A double-blind comparison of granisetron and placebo for the treatment of acute migraine in the emergency department

The effectiveness of parenteral agents for pain reduction in patients with migraine presenting to emergency settings: A systematic review and network analysis

OBJECTIVES

To assess the comparative effectiveness and safety of parenteral agents for pain reduction in patients with acute migraine.

BACKGROUND

Parenteral agents have been shown to be effective in treating acute migraine pain; however, the comparative effectiveness of different approaches is unclear.

METHODS

Nine electronic databases and gray literature sources were searched to identify randomized clinical trials assessing parenteral agents to treat acute migraine pain in emergency settings. Two independent reviewers completed study screening, data extraction, and Cochrane risk-of-bias assessment, with differences being resolved by adjudication. The protocol of the review was registered with the International Prospective Register of Systematic Reviews (PROSPERO; CRD42018100096).

RESULTS

A total of 97 unique studies were included, with most studies reporting a high or unclear risk of bias. Monotherapy, as well as combination therapy, successfully reduced pain scores prior to discharge. They also increased the proportion of patients reporting pain relief and being pain free. Across the pain outcomes assessed, combination therapy was one of the higher ranked approaches and provided robust improvements in pain outcomes, including lowering pain scores (mean difference -3.36, 95% confidence interval [CI] -4.64 to -2.08) and increasing the proportion of patients reporting pain relief (risk ratio [RR] 2.83, 95% CI 1.74-4.61). Neuroleptics and metoclopramide also ranked high in terms of the proportion of patients reporting pain relief (neuroleptics RR 2.76, 95% CI 2.12-3.60; metoclopramide RR 2.58, 95% CI 1.90-3.49) and being pain free before emergency department discharge (neuroleptics RR 4.8, 95% CI 3.61-6.49; metoclopramide RR 4.1, 95% CI 3.02-5.44). Most parenteral agents were associated with increased adverse events, particularly combination therapy and neuroleptics.

CONCLUSIONS

Various parenteral agents were found to provide effective pain relief. Considering the consistent improvements across various outcomes, combination therapy, as well as monotherapy of either metoclopramide or neuroleptics are recommended as first-line options for managing acute migraine pain. There are risks of adverse events, especially akathisia, following treatment with these agents. We recommend that a shared decision-making model be considered to effectively identify the best treatment option based on the patient's needs.

Pathophysiology and Therapy of Associated Features of Migraine

Migraine is a complex and debilitating disorder that is broadly recognised by its characteristic headache. However, given the wide array of clinical presentations in migraineurs, the headache might not represent the main troublesome symptom and it can even go unnoticed. Understanding migraines exclusively as a pain process is simplistic and certainly hinders management. We describe the mechanisms behind some of the most disabling associated symptoms of migraine, including the relationship between the central and peripheral processes that take part in nausea, osmophobia, phonophobia, vertigo and allodynia. The rationale for the efficacy of the current therapeutic arsenal is also depicted in this article. The associated symptoms to migraine, apart from the painful component, are frequent, under-recognised and can be more deleterious than the headache itself. The clinical anamnesis of a headache patient should enquire about the associated symptoms, and treatment should be considered and individualised. Acknowledging the associated symptoms as a fundamental part of migraine has permitted a deeper and more coherent comprehension of the pathophysiology of migraine.

Second-line interventions for migraine in the emergency department: A narrative review

OBJECTIVE

Millions of patients present to US emergency departments (ED) annually for the treatment of migraine. First-line treatments, including metoclopramide, prochlorperazine, and sumatriptan, fail to provide sufficient relief in up to one-third of treated patients. In this narrative review, we discuss the evidence supporting the use of injectable (intravenous, intramuscular, or subcutaneous) medications for patients in the ED who fail to improve sufficiently after treatment with first-line medication.

