Pitressin is a synthetic form of vasopressin, which is a hormone that plays a vital role in regulating the body's water balance. This hormone is also known by many other synonyms, including antidiuretic hormone (ADH), argipressin, lysine vasopressin, or simply vasopressin. All of these synonyms refer to the same hormone that helps control the reabsorption of water in the kidneys and works to increase blood pressure in the body. Pitressin and its synonyms are often used to treat various medical conditions, such as diabetes insipidus and cardiac arrest, where there is a decrease in vasopressin levels in the body.