Selected Medicines in Development for Mental Illness

Selected Medicines in Development for Mental Illness

Anxiety (Social Phobia) – Anxiety disorders affect more than 40 million adults in the U.S., with about 15 million of those suffering from acute social phobia, according to the National Institute of Mental Health.  A potential medicine in development is part of a new class of psychotropic pherines.  The drug, which has a unique mechanism of action, is administered in an intranasal spray and acts with rapid-onset on peripheral receptors from nasal chemosensory neurons that act on the hypothalamic-limbic system in the brain, which is thought to be the primary center of emotion.  In clinical trials, it was shown to improve social performance and social interaction anxiety within 10 minutes of administration.   

Attention-Deficit/Hyperactivity Disorder (ADHD) – ADHD is one of the most common reasons children in the United States are referred for mental health services and affects as many as one in every 20 children, according to Mental Health America.  A potential medicine in development for ADHD is an agonist of neuronal nicotinic receptors (NNR). NNRs serve as key regulators of nervous system functions.  When certain neurotransmitters bind to an NNR, the receptor normalizes chemical signaling in the brain, allowing neurons to communicate properly. This results in increased signaling when the nervous system is under-stimulated and decreased signaling when the nervous system is overstimulated. The medicine is designed to interact selectively with a specific NNR subtype that impacts cognition to achieve a therapeutic effect in ADHD.

Cocaine Addiction – The National Institute on Drug Abuse estimates that about one in six Americans – 15 percent in 2007 – have tried cocaine by the age of 30.  Currently no medication addresses cocaine addiction, but a therapeutic vaccine in development may prove an effective treatment.  The vaccine is designed to induce cocaine-specific antibodies that bind to cocaine in the blood, blocking its uptake into the brain.  The physiological response to cocaine is thus altered, reducing the reinforcing properties of cocaine and permitting patients to break the cycle of addiction.

Depression – Mood disorders, such as major depressive disorder, dysthymic disorder and bipolar disorder, affect nearly 21 million American adults, or 9.5 percent of the U.S. population, according to the National Institute on Mental Health.  A potential first-in-class medicine for the treatment of major depression is based on the theory that chronic exposure to stress hormones may prevent the growth of new neurons in the brain and can lead to depression, among other conditions.  The medicine, which can cross the blood-brain barrier, recruits the patients’ own neural stem cells to repair or protect against damage to the central nervous system.

Fragile X Syndrome is the most common cause of inherited intellectual disability (mental retardation).  It is caused by a change in a gene called FMR1 where a small part of the gene sequence is repeated on a fragile area of the X chromosome. The FMR1 gene is responsible for making the FMRP protein needed for the brain to grow properly.  A defect in the gene makes the body produce too little of the protein, or none at all. Boys and girls can both be affected, but because boys have only one X chromosome, a single fragile X is likely to affect them more severely.  A medicine in development for Fragile X is potentially the first to treat the underlying disorder instead of just its symptoms. The medicine is an antagonist of mGluR5 (metabotropic glutamate receptor 5), a receptor protein on brain cells that is involved in many aspects of normal brain function.  The FMRP protein normally acts as a blocker for the brain cell pathways activated by mGluR5.  When the FMRP protein is missing, mGluR5 pathways are overactive resulting in behavioral and cognitive impairments associated with Fragile X.  The medicine is designed to block the activity of mGluR5.

Insomnia is often thought of as trouble falling asleep. One form of it, sleep maintenance insomnia, is difficulty staying asleep, or waking too early and struggling to get back to sleep. Difficulty staying asleep often gives rise to worry over not getting enough sleep, which further interferes with sleep, creating a vicious cycle.  One medicine in development for sleep maintenance insomnia is a potential first-in-class dual acting serotonin receptor and dopamine modulator. At low doses it primarily acts as a serotonin receptor antagonist and works by maintaining sleep throughout the night, rather than inducing sleep.

Nicotine Addiction is characterized by compulsive seeking and abuse of nicotine, even in the face of negative health consequences. According to the National Institute in Drug Abuse, it is well documented that most smokers identify tobacco use as harmful and express a desire to reduce or stop using it, and nearly 35 million of them want to quit each year. Unfortunately, more than 85 percent of those who try to quit on their own relapse, most within a week. When cigarette smoke is inhaled, it passes into the bloodstream and quickly crosses the blood-brain barrier into the brain where addictive effects take place.  A vaccine in development to treat nicotine addiction has shown in clinical trials to induce nicotine-specific antibodies that bind to nicotine in the blood resulting in a nicotine complex too large to pass into the brain.  The vaccine is thought to interrupt the reward-inducing and addiction-driving cycle of nicotine.

Schizophrenia – Schizophrenia affects some 2.4 million American adults, or 1.1 percent of the U.S. population, according to the National Institute on Mental Health. Symptoms of schizophrenia are typically divided into positive and negative.  Positive symptoms reflect an excess or distortion of normal functions, while negative symptoms reflect a diminished or loss of normal functions.  One medicine in development has shown potential to control both types of symptoms in animal models of the disease.  In addition, the medicine may have a lower potential for side effects than some of the current antipsychotic medicines.

* From Medicines in Development for Mental Illnesses, PhRMA, 2012

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