METHODS

We used the American Headache Society's guideline, "Management of Adults with Acute Migraine in the Emergency Department: The American Headache Society Evidence Assessment of Parenteral Pharmacotherapies," published in 2016, to identify first-line medications for migraine. We then conducted a PubMed search to determine whether any evidence supported the use of these medications as second-line therapy and whether any evidence existed to support the use of injectable therapies not discussed in the guideline as second-line therapy.

RESULTS

We identified only scant high-quality randomized data of second-line therapy. Therefore, we based our recommendations on medications that have reliably demonstrated efficacy as first-line treatment of migraine. These medications include injectable non-steroidal anti-inflammatory drugs (NSAIDs) and acetaminophen. Dihydroergotamine and valproic acid have some data supporting efficacy. More recently, greater occipital nerve blocks (GONBs) have been shown to be efficacious. With the exception of meperidine, opioids have been shown to be not efficacious. Most data published to date demonstrate no role for propofol and ketamine.

CONCLUSIONS

There are no evidence-based second-line treatments of migraine in the ED setting. For patients with migraine, who fail to improve after treatment with a first-line medication, it is reasonable to use an intravenous NSAID or intravenous acetaminophen. Alternatively, clinicians adept at performing a GONB may offer this treatment.

Acute Treatments for Episodic Migraine in Adults: A Systematic Review and Meta-analysis

IMPORTANCE

Migraine is common and can be associated with significant morbidity, and several treatment options exist for acute therapy.

OBJECTIVE

To evaluate the benefits and harms associated with acute treatments for episodic migraine in adults.

DATA SOURCES

Multiple databases from database inception to February 24, 2021.

STUDY SELECTION

Randomized clinical trials and systematic reviews that assessed effectiveness or harms of acute therapy for migraine attacks.

DATA EXTRACTION AND SYNTHESIS

Independent reviewers selected studies and extracted data. Meta-analysis was performed with the DerSimonian-Laird random-effects model with Hartung-Knapp-Sidik-Jonkman variance correction or by using a fixed-effect model based on the Mantel-Haenszel method if the number of studies was small.

MAIN OUTCOMES AND MEASURES

The main outcomes included pain freedom, pain relief, sustained pain freedom, sustained pain relief, and adverse events. The strength of evidence (SOE) was graded with the Agency for Healthcare Research and Quality Methods Guide for Effectiveness and Comparative Effectiveness Reviews.

FINDINGS

Evidence on triptans and nonsteroidal anti-inflammatory drugs was summarized from 15 systematic reviews. For other interventions, 115 randomized clinical trials with 28 803 patients were included. Compared with placebo, triptans and nonsteroidal anti-inflammatory drugs used individually were significantly associated with reduced pain at 2 hours and 1 day (moderate to high SOE) and increased risk of mild and transient adverse events. Compared with placebo, calcitonin gene-related peptide receptor antagonists (low to high SOE), lasmiditan (5-HT1F receptor agonist; high SOE), dihydroergotamine (moderate to high SOE), ergotamine plus caffeine (moderate SOE), acetaminophen (moderate SOE), antiemetics (low SOE), butorphanol (low SOE), and tramadol in combination with acetaminophen (low SOE) were significantly associated with pain reduction and increase in mild adverse events. The findings for opioids were based on low or insufficient SOE. Several nonpharmacologic treatments were significantly associated with improved pain, including remote electrical neuromodulation (moderate SOE), transcranial magnetic stimulation (low SOE), external trigeminal nerve stimulation (low SOE), and noninvasive vagus nerve stimulation (moderate SOE). No significant difference in adverse events was found between nonpharmacologic treatments and sham.

CONCLUSIONS AND RELEVANCE

There are several acute treatments for migraine, with varying strength of supporting evidence. Use of triptans, nonsteroidal anti-inflammatory drugs, acetaminophen, dihydroergotamine, calcitonin gene-related peptide antagonists, lasmiditan, and some nonpharmacologic treatments was associated with improved pain and function. The evidence for many other interventions, including opioids, was limited.

Emergent management of primary headache: a review of current literature

PURPOSE OF REVIEW

The current article reviews recent data on treatment of acute headache patients in the acute care setting.

