Lonafarnib is a farnesyl transferase inhibitor that was studied in phase 2 clinical trials from 2007-2012 at Boston Children's Hospital for the treatment of Hutchinson-Gilford progeria syndrome. The trials involved doses of 100-175mg taken twice daily for 4-24 months. Lonafarnib works by inhibiting farnesyl transferase and preventing the farnesylation and activation of proteins involved in progerin production. The initial trials showed improvements such as reduced risks of stroke, headaches, increased height, and reduced bone fractures. However, dose-limiting toxicities included neutropenia, diarrhea, nausea and vomiting.