Dihydroergotamine: discrepancy between arterial, arteriolar and pharmacokinetic data

Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of the CGRP Binding Monoclonal Antibody LY2951742 (Galcanezumab) in Healthy Volunteers

Background: Calcitonin gene-related peptide (CGRP) is pivotal in the pathophysiology of migraine headaches and represents a promising target for migraine treatment. The humanized monoclonal antibody galcanezumab (LY2951742) binds to CGRP and may be effective in migraine prophylaxis.

Objectives: The primary objective was to evaluate the safety and tolerability of single and multiple doses of galcanezumab in humans. Secondary objectives included assessing the pharmacokinetics and evaluating target engagement.

Methods: A double-blind, randomized, placebo-controlled study (NCT 01337596) with single escalating and multiple subcutaneous (SC) doses of galcanezumab was performed in healthy male volunteers. Single doses of 1, 5, 25, 75, 200, and 600 mg of galcanezumab (n = 7/dose) or placebo (n = 2/dose) were injected SC in six consecutive cohorts of nine subjects each. One cohort of nine subjects received multiple (4) 150 mg doses of galcanezumab or placebo every other week. Target engagement was evaluated by measuring inhibition of capsaicin-induced increase in dermal blood flow (DBF).

Findings: Sixty-three subjects were randomized and included in the safety analyses. Galcanezumab was well tolerated in single doses (1–600 mg SC) and consecutive doses (150 mg SC). There was no dose-dependent difference in type or frequency of treatment-emergent adverse events, and no clinically meaningful difference when compared with placebo. Pharmacokinetics were linear. Galcanezumab induced a robust, dose-dependent, and durable inhibition of capsaicin-induced increase in DBF, supporting the continued clinical development of galcanezumab for prophylaxis in migraine patients.

The Levels of Circulating Proangiogenic Factors in Migraineurs

Migraine has been reported as a risk factor for ischemic stroke or cardiovascular events, and dysfunction of endothelial cells has been evidenced in migraine patients. Proangiogenic factors are potential endothelial stimulators, and their disturbances can link abnormalities of endothelium with increased risk of vascular disorders. The aim of this study was to evaluate the levels of circulating proangiogenic factors in sera of migraineurs during interictal period. Fifty-two patients aged 37.9 ± 9.6 years, fulfilling International Headache Society criteria for migraine, were included in this observational case-control study. The control group included 39 healthy volunteers, matched according to age and gender. All subjects underwent full neurological examination and clinimetric evaluation with the use of: MIDAS, MIGSEV, QVM, VAS and VRS scales. Serum concentrations of vascular endothelial growth factor (VEGF), angiogenin, angiopoietin-2, thrombopoietin and Tie-2 were estimated in migraineurs and in the control group with the use of ELISA. In migraineurs during interictal period, we have found decreased serum VEGF and angiogenin concentrations compared with controls. Age of migraine onset correlated with VEGF, angiopoietin-2 and thrombopoietin concentrations. Furthermore, angiopoietin-2 level correlated with QVM score and Tie-2 with pain intensity evaluated using MIGSEV scale. In migraine patients during interictal period, depletion of VEGF and angiogenin, two cooperating proangiogenic factors, can be responsible for endothelial dysfunction and increased risk for vascular disorders.

Kinetics of 5-HT2B receptor signaling: profound agonist-dependent effects on signaling onset and duration