RECENT FINDINGS

Intravenous fluid hydration, a common component of emergency department (ED) migraine therapy, does not improve pain outcomes and leads to longer ED lengths of stay. Therefore, intravenous fluids should be administered only to migraine patients with clinical evidence of dehydration. Similarly, intravenous ketamine has garnered interest as a treatment for acute pain but does not provide substantial relief to migraine patients. New studies on the serotonin (5-HT3; 5-hydroxytryptamine-3) antagonist granisetron, intranasal lidocaine, and high-flow oxygen have reported conflicting results for migraine patients. Finally, although experts recommend avoiding opioids in migraine treatment, opioid administration remains prevalent in the ED. A new study has demonstrated that patients who receive intravenous hydromorphone in the ED are much less likely to attain acute headache relief. Standardized headache protocols may decrease opioid use and provide significant pain relief for patients.

SUMMARY

Recent data have clarified the role of opioids and ketamine in the ED (do not use!). The role of treatment protocols and intravenous fluids is still ill-defined. Subpopulations of migraine patients may benefit from high-flow oxygen and intranasal lidocaine.

Blockade of 5-HT3 receptors with granisetron does not affect trigeminothalamic nociceptive transmission in rats: Implication for migraine

One way to expand the existing range of anti-migraine drugs seems to be the search for pharmacological agents with anti-cephalalgic properties among medicines approved for clinical indications other than migraine. Numerous experimental and clinical data imply that selective serotonin 5-HT3 receptor antagonists can be considered as potential anti-migraine agents. Therefore, the objective of our work was to examine the impact of selective 5-HT3 receptor blockade with granisetron on migraine-related nociceptive transmission within the spinal trigeminal nucleus (STN) and the ventroposteromedial nucleus of the thalamus (VPM). Using an electrophysiological model of trigemino-durovascular nociception in anaesthetised male Wistar rats, we evaluated the effects of intravenous administration of granisetron on ongoing firing and dural electrical stimulation-evoked responses of the spinal trigeminal and thalamic cells. Granisetron did not substantially affect responses of the STN and VPM neurons to electrical stimulation of the dura mater as well as did not cause steady changes in ongoing firing of the spinal trigeminal cells. The results obtained argue against the use of 5-HT3 receptor antagonists for treating migraine. These data also lead to the conclusion that in the absence of sustained sensitisation of neurons along the trigemino-thalamo-cortical pathway the role of 5-HT3 receptor-dependent mechanisms in serotonergic modulation of trigeminovascular nociceptive transmission can hardly be considered crucial.

Comparison of granisetron and metoclopramide in the treatment of pain and emesis in migraine patients: A randomized controlled trial study

Objectives

One of the irritating features of migraine is emesis that can compromise taking oral medications. We designed this study to compare the effectiveness of granisetron and metoclopramide in reducing pain and treating emesis in migraine patients.

Methods

We included a total of 148 patients with migraine headache presenting to two referral hospitals in a prospective, double-blinded randomized controlled trial. We compared the effect of granisetron (2 mg intravenous) with metoclopramide (10 mg intravenous). Pain intensity and emesis episodes were recorded before drug administration, one, two and four 4 h after drug administration.

Results

Of the 148 patients, 47 were male and 101 were female. 75 patients received granisetron and 73 metoclopramide. Mean pain intensity before the administration of the medications was 7.67 ± 1.30 in granisetron group and 7.68 ± 1.13 in metoclopramide group with an insignificant difference. Mean pain intensity at one, two, and 4 h after drug administration was 3.20 ± 1.37, 2.39 ± 1.28, and 1.31 ± 0.52 in granisetron group and 5.04 ± 1.77, 4.1 ± 1.8, and 1.56 ± 0.68 in metoclopramide group (P = 0.03). Mean emesis episodes before drug administration were 1.85 ± 0.81 and 1.80 ± 0.77 in granisetron and metoclopramide groups, respectively. These episodes were 1.33 ± 0.66, 0.25 ± 0.49, and 0.04 ± 0.19 in granisetron group and 1.38 ± 0.73, 0.21 ± 0.47, and 0.41 ± 0.19 in metoclopramide group at one, two, and 4 h after the drug administration (P = 0.7).

