Guanabenz

Guanabenz (pronounced GWAHN-a-benz, sold under the trade name Wytensin) is an alpha agonist of the alpha-2 adrenergic receptor that is used as an antihypertensive drug. It is used to treat high blood pressure (hypertension).
The most common side effects during guanabenz therapy are dizziness, drowsiness, dry mouth, headache and weakness.
Guanabenz can make one drowsy or less alert, therefore driving or operating dangerous machinery is not recommended.