DFN-02, Sumatriptan 10 mg Nasal Spray with Permeation Enhancer, for the Acute Treatment of Migraine: A Randomized, Double-Blind, Placebo-Controlled Study Assessing Functional Disability and Subject Satisfaction with Treatment.

BACKGROUND: The commercial formulation of sumatriptan nasal spray is an effective option for migraine patients requiring or preferring a non-oral route of drug administration, but its utility is limited by poor absorption and tolerability issues. DFN-02, a new formulation of sumatriptan 10 mg nasal spray, is co-formulated with a permeation enhancer that gives it pharmacokinetics comparable to subcutaneous sumatriptan. As reported previously, DFN-02 was significantly better than placebo on multiple efficacy endpoints at 2 h postdose, including pain freedom, absence of the most bothersome symptom, and pain relief, and its safety and tolerability profiles were excellent. OBJECTIVE: The objective of this study was to assess the efficacy of acute treatment of migraine with DFN-02, including its effect on migraine-related functional disability and patient satisfaction with treatment. METHODS: This was a multicenter, randomized, double-blind, placebo-controlled efficacy and safety study of DFN-02 in adults with episodic migraine. Functional disability and subject satisfaction with treatment were prespecified endpoints, assessed in real-time by subjects, using an electronic diary. RESULTS: In total, 107 subjects were randomized. DFN-02 was significantly superior to placebo for the reduction in functional disability score from predose level at 2 h after treatment (- 1.2 vs. - 0.6, p < 0.001). Subjects treated with DFN-02 were also more likely to be satisfied or very satisfied than subjects treated with placebo at 2 h postdose (70.0% vs. 44.2%, p = 0.027). Using the Patient Perception of Migraine Questionnaire-Revised at 24 h postdose, DFN-02 mean scores were significantly superior to placebo for the subscales of efficacy (65.2 vs. 42.5, p = 0.016) and function (68.9 vs. 42.1, p = 0.001), and for total score (71.0 vs. 56.6, p = 0.016); global medication effectiveness (p = 0.027); and overall satisfaction (p = 0.019). Placebo was significantly better than DFN-02 on the tolerability subscale (94.8 vs. 88.5, p = 0.026). At 24 h postdose, subjects reported significantly higher satisfaction with DFN-02 compared with satisfaction reported pre-randomization regarding their usual migraine medication (p = 0.012). CONCLUSION: DFN-02 was superior to placebo for the relief of migraine-related functional disability, and provided greater satisfaction than placebo or subjects' usual acute treatment. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02856802.

DFN-02 (Sumatriptan 10 mg With a Permeation Enhancer) Nasal Spray vs Placebo in the Acute Treatment of Migraine: A Double-Blind, Placebo-Controlled Study.

