Triptans and CNS side-effects: pharmacokinetic and metabolic mechanisms

Cytochromes P450: Roles in the Biotransformation of Chemicals in Cigarette Smoke and Impact of Smoking Cessation on Concurrent Drug Therapy

Cigarette smoke contains polycyclic aromatic hydrocarbons (PAHs) that activate the expression of cytochrome P450 family 1 (CYP1) enzymes in liver and other tissues; this process is dependent on the aryl hydrocarbon receptor (AhR) transcription factor. An important CYP1 enzyme, CYP1A2, has a critical role in the oxidation of drugs such as clozapine, olanzapine and theophylline; these drugs exhibit a high incidence of adverse effects that are linked to plasma concentrations. This article reviews the impact of smoking and smoking cessation on therapy with toxic drugs that undergo CYP-mediated elimination. PAHs in cigarette smoke activate the AhR and upregulate CYP1A2, which enhances the clearance of these drugs, diminishes their efficacy and necessitates the use of higher doses. However, smoking cessation decreases PAH exposure, which leads to a decline in clearance of CYP1A2 substrate drugs. Dose reductions and close therapeutic monitoring for such drugs are recommended in patients who cease smoking.

Migraine attacks the Basal Ganglia

Background

With time, episodes of migraine headache afflict patients with increased frequency, longer duration and more intense pain. While episodic migraine may be defined as 1-14 attacks per month, there are no clear-cut phases defined, and those patients with low frequency may progress to high frequency episodic migraine and the latter may progress into chronic daily headache (> 15 attacks per month). The pathophysiology of this progression is completely unknown. Attempting to unravel this phenomenon, we used high field (human) brain imaging to compare functional responses, functional connectivity and brain morphology in patients whose migraine episodes did not progress (LF) to a matched (gender, age, age of onset and type of medication) group of patients whose migraine episodes progressed (HF).

Results

In comparison to LF patients, responses to pain in HF patients were significantly lower in the caudate, putamen and pallidum. Paradoxically, associated with these lower responses in HF patients, gray matter volume of the right and left caudate nuclei were significantly larger than in the LF patients. Functional connectivity analysis revealed additional differences between the two groups in regard to response to pain.

Conclusions

Supported by current understanding of basal ganglia role in pain processing, the findings suggest a significant role of the basal ganglia in the pathophysiology of the episodic migraine.

Triptans for the management of migraine

Migraine is a chronic, recurrent, disabling condition that affects millions of people in the US and worldwide. Proper acute care treatment for migraineurs is essential for a full return of function and productivity. Triptans are serotonin (5-HT)(1B/1D) receptor agonists that are generally effective, well tolerated and safe. Seven triptans are available worldwide, although not all are available in every country, with multiple routes of administration, giving doctors and patients a wide choice. Despite the similarities of the available triptans, pharmacological heterogeneity offers slightly different efficacy profiles. All triptans are superior to placebo in clinical trials, and some, such as rizatriptan 10 mg, eletriptan 40 mg, almotriptan 12.5 mg, and zolmitriptan 2.5 and 5 mg are very similar to each other and to the prototype triptan, sumatriptan 100 mg. These five are known as the fast-acting triptans. Increased dosing can offer increased efficacy but may confer a higher risk of adverse events, which are usually mild to moderate and transient in nature. This paper critically reviews efficacy, safety and tolerability for the different formulations of sumatriptan, zolmitriptan, rizatriptan, naratriptan, almotriptan, eletriptan and frovatriptan.

Does sumatriptan cross the blood-brain barrier in animals and man?

Sumatriptan, a relatively hydrophilic triptan, based on several animal studies has been regarded to be unable to cross the blood–brain barrier (BBB). In more recent animal studies there are strong indications that sumatriptan to some extent can cross the BBB. The CNS adverse events of sumatriptan in migraine patients and normal volunteers also indicate a more general effect of sumatriptan on CNS indicating that the drug can cross the BBB in man. It has been discussed whether a defect in the BBB during migraine attacks could be responsible for a possible central effect of sumatriptan in migraine. This review suggests that there is no need for a breakdown in the BBB to occur in order to explain a possible central CNS effect of sumatriptan.

A review of smoking cessation: potentially risky effects on prescribed medications

AIMS AND OBJECTIVES

To identify prescription drugs that require dosage adjustment or monitoring in patients who quit smoking and to provide recommendations for dosage adjustment based on available evidence.

BACKGROUND

Health care providers are urged to facilitate smoking cessation for patients who smoke, but the effects of smoking cessation on the metabolism of some drugs is not routinely considered.

DESIGN

A comprehensive literature review.

