Tenormin

• Use caution when driving, operating machinery, or performing other hazardous activities. Atenolol may cause drowsiness, dizziness, and blood pressure changes. If you experience drowsiness or dizziness, avoid these activities.
• Tell your doctor and dentist that you are taking atenolol before having surgery.
• Use alcohol cautiously. Alcohol may increase drowsiness and dizziness while taking this medication

Another note from a taker of atenolol, and this took me by surprise because my doctor didn't mention it: this medication will lower your heart rate and if you're on a Cardio exercise program where you're attempting to reach a target heart rate, you'll have to adjust your target heart rate downward. Probably should have been obvious to me, but my first cardio workout after taking my first dose of this medicine was a little disconcerting.

Tenormin was introduced in 1976 and made by pharmaceutical company AstraZenica. It offered many benefits over the previous best-seller, Inderal (Propanalol), because the latter had a tendency to cross the blood-brain barrier and be absorbed, causing depression as a side effect. Tenormin caused much less of that side effect (though in 2006 studies suggested it increased the risk of type-2 diabetes).

It's chemical formula is C₁₄H₂₂N₂O₃. (thanks wikipedia)

Nowadays, almost everyone uses the generic form of it; Atenolol. I haven't seen a brand-name prescription for it in years.