OBJECTIVE: The objective of this study was to evaluate the efficacy, safety, and tolerability of DFN-02 - a nasal spray comprising sumatriptan 10 mg and a permeation-enhancing excipient (0.2% 1-O-n-Dodecyl-ß-D-Maltopyranoside [DDM]) - for the acute treatment of migraine with or without aura in adults. BACKGROUND: Prior work has shown that DFN-02, which contains only half the recommended adult dose of sumatriptan found in the original formulation (10 mg vs 20 mg), is more rapidly absorbed than commercial nasal spray of sumatriptan, with favorable pharmacokinetic and safety profiles. The efficacy of DFN-02 in the acute treatment of migraine has not been previously assessed. METHODS: This was a multicenter, randomized, 2-period, double-blind, placebo-controlled efficacy, safety, and tolerability phase 2 study of DFN-02. Subjects with at least a 12 month history of episodic migraine, who averaged 2-8 attacks per month, with no more than 14 headache days per month and a minimum of 48 headache-free hours between attacks, were randomized (1:1) to receive DFN-02 or a matching placebo. Subjects were instructed to treat a single migraine attack of moderate to severe pain intensity. The primary efficacy endpoint, the proportion of subjects who were pain-free at 2 hours postdose in the first double-blind treatment period, was assessed with 2 protocol prespecified primary analyses: last observation carried forward (LOCF) and observed cases (OC). Secondary efficacy endpoints at 2 hours included pain relief; absence of the most bothersome symptom (MBS) among nausea, photophobia, and phonophobia; freedom from nausea, photophobia, and phonophobia. Sustained pain freedom from 2 through 24 hours postdose was also assessed. RESULTS: Of 107 subjects randomized, 86.9% (N = 93 [DFN-02, n = 50; placebo, n = 43]) had data in the first double-blind treatment period. The study met its primary endpoint; the proportion of subjects who were free from headache pain at 2 hours postdose, was statistically significantly higher in the DFN-02 group than in the placebo group in both prespecified primary analyses: LOCF (DFN-02, n = 21/48; placebo, n = 9/40; 43.8% vs 22.5%, P = .044) and OC (DFN-02, n = 21/48; placebo, n = 8/39; 43.8% vs 20.5%, P = .025). For secondary efficacy endpoints, at 2 hours postdose, DFN-02 was also statistically significantly superior to placebo for the proportion of subjects who had pain relief (83.3% vs 55.0%, P = .005); who were free of their MBS (70.7% vs 39.5%, P = .007); and who were free of nausea (78.3% vs 42.1%, P = .026), photophobia (71.8% vs 38.9%, P = .005), and phonophobia (78.1% vs 40.0%, P = .004). Compared with placebo, statistically significantly greater proportions of subjects who were treated with DFN-02 had sustained pain freedom from 2 through 24 hours postdose (38.9% vs 13.8%, P = .029). In total, 9.7% (9/93) of subjects reported a treatment-emergent adverse event during the study: 10.0% (5/50) of DFN-02 subjects in the first double-blind treatment period and 13.5% (5/37) of DFN-02 subjects in the second double-blind treatment period. The most common treatment-emergent adverse event with DFN-02 was dysgeusia (3/37 subjects in the second double-blind treatment period). CONCLUSIONS: DFN-02 was shown to be effective, well tolerated, and safe in the acute treatment of episodic migraine. Additional studies are needed to confirm these preliminary results. (ClinicalTrials.gov Identifier: NCT02856802).

Pharmacokinetic Characterization and Dose Selection of a Novel Sumatriptan Nasal Spray Formulation, DFN-02.

This 3-way, single-dose, randomized crossover study evaluated the pharmacokinetics (PK) and dose proportionality of 5-, 10-, and 15-mg doses of intranasal sumatriptan (DFN-02) coformulated with a permeation enhancer (DDM) in 18 healthy adults. The objective was to determine which DFN-02 dose approximates the PK of a 6-mg dose of sumatriptan delivered via subcutaneous injection in the deltoid muscle of the arm. Sumatriptan plasma concentrations peaked with DFN-02 between 10 and 15 minutes postdose, declining thereafter, with a t1/2 of about 2.5 hours; mean Cmax and AUC0-∞ values increased linearly across doses. After DFN-02 doses of 5, 10, and 15 mg, mean Cmax was 40.7 ± 14.2, 71.2  ±  22.1, and 101.0  ±  49.5 ng/mL, and mean AUC0-∞ was 49.9  ±  20.6, 87.1  ± 31.2, and 120.5  ± 53.3 ng·h/mL, respectively. The increase in sumatriptan bioavailability was less than dose-proportional among the DFN-02 doses studied. Based on the established PK of a 6-mg subcutaneous sumatriptan injection (mean Tmax ,  12 minutes; mean Cmax ,  74  ± 15 ng/mL in the deltoid area of the arm) and the peak and time to peak sumatriptan concentrations of the DFN-02 doses tested, a 10-mg dose of DFN-02 was found to be the closest match. Overall, DFN-02 was well tolerated at doses of 5 to 15 mg, and no new safety concerns were identified.

A Randomized Trial Comparing the Pharmacokinetics, Safety, and Tolerability of DFN-02, an Intranasal Sumatriptan Spray Containing a Permeation Enhancer, With Intranasal and Subcutaneous Sumatriptan in Healthy Adults.

