SS-31 — also known as elamipretide — occupies a category no other compound in this series can claim: it is the first mitochondria-targeted therapy ever to receive FDA approval. In this episode, Dr. Ethan traces the compound from its accidental discovery in a Weill Cornell pharmacology lab through to its September 2025 accelerated approval for Barth syndrome, unpacking the biology of cardiolipin — the inner mitochondrial membrane phospholipid whose decline with age sits at the centre of SS-31's entire mechanistic rationale — and explaining precisely why a peptide that concentrates over 1,000-fold inside the mitochondrial membrane represents a genuinely novel class of therapeutic tool. The mechanism is well-supported, the preclinical literature is large and independently replicated, and the clinical trial programme is the most rigorous of any comp ...