Effects of Chronic Sumatriptan and Zolmitriptan Treatment on 5-HT1 Receptor Expression and Function in Rats

[Medication overuse headache]

Medication overuse headache (MOH) is a globally prevalent and debilitating condition that results from excessive use of acute therapies and can significantly affect quality of life, despite the fact that simple information about the causes and consequences of the condition can help prevent or stop MOH. In recent years, many new insights have been gained into headaches caused by medication overuse. In addition, the diagnostic criteria and guideline recommendations have changed considerably. This article provides a comprehensive overview of the clinic, definition/classification, epidemiology, risk factors, pathophysiology, controversies, prevention, and treatment of MOH.

Medication "underuse" headache

BACKGROUND

Many risk factors have been associated with migraine progression, including insufficient and ineffective utilization of migraine medications; however, they have been inadequately explored. This has resulted in suboptimal usage of medications without effective altering of prescribing recommendations for patients, posing a risk for migraine chronification.

METHODS

Our aim is to conduct a comprehensive review of the available evidence regarding the underuse of migraine medications, both acute and preventive. The term "underuse" includes, but is not limited to: (1) ineffective use of appropriate and inappropriate medication; (2) underutilization; (3) inappropriate timing of usage; and (4) patient dissatisfaction with medication.

RESULTS

The underuse of both acute and preventive medications has been shown to contribute to the progression of migraine. In terms of acute medication, chronification occurs as a result of insufficient drug use, including failure of the prescriber to select the appropriate type based on pain intensity and disability, patients taking medication too late (more than 60 minutes after the onset or after central sensitization has occurred as evidenced by allodynia), and discontinuation because of lack of effect or intolerable side effects. The underlying cause of inadequate effectiveness of acute medication lies in its inability to halt the propagation of peripheral activation to central sensitization in a timely manner. For oral and injectable preventive migraine medications, insufficient efficacy and intolerable side effects have led to poor adherence and discontinuation with subsequent progression of migraine. The underlying pathophysiology here is rooted in the repetitive stimulation of afferent sensory pain fibers, followed by ascending brainstem pain pathways plus dysfunction of the endogenous descending brainstem pain inhibitory pathway. Although anti-calcitonin gene-related peptide (CGRP) medications partially address pain caused by the above factors, including decreased efficacy and tolerability from conventional therapy, some patients do not respond well to this treatment. Research suggests that initiating preventive anti-CGRP treatment at an early stage (during low frequency episodic migraine attacks) is more beneficial than commencing it during high frequency episodic attacks or when chronic migraine has begun.

CONCLUSIONS

The term "medication underuse" is underrecognized, but it holds significant importance. Optimal usage of acute care and preventive migraine medications could potentially prevent migraine chronification and improve the treatment of migraine attacks.

The 5-HT1F receptor as the target of ditans in migraine - from bench to bedside

Migraine is a leading cause of disability in more than one billion people worldwide, yet it remains universally underappreciated, even by individuals with the condition. Among other shortcomings, current treatments (often repurposed agents) have limited efficacy and potential adverse effects, leading to low treatment adherence. After the introduction of agents that target the calcitonin gene-related peptide pathway, another new drug class, the ditans - a group of selective serotonin 5-HT_1F receptor agonists - has just reached the international market. Here, we review preclinical studies from the late 1990s and more recent clinical research that contributed to the development of the ditans and led to their approval for acute migraine treatment by the US Food and Drug Administration and the European Medicines Agency.

Gray matter alteration in medication overuse headache: a coordinates-based activation likelihood estimation meta-analysis

Medication overuse headache (MOH) is a prevalent secondary headache, bringing heavy economic burden and neuropsychological damage. Neuroimaging studies on the disease reported divergent results. To merge the reported neuroimaging alterations in MOH patients and explore a pathophysiological mechanism of this disorder. A meta-analytic activation likelihood estimation (ALE) analysis method was used. We systematically searched English and Chinese databases for both morphological and functional neuroimaging studies published before Nov 18, 2021. Reported altered brain regions and the stereotactic coordinates of their peaks were extracted and pooled by GingerALE using Gaussian probability distribution into brain maps, illustrating converged regions of alteration among studies. We identified 927 articles, of which five studies on gray matter changes, using voxel-based morphometry (VBM) were eventually included for ALE analysis, with 344 subjects and 54 coordinates put into GingerALE. No functional magnetic resonance imaging (fMRI) or positron emission topography (PET) studies were included for pooling. Compared with healthy controls (HCs), MOH featured increased gray matter density in midbrain, striatum, cingulate, inferior parietal cortex and cerebellum (P < 0.001 uncorrected), whereas decreased gray matter density in orbitofrontal cortex (P < 0.05, family-wise error), frontal, insular and parietal cortices (P < 0.001 uncorrected). Withdrawal of analgesics led to decreased gray matter density in superior temporal gyrus, cuneus, midbrain and cerebellum (P < 0.001 uncorrected). This meta-analysis confirmed that medication overuse headache is associated with morphologic alteration in the reward system, the prefrontal cortex and a reversible modification in the pain network. Further functional imaging paradigms and longitudinal studies are required for a more definite conclusion and a causal mechanism.

Medication overuse headache and awareness

BACKGROUND

Medication overuse headache (MOH) is the worsening of an underlying headache due to the overuse of its acute treatment. Unintentionally, healthcare professionals may contribute to this condition. Health professionals play an important role in preventing this increasingly frequent and difficult-to-treat condition.