OBJECTIVE/BACKGROUND: Intranasal sumatriptan (Imitrex® ) may be an alternative for patients who refuse injections and cannot tolerate oral agents, but due to low bioavailability and slow absorption, the clinical utility of the currently marketed formulation is limited, highlighting an unmet need for an effective non-oral migraine medication with a rapid onset of action. To overcome the slow absorption profile associated with intranasal administration, we evaluated the impact of 1-O-n-Dodecyl-ß-D-Maltopyranoside (DDM, Intravail A-3™), a permeation enhancer, on sumatriptan's pharmacokinetic profile by comparing the pharmacokinetic characteristics of two commercial sumatriptan products, 4 mg subcutaneous and 6 mg subcutaneous in healthy adults, with DFN-02 - a novel intranasal agent comprised of sumatriptan 10 mg plus 0.20% DDM. We also determined the pharmacokinetic characteristics of DDM and evaluated its safety and tolerability. METHODS: We conducted two studies: a randomized, three-way crossover study comparing monodose and multidose devices for delivery of single doses of DFN-02 with commercially available intranasal sumatriptan 20 mg in 18 healthy, fasted adults, and an open-label, randomized, single-dose, three-way crossover bioavailability study comparing DFN-02 with 4 mg and 6 mg subcutaneous sumatriptan in 78 healthy, fasted adults. In the study comparing DFN-02 with IN sumatriptan, subjects received a single dose of DFN-02 (sumatriptan 10 mg plus DDM 0.20%) via monodose and multidose delivery systems with at least 5 days between treatments. In the comparison with SC sumatriptan, subjects received a single dose of each treatment with at least 3 days between treatments. In both studies, blood was sampled for pharmacokinetic evaluation of sumatriptan and DDM through 24 hours post-dose; safety and tolerability were monitored throughout. RESULTS: In the comparison with commercially available intranasal sumatriptan 20 mg, DFN-02 had a more rapid absorption profile; tmax was 15 minutes for DFN-02 monodose, 10.2 minutes for DFN-02 multidose, and 2.0 hours for commercially available intranasal sumatriptan 20 mg. Compared with 4 and 6 mg subcutaneous sumatriptan, DFN-02's median tmax (10 minutes) was significantly earlier (15 minutes; P < .0001). Mean sumatriptan exposure metrics were similar for DFN-02 and 4 mg sumatriptan: AUC0-2 : 35.12 and 44.82 ng*hour/mL, respectively; AUC0-∞ : 60.70 and 69.21 ng*hour/mL, respectively; Cmax : 51.79 and 49.07 ng/mL, respectively. With 6 mg subcutaneous sumatriptan, these exposure metrics were about 50% larger (AUC0-2 : 67.17 ng*hour/mL; AUC0-∞ : 103.78 ng*hour/mL; Cmax : 72.75 ng/mL). Inter-subject variability of AUC0-2 , AUC0-∞ , and Cmax was 42-58% for DFN-02, 15-22% for 4 mg subcutaneous sumatriptan, and 15-25% for 6 mg subcutaneous sumatriptan. DDM exposure was low (mean Cmax : 1.63 ng/mL), tmax was 30 minutes, and it was undetectable by 4 hours. There were no serious adverse events, discontinuations due to adverse events, or remarkable findings for vital signs, physical examinations (including nasal and injection site examinations), or clinical laboratory assessments. The overall incidence of adverse events was comparable across treatments, and all treatment-related events were mild in severity. Adverse events occurring in ≥10% of subjects were dysgeusia (19%), headache (18%), nausea (15%), paresthesia (15%), and dizziness (12%). CONCLUSIONS: In healthy subjects, DFN-02, an intranasal spray containing 10 mg sumatriptan plus DDM, had a more rapid absorption profile than commercially available intranasal sumatriptan 20 mg, and systemic exposure from a single-dose administration of DFN-02 was similar to 4 mg SC sumatriptan and two-thirds that of 6 mg SC sumatriptan. With DFN-02, plasma sumatriptan peaked 5 minutes earlier than with both subcutaneous formulations. Systemic exposure to sumatriptan was similar with DFN-02 and 4 mg subcutaneous sumatriptan; both yielded lower systemic exposure than 6 mg subcutaneous sumatriptan. Systemic exposure to DFN-02's excipient DDM was short-lived. DFN-02's safety and tolerability appear to be comparable to subcutaneous sumatriptan. Addition of a permeation enhancer improved the absorption profile compared with commercially available intranasal sumatriptan 20 mg.