The kinetics of drug-receptor interactions can profoundly influence in vivo and in vitro pharmacology. In vitro, the potencies of slowly associating agonists may be underestimated in assays capturing transient signaling events. When divergent receptor-mediated signaling pathways are evaluated using combinations of equilibrium and transient assays, potency differences driven by kinetics may be erroneously interpreted as biased signaling. In vivo, drugs with slow dissociation rates may display prolonged physiologic effects inconsistent with their pharmacokinetic profiles. We evaluated a panel of 5-hydroxytryptamine2B (5-HT2B) receptor agonists in kinetic radioligand binding assays and in transient, calcium flux assays, and inositol phosphate accumulation assays; two functional readouts emanating from Gαq-mediated activation of phospholipase C. In binding studies, ergot derivatives demonstrated slow receptor association and dissociation rates, resulting in significantly reduced potency in calcium assays relative to inositol phosphate accumulation assays. Ergot potencies for activation of extracellular signal-regulated kinases 1 and 2 were also highly time-dependent. A number of ergots produced wash-resistant 5-HT2B signaling that persisted for many hours without appreciable loss of potency, which was not explained simply by slow receptor-dissociation kinetics. Mechanistic studies indicated that persistent signaling originated from internalized or sequestered receptors. This study provides a mechanistic basis for the long durations of action in vivo and wash-resistant effects in ex vivo tissue models often observed for ergots. The 5-HT2B agonist activity of a number of ergot-derived therapeutics has been implicated in development of cardiac valvulopathy in man. The novel, sustained nature of ergot signaling reported here may represent an additional mechanism contributing to the valvulopathic potential of these compounds.

Efficacy endpoints in migraine clinical trials: the importance of assessing freedom from pain

Many efficacy endpoints have been used in clinical trials of acute migraine pharmacotherapy. Headache response or headache relief (i.e., moderate/severe pain reduced to mild/no pain) at a single, specified time-point, traditionally the primary endpoint, and headache recurrence (i.e., return of pain after initial postdose relief) are inadequate. Headache relief does not provide information about pain-free response and counts a partial response as a treatment success. Headache recurrence can reflect sustained efficacy but is confounded by initial response to treatment, because ineffective drugs have low recurrence rates. The International Headache Society (IHS) guidelines state that 2 hour pain-free response and sustained pain-free response (i.e., freedom from pain with no recurrence or use of rescue or study medication 2-24 hours postdose) provide the most clinically relevant information about the efficacy of migraine pharmacotherapy. The pain-free criterion counts partial responses as failures and thus is a more rigorous test of therapeutic benefit than headache relief, and the two endpoints together incorporate the main treatment attributes that determine patient satisfaction. As an example, consider needle-free subcutaneous sumatriptan and oral triptan tablets. An open-label study of needle-free subcutaneous sumatriptan by Cady and colleagues found that 2 hour pain-free response and sustained pain-free response were 64% and 42% respectively. For oral triptan tablets, the 2001 metaanalysis by Ferrari and colleagues reported 2 hour pain-free response rates ranging from 23% to 38% and sustained pain-free response rates ranging from 11% to 26%. The measures of pain-free response 2 hours postdose and sustained pain-free response can differentiate among treatments and be used to guide therapeutic choices.

Relatively slow and long-lasting antimigraine effect of dihydroergotamine is most likely due to basic pharmacological attributes of the drug: A review

Introduction

If a drug has a slow dissociation from the receptor this can result in a long duration of effect and a slow effect. The long duration of the antimigraine effect of dihydroergotamine (DHE) has been reported previously whereas a possible slow onset of DHE’s antimigraine effect, which is the subject of this review, has only rarely been mentioned.

Methods

Eight randomised, controlled trials (RCT) with DHE for acute treatment with migraine were selected from the literature. The speed of the effect of DHE in migraine was evaluated by plotting the effect up to four hours against time.

Findings

Subcutaneous DHE 1 mg was inferior to subcutaneous sumatriptan 6 mg for headache relief for the first two hours but equally effective after three hours. After intranasal DHE 2 mg the mean therapeutic gain increased slowly up to four hours. For orally inhaled DHE 0.5 mg there was a considerable time lag between therapeutic gain (maximum after two hours) and plasma concentrations of DHE (Tmax = 12 min).

Conclusion

DHE has a slow dissociation from the receptor; and this basic attribute of the drug is the most likely cause of the general relatively slow anti-migraine effect of DHE.