OBJECTIVE

To investigate MOH awareness among physicians with headache through a survey conducted among medical doctors on our university campus.

METHODS

This was an observational cross-sectional study about MOH awareness. The total number of medical doctors working in the Dokuz Eylül University Health Campus was provided by the administrative unit. A total of 18 questions were prepared and administered on a voluntary basis to obtain information about MOH awareness.

RESULTS

A total of 312 medical doctors were surveyed, including 198 (63.5%) from internal medical sciences, 81 (26%) from surgical medical sciences, and 33 (10.5%) from basic medical sciences. Half of the physicians in our sample were unaware of MOH. Our results showed that awareness of MOH, was quite low even among medical doctors.

CONCLUSIONS

MOH causes both labor and financial losses to countries and impairs the quality of life of patients. Preventing excessive use of medications by raising awareness among doctors is an important step to prevent the development of MOH.

A prolactin-dependent sexually dimorphic mechanism of migraine chronification

OBJECTIVE

Determination of possible sex differences in mechanisms promoting migraine progression and the contribution of prolactin and the prolactin long (PRLR-L) and short (PRLR-S) receptor isoforms.

BACKGROUND

The majority of patients with chronic migraine and medication overuse headache are female. Prolactin is present at higher levels in women and increases migraine. Prolactin signaling at the PRLR-S selectively sensitizes nociceptors in female rodents, while expression of the PRLR-L is protective.

METHODS

Medication overuse headache was modeled by repeated sumatriptan administration in male and female mice. Periorbital and hindpaw cutaneous allodynia served as a surrogate of migraine-like pain. PRLR-L and PRLR-S isoforms were measured in the trigeminal ganglion with western blotting. Possible co-localization of PRLR with serotonin 5HT1B and 5HT1D receptors was determined with RNAscope. Cabergoline, a dopamine receptor agonist that inhibits circulating prolactin, was co-administered with sumatriptan. Nasal administration of CRISPR/Cas9 plasmid was used to edit expression of both PRLR isoforms.

RESULTS

PRLR was co-localized with 5HT1B or 5HT1D receptors in the ophthalmic region of female trigeminal ganglion. A single injection of sumatriptan increased serum PRL levels in female mice. Repeated sumatriptan promoted cutaneous allodynia in both sexes but down-regulated trigeminal ganglion PRLR-L, without altering PRLR-S, only in females. Co-administration of sumatriptan with cabergoline prevented allodynia and down-regulation of PRLR-L only in females. CRISPR/Cas9 editing of both PRLR isoforms in the trigeminal ganglion prevented sumatriptan-induced periorbital allodynia in females.

INTERPRETATION

We identified a sexually dimorphic mechanism of migraine chronification that involves down-regulation of PRLR-L and increased signaling of circulating prolactin at PRLR-S. These studies reveal a previously unrecognized neuroendocrine mechanism linking the hypothalamus to nociceptor sensitization that increases the risk of migraine pain in females and suggest opportunities for novel sex-specific therapies including gene editing through nasal delivery of CRISPR/Cas9 constructs.

The Evolution of Medication Overuse Headache: History, Pathophysiology and Clinical Update

Medication overuse headache (MOH), the development or worsening of chronic headache resulting from frequent and excessive intake of medications used for acute treatment of headache, is a common secondary headache disorder and is associated with significant personal and societal burdens. The plausible physiologic mechanism is that chronic exposure to acute care migraine treatment leads to suppression of endogenous antinociceptive systems, consequently facilitating the trigeminal nociceptive process via up-regulation of the calcitonin gene-related peptide (CGRP) system. Recognizing and preventing its development is an integral aspect of migraine management, as medication overuse is a modifiable risk factor in the progression from episodic to chronic migraine. Over the years, MOH has been difficult to treat and has generated much controversy. Ongoing debates exist over the diagnostic criteria and treatment strategies, particularly regarding the roles of formal detoxification and preventive treatment. The arrival of the anti-CGRP monoclonal antibodies has also challenged our views of MOH and its treatment. This review outlines the evolution of MOH diagnostic criteria, presents the current understanding of MOH pathogenesis and discusses the debates over its development and treatment. Data on the efficacy of anti-CGRP monoclonal antibodies in the setting of medication overuse is also presented. These results indicate that patients with medication overuse, who are treated with these new medications, may not need to be detoxified in order to treat MOH. In light of these developments, it is likely that in the future MOH will be more readily diagnosed and treatment will result in better outcomes.

Lasmiditan inhibits calcitonin gene-related peptide release in the rodent trigeminovascular system

Lasmiditan, an antimigraine drug with selective 5-HT_1F receptor affinity, prejunctionally inhibits calcitonin gene-related peptide release in peripheral and central trigeminal nerve terminals of rodents.