METHODS

The review was conducted in 2008 using a computerised drug interaction program and multiple PubMed and CINAHL searches to identify prescription drugs with clinically significant pharmacokinetic or pharmacodynamic changes caused by smoking cessation.

RESULTS

Although much of the evidence is case report, dosage adjustments are clearly indicated for warfarin, olanzapine, clozapine and theophylline since they are metabolised by cytochrome P450 CYP1A2 and also have narrow therapeutic ratios. Careful monitoring is recommended for other CYP1A2 metabolised drugs, including those for hypertension and Alzheimer's disease. For many affected drugs, smoking cessation reverses smoking-induced CYP1A2 hepatic enzyme levels to normal, increasing plasma concentrations in patients whose dose was established while smoking. Because the effect on hepatic microsomal enzymes is not related to the nicotine component of tobacco, nicotine replacement will not alter the effect.

CONCLUSIONS

The effects of smoking cessation on drugs metabolised by CYP1A2 have been under-appreciated by health care providers. Smoking cessation may increase plasma levels of some drugs to potentially toxic levels. Further research is warranted to clarify this effect.

RELEVANCE TO CLINICAL PRACTICE

When patients stop smoking, providers should carefully review prescribed drug regimens and adjust or monitor drugs whose metabolism is affected by smoking cessation. This is particularly important for patients who abruptly stop smoking due to hospitalisation and for older patients who are likely to be taking multiple medications.

Disposition and metabolism of almotriptan in rats, dogs and monkeys

Almotriptan is a new highly potent selective 5-HT1B/1D receptor agonist developed for the treatment of migraine, and the disposition of almotriptan in different animal species is now addressed in the current study. Almotriptan was well absorbed in rats (69.1%) and dogs (100%) following oral treatment. The absolute bioavailability was variable reflecting different degrees of absorption and first-pass metabolism (18.7-79.6%). The elimination half-life was short and ranged between 0.7 and 3 h. The main route of elimination of almotriptan was urine with 75.6% and 80.4% of the dose recovered over a 168-h period in rats and dogs, respectively. The gamma-aminobutyric acid metabolite formed by oxidation of the pyrrolidine ring was the main metabolite found in urine, faeces, bile, and plasma of rats and in monkey urine. By contrast, the unchanged drug, the indole acetic acid metabolite formed by oxidative deamination of the dimethylaminoethyl group, and the N-oxide metabolite were the main metabolites in dog.

Zolmitriptan compared to propranolol in the treatment of acute neuroleptic-induced akathisia: a comparative double-blind study

Neuroleptic-induced akathisia (NIA) is a common, sometimes incapacitating adverse effect of anti-psychotic medication. Zolmitriptan is a selective 5-HT(1D) agonist. We aimed to determine its anti-NIA efficacy in comparison to propranolol. Thirty-three neuroleptic-treated patients were randomly allocated in a double-blind design to receive either 7.5 mg/d of zolmitriptan or 120 mg/d of propranolol for 3 consecutive days, followed by 3 days without any anti-NIA treatment. Patients were assessed at baseline and on days 3 and 7 by the Barnes Akathisia Rating Scale (BARS), PANSS, HAMD, HAMA, Pulse, and Blood Pressure. Both groups showed improvement of akathisia (BARS) along the treatment period, with significant effect for time but not for group. No significant differences were found between the groups in all other measurements. Taken together, zolmitriptan was found to be as effective as propranolol for the treatment of NIA. Further placebo-controlled studies are warranted.

Migraine pain: reflections against vasodilatation

The original Wolff’s vascular theory of migraine was supported by the discovery of a class of drugs, the triptans, developed as a selective cephalic vasoconstrictor agents. Even in the neurovascular hypothesis of Moskowitz, that is the neurogenic inflammation of meningeal vessels provoked by peptides released from trigeminal sensory neurons, the vasodilatation provoked by calcitonin gene-related peptide (CGRP) is considered today much more important than oedema. The role of cephalic vasodilatation as a cause of migraine pain was recently sustained by studies showing the therapeutic effect of CGRP receptor antagonists. We discuss the evidence against vasodilatation as migraine pain generator and some findings which we suggest in support of a central (brain) origin of pain.