Conclusion

To came in conclusion, compared to metoclopramide, granisetron is a better choice in acute migraine ATTACK because it decreases the patients' pain as well as their emesis.

Is the Generally Held View That Intravenous Dihydroergotamine Is Effective in Migraine Based on Wrong "General Consensus" of One Trial? A Critical Review of the Trial and Subsequent Quotations

BACKGROUND

The claim that parenteral dihydroergotamine (DHE) is effective in migraine is based on one randomized, placebo-controlled, crossover trial from 1986. The aim of this review was to critically evaluate the original article. It was also found to be of interest to review quotes concerning the results in the more than 100 articles subsequently referring to the article.

METHODS

The correctness of the stated effect of intravenous DHE in the randomized clinical trial (RCT) was first critically evaluated. Then, Google Scholar was searched for references to the article and these references were classified as to whether they judged the reported RCT as positive or negative.

RESULTS

The design of the RCT, with a crossover within one migraine attack, only allows evaluation of the results for the first period and the effect of DHE and placebo were quite comparable. About 151 references were found for the article in Google scholar. Among the 95 articles with a judgment on the efficacy of intravenous DHE in the RCT, 90 stated that DHE was effective or likely effective whereas only 5 articles stated that DHE was ineffective.

CONCLUSIONS

Despite a "negative" RCT, authors of subsequent articles on the efficacy of parenteral DHE overwhelmingly reported this RCT as "positive." This is probably due to the fact that the authors concluded in the abstract that DHE is effective, and to a kind of "wrong general consensus."

Canadian Headache Society systematic review and recommendations on the treatment of migraine pain in emergency settings

BACKGROUND

There is a considerable amount of practice variation in managing migraines in emergency settings, and evidence-based therapies are often not used first line.

METHODS

A peer-reviewed search of databases (MEDLINE, Embase, CENTRAL) was carried out to identify randomized and quasi-randomized controlled trials of interventions for acute pain relief in adults presenting with migraine to emergency settings. Where possible, data were pooled into meta-analyses.

RESULTS

Two independent reviewers screened 831 titles and abstracts for eligibility. Three independent reviewers subsequently evaluated 120 full text articles for inclusion, of which 44 were included. Individual studies were then assigned a US Preventive Services Task Force quality rating. The GRADE scheme was used to assign a level of evidence and recommendation strength for each intervention.

INTERPRETATION

We strongly recommend the use of prochlorperazine based on a high level of evidence, lysine acetylsalicylic acid, metoclopramide and sumatriptan, based on a moderate level of evidence, and ketorolac, based on a low level of evidence. We weakly recommend the use of chlorpromazine based on a moderate level of evidence, and ergotamine, dihydroergotamine, lidocaine intranasal and meperidine, based on a low level of evidence. We found evidence to recommend strongly against the use of dexamethasone, based on a moderate level of evidence, and granisetron, haloperidol and trimethobenzamide based on a low level of evidence. Based on moderate-quality evidence, we recommend weakly against the use of acetaminophen and magnesium sulfate. Based on low-quality evidence, we recommend weakly against the use of diclofenac, droperidol, lidocaine intravenous, lysine clonixinate, morphine, propofol, sodium valproate and tramadol.

Rescue therapy for acute migraine, part 2: neuroleptics, antihistamines, and others

OBJECTIVES

This second portion of a 3-part series examines the relative effectiveness of headache treatment with neuroleptics, antihistamines, serotonin antagonists, valproate, and other drugs (octreotide, lidocaine, nitrous oxide, propofol, and bupivacaine) in the setting of an emergency department, urgent care center, or headache clinic.