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

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

Unanticipated acyloxymethylation of sumatriptan indole nitrogen atom and its implications in prodrug design.

Sumatriptan is a potent and selective 5-HT(1B) and 5-HT(1D )agonist used in the symptomatic treatment of migraine; it shows poor oral bioavailability ascribed, in part, to its low lipophilicity. In an attempt to develop acyloxymethyl prodrugs of sumatriptan suitable for oral administration, we carried out the reaction of sumatriptan with chloromethyl esters. To our surprise, acyloxymethylation occurred preferentially at the indole nitrogen rather than at sulfonamide nitrogen, reflecting a difference either in product stability or in the nucleophilicities of the indole and sulfonamide anions. The hydrolysis of the corresponding N(1)-acyloxymethyl derivatives was studied in aqueous buffers and in human plasma, by HPLC. N(1)-Acyloxymethyl derivatives of sumatriptan are rapidly hydrolysed to the chemically stable N(1)-hydroxymethylsumatriptan at pH 1-13. Slow formation of the parent drug was observed only at high pH values. Hydrolysis of sumatriptan derivatives is slower in human plasma than in phosphate buffer and also generates N(1)-hydroxymethylsumatriptan rather than the parent drug. These results indicate that N(1)-acyloxymethyl derivatives of sumatriptan cannot be considered as true prodrugs of sumatriptan.

The triptan formulations : how to match patients and products.

The 5-HT(1B/1D) receptor agonists (the 'triptans') are migraine-specific agents that have revolutionised the treatment of migraine. They are usually the drugs of choice to treat a migraine attack in progress. Different triptans are available in various strengths and formulations, including oral tablets, orally disintegrating tablets, nasal sprays and subcutaneous injections. In Europe, sumatriptan is also available as a suppository. Specific differences among the triptans exist, as evidenced by different pharmacological profiles including half-life, time to peak plasma concentrations, peak plasma concentrations, area under the concentration-time curve, metabolism and drug-drug interaction profiles. How or whether these differences translate to clinical efficacy and tolerability advantages for one agent over another is not well differentiated. However, delivery systems may play an important role in onset of action. Given that the clinical distinctions among these agents are subtle, identification of the most appropriate triptan for an individual patient requires consideration of the specific characteristics of the patient and knowledge of patient preference, an accurate history of the efficacy of previous acute-care medications and individual features of the drug being considered. The selection of an acute antimigraine drug also depends upon the stratification of the patient's migraine attack by peak intensity, time to peak intensity, level of associated symptoms such as nausea and vomiting, time to associated symptoms, comorbid diseases and concomitant treatments that might cause drug-drug interactions. Individual patient response to the triptans seems to be idiosyncratic and possibly genetically determined. Therefore, a set of specific questions can be used to determine whether a currently used triptan is optimally effective, whether the dose needs to be increased or whether another triptan should be tried. The clinician has in his/her armamentarium an ever-expanding variety of triptans, available in multiple formulations and dosages, which have good safety and tolerability profiles. Continued clinical use will yield familiarity with the various triptans, and it should become possible for the interested physician to match individual patient needs with the specific characteristics of a triptan to optimise therapeutic benefit. Use of the methods outlined in this review in choosing a triptan for an individual patient is probably more likely to lead to migraine relief than making an educated guess as to which triptan is most appropriate.

Practical approaches to migraine management.