The Link Between Pain Patient and Analgesic Medication is Greater in Migraine than in Rheumatic Disease Patients

Our aim was to measure and compare the link between pain patients and the different kinds of analgesic medications they use by the Leeds Dependence Questionnaire (LDQ). This is a self-completion 10-item instrument to measure the severity of dependence upon a variety of substances. LDQ was administered to 200 episodic migraine patients (EM group), 77 chronic migraine patients (CM group) overusing acute medications, and 114 patients suffering from rheumatic disease (RD group), consecutively attending the Headache Centre or the Rheumatology Clinic of the University Hospital of Modena in the course of the first semester of 2007. The link with analgesics was greater in migraine patients than in patients with rheumatic disease, since the LDQ total score was significantly higher in the EM (6.65 ± 0.32, P < 0.005) and CM groups (9.61 ± 0.59, P < 0.0001) than in the RD group (5.17 ± 0.37) (Kruskal–Wallis and Mann–Whitney U-tests). Migraine patients were significantly more linked to triptans and to combined medications than to non-steroidal anti-inflammatory drugs. The strength of the link between migraine patients and the analgesic medications they take could represent a factor of vulnerability: overusing these medications could develop medication overuse headache.

Pathways to the Best Fit of Triptans for Migraine Patients

Variability in drug response is a major barrier to the successful treatment of migraine, and most treatments are only optimal in a subset of patients. Although triptans provide the best therapeutic option for the treatment of acute migraine, it has not previously been possible to predict how well patients will respond to a specific triptan or whether they will experience unpleasant adverse events. Hence, it has been difficult for physicians to match individual patients with the most suitable agent to treat their migraine pain. Intrapatient variability has been associated with polymorphisms in genes encoding drug-metabolizing enzymes, drug transporters and drug targets. Pharmacogenetics provides the possibility of tailoring the therapeutic approach to individual patients, in order to maximize treatment efficacy while minimizing the potential for unwanted side-effects. This review demonstrates how almotriptan may overcome genetically determined responses by utilizing diverse metabolic pathways to provide therapeutic benefit to many migraineurs.

Headaches related to triptans therapy in patients of migrainous vertigo

Dizziness and vertigo are frequently reported by patients with migraine. In migrainous vertigo (MV), vertigo is causally related to migraine. Patients of MV usually have an attenuated or absent headache with their vertigo as compared with their usual headache of migraine. Here we report three female patients of MV in which administration of triptan was associated with induction (two patients) or exacerbation (one patient) of headache with disappearance of vertigo. We suggest that headache and vertigo of migraine may be inversely related to each other and suppression of one may induce or aggravate the other.

Repression of calcitonin gene-related peptide expression in trigeminal neurons by a Theobroma cacao extract

ETHNOPHARMACOLOGICAL RELEVANCE

Cocoa bean preparations were first used by the ancient Maya and Aztec civilizations of South America to treat a variety of medical ailments involving the cardiovascular, gastrointestinal, and nervous systems. Diets rich in foods containing abundant polyphenols, as found in cocoa, underlie the protective effects reported in chronic inflammatory diseases. Release of calcitonin gene-related peptide (CGRP) from trigeminal nerves promotes inflammation in peripheral tissues and nociception.

AIM OF THE STUDY

To determine whether a methanol extract of Theobroma cacao L. (Sterculiaceae) beans enriched for polyphenols could inhibit CGRP expression, both an in vitro and an in vivo approach was taken.

RESULTS

Treatment of rat trigeminal ganglia cultures with depolarizing stimuli caused a significant increase in CGRP release that was repressed by pretreatment with Theobroma cacao extract. Pretreatment with Theobroma cacao was also shown to block the KCl- and capsaicin-stimulated increases in intracellular calcium. Next, the effects of Theobroma cacao on CGRP levels were determined using an in vivo model of temporomandibular joint (TMJ) inflammation. Capsaicin injection into the TMJ capsule caused an ipsilateral decrease in CGRP levels. Theobroma cacao extract injected into the TMJ capsule 24h prior to capsaicin treatment repressed the stimulatory effects of capsaicin.

CONCLUSIONS

Our results demonstrate that Theobroma cacao extract can repress stimulated CGRP release by a mechanism that likely involves blockage of calcium channel activity. Furthermore, our findings suggest that the beneficial effects of diets rich in cocoa may include suppression of sensory trigeminal nerve activation.

Temporary confusion depending on the usage of naratriptan

In this report, a case with vitamin B12 deficiency showing a temporary confusion depending on the usage of naratriptan during the migraine attack was presented.

A case-control study on excessive daytime sleepiness in episodic migraine

Migraine patients often complain of sleepiness, a problem that manifests both during and outside an attack, may impair the quality of life and can lead to potentially harmful situations. Findings from an uncontrolled study suggest that a high percentage of migraineurs experience excessive daytime sleepiness (EDS). We investigated EDS in a case-control study on 100 patients with episodic migraine and 100 age- and sex-matched healthy controls and also assessed sleep quality, anxiety and depression. Although it was found that EDS was more frequent in migraineurs than in controls (14% vs. 5%; odds ratio 3.1; 95% confidence interval 1.1-8.9), the frequency was lower than previously reported. EDS correlated with migraine disability, sleep problems and anxiety. EDS in patients with migraine probably stems from the full constellation of headache-sleep-affective symptoms resulting from the complex clinical burden of the disease.

