Lonafarnib (Zokinvy™) is an orally active farnesyltransferase inhibitor developed by Eiger BioPharmaceuticals under license from Merck & Co. for the treatment of hepatitis D virus (HDV) infections, and progeria and progeroid laminopathies. The drug was originally discovered by Merck & Co as an investigational drug in oncology. In progeria, lonafarnib inhibits farnesyltransferase to prevent farnesylation and subsequent accumulation of progerin and progerin-like proteins in the nucleus and cellular cytoskeleton. In November 2020, lonafarnib received its first approval in the USA to reduce the risk of mortality in Hutchinson-Gilford Progeria Syndrome (HGPS) and for the treatment of processing-deficient progeroid laminopathies (with either heterozygous LMNA mutation with progerin-like protein accumulation, or homozygous or compound heterozygous ZMPSTE24 mutations) in patients ≥ 12 months of age with a body surface area (BSA) of ≥ 0.39 m2. Lonafarnib is under regulatory review in the European Union. Clinical development for the treatment of HDV infections is underway in multiple countries. This article summarizes the milestones in the development of lonafarnib leading to this first approval.