Study of KK3910 in Healthy Volunteers and Patients With Essential Hypertension

This study is testing a new investigational drug called KK3910, first in healthy volunteers to check safety, then in people with essential tremor — an uncontrolled shaking, usually of the hands, that is not caused by Parkinson's disease. **You may be eligible if...** - You are 18 or older - You have been diagnosed with essential tremor (or are a healthy volunteer for the first phase) - Your tremor is affecting your daily life - You are not currently taking medications that effectively control your tremor - You are generally healthy aside from your tremor **You may NOT be eligible if...** - You have Parkinson's disease or other neurological disorders causing tremor - You have serious heart, liver, or kidney disease - You have used certain medications or substances recently that could affect the results - You are pregnant or breastfeeding - You have had a serious allergic reaction to similar medications Talk to your doctor to see if this trial is right for you.