Use of the sustained pain-free plus no adverse events endpoint in clinical trials of triptans in acute migraine

OBJECTIVE

To assess the relationship between the sustained pain free (SPF) and adverse event (AE) rates associated with six oral serotonin 5-HT(1B/1D) receptor agonists (triptans) used for the treatment of acute migraine, employing data from a previous meta-analysis (that included almotriptan, eletriptan, naratriptan, rizatriptan, sumatriptan and zolmitriptan, but not frovatriptan) in order to provide a rationale for the use of the rate of patients who are SPF plus no AE (SNAE) as an endpoint in trials of medications for acute migraine.

BACKGROUND

The attributes of drug treatment for acute migraine that are most important to people who experience them are complete pain relief, lack of recurrence, rapid onset and lack of AEs. The endpoints used to assess therapy for acute migraine do not always address these elements.

METHODS

The relationship between SPF and AE rates was explored using nonparametric regression techniques, and the box-plot method was used to identify outliers. The estimated SNAE rate for each triptan was calculated with and without assuming independence between efficacy and tolerability.

RESULTS

At the level of the individual agent, there was a significant relationship between the efficacy and tolerability of each triptan, with the exception of almotriptan 12.5 mg, which had an AE rate approximately 30% lower than would be expected, and eletriptan 20 mg, which had an AE rate approximately 20% higher than would be expected, on the basis of their efficacy. Almotriptan 12.5 mg and eletriptan 20 mg had the highest and lowest base-case values for SNAE, respectively, and both qualified statistically as outliers to the distribution of SNAE values obtained with the other triptans. The probability that each triptan was superior to the reference agent (sumatriptan 100 mg) in terms of SNAE was calculated across all possible values (at the level of the individual patient) for the relationship between efficacy and tolerability. Again, almotriptan 12.5 mg and eletriptan 20 mg had the highest and lowest values for their SNAE rates, respectively, and almotriptan 12.5 mg qualified statistically as an outlier from the distribution of the probabilities obtained for the other triptans.

CONCLUSION

This analysis determined that higher SPF rates were strongly associated with higher AE rates, with the notable exception of almotriptan 12.5 mg, which had a lower than expected AE rate, resulting in the highest SNAE rate of the included triptans and doses. SNAE is a useful measure that can be used to discriminate between therapies and this endpoint incorporates the attributes that are most relevant to patient satisfaction with treatment. We recommend calculation of the SNAE rate at the level of the individual patient in future clinical trials of medication for the treatment of acute migraine to facilitate selection of a treatment for acute migraine that offers the best chance for effective management.

Patient preference in migraine therapy

OBJECTIVE

To assess patient preference for almotriptan 12.5 mg vs rizatriptan 10 mg for the acute treatment of migraine.

METHODS

Randomized, multicenter, open-label, crossover trial in which triptan-naïve patients treated two moderate/severe migraine attacks, the first with one triptan and the second with the other: 183 patients took rizatriptan followed by almotriptan and 189 treated in the reverse order. Patient preference was assessed with a self-administered questionnaire.

RESULTS

Of those recording a preference (209), 54.5% preferred almotriptan, but statistical significance was not achieved. The main reason for preference for one or the other triptan was efficacy: 43% of patients preferring almotriptan gave faster headache relief as the reason and 34% cited faster return to normal activities. The corresponding values for rizatriptan were 47% and 38%. A significantly greater proportion of those preferring almotriptan cited fewer adverse events (AEs) as the reason. Almotriptan and rizatriptan were of comparable efficacy and both treatments were well tolerated; 9% of patients experienced AEs probably or possibly related to study medication after almotriptan vs 14% after rizatriptan. Almotriptan was associated with a significantly lower incidence of triptan-associated AEs in triptan-naïve patients (8.5% vs 18% with rizatriptan).

CONCLUSION

Physicians should use information from meta-analyses and preference studies like this one to aid in the selection of a triptan with a high likelihood of providing rapid, sustained relief from pain coupled with an absence of AEs. About 55% of patients recording a preference in this trial preferred almotriptan, perhaps because of its combination of good efficacy and lower incidence of triptan-associated AEs.

