Cardiovascular safety of 5HT1B/1D agonists--is there a cause for concern?

Naratriptan is as effective as sumatriptan for the treatment of migraine attacks when used properly. A mini-review

BACKGROUND

Naratriptan, marketed in a low oral dose of 2.5 mg, is generally regarded as a less-effective triptan with a slower onset of action than most other triptans in the treatment of migraine attacks. In this review, naratriptan will be compared with sumatriptan, the standard triptan.

METHODS

Papers on pharmacodynamics and pharmacokinetics and results from comparative clinical trials with oral and subcutaneous naratriptan versus other triptans were retrieved from PubMed.

RESULTS

Naratriptan and sumatriptan have similar effects in relevant animal models. In a randomized controlled trial, oral naratriptan 2.5 mg is less effective than oral sumatriptan 100 mg after both 2 h and 4 h. In contrast, oral naratriptan 10 mg has a similar time-effect curve as oral sumatriptan 100 mg, in both its steepness and the efficacy at 2 h and 4 h. Subcutaneous naratriptan 10 mg (88% pain free at 2 h) was in one trial superior to subcutaneous sumatriptan 6 mg (55% pain free at 2 h).

CONCLUSION

Naratriptan was marketed for the treatment of migraine attacks as the "gentle triptan" in a low oral dose of 2.5 mg, a dose with no more adverse events than placebo. This low dose results in the slow onset of action and low efficacy of oral naratriptan, but in high doses oral naratriptan is similar to oral sumatriptan. Based on one randomized controlled trial, subcutaneous naratriptan has probably the greatest effect of any triptan.

Utilisation of prescription and over-the-counter triptans: a cross-sectional study in Stockholm, Sweden

PURPOSE

Triptans are widely used in acute migraine, and in some countries, they are also available over-the-counter (OTC). In Sweden, sales have increased for both prescription and OTC triptans. This study aimed to describe current prescribing and utilisation patterns of prescription and OTC triptans in Stockholm, Sweden.

METHODS

Register data from 4759 patients dispensed triptans in 2014 were used to study documented diagnosis of migraine, concomitant acute and preventive treatment for migraine, and contraindications. Survey data from 49 patients purchasing OTC triptans in three pharmacies were used to capture physician-diagnosed migraine, concomitant acute and preventive treatment for migraine, a behaviour of combining or alternating between prescription and OTC triptans, and pharmacy counselling rates.

RESULTS

Among the prescription triptan users, 52 % had a recorded diagnosis of migraine, 48 % had no other acute treatment, preventive treatment was rare (12 %) and contraindications were found in 2 % of the patients. Among the OTC triptan users, the majority (63 %) had been diagnosed by a physician and had a history of prescription triptan use, but combining or alternating between OTC and prescription triptans was rare. Concomitant acute treatment was reported in 53 % and preventive treatment was rare (4 %), despite high self-reported migraine frequencies. Some off-label use was detected, despite moderate to high counselling rates.

CONCLUSION

Triptans are prescribed with attention to safety but with poor recording of migraine diagnosis. OTC triptan users generally have a history of prescription triptan use. Preventive treatment rates are low in both groups. Strategies to discern patients who need other treatment options should be considered.

The spectroscopic (FT-IR, FT-Raman, (l3)C, (1)H NMR and UV) and NBO analyses of 4-bromo-1-(ethoxycarbonyl)piperidine-4-carboxylic acid

In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of 4-bromo-1-(ethoxycarbonyl)piperidine-4-carboxylic acid (BEPA). BEPA has been characterized by FT-IR, FT-Raman, (1)H NMR, (13)C NMR and UV spectroscopy. The FT-IR and FT-Raman spectra of BEPA were recorded in the solid phase. The optimized geometry was calculated by B3LYP and M06-2X methods using 6-311G(d,p) basis set. The FT-IR and FT-Raman spectra of BEPA were calculated at the same level and were interpreted in terms of Potential Energy Distribution (PED) analysis. The scaled theoretical wavenumber showed very good agreement with the experimental values. The (1)H and (l3)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge-Independent Atomic Orbital (GIAO) method. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using Natural Bond Orbital (NBO) analysis. Density plots over the highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) energy surface directly identifies the donor and acceptor atoms in the molecule. It also provides information about the charge transfer within the molecule. To obtain chemical reactivity of the molecule, the molecular electrostatic potential (MEP) surface map is plotted over the optimized geometry of the molecule.

Differential effects of calcitonin gene-related peptide receptor blockade by olcegepant on mechanical allodynia induced by ligation of the infraorbital nerve vs the sciatic nerve in the rat

Previous studies showed that 5-hydroxytryptamine (5-HT)(1B/1D) receptor stimulation by triptans alleviates neuropathic pain caused by chronic constriction injury to the infraorbital nerve (CCI-ION) but not the sciatic nerve (CCI-SN) in rats. To assess whether such differential effects in the cephalic vs extracephalic territories is a property shared by other antimigraine drugs, we used the same models to investigate the effects of olcegepant, which has an antimigraine action mediated through calcitonin gene-related peptide (CGRP) receptor blockade. Adult male rats underwent unilateral CCI to the ION or the SN, and subsequent allodynia and/or hyperalgesia were assessed in ipsilateral vibrissal territory or hindpaw, respectively, using von Frey filaments and validated nociceptive tests. c-Fos expression was quantified by immunohistochemistry and interleukin 6 and activating transcription factor 3 (ATF3) mRNAs by real-time quantitative reverse transcriptase-polymerase chain reaction. Like naratriptan (0.1 to 0.3mg/kg, subcutaneously), olcegepant (0.3 to 0.9mg/kg, intravenously) markedly reduced mechanical allodynia in CCI-ION rats. In contrast, in CCI-SN rats, mechanical allodynia was completely unaffected and hyperalgesia was only marginally reduced by these drugs. A supra-additive antiallodynic effect was observed in CCI-ION rats treated with olcegepant (0.3mg/kg intravenously) plus naratriptan (0.1mg/kg subcutaneously), whereas this drug combination remained inactive in CCI-SN rats. Olcegepant (0.6mg/kg, intravenously) significantly reduced the number of c-Fos immunolabeled cells in spinal nucleus of the trigeminal nerve and upregulation of ATF3 transcript (a marker of neuron injury) but not that of interleukin-6 in trigeminal ganglion of CCI-ION rats. These findings suggest that CGRP receptor blockade might be of potential interest to alleviate trigeminal neuropathic pain.