Migraine headache pathophysiology involves trigeminovascular system activation, calcitonin gene-related peptide (CGRP) release, and dysfunctional nociceptive transmission. Triptans are 5-HT_1B/1D/(1F) receptor agonists that prejunctionally inhibit trigeminal CGRP release, but their vasoconstrictor properties limit their use in migraine patients with cardiovascular disease. By contrast, lasmiditan is a novel antimigraine and selective 5-HT_1F receptor agonist devoid of vasoconstrictor properties. On this basis, this study has investigated the modulation of trigeminal CGRP release by lasmiditan. For this purpose, we have comparatively analysed the inhibition of several components of the trigeminovascular system induced by lasmiditan and sumatriptan through: ex vivo KCl-induced CGRP release from isolated dura mater, trigeminal ganglion, and trigeminal nucleus caudalis of mice; and in vivo dural vasodilation in the rat closed-cranial window model induced by endogenous (electrical stimulation and capsaicin) and exogenous CGRP. The ex vivo release of CGRP was similarly inhibited by sumatriptan and lasmiditan in all trigeminovascular system components. In vivo, intravenous (i.v.) lasmiditan or higher doses of sumatriptan significantly attenuated the vasodilatory responses to endogenous CGRP release, but not exogenous CGRP effects. These data suggest that lasmiditan prejunctionally inhibits CGRP release in peripheral and central trigeminal nerve terminals. Because lasmiditan is a lipophilic drug that crosses the blood–brain barrier, additional central sites of action remain to be determined.

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

Background

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

Main body

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

Conclusion

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

Acute and chronic triptan exposure neither alters rodent cerebral blood flow nor worsens ischemic brain injury

Although it is still debated whether vasoconstriction underlies migraine resolution by triptans, they are not recommended in patients at cardiovascular risk. However, relationship between stroke incidence and triptan use is unclear, and it is unknown whether acute or chronic use of these drugs worsens ischemic brain injury. To address this issue, we investigated the effect of clinically-relevant doses of the potent cerebral artery vasoconstrictor eletriptan on cerebral blood flow (CBF) and brain infarct volumes, as well as on expression of genes involved in cerebrovascular regulation. We report that acute treatment of rats or mice with eletriptan did not reduce basal CBF, which promptly dropped upon treatment with prazosin or dihydroergotamine. Acute of chronic (1month) eletriptan also did not affect CBF changes and infarct volumes in mice undergoing brain ischemia/reperfusion. Finally, chronic eletriptan reduced brain mRNAs for PACAP and VIP, leaving unaffected those for 5HT1_B/DR and CGRP. No significant transcript changes were found in dura mater. Data suggest that the impact of triptans on cerebral hemodynamic should be re-evaluated, as well as their propensity to increase stroke risk in migraineurs.

Up-regulation of calcitonin gene-related peptide in trigeminal ganglion following chronic exposure to paracetamol in a CSD migraine animal model

Previously, our group has demonstrated that chronic paracetamol (APAP) treatment induces alterations to the trigeminovascular nociceptive system in the cortical spreading depression (CSD) migraine animal model. The calcitonin gene related peptide (CGRP) is a key neuropeptide involved in the activation of the trigeminovascular nociceptive system. Therefore, this study examined the expression levels of CGRP in the trigeminal ganglion (TG) after chronic APAP exposure (0, 15, and 30 days) using a CSD model. Rats were divided into control, CSD only, APAP only and APAP treatment with CSD groups. A single injection (i.p.) of APAP (200 mg/kg body weight) was given to the 0-day APAP-treated groups, while the other APAP-treated groups received daily injections for 15 and 30 days. CSD was induced by the topical application of KCl to the parietal cortex. The protein expression of CGRP in the TG was evaluated by immunohistochemistry, and the CGRP mRNA level was investigated by real-time quantitative reverse transcription polymerase chain reaction. The results revealed that the induction of CSD significantly increased the level of CGRP protein but had no effect on CGRP mRNA level. Pretreatment with APAP 1 hour before CSD activation significantly reduced CGRP expression induced by CSD. In contrast, chronic treatment with APAP (15 and 30 days) significantly enhanced CGRP expression in both protein and mRNA levels when compared with the control groups. In combination with CSD, the expression of CGRP further increased in the animal with 30 day treatment. These findings indicate that chronic treatment with APAP induces an increase of CGRP expression in the TG. This alteration may be associated with the increased trigeminovascular nociception observed in our previous studies.

Medication overuse headache

BACKGROUND

Medication overuse headache (MOH) affects between 1% and 2% of the general population but is present in up to 50% of patients seen in headache centers. There are currently no internationally accepted guidelines for treatment of MOH.

METHODS

A review of the current literature on MOH treatment and pathophysiology.

RESULTS

We conclude that headache frequency can be reduced to episodic headache in more than 50% of the patients by simple detoxification and information. Approximately half the patients will not have need for prophylactic medication after withdrawal. Pain perception is altered in patients with MOH but can be restored to a baseline pattern, indicating a reversible mechanism in the central sensitization leading to chronic pain. The great comorbidity with depression and anxiety could be a consequence of the altered serotonin metabolism indicating a reversible and potentially treatable condition.

CONCLUSION

Increased focus on MOH is extremely important, as MOH both can and should be treated and prevented. MOH is thus a diagnosis that should be considered in all chronic headache patients as the very first step in their management strategy. In the general population, prevention campaigns against MOH are essential to minimize chronic pain disability.

Management of medication-overuse headache

Medication-overuse headache (MOH) has developed into the third most common type of headache after tension-type headache and migraine. The prevalence reaches approximately 1% of the world's population and shows an increasing trend. Many important studies on MOH have been published in the last year, some of which investigated the pathophysiology of headache chronicity, with others focusing on the evaluation of risk factors. The International Headache Society revised its classification criteria on MOH. Several large population-based longitudinal studies clearly demonstrated that overuse of any kind of acute headache medication is the main risk factor leading to the development of chronic headache. Management of MOH remains difficult; the only effective treatment concept is consequent withdrawal therapy.