Migraine is a recurrent clinical syndrome characterised by combinations of neurological, gastrointestinal and autonomic manifestations. The exact pathophysiological disturbances that occur with migraine have yet to be elucidated; however, cervico-trigemino-vascular dysfunctions appear to be the primary cause. Despite advances in the understanding of the pathophysiology of migraine and new effective treatment options, migraine remains an under-diagnosed, under-treated and poorly treated health condition. Most patients will unsuccessfully attempt to treat their headaches with over-the-counter medications. Few well designed, placebo-controlled studies are available to guide physicians in medication selection. Recently published evidence-based guidelines advocate migraine-specific drugs, such as serotonin 5-HT(1B/1D) agonists (the 'triptans') and dihydroergotamine mesylate, for patients experiencing moderate to severe migraine attacks. Additional headache attack therapy options include other ergotamine derivatives, phenothiazines, nonsteroidal anti-inflammatory agents and opioids. Preventative medication therapy is indicated for patients experiencing frequent and/or refractory attacks.

Triptans: do they differ?

Headache care specialists agree that the introduction of sumatriptan constitutes a major advance in headache therapy, but they differ about whether other triptans offer clinically significant advantages over sumatriptan. This article examines this issue by considering the similarities and differences among triptans.

Triptans: are they all the same?

The triptans have provided a major advance in the treatment of the pain and disability associated with migraine headache. With seven triptans in use or in clinical development, the clinician is faced with the decision of which triptan to prescribe to the patient with migraine. Although the triptans are pharmacologically similar, they each have unique attributes. This article focuses on the pharmacologic differences between triptans with regard to their pharmacokinetics and drug interactions, and provides some helpful tips on how to optimize migraine treatment with the triptans.

Neurogenic inflammation in the context of migraine.

Despite considerable research into the pathogenesis of idiopathic headaches, such as migraine, the pathophysiological mechanisms underlying them remain poorly understood. Although it is well established that the trigeminal nerve becomes activated during migraine, the consequences of this activation remain controversial. One theory, based on preclinical observations, is that activation of trigeminal sensory fibers leads to a painful neurogenic inflammation within the meningeal (dural) vasculature mediated by neuropeptide release from trigeminal sensory fibres and characterized by plasma protein extravasation, vasodilation, and mast cell degranulation. Effective antimigraine agents such as ergots, triptans, opioids, and valproate inhibit preclinical neurogenic dural extravasation, suggesting that this activity may be a predictor of potential clinical efficacy of novel agents. However, several clinical trials with other agents that inhibit this process preclinically have failed to show efficacy in the acute treatment of migraine in man. Alternatively, it has been proposed that painful neurogenic vasodilation of meningeal blood vessels could be a key component of the inflammatory process during migraine headache. This view is supported by the observation that jugular plasma levels of the potent vasodilator, calcitonin gene-related peptide (CGRP) are elevated during the headache and normalized by successful sumatriptan treatment. Preclinically, activation of trigeminal sensory fibers evokes a CGRP-mediated neurogenic dural vasodilation, which is blocked by dihydroergotamine, triptans, and opioids but unaffected by NK1 receptor antagonists that failed in clinical trials. These observations suggest that CGRP release with associated neurogenic dural vasodilation may be important in the generation of migraine pain, a theory that would ultimately be tested by the clinical testing of a CGRP receptor antagonist.

A systematic review of the use of triptans in acute migraine.

OBJECTIVE: A systematic review of the literature was undertaken, to consolidate evidence concerning the efficacy and safety of triptans currently available in Canada (sumatriptan, rizatriptan, naratriptan, zolmitriptan), and to provide guidelines for selection of a triptan. METHODS: Data from published, randomized, placebo-controlled trials were pooled and a combined number needed to treat (NNT) and number needed to harm (NNH) was generated for each triptan. Direct comparative trials of triptans were also examined. RESULTS: The lowest NNT for headache response/pain-free at one/two hours is observed with subcutaneous sumatriptan. Among the oral formulations, the lowest NNT is observed with rizatriptan and the highest NNT with naratriptan. The lowest NNH is observed with subcutaneous sumatriptan. CONCLUSIONS: Triptans are relatively safe and effective medications for acute migraine attacks. However, differences among them are relatively small. Considerations in selecting a triptan include individual patient response/tolerance, characteristics of the attacks, relief of associated symptoms, consistency of response, headache recurrence, delivery systems and patient preference.

pH-mediated field-amplified sample stacking of pharmaceutical cations in high-ionic strength samples.

