The US Food and Drug Administration has approved Emcitate (tiratricol), the first treatment for MCT8 deficiency, also known as Allan-Herndon-Dudley syndrome.The drug is indicated for peripheral thyrotoxicosis in adults and children with the rare X-linked genetic disorder, in which a faulty transporter disrupts thyroid hormone delivery to cells. It primarily affects males, with a reported median life expectancy of about 35 years.The approval was supported by two studies in patients from infancy to adulthood: an international randomized placebo-controlled trial and a longer open-label study. Patients on Emcitate showed lower blood thyroid hormone levels and improvements in heart rate and blood pressure."Until now, patients living with MCT8 deficiency and their families had no FDA-approved treatment option," said Marina Zemskova of the FDA. The drug received orphan drug, rare pediatric disease, fast track and breakthrough therapy designations. Egetis Therapeutics expects a US launch in 8-10 weeks. Emcitate is not recommended for treating primary hypothyroidism.