This study tests a new medicine called IPN10200 for treating Cervical Dystonia (CD) in adults. CD affects the head and neck, causing pain and stiffness. It might be linked to the brain's movement control and other factors. Current treatments like BoNT injections last only about 3 months. IPN10200 aims to work longer.

The study has two parts: a Screening Period (up to 4 weeks) to see if you can join, needing at least one visit, and a Treatment Period lasting 36 weeks. On Day 1, you'll get either IPN10200 or a placebo in your head, neck, and shoulder muscles. Participants will continue some medications but must record them.

You'll have up to 10 clinic visits (12 if you get Dose C) plus one phone visit. Tests include blood, urine, physical checks, and filling out questionnaires. The study lasts up to 40 weeks (about 9 months).

• You'll need to visit the clinic several times and one remote visit (phone call).
• The study lasts about 9 months.
• You might receive either IPN10200 or a placebo.