Friday, October 27, 2017

Dietary supplement could be promising therapeutic target for seizure disorders

We know that, Glucosamine  is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids. Glucosamine is part of the structure of the polysaccharides chitosan and chitin, which compose the exoskeletons of crustaceans and other arthropods, as well as the cell walls of fungiand many higher organisms. Glucosamine is one of the most abundant monosaccharides.

Stereo structural formula of glucosamine ((2S,6R)-6-meth,-2-ol)


Seizure disorders -- including epilepsy are associated with pathological hyperexcitability in brain neurons. Unfortunately, there are limited available treatments that can prevent this hyperexcitability. However, University of Alabama at Birmingham researchers have found that inducing a biochemical alteration in brain proteins via the dietary supplement glucosamine was able to rapidly dampen that pathological hyperexcitability in rat and mouse models.
These results represent a potentially novel therapeutic target for the treatment of seizure disorders, and they show the need to better understand the physiology underlying these neural and brain circuit changes.
Proteins are the workhorses of living cells, and their activities are tightly and rapidly regulated in responses to changing conditions. Adding or removing a phosphoryl group to proteins is a well-known regulator for many proteins, and it is estimated that human proteins may have as many as 230,000 sites for phosphorylation.
A lesser-known regulation comes from the addition or removal of N-acetylglucosamine to proteins, which is usually controlled by glucose, the primary fuel for neurons. Several years ago, neuroscientist Lori McMahon, Ph.D., professor of cell, developmental and integrative biology at UAB, found out from her colleague John Chatham, D.Phil., a UAB professor of pathology and a cardiac physiologist, that brain cells had the second-highest amounts of proteins with N-acetylglucosamine, or O-GlcNAcylation, in the body.
At the time, very little was known about how O-GlcNAcylation might affect brain function, so McMahon and Chatham started working together. In 2014, McMahon and Chatham, in a study led by graduate student Erica Taylor and colleagues, reported that acute increases in protein O-GlcNAcylation caused long-term synaptic depression, a reduction in neuronal synaptic strength, in the hippocampus of the brain. This was the first time acute changes in O-GlcNAcylation of neuronal proteins were shown to directly change synaptic function.
Since neural excitability in the hippocampus is a key feature of seizures and epilepsy, they hypothesized that acutely increasing protein O-GlcNAcylation might dampen the pathological hyperexcitability associated with these brain disorders.
That turned out to be the case, as reported in the Journal of Neuroscience study, "Acute increases in protein O-GlcNAcylation dampen epileptiform activity in hippocampus." The study was led by corresponding author McMahon and first author Luke Stewart, a doctoral student in the Neuroscience Theme of the Graduate Biomedical Sciences Program. Stewart is co-mentored by McMahon and Chatham.
"Our findings support the conclusion that protein O-GlcNAcylation is a regulator of neuronal excitability, and it represents a promising target for further research on seizure disorder therapeutics," they wrote in their research significance statement. The researchers caution that the mechanism underlying the dampening is likely to be complex.
Research details
Glucose, the major fuel for neurons, also controls the levels of protein O-GlcNAcylation on proteins. However, high levels of the dietary supplement glucosamine, or an inhibitor of the enzyme that removes O-GlcNAcylation, leads to rapid increases in O-GlcNAc levels.
In experiments with hippocampal brain slices treated to induce a stable and ongoing hyperexcitability, UAB researchers found that an acute increase in protein O-GlcNAcylation significantly decreased the sudden bursts of electrical activity known as epileptiform activity in area CA1 of the hippocampus. An increased protein O-GlcNAcylation in normal cells also protected against a later induction of drug-induced hyperexcitability.
The effects were seen in slices treated with both glucosamine and an inhibitor of the enzyme that removes O-GlcNAc groups. They also found that treatment with glucosamine alone for as short a time as 10 minutes was able to dampen ongoing drug-induced hyperexcitability.
In common with the long-term synaptic depression provoked by increased O-GlcNAcylation, the dampening of hyperexcitability required the GluA2 subunit of the AMPA receptor, which is a glutamate-gated ion channel responsible for fast synaptic transmission in the brain. This finding suggested a conserved mechanism for the two changes provoked by increased O-GlcNAcylation -- synaptic depression and dampening of hyperexcitability.
The researchers also found that the spontaneous firing of pyramidal neurons in another region of hippocampus, area CA3, was reduced by increased O-GlcNAcylation in normal brain slices and in slices with drug-induced hyperexcitability. This reduction in spontaneous firing of CA3 pyramidal neurons likely contributes to decreased hyperexcitability in area CA1 since the CA3 neurons directly excite those in CA1.
Similar to the findings for brain slices, mice that were treated to increase O-GlcNAcylation before getting drug-induced hyperexcitability had fewer of the brain activity spikes associated with epilepsy that are called interictal spikes. Several drug-induced hyperexcitable mice had convulsive seizures during the experiments -- this occurred in both the increased O-GlcNAcylation mice and the control mice. Brain activity during the seizures differed between these two groups: The peak power of the brain activity for the mice with increased O-GlcNAcylation occurred at a lower frequency, as compared with the control mice. 