Revisiting the role of ergots in the treatment of migraine and headache

The harmful side effects of the ergots described by early civilizations have been overcome with efficacious treatment for headaches including migraine, cluster, and chronic daily headache. Use of ergots contributed to initial theories of migraine pathogenesis and provided the substrate for development of the triptans. Triptans are very efficacious for many migraineurs, and since their widespread use, use of ergots has significantly declined. Unfortunately, there remain many migraineurs who benefit little from triptans, yet respond very well to ergots. Discoveries in migraine pathophysiology have given us better understanding of the complex processes involved, although there remain many unknown factors in migraine treatment. Additional, unrecognized therapeutic targets may exist throughout the neuronal connections of the brainstem, cortex, and cerebral vasculature. Ergots interact with a broader spectrum of receptors than triptans. This lack of receptor specificity explains potential ergot side effects, but may also account for efficacy. The role of ergots in headache should be revisited, especially in view of newer ergot formulations with improved tolerability and side effect profiles, such as orally inhaled dihydroergotamine. Redefining where in the headache treatment spectrum ergots belong and deciding when they may be the optimal choice of treatment is necessary.

Antipsychotic Drug Treatment for Patients with Schizophrenia: Theoretical Background, Clinical Considerations and Patient Preferences

The cornerstone in treatment of psychosis is antipsychotic drugs. Treatment options have increased over the years; newer antipsychotic drugs with a proposed increased efficacy regarding negative and cognitive symptoms, but also a shift in side-effects from neurological side-effects to metabolic side-effects have arisen as the new challenge. The basis of successful pharmacological treatment is a fundamental understanding of the mechanisms of action, the desired effects and side-effects of antipsychotic drugs, a good relationship with the patient and a thorough monitoring of the patient before and during treatment. The clinically relevant aspects of antipsychotic drug treatment are reviewed; mechanism of antipsychotic drug action, clinical considerations in treatment, switching antipsychotic drugs, polypharmacy, safety and patient preference.

Migraine and stroke: current perspectives

OBJECTIVE

The purpose of this article is to review the latest concepts regarding migraine and ischemic stroke. In addition, focal neurological deficits and MRI changes in migraine patients will be reviewed.

METHODS

A PubMed search of neurological literature pertaining to this study was conducted using specific keyword search terms pertaining to migraine and ischemic stroke.

RESULTS

Migraine, especially with aura, is a relative risk factor for stroke. Neuroimaging demonstrates the posterior circulation as being most vulnerable, although the reason for this distribution is unclear. Factors that may contribute to stroke in migraine include changes during cortical spreading depression with hyper- or hypoperfusion of neural tissue, vasospasm and endothelial dysfunction. Estrogen affects migraine expression as well as cerebral circulation, yet most women with migraine without aura are not at increased risk. Co-morbidity with patent foramen ovale can be mechanism of both disorders via presumed lack of filtration of microemboli or toxic substances; however, closure with reversal of right to left shunt seems to be more beneficial for cryptogenic stroke than migraine. Migraine and stroke are found in specific genetic disorders such as CADASIL, HERNS and MELAS giving clues to genetic factors. Stroke associated with migraine treatments such as ergots or triptans is rare, and usually associated with special circumstances such as overuse or concomitant thrombogenic conditions.

CONCLUSION

Although true migrainous infarction is rare, our understanding of the subtle associations between migraine and cerebrovascular behavior is expanding.

