Lidocaine for Sympathetic Activity in Healthy Subjects

(SPARK Trial)

This trial explores how lidocaine, a common local anesthetic, affects nerve activity and blood flow in healthy subjects. Researchers will use ultrasound to guide lidocaine application at the wrist and observe changes in blood vessel function during a cold exposure test. The study examines differences between applying the treatment to the left versus the right wrist. This trial suits healthy individuals without arm injuries or allergies to lidocaine and who can tolerate cold temperatures. As a Phase 4 trial, lidocaine is already FDA-approved and proven effective, and this research aims to understand how it benefits more patients.

The trial information does not specify whether you need to stop taking your current medications. It's best to discuss this with the study team to get a clear answer.

Research has shown that lidocaine is usually safe for people. It is often used to numb a specific part of the body. Studies have also found that it can help manage some heart conditions by affecting nerve signals.

In past studies, lidocaine lowered blood pressure and slowed the heart rate during medical procedures. These results suggest it can be used safely in those situations. However, very high doses in animal studies showed potential risks to brain areas related to emotions. This highlights the importance of using lidocaine in normal doses for most people.

Lidocaine is unique because it acts as a local anesthetic to block nerve signals, potentially reducing sympathetic nervous system activity. Unlike traditional treatments for managing sympathetic activity, which often involve systemic medications like beta-blockers or calcium channel blockers, lidocaine offers a targeted approach through an ultrasound-guided periarterial block. This delivery method at the wrist allows for precise, localized action, which could minimize systemic side effects. Researchers are excited because this could provide a safer, more effective way to manage conditions linked to sympathetic overactivity.

Research has shown that lidocaine affects the nervous system by lowering the activity of certain nerves, leading to changes in blood pressure and heart rate. Specifically, lidocaine can slow heart rhythms, potentially increasing blood pressure. Additionally, small amounts of lidocaine have been effective in reducing pain and anxiety. This trial will explore lidocaine's effects on nerve activity outside the brain and spinal cord in healthy individuals. Participants will receive either a left or right wrist block using an ultrasound-guided periarterial block with 2% lidocaine.¹⁶⁷⁸⁹