Altered coronary microvascular serotonin receptor expression after coronary artery bypass grafting with cardiopulmonary bypass

OBJECTIVE

We evaluated roles of serotonin 1B and 2A receptors, thromboxane synthase and receptor, and phospholipases A(2) and C in response to cardiopulmonary bypass.

METHODS

Patients' atrial tissues were harvested before and after cardiopulmonary bypass with cardioplegia (n = 13). Coronary microvessels were assessed for vasoactive response to serotonin with and without inhibitors of serotonin 1B and 2A receptors and phospholipases A(2) and C. Expressions of serotonin receptor messenger RNA were determined with reverse transcriptase polymerase chain reaction. Expressions of serotonin receptors and thromboxane A(2) receptor and synthase proteins were determined with immunoblotting and immunohistochemistry.

RESULTS

Microvessel exposure to serotonin elicited 7.3% +/- 2% relaxation before bypass, changing to contraction of -19.2% +/- 2% after bypass (P <.001). Additions of specific serotonin 1B receptor antagonist and inhibitor of phospholipase A(2) resulted in significantly decreased contraction, -8.6% +/- 1% (P < .001) and 2.8% +/- 3% (P = .001), respectively. Serotonin 1B receptor messenger RNA expression increased 1.82 +/- 0.34-fold after bypass (p = .044); serotonin 2A receptor messenger RNA expression did not change. Serotonin 1B but not 2A receptor protein expression increased after bypass by 1.35 +/- 0.7-fold (P = .0413). Thromboxane synthase and receptor expressions were unchanged after bypass. Serotonin 1B receptor increased mainly in arterial smooth muscle. There were no appreciable differences in arterial expressions of thromboxane synthase or receptor.

CONCLUSIONS

Serotonin-induced vascular dysfunction after cardiopulmonary bypass with cardioplegic arrest may be mediated by increased expression of serotonin 1B receptor and subsequent phospholipase A(2) activation in myocardial coronary smooth muscle.

Cutaneous allodynia and migraine: another view

The paradigm of early treatment of the migraine attack at mild pain intensity has become one alternative to circumventing the problem of compromised oral absorption of symptomatic drugs due to migraine-induced gastrointestinal dysmotility. Early treatment also has been proposed to be advantageous because most migraineurs could be less responsive to delayed treatment, owing to the development of central sensitization of the trigeminal pain transmission. Ranking the underlying principles, it seems that the improved response to an oral triptan formulation at mild migraine symptom intensity has more to do with less impaired gastrointestinal absorption in the early stage of the attack than decreasing the time and preventing chances for central sensitization and development of cutaneous allodynia. Furthermore, parenteral administration of a triptan is always more likely to provide relief of symptoms than conventional tablets, even when it is used later in the course of the migraine attack. Individually tailored use of the available triptan formulations will increase, without any doubt, the within-migraineur consistency of response. It also will reduce the overall proportion of migraine attacks or migraineurs not responding to triptan treatment. Notwithstanding, the recommendation of early treatment during the migraine attack when the pain is mild remains valid.

Cardiac repolarisation and drug regulation: assessing cardiac safety 10 years after the CPMP guidance

December 2007 marks the 10-year anniversary of the first regulatory guidance for evaluation of drug-induced QT interval prolongation. A decade on, it seems surprising that this document, which was released by the Committee on Proprietary Medicinal Products, caused such acrimony in the industry. Sponsors now routinely evaluate their new drugs for an effect on cardiac electrophysiology in preclinical studies, in addition to obtaining ECGs in all phases of drug development and conducting a formal thorough QT study in humans.However, concurrently, new concerns have also emerged on broader issues related to the cardiovascular safety of drugs because of their potential to shorten the QT interval as well as to induce proischaemic, profibrotic or prothrombotic effects. Drugs may also have an indirect effect by adversely affecting one or more of the cardiovascular risk factors (e.g. through fluid retention or induction of dyslipidaemia). In addition to peroxisome proliferator-activated receptor agonists and cyclo-oxygenase 2 selective inhibitors, three other drugs, darbepoetin alfa, pergolide and tegaserod, provide a more contemporary regulatory stance on tolerance of cardiovascular risk of drugs and their benefit-risk assessment. This recent, more assertive, risk-averse stance has significant implications for future drug development. These include the routine evaluation of cardiovascular safety for certain classes of drugs. Drugs that are intended for long-term use will almost certainly require long-term clinical evaluation in studies that enrol populations that most closely resemble the ultimate target population. Novel mechanisms of action and biomarkers by themselves are no guarantee of improved safety or benefits. Even some traditional biomarkers have come to be viewed with scepticism. Requirements for more extensive and earlier postmarketing assessment of clinical benefits and rare, but serious risks associated with new medicinal products should create a new standard of evidence for industry and regulators and almost certainly result in better assessment of benefit/risk, more effective and balanced regulatory actions and better care for patients.

Over-the-counter triptans for migraine : what are the implications?