Capillary electrophoretic separation of samples of physiological origin typically have both poor resolution and efficiency due to destacking. We have previously reported a stacking method for concentration of catecholamines in artificial dialysate, or Ringer's solution. However, pH-mediated sample stacking of other cations has not been investigated. In this report, pH-mediated stacking has been extended to eletripan, dofetilide, doxazosin, sildenafil, UK-103,320, UK-202,581, and CP-122,288. These compounds were chosen without prior structural screening except that they were cationic at the pH of our background electrolyte (BGE). Capillary electrophoretic behavior of samples in BGE is compared with those of samples in Ringer's solution with and without pH-mediated acid stacking. Results indicate that the peak heights and efficiencies for acid-stacked samples are increased compared to the unstacked samples in Ringer's solution or BGE. For example, the peak efficiencies for 5 s injections of eletriptan in BGE and Ringer's solution are 138,000 and 72,000 plates, respectively. In contrast, a 10 s injection of eletriptan followed by acid injection for 16 s produces a peak with 246,000 plates. Evaluation of the stacking effect was performed by comparison of the peak height at similar peak efficiencies for samples in Ringer's solution with and without stacking. Using this method, pH-mediated acid stacking provides a 10- to 27-fold sensitivity enhancement for the seven cations.

No acute antimigraine efficacy of CP-122,288, a highly potent inhibitor of neurogenic inflammation: results of two randomized, double-blind, placebo-controlled clinical trials.

CP-122,288 is a highly potent inhibitor of neurogenic plasma extravasation in animal models at doses without vasoconstrictor effect. We evaluated the acute antimigraine efficacy of intravenous and oral CP-122,288 in two double-blind studies. In a crossover design, patients randomly received 31.25 microg of CP-122,288 intravenously, placebo, or both. In the oral study, patients received placebo or one of four doses of CP-122,288 between 3.125 and 312.5 microg, using a novel "up and down" design for randomization. Both studies were stopped prematurely when target efficacy could not be achieved. Responder rates were 29% for CP-122,288 versus 30% for placebo (difference, -1%; 95% CI, -24-22%; intravenous study) and an overall rate of 25% for CP-122,288 versus 0% for placebo (difference, 25%; 95% CI; 10-40%; oral study). CP-122,288 was not clinically effective at doses and plasma concentrations in excess of those required to inhibit neurogenic plasma extravasation in animals. Neurogenic plasma extravasation is unlikely to play a crucial role in the pathophysiology of migraine headache.

Differential effects of low dose CP122,288 and eletriptan on fos expression due to stimulation of the superior sagittal sinus in cat.

