What is an orphan drug designation?
An orphan drug designation is given to a pharmaceutical product which has been specifically designed to treat a certain rare condition or disease, often known as an orphan disease.
An orphan disease, as its name implies, affect only a small percentage of the population. It it often genetic, so the condition is present often before symptoms begin to appear. The Rare Diseases Act (2002) defines a rare disease as occurring in only about 1 in 1,500 persons, or less than 200,000 persons in the United States. The definition of a rare disease varies from country to country – for example, Japan states that a rare disease is even less common, or 1 per 2,500 persons.
Ironically, some estimates claim that as many as 1 in 10 Americans suffer from a “rare” disease.
The FDA’s Orphan Drugs Grants Program encourages drug development by offering grants (monetary incentives) for clinical studies on the safety or effectiveness of potential products.
Examples of Orphan Diseases and Corresponding Orphan Drugs
Pulmonary hypertension (PH) indicates the presence of high blood pressure in the pulmonary artery, vein, or capillaries (collectively known as the lung vasculature.) Symptoms include shortness of breath while lying flat, fatigue, cough, dizziness, fainting, angina pectoris (chest pain), and peripheral edema (swelling in the legs and feet.)
Orphan Drug Designation: Ambrisentan.
Mechanism: The peptide endothelin is a muscle vasoconstrictor, the dysfunction of which interferes with vasodialation. This causes an increase in blood pressure. Ambrisentan, which relaxes the muscles, as it is an endothelin receptor antagonist. Antagonists bind to receptors without activating them, and block the offending neurotransmitter (in this case, endothelin) to therapeutic effects.
Chronic myelogenous leukemia (CML) is a cancer of the white blood cells. It presents with increased growth of myeloid cells, which function to fight infection, in bone marrow. In addition, they also accumulate in the blood. In the West CML represents about 14% of all leukemias.
Orphan Drug Designation: Nilotinib (AMN107)
Mechanism: Nilotinib, as hydrochloride monohydrate salt, is a tyrosine kinase inhibitor. Tyrosine-kinase inhibitors (TKI) work to suppress the enzymes responsible for the activation of many proteins. CML cells contain a gene not found in normal cells. This gene makes a protein which causes CML cells to grow unfettered.
Excessive Daytime Sleepiness (EDS)/Narcolepsy is a disorder characterized by extreme fatigue and drowsiness during the waking hours, despite the presence of a normal sleep cycle. Patients feel strongly compelled to take naps frequently, even at inappropriate times.
Orphan Drug Designation: Sodium oxybate
Mechanism: This sodium salt of GHB (gamma-Hydroxybutyric acid) functions in a manner that is not entirely understood. However, the therapeutic effects of GHB are the result of neurotransmitter bindings at GABA and GHB receptors, which relax the central nervous system, improve mood, and relieve anxiety.
Warning: This drug has the potential for abuse. It is only safely indicated for the treatment of sleeping disorders. If you or someone you know is using this drug illegally, please seek help immediately.
To learn more about orphan drugs, orphan diseases, or the Orphan Drug Act, visit the website of the Federal Drug Administration (FDA).