This study involves a medicine called MTR-601 for people aged 18-75 with cervical dystonia, a condition causing neck muscle spasms. Over 8 weeks, 80 participants will take either the medicine or a placebo (a pill with no medicine) without knowing which they receive. They must stop any botulinum toxin treatments, like Botox, before joining. The study checks if MTR-601 is safe and works well. Participants will take capsules daily at home and visit the clinic weekly for check-ups.

• Duration: 8 weeks with weekly check-ups.
• Medication: Daily capsules of MTR-601 or placebo.
• Eligibility: Must stop botulinum toxin treatments before starting.

Participants must be willing to follow study rules, including not using botulinum toxin during the study, and practice effective birth control. Some medical conditions or recent treatments might exclude you. Before joining, discuss your medical history with the study team to ensure you're a good fit. Participation is voluntary, and you can leave the study at any time.