Medication-overuse headache

PURPOSE OF REVIEW

Medication-overuse headache (MOH) is a well described clinical entity. There is a growing body of knowledge on the epidemiology of MOH, risk factors, and treatment strategies.

RECENT FINDINGS

The International Headache Society updated the classification criteria for MOH. Population-based studies provided an insight into the prevalence and peculiarities of MOH patients in eastern Europe and Asia. Large-scaled population-based longitudinal studies made it possible to analyze risk factors leading to the development of MOH. Imaging studies helped to better understand the pathophysiology of headache chronicity. New treatment strategies have been suggested.

SUMMARY

MOH is a common headache disorder and a serious public health problem all over the world. Although the treatment regimen for MOH patients is straightforward and the outcomes are favorable, it is time now to move forward and establish a predictive model for early recognition of patients at high risk, to intervene early and avoid development of chronic headache.

Decrease of gray matter volume in the midbrain is associated with treatment response in medication-overuse headache: possible influence of orbitofrontal cortex

Patients with chronic daily headache and overuse of analgesics, triptans, or other acute headache compounds, are considered to suffer from medication-overuse headache (MOH). This implies that medication overuse is the cause of headache chronification. It remains a key question why only two-thirds of patients with chronic migraine-like headache and overuse of pain medication improve after detoxification, whereas the remainder continue to have chronic headache. In the present longitudinal MRI study, we used voxel-based morphometry to investigate gray matter changes related to medication withdrawal in a group of humans with MOH. As a main result, we found that only patients with significant clinical improvement showed a significant decrease of previously increased gray matter in the midbrain including periaqueductal gray matter and nucleus cuneiformis, whereas patients without improvement did not. Patients without treatment response had less gray matter in the orbitofrontal cortex. Another striking result is the correlation of treatment response with the amount of orbitofrontal gray matter. Thus, we demonstrate adaptive gray matter changes within the pain modulatory system in patients with MOH who responded to detoxification, probably reflecting neuronal plasticity. Decreased gray matter in the orbitofrontal cortex at baseline may be predictive of poor response to treatment.

Pathophysiology of medication overuse headache--an update

The pathogenesis of medication overuse headache is unclear. Clinical and preclinical studies have consistently demonstrated increased excitability of neurons in the cerebral cortex and trigeminal system after medication overuse. Cortical hyperexcitability may facilitate the development of cortical spreading depression, while increased excitability of trigeminal neurons may facilitate the process of peripheral and central sensitization. These changes may be secondary to the derangement of central, probably serotonin (5-HT)-, and perhaps endocannabinoid-dependent or other, modulating systems. Increased expression of excitatory cortical 5-HT2A receptors may increase the susceptibility to developing cortical spreading depression, an analog of migraine aura. A reduction of diffuse noxious inhibitory controls may facilitate the process of central sensitization, activate the nociceptive facilitating system, or promote similar molecular mechanisms to those involved in kindling. Low 5-HT levels also increase the expression and release of calcitonin gene-related peptide from the trigeminal ganglion and sensitize trigeminal nociceptors. Thus, derangement of central modulation of the trigeminal system as a result of chronic medication use may increase sensitivity to pain perception and foster or reinforce medication overuse headache.

Medication overuse headaches

“An ounce of prevention is worth a pound of cure” in the management of MOH. Prevention of transformation of primary headache types to their chronic counterparts is necessary to prevent this most troubling transformation. Strict attention to what patients are telling you (and often times not telling you) about their episodic headaches will enable pharmacologic and nonpharmacologic measures to avoid that transformation to chronic daily headache, so often associated with MOH. Once MOH becomes manifest, withdrawal of the overused drug is mandatory; otherwise experience tells us the pattern of overuse will only be perpetuated and no measure will help alleviate the headache. At the same time, as detoxification takes place, measures to ensure that relapse will not take place should begin. These efforts include prophylactic pharmacologic measures as well as psychological support, education, and surveillance to prevent relapses. The rate of relapse is unfortunately high, but these general and specific measures enumerated above will add greatly to the chances of success.

Modulation of central sensitisation by detoxification in MOH: results of a 12-month detoxification study

BACKGROUND

Human and animal models suggest that central sensitisation plays a role in medication-overuse headache (MOH). We aimed to study pain perception in MOH patients before and a year after withdrawal.

METHODS

We examined pain perception in 35 MOH patients before and two, six and 12 months after detoxification. For baseline comparison, we tested 40 healthy controls. We measured cephalic and extra-cephalic pressure-pain thresholds and supra-threshold pressure-pain scores and extra-cephalic pain thresholds, supra-threshold pain scores and temporal summation for electrical stimulation.

RESULTS

Of the 35 patients, 21 patients completed the entire study and remained cured of MOH. Statistically significant differences between patients and healthy controls were found in cephalic pressure-pain thresholds (137.3 kPa vs. 170 kPa, P < 0.05), extra-cephalic pressure pain thresholds (213.3 vs. 274.3 kPa, P < 0.05), in cephalic supra-threshold pressure-pain scores measured on a 100 mm visual analogue scale (61 vs. 27 mm, P < 0.05) and extra-cephalic supra-threshold pain scores for electrical stimulation (19.0 vs. 10.0 mm, P < 0.05). Cephalic supra-threshold pain scores decreased statistically significantly from 50.3 mm at baseline to 28.0 mm at the 12-month follow-up. In contrast to controls, temporal summation was not found in MOH patients before withdrawal, but after detoxification temporal summation normalised.