In 2006, the triptans sumatriptan 50mg and naratriptan 2.5mg were approved as over-the-counter (OTC) drugs in pharmacies in the UK and Germany, respectively. Both drugs have been used in a large number of patients with migraine and are considered to have good safety profiles. The implications of OTC triptan availability for clinical practice are that more migraine patients will use a triptan and will tend to medicate early when their headache is still mild, which should be beneficial. The problem with OTC access to triptans is medication overuse; therefore, patients should be warned of this and advised to use a triptan on fewer than 10 days per month. Pharmacists should be educated regarding migraine types and symptoms and on contraindications to triptans, so they are then able to discern the patients who should receive triptans and, as importantly, those who should not. The annual cost of migraine is euro27 billion in Europe, $US1.4 billion in the UK and $US16.6 billion in the US. By far the greatest opportunity for cost-savings comes from the potential to reduce costs associated with lost productivity from migraine. OTC availability of triptans will inevitably result in easier access to these medications, which, in turn, may result in improved treatment and lower migraine-related disability. There is currently a lack of empirical evidence that treating migraine effectively does in fact recover lost productivity; well designed studies are required to show this. The availability of triptans OTC is a logical development for the better management of a common, benign, self-limiting but nonetheless burdensome disorder that is currently grossly undertreated. We welcome this development, but recognise that advice at the point of sale is crucial for effective and safe use of these drugs.

Non-oral formulations of triptans and their use in acute migraine

The introduction of triptans (5-HT (1B/1D) agonists) into clinical practice has expanded the therapeutic options for doctors treating migraine sufferers. The triptans are available in several different formulations such as conventional oral tablets, orally disintegrating wafers, subcutaneous injections, nasal sprays, and suppositories, which provide an excellent opportunity to tailor therapy to individual patients' needs. Although the oral formulations are the most popular with patients, they are not the most appropriate route of administration for drug delivery during the migraine attack. Due to gastrointestinal dysmotility, the intestinal absorption of any triptan administered orally may be impaired and treatment effects become inconsistent. For this reason, triptans preferably should be prescribed in a non-oral formulation (injection, nasal spray, or suppository). Parenteral administration of a triptan is more likely to provide relief of symptoms, even when it is used later in the course of the migraine attack.

Effects of sumatriptan and eletriptan on diseased epicardial coronary arteries

BACKGROUND

Triptans are contraindicated in patients with known or suspected coronary artery disease (CAD); however, few studies have evaluated triptans in patients with obstructive CAD to quantify the vasoconstrictive effect on diseased coronary vessels.

METHODS

Patients undergoing percutaneous transluminal coronary angioplasty for symptomatic single-vessel CAD were randomised to one of three parallel cohorts to receive (1) 6 mg intravenously (IV) infused eletriptan plus subcutaneous (SC) placebo, (2) IV infused placebo plus 6 mg SC sumatriptan or (3) IV infused placebo plus SC placebo, as simultaneous administrations in a double-blind manner. Serial arteriograms, hemodynamic indices, electrocardiography and triptan plasma concentrations were obtained.

RESULTS

. Fifteen minutes after triptan challenge, median (95% confidence interval) changes in coronary artery diameter (CADM) at the focal point of the stenosed segment were: dilation of 2.6% (-5.0, 11.4), eletriptan 6 mg IV (n = 18); constriction of 6.8% (-12.6, 0.4), sumatriptan 6 mg SC (n = 17), and constriction of 4.5% (-7.0, 7.9), placebo (n = 10). One patient had angiographic evidence of a new thrombus at the stenosis site, necessitating termination of study infusion and successful stenting of the lesion. There was no correlation between effects on CADM and triptan concentration, or between hemodynamic or electrocardiograph changes and the presence (n = 13) or absence (n = 33) of chest pain.

CONCLUSIONS

Triptans had very little effect on diseased epicardial coronary arteries in a small group of angina sufferers with established CAD. Results should be interpreted cautiously since there may be instances where even modest triptan-associated epicardial constriction is sufficient to precipitate myocardial ischemia in patients with severe obstructive CAD.

Open label study of intranasal sumatriptan (Imigran) for footballer's headache

OBJECTIVE

To study the efficacy and practicality of treating headache in professional footballers with intranasal sumatriptan.

METHODS

An open label drug trial was performed in elite Australian footballers using intranasal sumatriptan (20 mg) treatment for acute headache. The main outcome measures were treatment response at 30 minutes, two hours, and 24 hours using two criteria: (a) initial severity moderate or severe to nil or mild; (b) stricter criteria of initial severity moderate to severe to subsequent nil headache.

RESULTS

Thirty eight attacks were analysed. The two hour response showed that 86% of attacks of migraine with aura and all of the attacks of migraine without aura responded to treatment with sumatriptan nasal spray. Complete relief of headache at two hours was reported by 71% of players with migraine with aura and 90% of those without aura. Recurrence rates were generally low, with 0% of migraine headaches and 25% non-migraine attacks recurring at 24 hours. Minor side effects were reported in 28 attacks.

CONCLUSIONS

This pilot open label trial suggests that sumatriptan nasal spray may be a valuable, effective, and convenient treatment of headache in professional sport. There are potential risks of this drug that need to be considered.

Anti-migraine action of triptans is preceded by transient aggravation of headache caused by activation of meningeal nociceptors

Consistent with previous accounts, some of the patients visiting our pain clinic during the course of a migraine attack have indicated-without solicitation-that sumatriptan injection initially intensified their headache before they were able to appreciate any pain relief. In this study, those patients who came forward complaining about pain exacerbation were asked to rate their headache intensity every 5 min. Within 5-15 min of sumatriptan injection, 17 of the 31 patients studied (55%) reported that their migraine pain intensified for 10-15 min before they started to notice any pain relief. Similar pattern of pain exacerbation was also observed in migraine attacks treated with oral formulation of almotriptan, eletriptan, rizatriptan, and zolmitriptan. To investigate the possible mechanism underlying this transient exacerbation of pain, we examined whether intravenous administration of sumatriptan can alter the response properties of C- and Adelta-meningeal nociceptors in the rat. Five to twenty minutes after intravenous administration of 300 microg/kg sumatriptan, 8/10 C-units and 2/8 Adelta-units increased their firing rate, and 6/10 C-units and 7/8 Adelta-units developed mechanical hyper-responsiveness to dural indentation. The minimal effective dose for activation and sensitization of meningeal nociceptors by sumatriptan was 3 microg/kg, suggesting that relatively low levels of triptans entering the circulation shortly after their administration can alter the physiological properties of meningeal nociceptors and produce a transient exacerbation of headache.

