Abstract
Achondroplasia, characterized by short stature and skeletal abnormalities, is caused by a gain-of-function variant in the fibroblast growth factor receptor 3 gene. Vosoritide, a C-type natriuretic peptide analog, is an emerging treatment for achondroplasia that functions by promoting endochondral ossification. Vosoritide was approved for the treatment of achondroplasia in Europe and the United States in 2021, and in Japan, the following year. However, vosoritide is associated with a risk of hypotension and vomiting after subcutaneous injection due to its vasodilating effect. Herein, we present two cases of cardiovascular adverse events in infants following vosoritide injection. Case 1 involved a one-month-old female infant with achondroplasia who received the first subcutaneous injection of vosoritide 30 minutes after her last formula intake. Following injection, she developed transient symptomatic hypotension accompanied by vomiting. Although established guidelines recommend that injections be administered after approximately 30 minutes (Europe/Japan) or within one hour (USA) following the last feeding, an extended interval of 1.5 to two hours was required to prevent hypotension-associated vomiting. Case 2 involved a three-month-old female infant with achondroplasia. The first subcutaneous vosoritide injection was administered four hours after the last formula intake, and she subsequently developed prolonged compensated shock with marked tachycardia requiring intervention, including repetitive bolus saline injection. These cases indicate the need to monitor patients for cardiovascular adverse events following subcutaneous injection of vosoritide in early infancy.