Pharmacokinetics and interactions of headache medications, part I: introduction, pharmacokinetics, metabolism and acute treatments

Recent progress in the treatment of primary headaches has made available specific, effective and safe medications for these disorders, which are widely spread among the general population. One of the negative consequences of this undoubtedly positive progress is the risk of drug-drug interactions. This review is the first in a two-part series on pharmacokinetic drug-drug interactions of headache medications. Part I addresses acute treatments. Part II focuses on prophylactic treatments. The overall aim of this series is to increase the awareness of physicians, either primary care providers or specialists, regarding this topic. Pharmacokinetic drug-drug interactions of major severity involving acute medications are a minority among those reported in literature. The main drug combinations to avoid are: i) NSAIDs plus drugs with a narrow therapeutic range (i.e., digoxin, methotrexate, etc.); ii) sumatriptan, rizatriptan or zolmitriptan plus monoamine oxidase inhibitors; iii) substrates and inhibitors of CYP2D6 (i.e., chlorpromazine, metoclopramide, etc.) and -3A4 (i.e., ergot derivatives, eletriptan, etc.), as well as other substrates or inhibitors of the same CYP isoenzymes. The risk of having clinically significant pharmacokinetic drug-drug interactions seems to be limited in patients with low frequency headaches, but could be higher in chronic headache sufferers with medication overuse.

Use of Plasma and Brain Unbound Fractions to Assess the Extent of Brain Distribution of 34 Drugs: Comparison of Unbound Concentration Ratios to in Vivo P-Glycoprotein Efflux Ratios

The P-glycoprotein (P-gp)-deficient mouse model is used to assess the influence of P-gp-mediated efflux on the central nervous system (CNS) distribution of drugs. The steady-state unbound plasma/unbound brain concentration ratio ([plasma],(u)/[brain],(u)) is an alternative method for assessing CNS distribution of drugs independent of the mechanism(s) involved. The objective of this study was to compare the degree of CNS distributional impairment determined from the in vivo P-gp efflux ratio with that determined from the [plasma],(u)/[brain],(u) ratio. CNS distribution of 34 drugs, including opioids, triptans, protease inhibitors, antihistamines, and other clinically relevant drugs with either poor CNS distribution or blood-brain barrier efflux, was studied. Plasma and brain unbound fractions were determined by equilibrium dialysis. K(p,brain) and the P-gp efflux ratio were obtained from the literature or determined experimentally. The P-gp efflux ratio and the [plasma],(u)/[brain],(u) ratio were in concurrence (<3-fold difference) for 21 of the 34 drugs. However, the [plasma],(u)/[brain],(u) ratio exceeded the P-gp efflux ratio substantially (>4-fold) for 10 of the 34 drugs, suggesting that other, non-P-gp-mediated mechanism(s) may limit the CNS distribution of these drugs. The P-gp efflux ratio exceeded the [plasma],(u)/[brain],(u) ratio by more than 3-fold for three drugs, suggesting the presence of active uptake mechanism(s). These observations indicate that when mechanisms other than P-gp affect CNS distribution (non-P-gp-mediated efflux, poor passive permeability, cerebrospinal fluid bulk flow, metabolism, or active uptake), the P-gp efflux ratio may underestimate or overestimate CNS distributional impairment. The [plasma],(u)/[brain],(u) ratio provides a simple mechanism-independent alternative for assessing the CNS distribution of drugs.

Almotriptan and zolmitriptan in the acute treatment of migraine

OBJECTIVE

To compare almotriptan and zolmitriptan in the treatment of acute migraine.

METHODS

This multicentre, double-blind trial randomized adult migraineurs to almotriptan 12.5 mg (n = 532) or zolmitriptan 2.5 mg (n = 530) for the treatment of a single migraine attack. The primary end point was sustained pain free plus no adverse events (SNAE); other end points included pain relief and pain free at several time points, sustained pain free, headache recurrence, use of rescue medication, functional impairment, time lost because of migraine, treatment acceptability, and overall treatment satisfaction.

RESULTS

No significant difference was seen in SNAE (almotriptan 29.2% vs zolmitriptan 31.8%) or the other efficacy end points measured. The incidence of triptan-associated AEs and triptan-associated central nervous system AEs was significantly lower for patients receiving almotriptan compared to zolmitriptan.

CONCLUSIONS

Almotriptan and zolmitriptan were associated with similar efficacy and overall tolerability in the treatment of acute migraine. Almotriptan was associated with a significantly lower rate of triptan-associated AEs.

