Acetylsalicylic acid inhibits cerebral cortical vasodilatation caused by superior sagittal sinus stimulation in the cat*

Models of Trigeminal Activation: Is There an Animal Model of Migraine?

Migraine, recognized as a severe headache disorder, is widely prevalent, significantly impacting the quality of life for those affected. This article aims to provide a comprehensive review of the application of animal model technologies in unraveling the pathomechanism of migraine and developing more effective therapies. It introduces a variety of animal experimental models used in migraine research, emphasizing their versatility and importance in simulating various aspects of the condition. It details the benefits arising from the utilization of these models, emphasizing their role in elucidating pain mechanisms, clarifying trigeminal activation, as well as replicating migraine symptoms and histological changes. In addition, the article consciously acknowledges the inherent limitations and challenges associated with the application of animal experimental models. Recognizing these constraints is a fundamental step toward fine-tuning and optimizing the models for a more accurate reflection of and translatability to the human environment. Overall, a detailed and comprehensive understanding of migraine animal models is crucial for navigating the complexity of the disease. These findings not only provide a deeper insight into the multifaceted nature of migraine but also serve as a foundation for developing effective therapeutic strategies that specifically address the unique challenges arising from migraine pathology.

Migraine neuroscience: from experimental models to target therapy

Migraine sciences have witnessed tremendous advances in recent years. Pre-clinical and clinical experimental models have contributed significantly to provide useful insights into the brain structures that mediate migraine attacks. These models have contributed to elucidate the role of neurotransmission pathways and to identify the role of important molecules within the complex network involved in migraine pathogenesis. The contribution and efforts of several research groups from all over the world has ultimately lead to the generation of novel therapeutic approaches, specifically targeted for the prevention of migraine attacks, the monoclonal antibodies directed against calcitonin gene-related peptide or its receptor. These drugs have been validated in randomized placebo-controlled trials and are now ready to improve the lives of a large multitude of migraine sufferers. Others are in the pipeline and will soon be available.

Central effects of acetylsalicylic acid on trigeminal-nociceptive stimuli

BACKGROUND

Acetylsalicylic acid is one of the most used analgesics to treat an acute migraine attack. Next to the inhibitory effects on peripheral prostaglandin synthesis, central mechanisms of action have also been discussed.

METHODS

Using a standardized model for trigeminal-nociceptive stimulation during fMRI scanning, we investigated the effect of acetylsalicylic acid on acute pain compared to saline in 22 healthy volunteers in a double-blind within-subject design. Painful stimulation was applied using gaseous ammonia and presented in a pseudo-randomized order with several control stimuli. All participants were instructed to rate the intensity and unpleasantness of every stimulus on a VAS scale. Based on previous results, we hypothesized to find an effect of ASA on central pain processing structures like the ACC, SI and SII as well as the trigeminal nuclei and the hypothalamus.

RESULTS

Even though we did not find any differences in pain ratings between saline and ASA, we observed decreased BOLD signal changes in response to trigemino-nociceptive stimulation in the ACC and SII after administration of ASA compared to saline. This finding is in line with earlier imaging results investigating the effect of ASA on acute pain. Contrary to earlier findings from animal studies, we could not find an effect of ASA on the trigeminal nuclei in the brainstem or within the hypothalamic area.

CONCLUSION

Taken together our study replicates earlier findings of an attenuating effect of ASA on pain processing structures, which adds further evidence to a possibly central mechanism of action of ASA.

Intravenous lysine clonixinate for the acute treatment of severe migraine attacks: a double-blind, randomized, placebo-controlled study

BACKGROUND

Several nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to be effective in the treatment of migraine. However, few commercially available NSAIDs can be administered IV. Lysine clonixinate (LC), an NSAID derived from nicotinic acid, has been proved effective in various algesic syndromes (eg, renal colic, muscular pain, nerve compression, odontalgia). The oral formulation of LC has been shown to be effective in the treatment of migraine of moderate severity.

OBJECTIVE

The aim of this study was to assess the efficacy and tolerability of the IV formulation of LC in the treatment of severe migraine.