METHODS

MEDLINE was searched using the terms "migraine" AND "emergency" AND "therapy" OR "treatment." Reports were from emergency department and urgent care settings and involved all routes of medication delivery. Reports from headache clinics were only included if medications were delivered by a parenteral route.

RESULTS

Prochlorperazine, promethazine, and metoclopramide, when used alone, were superior to placebo. Droperidol and prochlorperazine were superior or equal in efficacy to all other treatments, although they also have more side effects (especially akathisia). Metoclopramide was equivalent to prochlorperazine and, when combined with diphenhydramine, was superior in efficacy to triptans and non-steroidal anti-inflammatory drugs. Meperidine was inferior to chlorpromazine and equivalent to the other neuroleptics. The overall percentage of patients with pain relief after taking droperidol and prochlorperazine was equivalent to sumatriptan.

CONCLUSIONS

Prochlorperazine and metoclopramide are the most frequently studied of the anti-migraine medications in the emergent setting, and the effectiveness of each is superior to placebo. Prochlorperazine is superior or equivalent to all other classes of medications in producing migraine pain relief. Dopamine antagonists, in general, appear to be equivalent for migraine pain relief to the migraine-"specific" medications sumatriptan and dihydroergotamine, although there are fewer studies involving the last two. Lack of comparisons to placebo and the frequent use of combination medications in treatment arms complicate the comparison of single agents to one other.

Management of primary headaches in adult Emergency Departments: a literature review, the Parma ED experience and a therapy flow chart proposal

Adults seeking treatment at hospitals' Emergency Departments (EDs) because of headache represent a major health-care issue. To date, there are no special guidelines for management of primary headache in adults seen at EDs and therapeutic approaches are often inconsistent. This review describes the therapeutic strategies that are most frequently used to treat primary headache in adult ED patients and their in situ efficacy, based on literature data, the type of medications studied in randomized clinical trials for the management of adult ED patients, and the recommendations found in the guidelines for symptomatic treatment of migraine. We also report on the experience of the Parma University Hospital ED in the year 2007 for the management of adult patients diagnosed with primary headache. Finally, we propose an algorithm for primary headache management in ED patients, which is based on the literature data and clinical experience, and is suitable for application in Italy.

Anti-emetics

Nausea and vomiting are common symptoms of migraine, which can be controlled with a variety of anti-emetics including phenothiazines and antihistamines. Metoclopramide and domperidone have an additional prokinetic effect which may be important in migraine to overcome gastric stasis and enhance absorption of oral medication.

Differential influence of two serotonin 5-HT3 receptor antagonists on spinal serotonin-induced analgesia in rats

We tested the antinociceptive effect of intrathecal (i.t.) administration of 5-HT3 and the 5-HT3 receptor agonist, 1-(m-chlorophenyl)-biguanide (mCPBG), in rats submitted to a mechanical noxious stimulus and the influence of the 5-HT3 receptor selective antagonists, tropisetron and granisetron. Both 5-HT and mCPBG (0.01, 0.1, 1, 10, 20 micrograms/rat) produced a significant dose-dependent antinociception. The lowest active doses were 0.1 and 1 microgram for 5-HT and mCPBG, respectively. The effect, observed with 20 micrograms, was significantly lower with mCPBG (+33 +/- 6%) than with 5-HT (+63 +/- 7%). For 5-HT-induced antinociception, the minimal inhibitory doses were 0.001 micrograms/rat for tropisetron and 10 micrograms/rat for granisetron. In contrast, the same doses of the two antagonists (from 0.1 microgram/rat) similarly inhibited the effect of mCPBG. This study provides evidence that contrary to tropisetron, doses of granisetron able to inhibit the effect of a 5-HT3 receptor agonist failed to reduce that of 5-HT. This demonstrates a heterogeneity between 5-HT3 receptor antagonists and questions the true involvement of these receptors in spinal 5-HT-induced antinociception.