CONCLUSION

The central nervous system is sensitised in patients with MOH. For the first time we demonstrate that the pain perception continues to normalise up to a year after detoxification. This emphasises the importance of detoxification and follow-up to prevent relapse.

Prevalence of medication overuse headache in an interdisciplinary pain clinic

Background

Medication overuse headache (MOH) has been recognized as an important problem in headache patients although the pathophysiological mechanisms remain unclear. The diagnosis of MOH is based on clinical characteristics defined by the International Headache Society. The aim was the evaluation of the diagnostic criteria of MOH in a mixed population of chronic pain patients to gain information about the prevalence and possible associations with MOH.

Methods

Data of all patients referred to the interdisciplinary pain clinic at the University Hospital of Zurich between September 2005 and December 2007 were retrospectively analyzed. Demographic data (age, sex, history of migration), as well as data about duration of pain disease, category of pain disease (neurological, psychiatric, rheumatologic, other), use of medication, history of trauma, and comorbidity of depression and anxiety have been collected.

Results

Totally 178 of 187 consecutive chronic pain patients were included in the study. A total of 138 patients (78%) used analgesics on 15 or more days per month. Chronic headache was more prevalent among patients with analgesic overuse (39.8%) than without analgesic overuse (18%). The prevalence of MOH was 29%. The odds ratio (OR) for a patient with medication overuse to have chronic headache was 13.1 if he had a history of primary headache, compared to a patient without a primary headache syndrome. Furthermore, history of headache (OR 2.5, CI [1.13;5.44]), history of migration (OR 2.9, CI [1.31;6.32]) and comorbid depression (OR 3.5, CI [1.46;8.52]) were associated with overuse of acute medication, in general.

Conclusions

Primary headaches have a high risk for chronification in patients overusing analgesics for other pain disorders. Whereas history of headache, history of migration and comorbidity of depression are independentely associated with analgesic overuse in this group of patients.

Zolmitriptan: a novel portal hypotensive agent which synergizes with propranolol in lowering portal pressure

OBJECTIVE

Only a limited proportion of patients needing pharmacological control of portal hypertension are hemodynamic responders to propranolol. Here we analyzed the effects of zolmitriptan on portal pressure and its potential interaction with propranolol.

METHODS

ZOLMITRIPTAN, PROPRANOLOL OR BOTH WERE TESTED IN TWO RAT MODELS OF PORTAL HYPERTENSION: common bile duct ligation (CBDL) and CCl4-induced cirrhosis. In these animals we measured different hemodynamic parameters including portal venous pressure, arterial renal flow, portal blood flow and cardiac output. We also studied the changes in superior mesenteric artery perfusion pressure and in arterial wall cAMP levels induced by zolmitriptan, propranolol or both. Moreover, we determined the effect of splanchnic sympathectomy on the response of PVP to zolmitriptan.

RESULTS

In both models of portal hypertension zolmitriptan induced a dose-dependent transient descent of portal pressure accompanied by reduction of portal flow with only slight decrease in renal flow. In cirrhotic rats, splanchnic sympathectomy intensified and prolonged zolmitriptan-induced portal pressure descent. Also, propranolol caused more intense and durable portal pressure fall when combined with zolmitriptan. Mesenteric artery perfusion pressure peaked for about 1 min upon zolmitriptan administration but showed no change with propranolol. However propranolol enhanced and prolonged the elevation in mesenteric artery perfusion pressure induced by zolmitriptan. In vitro studies showed that propranolol prevented the inhibitory effects of β2-agonists on zolmitriptan-induced vasoconstriction and the combination of propranolol and zolmitriptan significantly reduced the elevation of cAMP caused by β2-agonists.

CONCLUSION

Zolmitriptan reduces portal hypertension and non-selective beta-blockers can improve this effect. Combination therapy deserves consideration for patients with portal hypertension failing to respond to non-selective beta-blockers.

Pathophysiology of medication-overuse headache: implications from animal studies

Recent animal experiments have shown that chronic medication exposure profoundly affects the function of several areas in the nervous system related to headache pathogenesis. These changes include upregulation of calcitonin gene-related peptide, substance P, and nitric oxide synthase in trigeminal ganglia; expansion of receptive field and decreased nociceptive threshold of central trigeminal neurons; decrease in diffuse noxious inhibitory control; and increased susceptibility to develop cortical spreading depression (CSD). These changes indicate an increase in excitability of cortical and trigeminal neurons. The neuronal hyperexcitability may be the result of derangement of a central, possibly serotonin (5-HT)-dependent, modulating control system. Experiments with animals with low 5-HT showed that the processes of CSD and trigeminal nociception are enhanced in this condition. Derangement in the central 5-HT-dependent modulating system as a result of chronic medication use may underlie the chronification of headache as observed in patients with medication-overuse headache.