METHODS

This double-blind, randomized, placebo-controlled, prospective study enrolled patients with severe migraine (without aura) as defined by the criteria of the International Headache Society. When patients presented to a neurology hospital with an outpatient headache unit (Instituto de Neurologia Deolindo Couto, Rio de Janeiro, Brazil) with a severe migraine attack that had lasted <4 hours, they were randomized to 1 of 2 groups (IV placebo [25 mL of 0.9% saline] or IV LC [21 mL of 0.9% saline plus 4 mL of LC 200 mg]). Headache intensity and adverse effects (AEs) were assessed before (0 minute) and 30, 60, and 90 minutes after study drug administration. Rescue medication was available 2 hours after study drug administration, and its use was compared between groups.

RESULTS

Thirty-two patients (23 women, 9 men; mean [SD] age, 32 [2] years; range, 18-58 years) entered the study. Twenty-nine patients (21 women, 8 men; mean [SD] age, 32 [2] years; range, 18-56 years) completed the study. Three patients (all in the placebo group) did not complete the study (1 patient was unable to rate the pain severity after drug administration and 2 patients refused IV drug administration). Among study completers, 17 patients received LC and 12 placebo. At 30 minutes, 1 patient (8.3%) in the placebo group and 5 patients (29.4%) in the LC group were pain free; the between-group difference was not statistically significant. At 60 and 90 minutes, respectively, 3 (25.0%) and 5 (41.7%) patients in the placebo group and 12 (70.6%) and 14 (82.4%) patients in the LC group were pain free (P = 0.021 and P = 0.028 between groups at 60 and 90 minutes, respectively). Six patients (50.0%) in the placebo group and 1 patient (5.9%) in the LC group required rescue medication at 2 hours (P = 0.010 between groups). Three patients (25.0%) in the placebo group experienced AEs, including vomiting, dizziness, and malaise (1 patient [8.3%] each); 11 patients (64.7%) in the LC group experienced 1 AE, including burning pain at the injection site (5 patients [29.4%]), heartburn (4 patients [23.5%]), and dizziness and malaise (1 patient [5.9%] each) (P = 0.025).

CONCLUSIONS

NSAIDs administered by the IV route cannot be used routinely in an outpatient environment, although an attempt to improve drugs in this class is clearly justified. This study demonstrated that IV LC was effective and well tolerated in the treatment of severe migraine attacks. This finding differs from results with the oral formulation, which is effective only in migraine of moderate severity.

Lysine clonixinate versus dipyrone (metamizole) for the acute treatment of severe migraine attacks: a single-blind, randomized study

BACKGROUND AND OBJECTIVE: Nonsteroidal anti-inflammatory drugs (NSAID) are effective to treat migraine attacks. Lysine clonixinate (LC) and dipyrone (metamizol) have been proven effective to treat acute migraine. The aim of this study was to evaluate the efficacy and tolerability of the intravenous formulations of LC and dipyrone in the treatment of severe migraine attacks. METHOD: Thirty patients (28 women, 2 men), aged 18 to 48 years with migraine according the International Headache Society (IHS) (2004) were studied. The patients were randomized into 2 groups when presenting to an emergency department with a severe migraine attack. The study was single-blind. Headache intensity, nausea, photophobia and side effects were evaluated at 0, 30, 60 and 90 minutes after the drug administration. Rectal indomethacin as rescue medication (RM) was available after 2 hours and its use compared between groups. RESULTS: All patients completed the study. At 30 minutes, 0% of the dipyrone group 13% of the LC group were pain free (p=0.46). At 60 and 90 minutes, 2 (13%) and 5 (33%) patients from the dipyrone group and 11 (73%) and 13 (86.7%) patients from the LC group were pain free (p<0.001). At 60 minutes, significantly more patients from the LC group were nausea-free (p<0.001). Regarding photophobia, there were no differences between groups at 60 minutes (p=0.11). The use of RM at 2 hours did not differ among groups (p=0.50). Pain in the site of the injection was reported by more patients of the LC group compared to the dipyrone group (p<0.0001). CONCLUSION: LC is significantly superior to dipyrone in treating severe migraine attacks. LC promotes significantly more burning at the site of the injection.