Rizatriptan: a new 5-HT1B/1D receptor agonist for the treatment of migraine

Rizatriptan (MAXALT MK-0462) is a new 5-HT(1B/1D) receptor agonist for the acute treatment of migraine. The marketed 10 mg and 5 mg oral doses are rapidly and consistently effective in relieving headache pain with associated migraine symptoms, and in enabling patients to return to their normal activities of daily living. Rizatriptan 10 mg is more effective than rizatriptan 5 mg. Compared to oral sumatriptan, the established agent in this class, rizatriptan has a shorter Tmax and greater bioavailability. In comparative clinical trials, the probability of having pain relief sooner was higher for rizatriptan 10 mg than for sumatriptan 100 mg or 50 mg. Over the 2 h after dosing, rizatriptan 10 mg was also superior to sumatriptan 100 mg and 50 mg on a range of other outcome measures. Both doses of rizatriptan are well-tolerated. The most common side-effects are dizziness, drowsiness, and asthenia/fatigue, which are short-lasting and of mild or moderate severity. In summary, rizatriptan is an effective and well-tolerated acute treatment for migraine, which may offer some advantages over oral sumatriptan.

Challenging or difficult headache patients

This article addresses interesting and enigmatic presentations of headache from a diagnostic and treatment perspective. The emphasis is on migraineurs and other headache patients who represent a significant burden for the primary care provider. In particular, the author focuses on undiagnosed migraine, menstrual migraine, migraine in pregnancy, intractable migraine and status migrainosus,transformed migraine, hemiplegic migraine, basilar migraine, "triptan syndrome," sudden onset of severe headache, post-traumatic headache, and headache in elderly patients.

Cardiovascular tolerability and safety of triptans: a review of clinical data

Triptans are not widely used in clinical practice despite their well-established efficacy, endorsement by the US Headache Consortium, and the demonstrable need to employ effective intervention to reduce migraine-associated disability. Although the relatively restricted use of triptans may be attributed to several factors, research suggests that prescribers' concerns about cardiovascular safety prominently figure in limiting their use. This article reviews clinical data--including results of clinical trials, postmarketing studies and surveillance, and pharmacodynamic studies--relevant to assessing the cardiovascular safety profile of the triptans. These data demonstrate that triptans are generally well tolerated. Chest symptoms occurring during use of triptans are usually nonserious and usually not attributed to ischemia. Incidence of triptan-associated serious cardiovascular adverse events in both clinical trials and clinical practice appears to be extremely low. When they do occur, serious cardiovascular events have most often been reported in patients at significant cardiovascular risk or in those with overt cardiovascular disease. Adverse cardiovascular events also have occurred, however, in patients without evidence of cardiovascular disease. Several lines of evidence suggest that nonischemic mechanisms are responsible for sumatriptan-associated chest symptoms, although the mechanism of chest symptoms has not been determined to date. Importantly, most of the clinical trials and clinical practice data on triptans are derived from patients without known cardiovascular disease. Therefore, the conclusions of this review cannot be extended to patients with cardiovascular disease. The cardiovascular safety profile of triptans favors their use in the absence of contraindications.

Frequent Triptan Use: Observations on Safety Issues

OBJECTIVE

To examine the safety of frequent triptan use over extended periods. For a small group of patients with refractory migraine plus chronic daily headache, triptans are effective.

METHODS

This retrospective study primarily evaluated the cardiac safety of daily triptan use in 118 patients and, in addition, hematologic tests were assessed. Each patient had utilized a triptan for a minimum of 4 days per week for at least 6 months. Patients with rebound headache had been withdrawn from the triptans. Most patients (97 of 118) averaged 1 tablet daily; most would occasionally go for several days without a triptan. Forty patients had taken a triptan for 6 months to 2 years, 37 patients from 2 to 4 years, and 41 for 4 or more years.

RESULTS

Routine hematologic tests were performed periodically on all patients, and no abnormalities were attributable to triptans. Almost all patients had an electrocardiogram, and no abnormal electrocardiograms were felt to be related to triptans. Cardiac echocardiography was performed in 57 patients. The 10 abnormal echocardiograms were not due to triptans. All 20 cardiac stress tests revealed normal findings. Adverse events were minimal; 9 patients described fatigue due to triptans, and 5 had mild chest tightness.

CONCLUSION

This long-term study of 118 patients indicates that frequent triptan use may be relatively safe.

Headache case studies for the primary care physician

In a given year, over 5% of persons in the United States seek medical care for headaches, most often seeing their primary care physician. The five cases here review diagnosis and treatment of migraine and other primary headaches, medication rebound headaches, and headaches in the elderly including temporal arteritis. Although headaches (along with dizziness and back pain) may be one of the least preferred diseases internists see, the increasing number of effective treatments may favorably change this opinion and result in better care for their patients.