Cortical hyperexcitability and mechanism of medication-overuse headache

The present study was conducted to determine the effect of acute (1 h) and chronic (daily dose for 30 days) paracetamol administration on the development of cortical spreading depression (CSD), CSD-evoked cortical hyperaemia and CSD-induced Fos expression in cerebral cortex and trigeminal nucleus caudalis (TNC). Paracetamol (200 mg/kg body weight, intraperitonealy) was administered to Wistar rats. CSD was elicited by topical application of solid KCl. Electrocorticogram and cortical blood flow were recorded. Results revealed that acute paracetamol administration substantially decreased the number of Fos-immunoreactive cells in the parietal cortex and TNC without causing change in CSD frequency. On the other hand, chronic paracetamol administration led to an increase in CSD frequency as well as CSD-evoked Fos expression in parietal cortex and TNC, indicating an increase in cortical excitability and facilitation of trigeminal nociception. Alteration of cortical excitability which leads to an increased susceptibility of CSD development can be a possible mechanism underlying medication-overuse headache.

Headache attributed to a substance or its withdrawal

Medication overuse, and subsequent medication overuse headache (MOH), is a growing and still underestimated problem worldwide. A significant number of recent epidemiological studies suggest that up to 4% of the general population in Europe, North America, and Asia overuse analgesics and other drugs for the treatment of pain conditions such as migraine. These studies also provide convincing evidence that about 1% of the general population suffers from MOH. The condition can be caused by almost all antiheadache drugs, including analgesics, ergots, triptans, and combined preparations. The clinical symptoms of MOH are heterogeneous and may vary from just an increase in headache attack frequency to a constant holocranial pain over years. The International Headache Society (IHS) defined MOH in its first classification in 1988 but modified the diagnostic criteria in its second classification in 2004 to facilitate diagnosis and the conduct of clinical trials. The underlying pathophysiology of MOH is not well understood. The only therapy is withdrawal from the overused substances. The only strategy to reduce the prevalence of MOH is to prevent the development of MOH in the first place by clear restriction of monthly doses of antiheadache drugs and constant education of both patients and physicians prescribing or recommending antiheadache drugs.

Involvement of pro-nociceptive 5-HT2A receptor in the pathogenesis of medication-overuse headache

OBJECTIVES

To determine the involvement of 5-HT(2A) (5-HT(2A)) receptor in the process of trigeminal plasticity induced by chronic analgesic exposure and in the process of inflammatory-induced thermal hyperalgesia.

BACKGROUND

Derangement in 5-HT(2A) serotonin receptor has been reported to implicate in pathogenesis of medication-overuse headache. No clear explanation concerning the precise roles of these receptors in the process.

METHODS

Wistar rats were daily administered with paracetamol (200 mg/kg) for 30 days. On the next day, ketanserin, a 5-HT(2A) antagonist, or saline was given prior to cortical spreading depression (CSD) induction. Electrocorticogram, cortical blood flow, Fos and 5-HT(2A)-immunoreactivity in cortex and trigeminal pathway were studied. In the other experiment, complete Freund's adjuvant was injected into the rat hind paw to induce tissue inflammation. Three days later, ketanserin was given and noxious heat was applied to both inflamed and noninflamed paws. The response between 2 sides was compared by measuring paw withdrawal latency.

RESULTS

Chronic paracetamol exposure led to an increase in CSD frequency and CSD-evoked Fos expression in cerebral cortex indicating the increase in neuronal excitability. Prolonged medication exposure also facilitated trigeminal nociception as evident by an increase in CSD-evoked Fos expression in trigeminal nucleus caudalis. The expression of 5-HT(2A) receptor in cerebral cortex and trigeminal ganglia was enhanced by chronic paracetamol administration. Pretreatment with ketanserin significantly attenuated these effects. The second experiment showed that ketanserin was able to lengthen the paw withdrawal latency in the inflamed side but did not alter nociceptive response in the noninflamed side.

CONCLUSION

These findings suggest that up-regulation of pro-nociceptive 5-HT(2A) receptor is an important step in the process of cortical hyper-excitation and nociceptive facilitation induced by chronic analgesic exposure.

Epidemiology, risk factors, and treatment of chronic migraine: a focus on topiramate

The term chronic daily headache refers to a heterogeneous group of headache disorders characterized by a frequency of headaches on > or = 15 days per month. Chronic migraine is a subtype of chronic daily headache. The prevalence of chronic migraine is approximately 1%. Baseline attack frequency and acute medication overuse have been identified as potential risk factors for the progression of migraine from an episodic disorder to a chronic condition. There is an unmet patient need for effective and safe treatments for patients with chronic migraine, but data from rigorous controlled trials are limited. Previous studies have demonstrated that topiramate is an effective and safe preventive treatment for episodic migraine. In addition, pilot studies have suggested the utility of topiramate for the prevention of chronic migraine. Two randomized, double-blind, placebo-controlled, multicenter trials investigating the efficacy and safety of topiramate in the treatment of patients with chronic migraine have recently been completed. This review presents comparative data from these 2 clinical trials, which suggest that topiramate at a dose of 100 mg daily is effective and generally well tolerated in chronic migraine.

The effects of chronic administration of sumatriptan and dipyrone on serotonergic system in the rat brain: an immunohistochemical study

OBJECTIVE

To investigate the effects of chronic high dose sumatriptan and dipyrone treatment on central serotonergic system in rats.

MATERIALS AND METHODS

Male Sprague-Dawley rats (seven per group) were daily injected with sumatriptan (3 mg/kg), dipyrone (400 mg/kg) or saline for 30 days. The brains of animals were surgically removed and immunohistochemically stained for serotonin. Serotonin-positive stained cells were counted automatically by using a computerized image analysis program. Statistical analysis carried out using one-way ANOVA followed by post hoc Tukey test.