The real dimension of analgesic activity of aspirin

Aspirin, despite being 100-years old, even in the era of evidence-based medicine, remains a valuable analgesic. Results of randomized trials have shown that it is as well effective and safe as other analgesics in relieving mild pain and can be used in the first-line therapy of migraine.

Mouth-dispersible aspirin in the treatment of migraine: a placebo-controlled study

OBJECTIVE

To compare the efficacy of mouth-dispersible aspirin 900 mg and placebo in the treatment of migraine.

BACKGROUND

Aspirin is widely accepted as an effective therapy for migraine. Previous studies have indicated that gastric stasis and delayed gastric emptying, which occur during migraine attacks, delay aspirin absorption. Mouth-dispersible formulations are considered to be more quickly absorbed than solid formulations and, therefore, may be more effective in treating migraine.

DESIGN

Randomized, double-blind, placebo-controlled, crossover study in four specialized migraine clinics in the United Kingdom.

METHODS

One hundred one patients diagnosed with migraine (according to the International Headache Society diagnostic criteria) participated in the study. Patients received either single doses of mouth-dispersible aspirin (3 x 300 mg) or placebo for moderate pain in the treatment of two migraine attacks. Rescue medication could be taken after 2 hours, if required. The primary efficacy parameter was response to therapy at 2 hours posttreatment. Other efficacy parameters were response to treatment, pain-free, and pain intensity at all other time points. Functional disability, nausea, vomiting, photophobia, phonophobia, symptom relief, patient and investigator global evaluation, use of rescue medication, headache recurrence, and palatability and convenience were also recorded.

RESULTS

Of 101 patients, 73 took both treatments. At 2 hours, 48% of patients taking mouth-dispersible aspirin responded, compared to only 19% taking placebo (P =.0005). Mouth-dispersible aspirin was significantly better than placebo for response to treatment (P<.05) and pain intensity difference (P<.01) at all time points from 30 minutes posttreatment; for pain-free (P<.05) and use of rescue medication (P<.01) from 3 hours posttreatment; for headache recurrence (P<.05); and for patients' and investigators' global evaluations of efficacy (P =.0001 in both cases).

CONCLUSIONS

Mouth-dispersible aspirin 900 mg is effective compared with placebo for the treatment of moderate migraine head pain, with relief seen from as early as 30 minutes after taking medication.

Low-dose aspirin for migraine prophylaxis in women

Although migraine is more common among women than men, the only two large, randomized trials of low-dose aspirin for migraine prophylaxis have been conducted in men. As part of the Women's Health Study, an ongoing randomized trial of low-dose aspirin and vitamin E among 39 876 female health professionals aged 45 and older, 1001 women with frequent migraine attacks were assigned to 100 mg of aspirin every other day (n = 525) or aspirin placebo (n = 476). Migraine frequency, as well as severity, duration, and degree of incapacitation, were assessed by self-report on questionnaires 12 months and 36 months after randomization, and also by monthly diaries kept before and after randomization. Women assigned to aspirin reported small and consistent decreases in migraine frequency (59.6% vs. 56.4% assigned to placebo reporting improvement at 36 months; odds ratio 1.13, 95% confidence interval, 0.86--1.48), as well as decreases in severity, duration, and migraine-related incapacitation. These reductions were not, however, statistically significant. These data are compatible with a small treatment effect of low-dose aspirin in the prophylaxis of migraine among middle-aged women.

Acetylsalicylic acid in the treatment of headache

Acetylsalicylic acid (ASA) is used to treat a broad range of symptoms and disorders. Since its discovery in 1897, it has been used to treat fever and rheumatic pain, to inhibit the formation of thrombocytes, to prevent myocardial ischemia and strokes, and as preventive medication against neoplasms. ASA is best known, however, as a headache medication. For this function alone, ASA underwent an evolution: from powder to tablet to effervescent and chewable tablets. In addition to these oral formulations, an injectable form was developed in the 1970s for intravenous and intramuscular application. Furthermore, coated (slow-releasing) tablets are now used in the prophylactic treatment of migraine. The various forms of ASA used to treat headache are discussed and the controlled studies conducted to evaluate ASA's efficacy in headache treatment are summarized.