Response heterogeneity of 5-HT3 receptor antagonists in a rat visceral hypersensitivity model

Subcutaneous administration of granisetron (BRL 43694, endo-1-methyl-N-(9-methyl-9-azabicyclo[3.3.1.]non-3-yl-1 H-indazole-3-carboxamide) and zacopride (4-amino-N-(1-azabicyclo[2.2.2.]oct-3-yl)-5-chloro-2-methoxybenzamide), two 5-HT3 receptor antagonists, at doses ranging from 3 to 1000 micrograms/kg, inhibited abdominal contractions induced by distension (30 mmHg, 10 min) of irritated colon (0.6% acetic acid) in conscious rats with a bell-shaped dose-response curve. The ED50 of granisetron and zacopride were 17.6 and 8.2 micrograms/kg, respectively. In contrast, both tropisetron (ICS 205-930, (3-a-tropanyl)t-indole-3-carboxylic ester) and ondansetron (GR38032F, 1,2,3,9-tetrahydro-9-methyl-3-[(2-methyl-1 H-imidazol-1-yl)methyl]-4 H-carbazol-4-one hydrocloride dihydrate) were inactive in this model. These data further support the concept of a heterogeneity in the potency of 5-HT3 receptor antagonists in modulating visceral hypersensitivity in conscious rats. This finding is in agreement with a reported efficacy of granisetron but not of ondansetron in patients with irritable bowel syndrome.

5-Hydroxytryptamine and functional bowel disorders

The possibility that 5-hydroxytryptamine (5-HT) acts as a key sensitising agent in the aetiology of irritable bowel syndrome (IBS) is reviewed. The strategic locations of 5-HT and its receptors are described, the most dominant being the 5-HT3 and 5-HT4 type. 5-HT, acting mostly at 5-HT3 or 5-HT3-like receptors, enhances the sensitivity of visceral neurones projecting between the gut and the central nervous systems. 5-HT, acting at 5-HT4 receptors promotes the sensitivity of enteric neurones that react to luminal stimuli. 5-HT4 and 5-HT3 receptors also mediate, respectively, sensitising and physiological actions of 5-HT on gastro-intestinal motor and secretory functions. This distribution implies that some 5-HT3 receptor antagonists might reduce certain symptoms of IBS, such as pain, by reducing the reactivity of the visceral afferent neurones linking the gut with the brain and spinal cord. However, such antagonists are not likely to find widespread clinical acceptance because they can also affect normal lower bowel function and promote constipation. 5-HT4 receptor antagonists, by contrast, reduce 5-HT-induced enteric nerve hypersensitivity without notably affecting the function of the normal bowel. Accordingly, these agents may reduce the symptoms of IBS directly, by reducing the incidence of defecation and diarrhoea and indirectly, by reducing both 'rebound' constipation and the post-prandial discomfort and pain associated with gastrointestinal hyper-reactivity.

5-Hydroxytryptamine3 receptor antagonism modulates a noxious visceral pseudoaffective reflex

5-Hydroxytryptamine (5-HT) receptor agonists and antagonists were dosed intravenously (i.v.) and studied for their effects on the depressor cardiovascular pseudoaffective reflex evoked by acute noxious colo-rectal distension in the anaesthetized rat. Methiothepin (100 micrograms kg-1) caused an initial, unsustained blockade of evoked depressor responses whilst ketanserin (100 micrograms kg-1) was without effect. By comparison, ondansetron dose dependently inhibited evoked depressor responses and was maximally active at 100 micrograms kg-1, causing a 57.5 +/- 0.9% reduction. An ID50 value of 36.7 micrograms kg-1 was estimated by regression analysis. In contrast, granisetron caused complete blockade of the depressor response with an ID50 of 0.4 microgram kg-1. Bell-shaped dose-effect curves were demonstrated for both granisetron and ondansetron. Intrathecal dosing with granisetron (100 ng) into the thoracolumbar region of the spinal cord prevented the depressor response to colo-rectal distension, suggesting a spinal site of action. The pseudoaffective depressor responses were not facilitated by pre-dosing with the 5-HT receptor agonists, 8-OH DPAT, alpha-methyltryptamine or 1-phenyl-biguanide. However, 8-OH DPAT (100 micrograms kg-1) facilitated pressor responses. It is suggested that 5-HT3-like receptors may have a role in modulating depressor responses to visceral pain and that in this action different 5-HT3 receptor antagonists are not necessarily equi-effective.

