Pharmacological Profiling of KATP Channel Modulators: An Outlook for New Treatment Opportunities for Migraine

Resistant and refractory migraine: clinical presentation, pathophysiology, and management

Migraine is a leading cause of disability worldwide. A minority of individuals with migraine develop resistant or refractory conditions characterised by ≥ 8 monthly days of debilitating headaches and inadequate response, intolerance, or contraindication to ≥3 or all preventive drug classes, respectively. Resistant and refractory migraine are emerging clinical definitions stemming from better knowledge of the pathophysiology of migraine and from the advent of migraine-specific preventive treatments. Resistant migraine mostly results from drug failures, while refractory migraine has complex and still unknown mechanisms that impair the efficacy of preventive treatments. Individuals with resistant migraine can be treated with migraine-specific preventive drugs. The management of refractory migraine is challenging and often unsuccessful, being based on combinations of different drugs and non-pharmacological treatment. Future research should aim to identify individuals at risk of developing treatment failures, prevent the condition, investigate the mechanisms of refractoriness to treatments, and find effective treatment strategies.

The shortcoming of using glibenclamide in exploratory clinical headache provocation studies

OBJECTIVE

Preclinical and clinical studies implicate the vascular ATP-sensitive potassium (KATP) channel in the signaling cascades underlying headache and migraine. However, attempts to demonstrate that the KATP channel inhibitor glibenclamide would attenuate triggered headache in healthy volunteers have proven unsuccessful. It is questionable, however, whether target engagement was achieved in these clinical studies.

METHODS

Literature data for human glibenclamide pharmacokinetics, plasma protein binding and functional IC50 values were used to predict the KATP receptor occupancy (RO) levels obtained after glibenclamide dosing in the published exploratory clinical headache provocation studies. RO vs. time profiles of glibenclamide were simulated for the pancreatic KATP channel subtype Kir6.2/SUR1 and the vascular subtype Kir6.1/SUR2B.

RESULTS

At the clinical dose of 10 mg of glibenclamide used in the headache provocation studies, predicted maximal occupancy levels of up to 90% and up to 26% were found for Kir6.2/SUR1 and Kir6.1/SUR2B, respectively.

CONCLUSIONS

The findings of the present study indicate that effective Kir6.1/SUR2B target engagement was not achieved in the clinical headache provocation studies using glibenclamide. Therefore, development of novel selective Kir6.1/SUR2B inhibitors, with good bioavailability and low plasma protein binding, is required to reveal the potential of KATP channel inhibition in the treatment of migraine.

Synthesis and SAR of a novel Kir6.2/SUR1 channel opener scaffold identified by HTS

Kir6.2/SUR1 is an ATP-regulated potassium channel that acts as an intracellular metabolic sensor, controlling insulin and appetite-stimulatory neuropeptides secretion. In this Letter, we present the SAR around a novel Kir6.2/SUR1 channel opener scaffold derived from an HTS screening campaign. New series of compounds with tractable SAR trends and favorable potencies are reported.