Tolerability of the triptans: clinical implications

The triptans represent a relatively new class of compounds effective in the treatment of migraine. The safety and tolerability of these drugs have been extensively investigated since the first triptan (sumatriptan) became commercially available. A report on a very large population of patients tested during clinical trials and in postmarketing studies, confirms that these drugs are safe and well tolerated when correctly used. Adverse events are frequently reported, but are usually mild and only a few patients discontinue therapy because of them. These adverse events include, in particular, the so-called 'triptan symptoms' (tingling, sensation of warmth, etc.). The exact mechanism of chest symptoms reported by 20% of patients with migraine treated with triptans remains unclear, but are exceptionally related to a cardiac mechanism. CNS adverse events (i.e. somnolence) are also reported, but it is a matter of debate whether they are related to the pharmacological properties (i.e. lipophilicity) of the drug or are symptoms of the disease itself. The potential risk for drug overuse must be taken into account when the triptans are given to patients with a high frequency of migraine attacks. Clinical interaction of triptans with other drugs metabolised in the liver may theoretically influence the incidence of adverse events, but there is little evidence to support this assumption. There is no evidence of a teratogenic risk of triptans in pregnant women taking these drugs.

Preclinical studies characterizing the anti-migraine and cardiovascular effects of the selective 5-HT1D receptor agonist PNU-142633

The present study describes the preclinical pharmacology of a highly selective 5-HT1D receptor agonist PNU-142633. PNU-142633 binds with a Ki of 6 nm at the human 5-HT1D receptor and a Ki of> 18 000 nm at the human 5-HT1B receptor. The intrinsic activity of PNU-142633 at the human 5-HT1D receptor was determined to be 70% that of 5-HT in a cytosensor cell-based assay compared with 84% for that of sumatriptan. PNU-142633 was equally effective as sumatriptan and a half-log more potent than sumatriptan in preventing plasma protein extravasation induced by electrical stimulation of the trigeminal ganglion. Like sumatriptan, PNU-142633 reduced the increase in cat nucleus trigeminal caudalis blood flow elicited by electrical stimulation of the trigeminal ganglion compared with the vehicle control. The direct vasoconstrictor potential of PNU-142633 was evaluated in vascular beds. Sumatriptan increased vascular resistance in carotid, meningeal and coronary arteries while PNU-142633 failed to alter resistance in these vascular beds. These data are discussed in relation to the clinical findings of PNU-142633 in a phase II acute migraine study.

The effect of rizatriptan, ergotamine, and their combination on human peripheral arteries: a double-blind, placebo-controlled, crossover study in normal subjects

AIMS

To compare the peripheral vasoconstrictor effects of ergotamine, rizatriptan, and their combination, in normal subjects.

METHODS

This was a double-blind, four-way, crossover study. Sixteen young male volunteers, selected as responders to the vasoconstrictor effect of 0.5 mg ergotamine i.v., were administered 10 mg oral rizatriptan, 0.25 mg i.v. ergotamine, 10 mg oral rizatriptan+0.25 mg i.v. ergotamine, and placebo. The vasoconstrictor effect on peripheral arteries was measured with strain gauge plethysmography up to 8 h after dosing. The 8 h assessment period was divided into two 4 h intervals to assess the immediate (0-4 h) vs sustained effect (4-8 h) of treatment.

RESULTS

For the 0-4 h interval, the decreases in peripheral systolic blood pressure gradients were: placebo (-1 mmHg [95% CI: -3, 1])<rizatriptan (-5 mmHg [95% CI: -7, -3])<ergotamine (-15 mmHg [95% CI: -16, -13])=rizatriptan+ergotamine (-15 mmHg [95% CI: -17, -13]). For the 4-8 h interval, the decreases were: placebo (-5 mmHg [95% CI: -8, -3])=rizatriptan (-8 mmHg [95% CI: -11, -5])<ergotamine (-26 mmHg [95% CI: -29, -24])=rizatriptan+ergotamine (-28 mmHg [95% CI: -31, -26]).

CONCLUSIONS

In normal subjects, rizatriptan 10 mg orally had only a small transient vasoconstrictor effect on peripheral arteries compared with the sustained and more pronounced effect of 0.25 mg i.v. ergotamine. Furthermore, rizatriptan exerted no additional effect on ergotamine-induced constriction of peripheral arteries when the two drugs were given in combination.

Integrating the triptans into clinical practice

The triptans (selective serotonin agonists) are becoming the first-line alternatives in the acute pharmacological treatment of migraine, at least for attacks of moderate-to-severe intensity. Although clinical trials demonstrate significant differences in efficacy between triptan tablets, they often appear similar in efficacy when used in clinical practice, particularly after dose adjustments. Most patients with migraine consider drugs that can be administered orally to be the most user-friendly. However, gastrointestinal absorption may be impaired during migraine attacks because gastric motility is inhibited, and there is a risk that nausea during the attack will culminate in vomiting. Furthermore, in addition to their antimigraine properties, triptans may prolong the gastric emptying time. For this reason the absorption of any triptan taken orally during the migraine attack will be erratic and treatment effects inconsistent. Despite these barriers to good efficacy and high reliability, the tablet is the most commonly used triptan formulation.

Almotriptan: a review of its use in migraine

Almotriptan is a selective serotonin 5-HT(1B/1D) receptor agonist ('triptan'). Its efficacy and tolerability have been assessed in a number of randomised, controlled trials in over 4800 adults with moderate or severe attacks of migraine. Oral almotriptan has a rapid onset of action (significant headache relief is observed 0.5 hours after administration of a 12.5mg dose) and efficacy is sustained in most patients who respond by 2 hours. The drug is significantly more effective than placebo as measured by a number of parameters including 2-hour headache response and pain-free response rates. Other symptoms of migraine, including nausea, photophobia and phonophobia, are also alleviated by almotriptan. The efficacy of oral almotriptan appears to be maintained over repeated doses for multiple attacks of migraine treated over a long period (up to 1 year). High headache response rates were reported over all attacks without tachyphylaxis. For the relief of single attacks of migraine, oral almotriptan 12.5mg had similar efficacy to oral sumatriptan 50mg. Patients given almotriptan report less concern with adverse effects than patients given sumatriptan. The lower incidence of chest pain following treatment with almotriptan than with sumatriptan may lead to a reduction in direct costs, with fewer patients requiring management of chest pain. Almotriptan is well tolerated. Most adverse events were of mild or moderate intensity, transient, and generally resolved without intervention or the need for treatment withdrawal. The most common adverse events associated with oral almotriptan 12.5mg treatment were dizziness, paraesthesia, nausea, fatigue, headache, somnolence, skeletal pain, vomiting and chest symptoms. The incidence of adverse events did not differ from placebo and decreased in the longer term. Almotriptan can be coadministered with drugs that share a common hepatic metabolic path; in addition, dosage reduction is required only in the presence of severe renal or hepatic impairment.

