Atenolol is the most used drug in Brazil to hypertension treatment. Two crystal structures are known for this molecule: a racemic form (R,S)-atenolol and a pure form S-atenolol. The racemic form is found in commercial tablets. X-ray powder diffraction (XRD) is an adequate tool to study crystalline structures including drugs. Using the Rietveld Method with XRD data it is possible to quantify the crystalline structures existing in the raw material. Other methods like Le Bail and Pawley can be used to the profile fit and phases identification. For this work we analyzed three tablets of atenolol, two generics and the reference (materials were purchased from a drugstore at the city of Araraquara). These tablets were analyzed by Rietveld, Le Bail and Pawley methods. All tablets exhibited the racemic mixture API (R,S)-atenolol. Some crystalline excipients could be characterized: magnesium carbonate hydrate, lactose monohydrate and talc. The conclusion is that the three methods can be efficiently used to characterize the three atenolol tablets.

Atenolol, a selective β1-adrenergic antagonist, is commonly used to treat hypertension, ischemic heart disease and cardiac dysrhythmias. Few cases of severe atenolol intoxication have been described, and only one of these reports discussed the use of calcium chloride as a treatment. We present a case of atenolol overdose associated with shock and first-degree heart block, in which administration of calcium chloride led to dramatic improvement after failure of conventional treatment. In addition, we discuss the pharmacokinetics, toxicology and management of β-blocker overdose, focusing on the possible role of calcium chloride.