase I and II clinical trials are promising, a long-term follow-up of these therapies is still needed.

Treatment of Chronic Migraine with OnabotulinumtoxinA: Mode of Action, Efficacy and Safety.

Background: Chronic migraine is a common, highly disabling, underdiagnosed and undertreated entity of migraine. It affects 0.9%–2.2% of the general adult population. The present paper overviews the preclinical and clinical data regarding the therapeutic effect of onabotulinumtoxinA in chronic migraineurs. Methods: A literature search was conducted in the database of PubMed up to 20 May 2015 for articles related to the pathomechanism of chronic migraine, the mode of action, and the efficacy, safety and tolerability of onabotulinumtoxinA for the preventive treatment of chronic migraine. Results: The pathomechanism of chronic migraine has not been fully elucidated. The mode of action of onabotulinumtoxinA in the treatment of chronic migraine is suggested to be related to the inhibition of the release of calcitonin gene-related peptide and substance P in the trigeminovascular system. Randomized clinical trials demonstrated that long-term onabotulinumtoxinA fixed-site and fixed-dose (155–195 U) intramuscular injection therapy was effective and well tolerated for the prophylactic treatment of chronic migraine. Conclusions: Chronic migraine is a highly devastating entity of migraine. Its exact pathomechanism is unrevealed. Two-third of chronic migraineurs do not receive proper preventive medication. Recent clinical studies revealed that onabotulinumtoxinA was an efficacious and safe treatment for chronic migraine.

Drug safety in acute migraine treatment

Introduction: A number of drugs are available for acute migraine treatment, but they are not all effective for all patients and all attacks. The safety profiles of migraine drugs limit their use in patients with certain comorbid conditions, and adverse effects may also reduce the level of patient compliance. Areas covered: The different types of acute migraine drugs are discussed, with particular regard to safety issues and potential adverse effects. The frequent use of analgesics, ergot alkaloids and triptans may result in the development of medication overuse headache (MOH). Expert opinion: The initiation of a migraine attack is not fully understood, and therefore treatment aimed at causative factors is currently not available. The tolerability and adverse effects of the drugs available at present often limit their use. NSAIDs are frequently associated with gastrointestinal, and possibly also cardiovascular side effects. Ergot alkaloids may induce arterial vasoconstriction, while the administration of triptans is contraindicated in cardiovascular, cerebrovascular and peripheral vascular diseases. The frequent use of these drugs poses the risk of the development of MOH. There is a need for pathomechanism-based drugs, and for the future achievement of personalized medicine.

Prion diseases: New considerations

The transmissible spongiform encephalopathies, which include Creutzfeldt-Jakob disease, are fatal neurodegenerative disorders caused by the pathological accumulation of abnormal prion protein. The diagnosis of Creutzfeldt-Jakob disease is complex. The electroencephalogram, magnetic resonance imaging, lumbar puncture and genetic testing findings can help in the differential diagnosis of rapidly progressive dementia. There has recently been considerable debate as to whether proteins involved in the development of neurodegenerative diseases should be regarded as prions or only share prion-like mechanisms. Two recent reports described the detection of abnormal prion protein in the nasal mucosa and urine of patients with Creutzfeldt-Jakob disease. These findings raise major health concerns regarding the transmissibility of human prion diseases. We set out to address this neurological hot topic and to draw conclusions on the basis of what is known in the literature thus far.

Novel Kynurenic Acid Analogues in the Treatment of Migraine and Neurodegenerative Disorders: Preclinical Studies and Pharmaceutical Design

Though migraine and neurodegenerative disorders have a high socioeconomic impact, their therapeutic management has not been fully addressed. Their pathomechanisms are not completely understood, but glutamateinduced excitotoxicity, mitochondrial disturbances and oxidative stress all seem to play crucial roles. The overactivation of glutamate receptors contributes to the hyperexcitability observed in migraine and also to the neurodegenerative process. The kynurenine pathway of the tryptophan metabolism produces the only known endogenous Nmethyl- D-aspartate receptor antagonist, kynurenic acid, which has been proven in different preclinical studies to exert a neuroprotective effect. Influencing the kynurenine pathway might be beneficial in migraine and neurodegenerative diseases, and in the normalization of glutamatergic neurotransmission and the prevention of excitotoxic neuronal damage. The synthesis of kynurenic acid analogues may offer a valuable tool for drug development.