History of the Use of Ergotamine and Dihydroergotamine in Migraine From 1906 and Onward

Dale showed in 1906 in a seminal work that ergot inhibits the pressor effect of adrenaline. Stoll at Sandoz isolated ergotamine from ergot in 1918. Based on the belief that migraine was due to increased sympathetic activity, ergotamine was first used in the acute treatment of migraine by Maier in Switzerland in 1925. In 1938 Graham and Wolff demonstrated the parallel decrease of temporal pulsations and headache after ergotamine i.v. This inspired the vascular theory of Wolff: an initial cerebral vasoconstriction followed by an extracranial vasodilation. Dihydroergotamine (DHE) was introduced as an adrenolytic agent in 1943. It is still in use parenterally and by the nasal route. Before the triptan era ergotamine and DHE had widespread use as the only specific antimigraine drugs. From 1950 the world literature on ergotamine was dominated by two adverse events: ergotamine overuse headache and the relatively rare overt ergotism. Recently, oral ergotamine, which has an oral bioavailability of < 1%, has been inferior to oral triptans in randomized clinical trials. A European Consensus in 2000 concluded that ergotamine is not a drug of first choice. In an American review of 2003 it was suggested that ergotamine may be considered in the treatment of selected patients with moderate to severe migraine.

Dihydroergotamine and its metabolite, 8'-hydroxy-dihydroergotamine, as 5-HT1A receptor agonists in the rat brain

1 In addition to stopping migraine attacks, dihydroergotamine (DHE) is an efficient drug for migraine prophylaxis. Whether 5-HT(1A) receptors could contribute to the latter action was assessed by investigating the effects of DHE and its metabolite, 8'-OH-DHE, on these receptors in the rat brain. 2 Membrane binding assays with [(3)H]8-OH-DPAT and [(3)H]WAY 100635 as radioligands showed that both DHE (IC(50)=28-30 nM) and 8'-OH-DHE (IC(50)=8-11 nM) are high-affinity 5-HT(1A) receptor ligands. 3 Both DHE and 8'-OH-DHE enhanced the specific binding of [(35)S]GTP-gamma-S to the dorsal raphe nucleus and the hippocampus in brain sections, but to a lower extent than 5-carboxamido-tryptamine (5-CT) in the latter area. 4 Both DHE (EC(50)=10.9+/-0.3 nM) and 8'-OH-DHE (EC(50)=30.4+/-0.8 nM) inhibited the firing of serotoninergic neurons in the dorsal raphe nucleus within brain stem slices. 5 Intracellular recording showed that 8'-OH-DHE was more potent than DHE to hyperpolarize CA1 pyramidal cells in rat hippocampal slices. 6 Both the stimulatory effects of DHE and 8'-OH-DHE on [(35)S]GTP-gamma-S binding and their electrophysiological effects were completely prevented by the selective 5-HT(1A) receptor antagonist WAY 100635. 7 As expected of 5-HT(1A) receptor partial agonists, DHE and 8'-OH-DHE prevented any subsequent hyperpolarization of CA1 pyramidal cells by 5-HT or 5-CT. 8 Through their actions at 5-HT(1A) auto- (in the dorsal raphe nucleus) and hetero-(notably in the hippocampus) receptors, DHE, and even more its metabolite 8'-OH-DHE, can exert both an inhibitory influence on neuronal excitability and anxiolytic effects which might contribute to their antimigraine prophylactic efficiency.

Cranial and peripheral interictal vascular changes in migraine patients

As migraine is associated with an increased risk for ischaemic stroke and peripheral vasospastic disorders, it was hypothesized that interictal vascular changes may be present in migraine patients. Using ultrasound and applanation tonometry, the cardiovascular properties of migraine patients were compared with those of matched control subjects. Vascular parameters of the carotid arteries, cardiac output and systemic vascular resistance did not differ between both groups. Right temporal artery diameter was larger in migraine patients (mean difference 101 micro m; 95% confidence interval (CI) 9/194 micro m; P = 0.033). At the brachial artery, migraine patients displayed a smaller distension (difference -24 micro m; 95% CI -45/-4 micro m; P = 0.021) and a decreased compliance (difference -0.025 mm2/kPa; 95% CI -0.047/-0.003 mm2/kPa; P = 0.024). Thus, migraine patients display an increased peripheral arterial stiffness. The presence of these interictal vascular changes suggests that migraine might be part of a more generalized vascular disorder.