Differences between 5-HT3 receptor antagonists in modulation of visceral hypersensitivity

1. Noxious colo-rectal distension was applied in conscious rats by acute balloon inflation and the effects observed as abdominal muscle contraction with the threshold typically between 10-40 mmHg. The effects of 5-HT3 receptor antagonists on responses to noxious colo-rectal distension were then studied in both normal rats and those pretreated with 5-hydroxytryptophan (5-HTP). 2. Granisetron and ondansetron (10 micrograms kg-1 and 1 mg kg-1, s.c.) had no effect on visceromotor thresholds to colo-rectal distension in normal rats. 3. Hypersensitivity of the colo-rectum was achieved by systemic administration of a low dose of 5-HTP (10 mg kg-1, s.c.) which lowered the distension pressure required to induce the visceromotor reflex; analysis of variance showed a highly significant treatment effect (F1,11 = 84.26, P < 0.001). 4. Granisetron, zatosetron, bemesetron and renzapride equi-potently increased the threshold values at which distension evoked a visceromotor reflex after dosing with 5-HTP, with a maximal response 3.6 to 4.2 fold above saline controls, at 10 micrograms kg-1, s.c. Metoclopramide (10 micrograms kg-1) also raised the level of distension required to elicit a response. By comparison, tropisetron caused a small, non-significant increase in visceromotor threshold values and only at high doses (1 mg kg-1), whilst ondansetron and BRL 46470 had no significant effects at doses up to 10 mg kg-1. 5. The response to granisetron (10 micrograms kg-1, s.c.) in 5-HTP-treated rats was unaltered by pre-administration of naloxone (5 mg kg-1, s.c.). 6. These results suggest that a 5-HT3-like receptor modulates 5-HTP- evoked visceral hypersensitivity.However, the rank order of antagonist potency does not correlate with their order of potency against the classically defined 5-HT3 receptor.

Zatosetron, a 5-HT3 receptor antagonist in a multicenter trial for acute migraine

Zatosetron (13 mg or 0.19 mg/kg), a potent and selective 5-HT3 receptor antagonist was studied with a 30 min infusion in a crossover double-blind placebo-controlled trial for acute migraine therapy. Groups receiving zatosetron and placebo were demographically similar and zatosetron was well-tolerated in all patients with no clinically significant adverse effects. Migraine severity was reduced in both the placebo and zatosetron groups with no statistically significant differences between zatosetron and placebo. Likewise, no statistically significant differences between placebo and zatosetron treatment groups were identified with regard to migraine duration, overall migraine severity or the relief medication required. Although several limitations of this study exist, these data documenting a lack of benefit of intravenously-administered zatosetron in alleviating the acute pain of migraine add to the list of 5-HT3 receptor antagonists that have failed to support efficacy of this therapeutic modality in the acute treatment of migraine.

On serotonin and migraine: a clinical and pharmacological review

Migraine patients have chronically low systemic 5-HT, predisposing them to develop migrainous headache once an attack has been initiated. Changes in platelet 5-HT content are not causally related, but reflect similar changes at a neuronal level. Stimulation of vascular 5-HT1 receptors, probably located in the vessel wall within the dural vascular bed, may alleviate the headache and associated symptoms, but does not interact with earlier mechanisms within the pathophysiological cascade. These receptors are of an as yet unidentified 5-HT1 subtype, closely resembling, but not identical to 5-HT1D receptors. Activation of these receptors results in vasoconstriction, inhibiting depolarization of sensory perivascular afferents within the trigemino-vascular system and thus stopping the headache. Additional inhibition of the release of vasoactive neuropeptides may be involved, but seems to be of only secondary clinical importance.