In heart cells, calcium is important in generating electrical signals for heart muscle contraction, as well as generating force for this contraction. In consideration of these important properties of calcium, two conclusions can be drawn. First, with less calcium in the cell, there is a decrease in electrical signals for contraction, thus allowing time for the hearts natural pacemaker to rectify arrhythmic contractions. Secondly, lower calcium means a decrease in strength and rate of the contractions, which can be helpful in treatment of abnormally fast heart rates. Type III antiarrhythmic action
Sotalol also acts on potassium channels and causes a delay in relaxation of the ventricles. By blocking these potassium channels, sotalol inhibits efflux of K+ ions, which results in an increase in the time before another electrical signal can be generated in ventricular myocytes. This increase in the period before a new signal for contraction is generated, helps to correct arrhythmias by reducing the potential for premature or abnormal contraction of the ventricles but also prolongs the frequency of ventricular contraction to help treat tachycardia. History
Sotalol was first synthesized in 1960 by A. A. Larsen of Mead-Johnson Pharmaceutical. It was originally recognized for its blood pressure lowering effects and its ability to reduce the symptoms of angina. It was made available in the United Kingdom and France in 1974, Germany in 1975, and Sweden in 1979. It became widely used in the 1980s. In the 1980s, its antiarrhythmic properties were discovered. The United States approved the drug in 1992.
Diagnosis
Classification
The World Health Organization (WHO) has identified three subtypes of nasopharyngeal carcinoma:
type 1: squamous cell carcinoma, typically found in older adults
type 2: non-keratinizing carcinoma
type 3: undifferentiated carcinomaType 3 is most commonly found among younger children and adolescents, with a few type 2 cases. Both type 2 and 3 have been found to be associated with elevated levels of Epstein-Barr virus titers, but not type 1. Additionally, type 2 and type 3 may be followed with an influx of inflammatory cells, including lymphocytes, plasma cells, and eosinophils, generating the term lymphoepithelioma.Nasopharyngeal carcinoma, also known as nasopharyngeal cancer, is classified as a malignant neoplasm, or cancer, arising from the mucosal epithelium of the nasopharynx, most often within the lateral nasopharyngeal recess or fossa of Rosenmüller (a recess behind the entrance of the eustachian tube opening). The World Health Organization classifies nasopharyngeal carcinoma in three types, in order of frequency: Non-keratinizing squamous cell carcinoma; keratinizing squamous cell carcinoma; and basaloid squamous cell carcinoma. The tumor must show evidence of squamous differentiation, with the non-keratinizing type (also known as lymphoepithelioma) the tumor most strongly associated with Epstein–Barr virus infection of the cancerous cells. Staging
Staging of nasopharyngeal carcinoma is based on clinical and radiologic examination. Most patients present with Stage III or IV disease. Stage I is a small tumor confined to nasopharynx. Stage II is a tumor extending in the local area, or that with any evidence of limited neck (nodal) disease. Stage III is a large tumor with or without neck disease, or a tumor with bilateral neck disease.