RESULTS

A significant decrease in serotonin-positive cells in the brainstem was observed after chronic sumatriptan administration while chronic use of dipyrone induced a significant increase in serotonin-positive cells both in the cortex and midbrain.

CONCLUSION

Our data suggest that central serotonergic system might be modified by chronic use of sumatriptan and dipyrone.

Sensitisation of spinal cord pain processing in medication overuse headache involves supraspinal pain control

Medication overuse could interfere with the activity of critical brain regions involved in the supraspinal control of pain signals at the trigeminal and spinal level, leading to a sensitisation phenomenon responsible for chronic pain. We hypothesised that medication-overuse headache (MOH) patients might display abnormal processing of pain stimuli at the spinal level and defective functioning of the diffuse noxious inhibitory controls. We tested 31 MOH patients before (bWT) and after (aWT) standard inpatient withdrawal treatment, 28 episodic migraine (EM) patients and 23 healthy control subjects. We measured the threshold, the area and the temporal summation threshold (TST) of the nociceptive withdrawal reflex before, during and after activation of the diffuse noxious inhibitory controls by means of the cold pressor test. A significantly lower TST was found in both the MOH (bWT and aWT) and the EM patients compared with the controls, and in the MOH patients bWT compared with both the MOH patients aWT and the EM patients. In the MOH bWT patients the cold pressor test induced a TST increase significantly lower than that found in the MOH aWT, EM and control groups. Abnormal spinal cord pain processing and a decrease of the antinociceptive activity of the supraspinal structures in MOH patients can be hypothesised. These abnormalities could, in part, be related to the medication overuse, given that the withdrawal treatment was related to an improvement in the neurophysiological findings.

Medication overuse headache

The term medication overuse headache (MOH) was recently introduced by the International Headache Society to describe daily or nearly daily (chronic) headache that occurs after the regular intake (overuse) of any kind of antiheadache or antimigraine drug. Chronic headache is a growing problem throughout the world. It affects up to 3% to 4% of the general population, and 30% to 50% of such headaches are attributed to overuse of antiheadache drugs. This article reviews the literature on the epidemiology, risk factors, and pathophysiology of MOH. It also summarizes current strategies for treating and preventing headache chronicity.

Increased activity of serotonin uptake in platelets in medication overuse headache following regular intake of analgesics and triptans

We investigated the effect of chronic administration of different pain medications on the activity of the serotonin transporter (SERT) in patients with medication overuse headache (MOH). We measured the kinetic of platelet 5-HT uptake (maximal velocity, V_max and the Michaelis–Menten constant, K_m) in patients with overuse of triptans (tMOH, n = 15) or analgesics (aMOH, n = 14) before and after drug withdrawal, as well as in headache-free healthy subjects (n = 15) and patients with episodic migraine (EM, n = 16). V_max was increased similarly in both, tMOH and aMOH compared to healthy subjects and patients with EM and normalized after withdrawal in parallel to the improvement of headache frequency. Average K_m was similar in all groups at baseline and not affected by the withdrawal. The data demonstrate a transient increase of SERT activity in patients with analgesic and triptan induced MOH but do not allow to differentiate whether the increase of serotonin uptake is caused by regular intake of analgesics or triptans or is a consequence of frequent headache attacks.

Medication-overuse headache: where are we now?

PURPOSE OF REVIEW

Many important studies on medication-overuse headache have been published in the last year. Some of them investigated the pathophysiology of headache chronicity, others focused on evaluation of risk factors. The International Headache Society revised the classification criteria. We provide a summary of the new findings and concepts.

RECENT FINDINGS

Medication-overuse headache was previously defined by the International Headache Society as a chronic headache which occurs following overuse of headache drugs and improves after withdrawal. Hence, the improvement of headache after withdrawal was mandatory for diagnosis. The new appendix criteria appeared last year and established a broader concept of medication-overuse headache no longer requiring improvement after discontinuation of medication overuse. Several large population-based longitudinal studies clearly demonstrated that overuse of any kind of acute headache medication is the main risk factor leading to development of chronic headache. Imaging studies provided new important insights into the pathophysiology of headache chronicity. New treatment strategies have been suggested.

SUMMARY

Recent data provide better insight into pathophysiology of medication-overuse headache. Epidemiological studies clearly demonstrate the necessity of establishing a predictive model for early recognition of patients at high risk to intervene early and avoid development of chronic headache.

Endocrine Function Is Altered in Chronic Migraine Patients with Medication-Overuse

OBJECTIVE

To evaluate the effects of analgesic overuse on endocrine function in patients with chronic migraine and medication-overuse headache (CM-MOH).

BACKGROUND

Chronic migraine is frequently associated with an overuse of symptomatic medications. Drugs currently used in acute migraine attacks are associated with several endocrine effects. At present, the endocrine effects of medication overuse in chronic migraine patients are unknown.

METHODS

Eighteen patients with CM-MOH, diagnosed according to the ICHD-II criteria, and 18 healthy controls received an intravenous administration of GHRH, hCRH, and TRH. Plasma concentrations of GH, TSH, ACTH, and cortisol were measured for a 90-minute period after administration of the specific releasing hormones.

