Tenormin 50mg is a prescription medication containing atenolol, a beta-blocker used to treat various cardiovascular conditions. Each pack contains 28 tablets in a calendar pack format, manufactured by AstraZeneca. The active ingredient in Tenormin is atenolol 50mg per tablet. The medication comes in a convenient calendar pack containing 28 tablets to help track daily doses. This is a prescription-only medication that should be taken as directed by your healthcare provider.