Tenormin 50mg tablets contain atenolol, a prescription medication used to treat various cardiovascular conditions. Each pack contains 28 tablets in a calendar pack format, with each tablet containing 50mg of the active ingredient atenolol. Tenormin is manufactured by AstraZeneca and comes in a calendar pack format to help track doses. The medication requires a prescription and should only be taken under medical supervision. The dosage and duration of treatment should be determined by your healthcare provider based on your specific medical condition.