RESULTS

Hormonal basal concentrations were similar in both groups. GH response to GHRH was significantly reduced in patients with CM-MOH in comparison with controls. TRH induced a reduction of TSH concentrations only at the end of the test. After hCRH administration, ACTH and cortisol concentrations were significantly higher in cases than in controls. A significant correlation between duration of the disease and altered hormonal response was found.

CONCLUSIONS

Our study shows that both corticotropic and somatotropic functions are significantly impaired in CM-MOH patients and suggests a role for hormones in the development of chronic migraine.

Medication overuse headache

Medication overuse headache (MOH) has developed into the third most common type of headache after tension-type headache and migraine. The prevalence of MOH is approximately 1% of the world's population and it shows an increasing trend as recent studies reveal a common involvement throughout the ages, even starting in childhood. All antiheadache drugs, such as triptans, analgesics, ergots and opioids, along with the common combination substances currently on the pharmacological market are capable of inducing MOH. New data on specific clinical features and mean critical monthly dosages and mean critical monthly intake frequencies are now available. The only effective treatment concept is consequent withdrawal therapy. Data of prospective studies on relapse rates and predictors of relapse after successful withdrawal therapy are presented.

Medication-overuse headache: similarities with drug addiction

Medication-overuse headache (MOH) is a clinically important entity and it is now well documented that the regular use of acute symptomatic medication by people with migraine or tension-type headache increases the risk of aggravation of the primary headache. MOH is one the most common causes of chronic migraine-like syndrome. In this article, we analyse the possible mechanisms that underlie sensitization in MOH by comparing these mechanisms with those reported for other forms of drug addiction. Moreover, the evidence for cognitive impulsivity in drug overuse in headache and in other forms of addiction associated with dysfunction of the frontostriatal system will be discussed. An integrative hypothesis for compulsive reward-seeking in MOH will be presented.

Triptans induce vasoconstriction of human arteries and veins from the thoracic wall

A common side effect of migraine treatment with triptans is chest symptoms. The origin of these symptoms is not known. The aim of the present study was to examine the vasocontractile effect of triptans in human arteries and veins from the thoracic wall and in coronary artery bypass grafts. In vitro pharmacology experiments showed that the 5-hydroxytryptamine (5-HT) type 1B and 1D receptor agonists, eletriptan, naratriptan, rizatriptan, sumatriptan, and zolmitriptan, induced vasoconstriction in the thoracic blood vessels from 38% to 57% of the patients. 5-carboxamidotryptamine (5-CT) and sumatriptan elicited a vasoconstriction that was antagonized by the 5-HT1B receptor antagonist SB224289, whereas the 5-HT1D receptor antagonist BRL115572 had no effect. 5-HT induced a contraction that was inhibited by the 5-HT2A receptor antagonist ketanserin. 5-HT2A, 5-HT1B, and 5-HT1D receptor mRNA levels were detected by real-time PCR in all blood vessels studied. In conclusion, triptans induce vasoconstriction in arteries and veins from the thoracic wall, most likely by activation of 5-HT1B receptors. This response could be observed in only 38% to 57% of the patients, which may provide an explanation for why a similar number of patients experience chest symptoms as a side effect of migraine treatment with triptans.

The 5-HT1D receptor agonist zolmitriptan for neuroleptic-induced akathisia: an open label preliminary study

Neuroleptic-induced akathisia (NIA) is a common, sometimes incapacitating, adverse side-effect of antipsychotic drugs (APDs). Several non-selective post-synaptic 5-HT2 blockers have shown a beneficial antiakathisic effect. We hypothesized that selective stimulation of the presynaptic 5-HT1D serotonergic inhibitory autoreceptor could also be beneficial in NIA. The study group included eight schizophrenia inpatients with acute or chronic NIA who were treated with unchanged doses of APDs. Participants received, in an open-labelled design, 7.5 mg/day of zolmitriptan (selective 5-HT1D agonist) for 3 consecutive days. Positive and Negative Syndrome Scale and Barnes akathisia scale (BAS) scores were monitored before and at the end of the study. BAS score decreased by 5.25 points following zolmitriptan administration (9.0+/-2.27 to 3.75+/-2.55, t=6.1, d.f.=7, P=0.0005). In one case, the BAS score dropped from a 3-year score >or=9 points (while relatively non-responsive to numerous antiakathisic agents) to 4 points at endpoint. In conclusion, zolmitriptan appears to exert significant and rapid beneficial antiakathisic effect, even in chronic and resistant NIA. Larger, long-term, double-blind, placebo- and comparator- (e.g. propranolol) controlled studies are required to substantiate the efficacy, safety and tolerability of zolmitriptan, as well as the role of serotonergic neurotransmission in NIA.

Medication-overuse headache: a worldwide problem

Medication overuse and subsequent medication-overuse headache (MOH) is a growing problem worldwide. Epidemiological data suggest that up to 4% of the population overuse analgesics and other drugs for the treatment of pain conditions such as migraine and that about 1% of the general population in Europe, North America, and Asia have MOH. Recent clinical studies gave further insights in clinical and pharmacological features, such as critical monthly doses and frequencies. These features seem to vary significantly and depend on the primary headache disorder and the type of drug that is overused. Along with these findings the new international classification of headache disorders has now incorporated additional criteria and new headache entities that will facilitate the diagnosis of MOH. Withdrawal therapy is the only treatment for this disorder and clear restriction of monthly doses is the central requirement for successful prevention.