CP122,288, a conformationally restricted analogue of sumatriptan, is a highly potent inhibitor of neurogenic plasma protein extravasation (PPE) in rat and guinea pig at low doses where it has no 5HT1B-mediated vascular actions. We have examined its effect on a model of trigeminovascular nociception to assess the relative importance of vasoconstrictor and serotonin (5HT)(1B/1D) agonist activity to the modulation trigeminal neuronal activation. For comparison to activate relevant 5HT receptors, the clinically effective relatively lipophilic 5HT(1B/1D) agonist eletriptan was studied in parallel. The superior sagittal sinus was isolated in the alpha-chloralose (60 mg/kg, i.p. and 15-20 mg/kg i.v. supplement every 2 h) anaesthetized cat. Animals were prepared for stimulation and then maintained for 24 h before stimulation and perfusion for Fos immunohistochemistry. Stimulation of the superior sagittal sinus (250 micros, 100 V, 0.3 Hz) resulted in Fos expression in cells in the trigeminal nucleus caudalis and superficial laminae of the dorsal horns of C(1-2). Administration of low dose CP122,288 (100 ng/kg) had no effect on Fos expression after sinus stimulation either when administered alone or in combination with mannitol; the latter to ensure access to the trigeminocervical complex. The number of cells in the superficial laminae of the trigeminal nucleus caudalis with stimulation being a median of 50 (quartile range: 47-53) and 48 (35-48) after CP122,288, and after CP122,288 and mannitol 45 (41-53). In comparison, the clinically effective 5HT(1B/1D) agonist, eletriptan, reduced Fos expression in the trigeminocervical complex to a median of 24 (21-33). These data demonstrate that the potent inhibitor of neurogenic plasma protein extravasation (PPE) CP122,288 has no effect on Fos expression in central trigeminal neurons when administered at a dose which blocks PPE in rat and guinea pig, but has no vasoconstrictor 5HT(1B/1D) activity, and while ensuring its access to central trigeminal neurons. The data suggest that activation of the 5HT(1B/1D) receptor is important for the clinical action of this class of compounds and is consistent with the fact the CP122,288 is ineffective in the treatment of the acute attack of migraine.

Present and future of 5-HT receptor agonists as antimigraine drugs.

Serotonin (5-hydroxytryptamine; 5-HT) is thought to play an important role in the pathogenesis of migraine. The discovery of the 5-HT1B/1D/1F agonist sumatriptan constitutes a substantial advance in the acute treatment of migraine, though it displays a number of nonnegligible shortcomings. Today, a number of second-generation drugs derived from tryptamine are under advanced clinical development or are about to be marketed worldwide for the acute treatment of migraine. These tryptamine derivatives display partial agonist properties at 5-HT1B/1D receptors. It is not yet clearly established whether these agents represent a major improvement over sumatriptan in therapeutic effectiveness. Most of them also show affinity for 5-ht1F binding sites and have better oral pharmacokinetics than sumatriptan. The acute antimigraine effects of this second-generation of triptans seem to be obtained in largely the same way as with sumatriptan: by cranial vasoconstriction and inhibition of trigeminovascular activation from both peripheral and central projections. Future directions in migraine therapy should focus on agents that exhibit high intrinsic activity at 5-HT1B/1D receptors, offer a good safety profile, and demonstrate long-lasting action which might also be considered in migraine prophylaxis.

Triptans. A support to the central link between serotonin and acetylcholine in migraine.

Recently synthesized triptans, sumatriptan derivatives, display aborting migraine activity at doses and with plasmatic maximum peak dramatically lower (20-40 times) than sumatriptan, the 5-HT like agonist, which is the original molecule. That triptans easily cross blood-brain barrier strongly supports the central theory of migraine. We recently discovered the anti-migraine prophylactic action of centrally acting anti-cholinesterase agents, that seems a further support to the central theory of migraine. Indeed, acetylcholine is an important analgesia neurotransmitter and is intertwined with 5-HT central pathways.

Blockade of calcitonin gene-related peptide release after superior sagittal sinus stimulation in cat: a comparison of avitriptan and CP122,288.

