Tenormin 100mg tablets contain atenolol, a beta-blocker medication that comes in a calendar pack of 28 tablets. Each tablet contains 100mg of atenolol B.P. as the active ingredient. This prescription medication is manufactured by AstraZeneca. This product comes in a calendar pack format containing 28 tablets (14x2 configuration) to help track daily medication intake. The tablets should be taken as prescribed by your healthcare provider. As this is a prescription medication, it should only be used under medical supervision.