The Neuropsychology of Recurrent Headache

Headache is recognized as one of the most prevalent neurological disorders, and is the most frequently reported symptom following injury to the head, brain, or neck. Although studies of central nervous system abnormalities in headache sufferers have emerged in recent years, less is known about the associated functional impairments. The research literature addressing neuropsychological consequences of headache has been far from conclusive. Migraine has been most extensively studied, with some consistent evidence of subtle but potentially significant changes in cognition occurring during and between migraine episodes. It also appears likely that migraine patients with aura experience more neuropsychological deficits than those without aura. While the literature devoted to understanding the neurocognitive profile of migraine sufferers is growing, much less research has addressed the neuropsychology of tension-type headache and posttraumatic headache (PTHA). There is some suggestion of poorer neuropsychological function in tension-type headache than controls, but the evidence is inconclusive. The PTHA population is highly varied in degree and location of trauma, preexisting headache condition, and other injury-related variables, allowing little generalization across studies. This paper summarizes research regarding the cognitive symptoms associated with migraine, tension-type headache, and PTHA, provides an overview of the cognitive side effects of headache medications, and addresses clinical implications and priorities for future research.

Focus on trial endpoints of clinical relevance and the use of almotriptan for the acute treatment of migraine

Almotriptan is a 5-HT(1B/1D) receptor agonist, or triptan, indicated for the acute treatment of migraine. It has been shown to be effective and well tolerated for the treatment of acute migraine in approximately 5000 patients enrolled in short-term placebo- and active-controlled trials and long-term open-label trials. A recent meta-analysis reported that almotriptan has the highest sustained pain-free (SPF) rate and lowest adverse-event (AE) rate of all oral triptans. Sustained pain free is a composite endpoint of pain freedom at 2 h, no recurrence of moderate-to-severe headache and no use of rescue medication from 2 to 24 h after dosing. Patient surveys have indicated that migraine sufferers consider complete pain relief, no recurrence, rapid onset and no side-effects to be the most important attributes of their acute treatment. Composite endpoints such as SPF and SPF with no AEs (SNAE) contain the attributes that migraine sufferers express as being the most important elements of an acute migraine therapy, and their use in future clinical trials should aid in the selection of agents that can offer patients the highest likelihood of consistent treatment success.

Myalgia and Cramps Associated With Zolmitriptan

OBJECTIVE

To report a patient with myalgia and cramps possibly induced by the antimigrainous agent zolmitriptan.

CASE REPORT

A 27-year-old woman with episodes of common migraine developed cramps and generalized myalgia after the use of intranasal zolmitriptan 5 mg to treat 3 episodes of migraine. This side effect had not occurred with oral zolmitriptan 2.5 mg.

CONCLUSION

Myalgia and cramps should be considered a possible dose-dependent adverse effect of zolmitriptan.

Migraine during pregnancy: options for therapy

Migraine is common during pregnancy, but fortunately this combination of conditions obviously exists for only a finite period. The greatest frequency of migraine attacks occurs during the first trimester. Accurate diagnosis is a sine qua non in this setting as in any headache patient. It is in the first trimester that the fetus is at greatest risk from abortifacient and teratogenic drugs, and when very early pregnancy may be undiagnosed. Ergot alkaloids (including methysergide) should be avoided during pregnancy because of their teratogenicity, and most other drug classes should be used only when unavoidable. The use of prophylactic agents during pregnancy should be the exception, not the rule, and preferably only during the second and third trimesters; propranolol is probably safest in this situation. De novo headache during pregnancy usually requires expert review of the patient. Treatment tactics for uncomplicated migraine in pregnancy depend on the concurrent clinical situation. Paracetamol (acetaminophen) is the mainstay for the patient whose typical attacks continue into the first trimester. If paracetamol is insufficient, then partial agonist opioids may be used if typical migraine attacks persist in the second and third trimesters (which is uncommon). 'Chronic migraine' in pregnancy, i.e. >or=15 headache days per month, is rare, and is the greatest therapeutic challenge. Co-morbidities such as depression or epilepsy require specialised approaches. The complexities associated with these tactics are discussed in this article, and it is emphasised that none has the specific approval of regulatory authorities. Heightened pharmacovigilance will better inform the future pregnant migraineur. However, this type of information is less likely to be available for novel classes of neuropharmacological agents than for existing ones.

Optimizing the Diagnosis and Treatment of Migraine

PURPOSE

To describe and discuss short headache questionnaires, which can simplify and improve the diagnosis of migraine.

DATA SOURCES

Review of the worldwide scientific literature on short diagnostic questionnaires for migraine.

CONCLUSIONS

A new three-question Headache Screen addressing disability due to recurring headaches, headache duration, and changes in headache characteristics and/or pattern over the previous 6 months displayed high sensitivity when used to survey >3000 migraineurs, correctly identifying 77% of migraineurs diagnosed by International Headache Society (IHS) criteria, clinical impression, or the presence of recurring, disabling headaches.