CONCLUSIONS

Almotriptan is an effective drug for the acute treatment of moderate or severe attacks of migraine in adults. An oral dose of almotriptan 12.5mg has shown greater efficacy than placebo; current data indicate that efficacy is similar to that of oral sumatriptan 50mg, and is maintained in the long term (<or=1 year). Almotriptan has a good adverse event profile and a generally similar overall tolerability profile to sumatriptan; of note, almotriptan is associated with a significantly lower incidence of chest pain than sumatriptan. However, further clinical experience is required to clearly define the place of almotriptan among the other currently available triptans. Nevertheless, because triptans have an important place in various management regimens, and because the nature of individual patient response to triptans is idiosyncratic, almotriptan is likely to become a useful treatment option in the management of adults with moderate or severe migraine headaches.

The safety of triptans in the treatment of patients with migraine

The introduction of the triptans (5-hydroxytryptophan [5-HT] (1B/1D) agonists) in the past decade has brought migraine-specific pain relief to those suffering from migraine. These drugs activate the serotonin receptors 5-HT(1B) and 5-HT(1D) on cerebral vessels. Concerns about their safety, particularly in patients with vascular risk factors, have been raised because triptans also activate the 5-HT(1B) receptors on coronary arteries. Although triptans are contraindicated in patients with cardiac or cerebrovascular disease, they are safer than many other medications used to treat patients with migraine, including the nonspecific serotonin-agonist ergot preparations.

Impact of chest pain on cost of migraine treatment with almotriptan and sumatriptan

Chest-related symptoms occur with all triptans; up to 41% of patients with migraine who receive sumatriptan experience chest symptoms, and 10% of patients discontinue treatment. Thus, the cost of chest pain-related care was estimated in migraineurs receiving almotriptan 12.5 mg versus sumatriptan 50 mg. A population-based, retrospective cohort study used data to quantify the incidence and costs of chest pain-related diagnoses and procedures. An economic model was constructed to estimate annual cost savings per 1000 patients receiving almotriptan versus sumatriptan based on the reported rates of chest pain. Annual direct medical cost avoided was calculated for a hypothetical health plan covering 1 million lives. Among a cohort of 1390 patients, the incidence of chest pain-related diagnoses increased significantly by 43.6% with sumatriptan (P=.003). Aggregate costs for chest pain-related diagnoses and procedures increased from $22,713 to $30,234. Payments for inpatient hospital services, costs for primary care visits, and costs for outpatient hospital visits increased by over 100%, 53.1%, and 14.4%, respectively. The model predicted $11,215 in direct medical cost savings annually per 1000 patients treated with almotriptan versus sumatriptan. Annual direct medical costs avoided totaled $194,358, and when applied to recent estimates of 86 million lives currently covered by almotriptan treatment, translates into an annual cost savings of just under $17 million for chest pain and associated care. Thus, using almotriptan in place of sumatriptan will likely reduce the cost of chest pain-related care.

Pharmacokinetics and pharmacodynamics of the triptan antimigraine agents: a comparative review

The current approach to antimigraine therapy comprises potent serotonin 5-HT1B/1D receptor agonists collectively termed triptans. Sumatriptan was the first of these compounds to be developed, and offered improved efficacy and tolerability over ergot-derived compounds. The development of sumatriptan was quickly followed by a number of 'second generation' triptan compounds, characterised by improved pharmacokinetic properties and/or tolerability profiles. Triptans are believed to effect migraine relief by binding to serotonin (5-hydroxy-tryptamine) receptors in the brain, where they act to induce vasoconstriction of extracerebral blood vessels and also reduce neurogenic inflammation. Although the pharmacological mechanism of the triptans is similar, their pharmacokinetic properties are distinct. For example, bioavailability of oral formulations ranges between 14% (sumatriptan) and 74% (naratriptan), and their elimination half-life ranges from 2 hours (sumatriptan and rizatriptan) to 25 hours (frovatriptan). Clearly, such diverse pharmacokinetic properties will influence the effectiveness of the compounds and favour the prescription of one over another in different patient populations. This article reviews the pharmacological properties of the triptans (time to peak plasma concentration, half-life, bioavailability and receptor binding) and relates these properties to efficacy and time of onset. It also considers the effects of concomitant medication, food, age and disease on the pharmacokinetics of the compounds. In addition, the relative merits, such as headache recurrence, tolerability and route of administration, are discussed. Finally, the performance of the triptans is considered in the context of direct head-to-head comparative trials that have assessed the efficacy profile of the compounds.

Tolerability and efficacy of almotriptan in the long-term treatment of migraine

BACKGROUND

Almotriptan is a highly specific 5-HT(1B/1D) receptor agonist, which acts selectively on blood vessels of the brain. Short-term studies have demonstrated that almotriptan provides rapid, effective and reliable relief of migraine attacks, while offering excellent tolerability.

PURPOSE

To assess the long-term tolerability and efficacy of oral almotriptan 12.5 mg administered for every migraine attack over a 1-year period.

METHODS

A total of 762 patients treated 13,751 attacks (1-97 per patient); 61.5% of attacks were treated with one 12.5-mg dose, while for 38.5% of attacks, patients took a second dose within 24 h.

