Sotalol, sold under the brand name Betapace among others, is a medication used to treat and prevent abnormal heart rhythms. It is only recommended in those with significant abnormal heart rhythms due to potentially serious side effects. Evidence does not support a decreased risk of death with long term use. It is taken by mouth or injection into a vein.Common side effects include a slow heart rate, chest pain, low blood pressure, feeling tired, dizziness, shortness of breath, problems seeing, vomiting, and swelling. Other serious side effects may include QT prolongation, heart failure, or bronchospasm. Sotalol is a non-selective beta-adrenergic receptor blocker which has both class II and class III antiarrhythmic properties.Sotalol was first described in 1964 and came into medical use in 1974. It is available as a generic medication. In 2017, it was the 267th most commonly prescribed medication in the United States, with more than one million prescriptions. Medical uses
According to the U.S. Food and Drug Administration (FDA), sotalol can be validly used to maintain a normal heart rhythm in people with life-threatening ventricular arrhythmias (e.g., ventricular tachycardia), or very symptomatic atrial fibrillation or flutter. Due to the risk of serious side effects, the FDA states that sotalol should generally be reserved for people whose ventricular arrhythmias are life-threatening, or whose fibrillation/flutter cannot be resolved using the Valsalva maneuver or another simple method. Contraindications
According to the FDA, sotalol should not be used in people with a waking heart rate lower than 50 beats per minute.
In the other enzymatic reaction, methylcobalamin supports the methionine synthase reaction, which is essential for normal metabolism of folate. The folate-cobalamin interaction is pivotal for normal synthesis of purines and pyrimidines and the transfer of the methyl group to cobalamin is essential for the adequate supply of tetrahydrofolate, the substrate for metabolic steps that require folate. In a state of vitamin B12 deficiency, the cell responds by redirecting folate metabolic pathways to supply increasing amounts of methyltetrahydrofolate. The resulting elevated concentrations of homocysteine and MMA are often found in patients with low serum vitamin B12 and can usually be lowered with successful vitamin B12 replacement therapy. However, elevated MMA and homocysteine concentrations may persist in patients with cobalamin concentrations between 200 and 350 pg/mL. Supplementation with vitamin B12 during conditions of deficiency restores the intracellular level of cobalamin and maintains a sufficient level of the two active coenzymes: methylcobalamin and deoxyadenosylcobalamin. See also
Methylcobalamin
Cyanocobalamin
Adenosylcobalamin
 Vitamin B12
Cobalamin biosynthesis
Nitric oxide

References
External links
Hydroxocobalamin in the ChEBI database
"Hydroxocobalamin". Drug Information Portal. U.S. National Library of Medicine.