IMPLICATIONS FOR PRACTICE

The underdiagnosis and undertreatment of migraine are problems that may be attributed to many causes involving both patients and medical providers. These include stringent diagnostic criteria established by the IHS, which fail to easily classify many common migraine presentations, the lack of clear outcome measures of successful management of migraine, and failure to recognize the iatrogenic role of prescription and nonprescription medications as an etiologic factor in chronic daily headache. The recent development of reliable, clinically useful, short headache questionnaires that are focused on headache impact facilitates the understanding and diagnosis of migraine for both patients and healthcare professionals. As a diagnostic tool, the Headache Screen has the potential to expand appropriate medication use, leading to improved functional status and quality of life for migraineurs.

Eletriptan review

Eletriptan is a selective, high affinity serotonin 5-HT(1B/1D)-receptor agonist which is rapidly absorbed and has a long half-life in plasma. Eletriptan has been shown to be effective and well tolerated in randomised, double-blind, placebo-controlled acute migraine trials and long-term open-label trials. Eletriptan maintains a consistency of response across three attacks and patients continue to respond to eletriptan for at least up to 1 year. Eletriptan has been compared with sumatriptan, zolmitriptan, naratriptan and ergotamine/caffeine in placebo-controlled, randomised, head-to-head trials, and has shown better efficacy with similar adverse events. In a large triptan meta-analysis, including 53 trials and > 24,000 patients, eletriptan 80 mg showed better efficacy, similar consistency but lower tolerability compared with sumatriptan 100 mg. Eletriptan has also shown efficacy in difficult-to-treat patients who were dissatisfied with their previous treatment with sumatriptan, rizatriptan, nonsteroidal anti-inflammatory drugs or Excedrin.

Efficacy and Tolerability of Almotriptan in Postmarketing Surveillance Studies

While randomized, double-blind, placebo-controlled trials are considered the gold standard of clinical evidence, they are limited by patient numbers, duration of patient exposure, and restricted patient populations. Data from controlled trials may not be generalizable to all individuals likely to take the drug under investigation. Postmarketing surveillance studies are designed to measure efficacy and safety in larger and more diverse populations, allowing them to detect less common and delayed adverse events. However, postmarketing surveillance studies are limited by their lack of randomization, open-label design that can result in patient and physician bias, incomplete follow-up, less than rigorous outcome measurement, and lack of a contemporaneous control group. With regard to acute treatment of migraine, clinical trials using per protocol primary endpoints do not reflect the more favorable experience with triptans in general practice. Postmarketing surveillance studies have been performed to determine whether the high levels of efficacy and tolerability of almotriptan reported in controlled clinical trials can been reproduced in routine practice. An observational study conducted in Spain with 2,074 migraine sufferers (4,183 attacks) reported a 2-hour pain-relief rate of 86.9%, a 2-hour pain-free rate of 51.5%, and a sustained pain-free rate of 46.0%; 1.1% of patients reported adverse reactions. A German postmarketing study in 899 patients (2,131 attacks) with acute migraine treated with almotriptan 12.5 mg reported 2-hour pain relief in 84.5% of attacks and 2-hour pain free in 41.4%; 1.1% of patients reported adverse reactions. The consistency of response (at least two out of three attacks successfully treated) with almotriptan 12.5 mg was 87.3%. Regarding satisfaction, 88.5% of patients were satisfied or very satisfied and 80.3% of patients stated that almotriptan was better compared to their prior therapy; 92% of physicians indicated that they would continue treating their patients' migraines with almotriptan. The results of these studies demonstrate that the high levels of efficacy and tolerability seen with almotriptan in controlled clinical trials are achieved in real-world clinical settings. In conclusion, a combination of controlled clinical trials, postmarketing surveillance studies, and physician's experience in the general population can give us a better understanding of the efficacy and tolerability of acute migraine agents.

Reinforced spatial alternation as an animal model of obsessive-compulsive disorder (OCD): investigation of 5-HT2C and 5-HT1D receptor involvement in OCD pathophysiology

BACKGROUND

This study introduces a laboratory model of compulsive behavior based on persistence in the context of rewarded spatial alternation.

METHODS

Rats were screened for spontaneous persistence during T-maze reinforced alternation. Experiment 1: One high and one low spontaneous persistence group (n = 8) received 20 injections of fluoxetine, a matched pair saline, both followed by 4 days of meta-chlorophenylpiperazine (mCPP) challenge. Experiment 2: Five matched groups of rats (n = 9) received pretreatment (20 injections) with fluoxetine, mCPP, desipramine, diazepam or saline, followed by 4 days of mCPP challenge (fluoxetine in mCPP group). After washout, animals received 2 days of naratriptan, followed by another 2-day mCPP challenge.

