Potassium-aggravated myotonia is a rare genetic disorder that affects skeletal muscle. Beginning in childhood or adolescence, people with this condition experience bouts of sustained muscle tensing (myotonia) that prevent muscles from relaxing normally. Myotonia causes muscle stiffness, often painful, that worsens after exercise and may be aggravated by eating potassium-rich foods such as bananas and potatoes. Stiffness occurs in skeletal muscles throughout the body. Potassium-aggravated myotonia ranges in severity from mild episodes of muscle stiffness to severe, disabling disease with frequent attacks. Potassium-aggravated myotonia may, in some cases, also cause paradoxical myotonia, in which myotonia becomes more severe at the time of movement instead of after movement has ceased. Unlike some other forms of myotonia, potassium-aggravated myotonia is not associated with episodes of muscle weakness.Mutations in the SCN4A gene cause potassium-aggravated myotonia. The SCN4A gene provides instructions for making a protein that is critical for the normal function of skeletal muscle cells. For the body to move normally, skeletal muscles contract and relax in a coordinated way. Muscle contractions are triggered by the flow of positively charged ions, including sodium, into skeletal muscle cells. The SCN4A protein forms channels that control the flow of sodium ions into these cells. Mutations in the SCN4A gene alter the usual structure and function of sodium channels. The altered channels cannot properly regulate ion flow, increasing the movement of sodium ions into skeletal muscle cells.
Sacituzumab govitecan, sold under the brand name Trodelvy, is a Trop-2-directed antibody and topoisomerase inhibitor drug conjugate used for the treatment of metastatic triple-negative breast cancer and metastatic urothelial cancer.The most common side effects include nausea, neutropenia, diarrhea, fatigue, anemia, vomiting, alopecia (hair loss), constipation, decreased appetite, rash and abdominal pain. Sacituzumab govitecan has a boxed warning about the risk of severe neutropenia (abnormally low levels of white blood cells) and severe diarrhea. Sacituzumab govitecan may cause harm to a developing fetus or newborn baby. Women are advised not to breastfeed while on sacituzumab govitecan and one month after the last dose is administered.The U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) consider it to be a first-in-class medication. Sacituzumab govitecan was approved for medical use in the European Union in November 2021. Medical uses
Sacituzumab govitecan is indicated for the treatment of adults with metastatic triple-negative breast cancer who received at least two prior therapies for metastatic disease; people with unresectable locally advanced or metastatic triple-negative breast cancer (mTNBC) who have received two or more prior systemic therapies, at least one of them for metastatic disease; and for people with locally advanced or metastatic urothelial cancer (mUC) who previously received a platinum-containing chemotherapy and either a programmed death receptor-1 (PD-1) or a programmed death-ligand 1 (PD-L1) inhibitor. Administration
Sacituzumab govitecan is given in a 21-day treatment cycle in which an injection is only given a few days of the cycle.