RESULTS

Three hundred and ninety-one patients (51.3%) experienced a total of 1,617 adverse events (AEs). The majority (88.6%) of AEs were of mild-to-moderate intensity, and only 28.8% of AEs were considered to be related to the study drug. Only 2 patients experienced serious AEs possibly related to almotriptan, syncope and chest pain; both recovered without any sequelae. Patients reported at least 1 AE in 11% of attacks treated. The incidence of AEs decreased during the study. Only 6 (0.8%) study withdrawals were due to AEs considered to be related to almotriptan. Tolerability was not compromised in patients taking 2 doses of almotriptan or in those using migraine prophylactics. Patient age or sex did not influence the incidence of AEs. There was no evidence of tachyphylaxis in those patients completing the study. Pain relief at 2 h after the initial dose was achieved in 84.2% of moderate/severe attacks. Patients were pain free at 2 h after dose in 58.2% of all attacks. Older patients (> 40 years) tended to respond better than younger ones (< 40 years). Efficacy was not modified by use of migraine prophylactics or hormonal contraceptives. Efficacy measurements were consistent on treating repeated moderate/severe migraine attacks.

CONCLUSION

This large, open study indicates that the new, specific 5-HT(1B/1D) agonist almotriptan, at a dose of 12.5 mg, is a well tolerated and effective treatment for migraine pain when used over a period of up to 1 year.

Pharmacological opportunities and pitfalls in the therapy of migraine

The mild vasoconstrictor effects of modern antimigraine drugs, such as serotonin (5-HT; 5-hydroxytryptamine)1B/D agonists, have led to a search for nonvasoconstrictor approaches to therapy. Such approaches have included substance P (neurokinin I) antagonists, endothelin antagonists and highly specific 5HT1D agonists. All of these substances are effective in animal models and have no significant vasoconstrictive effects. However, all of them failed to demonstrate any antimigraine effects. Current clinical and experimental evidence therefore supports the view that isolated peripheral trigeminal nerve inhibition is insufficient to relieve acute migraine.

Topics in migraine management: a survey of headache specialists highlights some controversies

The authors' Survey of headache specialists highlights a number of controversial issues in migraine management including the following: acute treatment, focusing on use of triptans, and preventative medications; treatment of migraine with prolonged aura and basilar migraine; and the use of oral contraceptives in migraine. Interestingly, the prevalence of migraine among the headache specialists themselves is much higher than in the general population. Although triptans have revolutionized the acute treatment of migraine, treatment is still problematic for the sizable percentages of patients with an incomplete or no response and recurrence of headache. Triptans are generally very safe when the physician, aware of the potential for coronary artery vasoconstriction, appropriately screens patients before and during their use. Serotonin syndrome as a complication of triptan use is quite rare. Although there is no definite evidence of teratogenesis, triptans should not be taken during pregnancy unless the potential benefit justifies the potential risk to the fetus. Caution is also advised when using a triptan during breastfeeding. The United States Headache Consortium parameters, which consider indications for preventative treatment and propose general principles of management, are reviewed. Unfortunately, the experience of many migraineurs with preventative medications is less than satisfactory because of side effects or lack of efficacy. Treatment of both migraine with prolonged aura and basilar migraine is anecdotally based. Many headache specialists do not use beta blockers for prevention for those with prolonged aura and basilar migraines because of concerns over the potential limitation of compensatory vasodilatory capacitance. There are seven case reports in the literature of an association between stroke and the use of beta blockers in migraineurs. Prevention using divalproex sodium and verapamil is favored by many headache specialists. Triptans are contraindicated in the treatment of patients with hemiplegic or basilar migraine because of concern over the potential for cerebral vasoconstriction. The frequency of migraine is usually unchanged with the use of oral contraceptives although, occasionally, migraine may occur for the first time or increase in frequency. Studies have produced conflicting results as to whether low-dose estrogen oral contraception increases the risk of stroke. Migraine alone increases the risk of stroke, at least in women under the age of 45 years. Most women with migraine without aura and migraine with visual aura lasting less than 1 hour can safely use low-dose estrogen oral contraceptives when there are no other contraindications. Those with aura symptoms such as hemiparesis or dysphasia or prolonged focal neurologic symptoms and signs lasting more than 1 hour should avoid starting low-dose estrogen oral contraceptives and stop the medication if they are already taking it.

Cardiac risk factors and the use of triptans: a survey study

OBJECTIVE

To describe current practice in triptan use.

BACKGROUND

Triptans are effective migraine treatments that cause chest symptoms in some patients. True cardiac ischemia is rare. Design.-Headache specialists and family practitioners completed questionnaires regarding the times when triptans are contraindicated, obtaining electrocardiograms (ECGs), and giving the first dose in the office.

RESULTS

Sixty-five headache specialists and 67 family practitioners responded. Headache specialists saw an average of 36.3 patients with headache per week. Family practitioners saw an average of 7.2. Family practitioners and headache specialists had similar opinions regarding the age at which triptans were contraindicated with various numbers of risk factors. Sixty-one percent of headache specialists and 50% of family practitioners would not use a triptan at any age for patients with more than three risk factors (P = NS). Ten percent of headache specialists obtained an ECG for all patients being prescribed triptans, while no family practitioners did (P =. 008). Ten percent of both family practitioners and headache specialists never obtained an ECG, even with multiple cardiac risk factors. Headache specialists obtained ECGs more often than family practitioners (P <.002 for one to three risk factors). Family practitioners were more likely to give the first dose of the triptan in the office regardless of cardiovascular risk (58% versus 20%, P <. 001). Forty-five percent of headache specialists and 2% of family practitioners never gave the first dose in the office (P <.001). Family practitioners gave the first dose in the office more readily than headache specialists in patients with no risk factors (P =.001), but not for one or more risk factors.