The pathophysiological basis for the pain of migraine has been the subject of substantial attention and must include activation of elements of the trigeminal innervation of the cranial vessels, the trigeminovascular system. Recently, consideration of trigeminal-evoked neurogenic plasma protein extravasation (PPE) as a model for the pain has driven the search for compounds with specific anti-extravasation properties. Calcitonin gene-related peptide (CGRP) is a marker for trigeminovascular activation and is released during the headache phase of migraine and cluster headache. CGRP may have a role in migraine through its potent cranial vasodilator effects or by an action on trigeminal nerve activity, both of which are targeted by 5HT(1B/1D)agonist drugs but does not itself produce PPE. It has been suggested that 5HT(1B/1D)agonists may have an anti-migraine effect via inhibition of PPE in the dura mater. Avitriptan and CP122,288 both have strong binding affinities for 5HT(1B/1D)receptors, but only CP122,288 is a potent inhibitor of PPE. In this study we sought to compare the effects of CP122,288 and avitriptan on jugular vein CGRP release after stimulation of the superior sagittal sinus (SSS) in the cat. In eleven anaesthetized cats external jugular vein blood samples were analyzed by radioimmunoassay for CGRP levels in three settings: a) control, b) 1 min after SSS stimulation and c) 1 min after SSS stimulation in presence of drug. Stimulation of the SSS resulted in release of CGRP from the external jugular vein (77+/-1 pmol/L). At a PPE-inhibitory dose in rat (100 ng/kg intravenously) CP122, 288 had no effect on CGRP release (77+/-6 pmol/L) whereas at a clinically relevant dose (50 microgram/kg intravenously) avitriptan blocked CGRP release. This study demonstrates that the potent inhibitor of PPE, CP122, 288, which has been shown in clinical trials to be ineffective in treating acute migraine attacks, had no effect on CGRP release, whereas the effective anti-migraine drug and relatively impotent inhibitor of PPE, avitriptan, blocked CGRP release. These data emphasize the importance of CGRP release and its possible independence from PPE in migraine and more importantly suggest that other non-5HT-based pharmacological targets may account for PPE blockade in animal studies.

A fluorescence-based method for assessing dural protein extravasation induced by trigeminal ganglion stimulation.

Neurogenic dural inflammation has been proposed as a source of pain during migraine. Unilateral electrical stimulation of the trigeminal ganglion causes the ipsilateral release of inflammatory neuropeptides and subsequent dural plasma protein extravasation, a component of neurogenic inflammation. We measured the amount of protein leaking into the dural tissue of guinea pigs following trigeminal ganglion stimulation by exploiting the complexation reaction of endogenous proteins with the fluorescent dye Evans Blue, instead of utilizing exogenous radiolabeled albumin as commonly done in the literature. The amount of Evans Blue trapped in dural tissue following electrical stimulation of the trigeminal ganglion was measured using a fluorescence microscope equipped with a spectrophotometer. This method utilized multiple measurements on each dura sample which resulted in very precise values using a small number of animals per point (n = 3). Sumatriptan and CP-122,288 were found to dose-dependently prevent neurogenic dural extravasation. The potencies of CP-122,288 and sumatriptan were found to be similar to those reported in the literature when similar experimental protocols were used.

Naratriptan: biological profile in animal models relevant to migraine.

The biological profile of naratriptan (N-methyl-3-(1-methyl-4-piperidinyl)-1H-indole-5-ethane-sulphonamide), a novel 5HT1B/1D receptor agonist, was investigated in a variety of experimental models of relevance to migraine. Naratriptan has high affinity for human recombinant 5HT1B and 5HT1D receptors (pKi = 8.7 +/- 0.03 and 8.3 +/- 0.1, respectively) and causes contractions of dog isolated basilar and middle cerebral artery (EC50 values of 0.11 and 0.07 microM, respectively). Naratriptan causes small contractions of human isolated coronary arteries (EC50 value of 0.17 microM; maximum contraction equivalent to 33% of 5HT maximum). In anaesthetized dogs, naratriptan causes selective vasoconstriction of the carotid arterial bed (CD50 dose = 19 +/- 3 micrograms kg-1) and, in anaesthetized rats, naratriptan selectively inhibits neurogenic plasma protein extravasation in the dura (ID50 = 4.1 micrograms kg-1). In a variety of antinociceptive tests, naratriptan has no effect even at high doses. In conscious rats and dogs, naratriptan has high oral bioavailability (71% and 95%, respectively). The data show that naratriptan is a selective agonist at 5HT1B/1D receptors, with a pharmacological profile very similar to that of sumatriptan, albeit 2-3 fold more potent. These observations, coupled with high oral bioavailability in animals, suggest that naratriptan has the profile of an orally effective anti-migraine drug.