RESULTS

In both experiments mCPP significantly increased persistence in saline controls. Fluoxetine also acutely increased persistence scores: after a gradual return to baseline, these scores showed tolerance to mCPP. Experiment 1: This pattern was significant in high but not low initial persistence groups. Experiment 2: Fluoxetine and mCPP showed cross-tolerance. Neither desipramine nor diazepam protected against mCPP challenge. Persistence scores returned to baseline during washout and naratriptan and were thereafter increased by another mCPP challenge in all but the fluoxetine and mCPP groups, suggesting 5-HT2C receptor mediation.

CONCLUSIONS

This model is based on spontaneous persistence behavior showing pharmacological responses concordant with those of compulsive symptomatology.

Defining response in migraine: which endpoints are important?

The primary endpoint traditionally measured in clinical trials of triptans for acute migraine therapy has been 2-hour pain relief, a decrease in pain intensity from moderate/severe to mild/none. Although harder to achieve, endpoints such as 2-hour pain free and the composite measure sustained pain free are now preferred as they better reflect what patients desire from medication, namely rapid onset of action, and complete and lasting relief of pain. A comprehensive meta-analysis has shown that oral triptans differ in their ability to achieve these endpoints, with almotriptan 12.5 mg, eletriptan 80 mg and rizatriptan 10 mg providing the highest likelihood of success. Although all triptans have simple and consistent pharmacokinetic features, they also have specific differences that may play a part in their differing clinical attributes. Incorporating tolerability to generate a more stringent endpoint, sustained pain free with no adverse events (SNAE), may provide an even better representation of patients' expectations. Comparison of SNAE rates using data from the meta-analysis of oral triptans indicates that almotriptan 12.5 mg has the best balance of high efficacy and good tolerability.

Migraine headache: Options for acute treatment

The optimal acute treatment of migraine requires recognition of the multitude of migraine presentations, the frequency of total attacks, and number of days of headache disability. These initial diagnostic steps are initiated in the waiting room, but phase-specific and stratified treatment selection requires having mutual understanding, trust, and belief through extensive discussion. The imperative acute treatment goal must be to treat early, but not too often, a fact represented by a 75% or better occurrence of pain freedom at 2 hours with two or fewer drug doses averaging 2 or fewer days a week. Migraine-specific therapy best wins the race against time and allodynia. Employing this formulary, multiple triptan formulations and phase and stratified patient-centered therapy creates success.

Preclinical neuropharmacology of naratriptan

The basic CNS neuropharmacology of naratriptan is reviewed here. Naratriptan is a second-generation triptan antimigraine drug, developed at a time when CNS activity was thought not to be relevant to its therapeutic effect in migraine. It was, however, developed to be a more lipid-soluble, more readily absorbed and less readily metabolized variant on preexisting triptans and these variations conferred on it a higher CNS profile. Naratriptan is a 5-HT(1B/1D) receptor agonist with a highly selective action on migraine pain and nausea, without significant effect on other pain or even other trigeminal pain. Probable sites of therapeutic action of naratriptan include any or all of: the cranial vasculature; the peripheral terminations of trigeminovascular sensory nerves; the first-order synapses of the trigeminovascular sensory system; the descending pain control system; and the nuclei of the thalamus. Naratriptan may prevent painful dilatation of intracranial vessels or reverse such painful dilatation. Naratriptan can prevent the release of sensory peptides and inhibit painful neurogenic vasodilatation of intracranial blood vessels. At the first order synapse of the trigeminal sensory system, naratriptan can selectively suppress neurotransmission from sensory fibers from dural and vascular tissue, while sparing transmission from other trigeminal fibers, probably through inhibition of neuropeptide transmitter release. In the periaqueductal gray matter and in the nucleus raphe magnus, naratriptan selectively activates inhibitory neurons which project to the trigeminal nucleus and spinal cord and which exert inhibitory influences on trigeminovascular sensory input. Naratriptan has also a therapeutic effect on the nausea of migraine, possibly exerting its action at the level of the nucleus tractus solitarius via the same mechanisms by which it inhibits trigeminovascular nociceptive input. The incidence of naratriptan-induced adverse effects in the CNS is low and it is not an analgesic for pain other than that of vascular headache. In patients receiving selective serotonin uptake inhibitors (SSRIs) naratriptan may cause serotonin syndrome-like behavioral side effects. The mechanism of action involved in the production of behavioral and other CNS side effects of naratriptan is unknown.