CONCLUSIONS

No consensus exists among family practitioners or headache specialists about when to avoid using a triptan due to excessive cardiac risk factors, when to obtain an ECG prior to using a triptan, and when to give the first dose of a triptan in the office. Headache specialists are more likely to obtain ECGs, whereas family practitioners are more likely to give the first dose of a triptan in the office.

Current and emerging second-generation triptans in acute migraine therapy: a comparative review

Sterile neurogenic inflammation within cephalic tissue, involving vasodilation and plasma protein extravasation, has been proposed as a pathophysiological mechanism in acute migraine. The action of 5-hydroxytryptamine (5-HT1B/1D) agonists--so-called triptans--on receptors located in meningeal arteries (5-HT1B) and trigeminovascular fiber endings (5-HT1D) has an inhibitory effect on this neurogenic inflammation. Recently, a series of second-generation 5-HT1B/1D agonists (almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, and zolmitriptan) have been developed and are reviewed in this article. Their in vitro pharmacological properties, pharmacokinetics, clinical efficacy, drug interactions, and adverse effects are evaluated and compared to the golden standard in the treatment of acute migraine, sumatriptan.

No contractile effect for 5-HT1D and 5-HT1F receptor agonists in human and bovine cerebral arteries: similarity with human coronary artery

1. Using subtype-selective 5-HT1 receptor agonists and/or the 5-HT1 receptor antagonist GR127935, we characterized in vitro the 5-HT receptor that mediates the contraction of human and bovine cerebral arteries. Further, we investigated which sumatriptan-sensitive receptors are present in human coronary artery by reverse-transcriptase polymerase chain reaction (RT-PCR). 2. Agonists with affinity at the 5-HT1B receptor, such as sumatriptan, alniditan and/or IS-159, elicited dose-dependent contraction in both human and bovine cerebral arteries. They behaved as full agonists at the sumatriptan-sensitive 5-HT1 receptors in both species. In contrast, PNU-109291 and LY344864, selective agonists at 5-HT1D and 5-HT1F receptors, respectively, were devoid of any significant vasocontractile activity in cerebral arteries, or did not affect the sumatriptan-induced vasocontraction. The rank order of agonist potency was similar in both species and could be summarized as 5-HT = alniditan > sumatriptan = IS-159 >>> PNU-109291 = LY344864. 3. In bovine cerebral arteries, the 5-HT1 receptor antagonist GR127935 dose-dependently inhibited the vasoconstrictions elicited by both 5-HT and sumatriptan, with respective pA2 values of 8.0 and 8.6. 4. RT-PCR studies in human coronary arteries showed a strong signal for the 5-HT1B receptor while message for the 5-HT1F receptor was weak and less frequently detected. Expression of 5-HT1D receptor mRNA was not detected in any sample. 5. The present results demonstrate that the triptan-induced contraction in brain vessels is mediated exclusively by the 5-HT1B receptor, which is also present in a majority of human coronary arteries. These results suggest that selective 5-HT1D and 5-HT1F receptor agonists might represent new antimigraine drugs devoid of cerebro- and cardiovascular effects.

Rizatriptan in the treatment of migraine

Rizatriptan is a selective 5-hydroxytriptamine1B/1D receptor agonist that was launched in 1998 for the acute treatment of migraine in adults. Based on data from 6 large clinical trials in patients > or =18 years of age in whom migraine was diagnosed according to International Headache Society criteria, the marketed 10-mg and 5-mg oral doses of rizatriptan are effective in relieving headache pain and associated migraine symptoms. The 10-mg dose is more effective than the 5-mg dose. At 2 hours after dosing, up to 77% of patients taking rizatriptan 10 mg had pain relief compared with 37% of those taking placebo, up to 44% were completely pain free compared with 7% of those taking placebo, and up to 77% were free of nausea compared with 58% of those taking placebo (P < 0.05 for all 3 comparisons). Both doses of rizatriptan are generally well tolerated. In placebo-controlled studies involving treatment of a single migraine attack, the most common side effects (incidence > or =2%) occurred in <10% of patients, typically were transitory (2 to 3 hours), and were mild or moderate. Rizatriptan is an effective and well-tolerated acute treatment for migraine.

Safety trial with the 5HT1B/1D agonist avitriptan (BMS-180048) in patients with migraine who have experienced pressure, tightness, and/or pain in the chest, neck, and/or throat following sumatriptan

We investigate whether symptoms of pressure, tightness, and/or pain in the chest, neck, and/or throat after administration of the 5HT1B/1D agonist avitriptan were associated with objective impairment of the myocardial function on 12-lead electrocardiogram (ECG), continuous ECG (Holter) monitoring, and echocardiography. Migraine sufferers who in two-thirds of all attacks treated with sumatriptan had experienced chest/throat/neck symptoms were chosen for study. Baseline measures included vital signs, a 12-lead ECG and an echocardiogram. Patients (n = 51) who had no clinically significant abnormality at baseline received a high dose (150 mg) of avitriptan orally outside of a migraine attack. If pressure, tightness, and/or pain in the chest, neck, and/or throat occurred, an ECG was obtained, and a repeat echocardiogram was done while the symptoms were present in order to monitor for impairment of myocardial function. If symptoms of these types did not occur within 60 min after administration of the study drug, a second echocardiogram was obtained. Forty-five patients (88%) reported at least one adverse event and 23 (45%) experienced pressure, tightness, and/or pain in the chest, neck, and/or throat after administration of avitriptan. No clinically significant myocardial abnormalities were observed in any patients, even in those who had experienced the targeted symptoms. No other serious adverse event occurred. We concluded that the typical 5HT1B/1D agonist-induced chest/throat/neck symptoms are most unlikely to be of cardiovascular origin.