Why is the therapeutic effect of acute antimigraine drugs delayed? A review of controlled trials and hypotheses about the delay of effect

The endocannabinoid system and related lipids as potential targets for the treatment of migraine-related pain

BACKGROUND

Migraine is a complex and highly disabling neurological disease whose treatment remains challenging in many patients, even after the recent advent of the first specific-preventive drugs, namely monoclonal antibodies that target calcitonin gene-related peptide. For this reason, headache researchers are actively searching for new therapeutic targets. Cannabis has been proposed for migraine treatment, but controlled clinical studies are lacking. A major advance in cannabinoid research has been the discovery of the endocannabinoid system (ECS), which consists of receptors CB1 and CB2; their endogenous ligands, such as N-arachidonoylethanolamine; and the enzymes that catalyze endocannabinoid biosynthesis or degradation. Preclinical and clinical findings suggest a possible role for endocannabinoids and related lipids, such as palmitoylethanolamide (PEA), in migraine-related pain treatment. In animal models of migraine-related pain, endocannabinoid tone modulation via inhibition of endocannabinoid-catabolizing enzymes has been a particular focus of research.

METHODS

To conduct a narrative review of available data on the possible effects of cannabis, endocannabinoids, and other lipids in migraine-related pain, relevant key words were used to search the PubMed/MEDLINE database for basic and clinical studies.

RESULTS

Endocannabinoids and PEA seem to reduce trigeminal nociception by interacting with many pathways associated with migraine, suggesting a potential synergistic or similar effect.

CONCLUSIONS

Modulation of the metabolic pathways of the ECS may be a basis for new migraine treatments. The multiplicity of options and the wealth of data already obtained in animal models underscore the importance of further advancing research in this area. Multiple molecules related to the ECS or to allosteric modulation of CB1 receptors have emerged as potential therapeutic targets in migraine-related pain. The complexity of the ECS calls for accurate biochemical and pharmacological characterization of any new compounds undergoing testing and development.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Pharmacological strategies to treat attacks of episodic migraine in adults

INTRODUCTION

Migraine patients prioritize early complete relief of headache and associated symptoms, sustained freedom of pain, and good tolerability. One major obstacle for the successful use of drug treatment of migraine attack is that the speed of action of triptans, 5-HT_1B/1D receptor agonists, is delayed.

AREAS COVERED

In this review, the author discusses the following features of acute migraine drugs: pharmacology; pharmacokinetics, and absorption of drugs during migraine attacks. Next, dose-response curves for effect; and the delayed onset of action is reviewed. In the more clinical part of the review, the following items are discussed: overall clinical judgments; comparison of triptans; comparison of triptans with NSAIDs; early intervention with triptans; medication-overuse headache; comments on the effect of gepants; and the general principle of acute migraine therapy.

EXPERT OPINION

The delay in the onset of effect of acute migraine drugs is likely due to a complex antimigraine system involving more than one site of action. Investigations into the mechanisms of the delay should have a high priority, both in studies with animals, migraine models, and in migraine patients during attacks. Non-oral administration of antimigraine drugs resulting in early absorption of drugs should be developed as they possibly also can increase E_max.

European Headache Federation recommendations for placebo and nocebo terminology

Background and aim

Despite recent publications, practitioners remain unfamiliar with the current terminology related to the placebo and nocebo phenomena observed in clinical trials and practice, nor with the factors that modulate them. To cover the gap, the European Headache Federation appointed a panel of experts to clarify the terms associated with the use of placebo in clinical trials.

Methods

The working group identified relevant questions and agreed upon recommendations. Because no data were required to answer the questions, the GRADE approach was not applicable, and thus only expert opinion was provided according to an amended Delphi method. The initial 12 topics for discussion were revised in the opinion of the majority of the panelists, and after a total of 6 rounds of negotiations, the final agreement is presented.

Results/recommendations

Two primary and mechanism-based recommendations are provided for the results of clinical trials: [1] to distinguish the placebo or nocebo response from the placebo or nocebo effect; and [2] for any favorable outcome observed after placebo administration, the term “placebo response” should be used, and for any unfavorable outcome recorded after placebo administration, the term “nocebo response” should be used (12 out of 17 panelists agreed, 70.6% agreement). The placebo or nocebo responses are attributed to a set of factors including those that are related to the medical condition (e.g. natural history, random comorbidities, etc.), along with idiosyncratic ones, in which the placebo or nocebo effects are attributed to idiosyncratic, or nonspecific mechanisms, exclusively (e.g. expectation, conditioning, observational learning etc.). To help investigators and practitioners, the panel summarized a list of environmental factors and idiosyncratic dynamics modulating placebo and nocebo effects. Some of them are modifiable, and investigators or physicians need to know about them in order to modify these factors appropriately to improve treatment. One secondary recommendation addresses the use of the terms “placebo” and “nocebo” (“placebos” and “nocebos” in plural), which refer to the triggers of the placebo/nocebo effects or responses, respectively, and which are inert agents or interventions that should not be confused with the placebo/nocebo responses or effects themselves (all panelists agreed, 100% agreement).

Conclusion

The working group recommends distinguishing the term response from effect to describe health changes from before to after placebo application and to distinguish the terms placebo(s) or nocebo(s) from the health consequences that they cause (placebo/nocebo responses or effects).

Why is the therapeutic effect of acute antimigraine drugs delayed? A review of controlled trials and hypotheses about the delay of effect

In randomised controlled trials (RCTs) of oral drug treatment of migraine attacks, efficacy is evaluated after 2 hours. The effect of oral naratriptan 2.5 mg with a maximum blood concentration (Tmax ) at 2 hours increases from 2 to 4 hours in RCTs. To check whether such a delayed effect is also present for other oral antimigraine drugs, we hand-searched the literature for publications on RCTs reporting efficacy. Two triptans, 3 nonsteroidal anti-inflammatory drugs (NSAIDs), a triptan combined with an NSAID and a calcitonin gene-related peptide receptor antagonist were evaluated for their therapeutic gain with determination of time to maximum effect (Emax ). Emax was compared with known Tmax from pharmacokinetic studies to estimate the delay to pain-free. The delay in therapeutic gain varied from 1-2 hours for zolmitriptan 5 mg to 7 hours for naproxen 500 mg. An increase in effect from 2 to 4 hours was observed after eletriptan 40 mg, frovatriptan 2.5 mg and lasmiditan 200 mg, and after rizatriptan 10 mg (Tmax  = 1 h) from 1 to 2 hours. This strongly indicates a general delay of effect in oral antimigraine drugs. A review of 5 possible effects of triptans on the trigemino-vascular system did not yield a simple explanation for the delay. In addition, Emax for triptans probably depends partly on the rise in plasma levels and not only on its maximum. The most likely explanation for the delay in effect is that a complex antimigraine system with more than 1 site of action is involved.