Ref : http://www.uab.edu/news/innovation/item/8796?utm_source=eurekaalert&utm_medium=referral&utm_campaign=&utm_content=

Monday, October 16, 2017

Flexion Therapeutics Announces FDA Approval of Zilretta (triamcinolone acetonide extended-release injectable suspension) for Osteoarthritis Knee Pain

In continuation of my update on Zilretta 

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Flexion Therapeutics, Inc. announced,  that  Food and Drug Administration (FDA) approved Zilretta (triamcinolone acetonide extended-release injectable suspension), the first and only extended-release, intra-articular injection for osteoarthritis knee pain. Zilretta is a non-opioid medicine that employs Flexion's proprietary microsphere technology to provide proven pain relief over 12 weeks.

"The approval of Zilretta marks a major advancement in the treatment landscape for managing OA knee pain," said Michael Clayman, M.D., President and Chief Executive Officer of Flexion. "It comes at a time when our society is in urgent need of non-addictive therapies to help the millions of Americans who suffer from this condition." Dr. Clayman added, "We believe that Zilretta has the potential to be a transformative medicine for the more than five million patients who receive an intra-articular injection for OA knee pain each year."
The FDA approval of Zilretta is based upon data from Flexion's pivotal Phase 3 clinical trial. The randomized, double-blind study enrolled 484 patients at 37 centers worldwide.
Commenting on the approval, Andrew Spitzer, M.D., Co-Director, Joint Replacement Program, Cedars-Sinai Orthopaedic Center, said, "OA knee pain presents a host of challenges for patients and clinicians alike, and there has been very little innovation in this area in recent years. Zilretta is a groundbreaking new therapy, providing clinically meaningful pain relief with a safety profile that is similar to saline."
Sometimes called degenerative joint disease or "wear and tear" arthritis, OA is a progressive and incurable condition and the most common form of arthritis. Its effects may range from intermittent discomfort to the loss of function and severe chronic pain associated with irreversible structural damage.
"As OA progresses, many patients experience intractable joint pain, which can ultimately lead to the need for a total joint replacement," said John Richmond, M.D., Medical Director for Network Development, New England Baptist Hospital. "As a result, healthcare providers are eager for new, non-opioid therapies that may help patients manage their OA pain for extended periods of time. Zilretta gives us an important new non-surgical intervention."
Zilretta's label also includes the results from a double-blind, randomized, parallel-group trial, which examined blood glucose concentrations in patients with type 2 diabetes.
Steven Russell, M.D., Ph.D., Assistant Professor of Medicine, Massachusetts General Hospital Diabetes Research Center, commented, "Our trial demonstrated that Zilretta may avoid the disruptive blood glucose spikes that can be seen with corticosteroid use in patients coping with both knee OA and type 2 diabetes. As a practicing diabetologist, I believe the availability of Zilretta will make intra-articular injection of glucocorticoid an attractive option for these patients."
The pain from OA of the knee can have a profound impact on the people it afflicts, often resulting in a cascade of consequences, which patient advocates warn is only expected to grow.
According to Seth Ginsberg, President and Co-Founder of CreakyJoints®, a national patient advocacy organization for people with all forms of arthritis, "Despite common misperceptions, OA is not a disease that is limited to the elderly. In fact, the average age of knee OA diagnosis has decreased while the number of people diagnosed with OA of the knee has been steadily rising. That's why our community advocates for and welcomes new therapeutic options for people to consider in consultation with their doctor."
Flexion expects Zilretta will be available in the U.S. by the end of October. 
Ref :  www.Zilretta.com

Friday, October 13, 2017

FDA Approves Lyrica CR (pregabalin) Extended-Release Tablets for Neuropathic Pain Conditions

In continuation of my update on Pregabalin
Pfizer Inc.  announced today that the  Food and Drug Administration (FDA) has approved Lyrica CR (pregabalin) extended-release tablets CV as once-daily therapy for the management of neuropathic pain associated with diabetic peripheral neuropathy (pDPN) and the management of postherpetic neuralgia (PHN). Lyrica CR did not receive approval for the management of fibromyalgia.
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“Lyrica CR was developed to offer patients an effective treatment option with the convenience of once-daily dosing,” said James M. Rusnak, MD, PhD, Chief Development Officer, Internal Medicine, Pfizer Global Product Development. “It provides an important option for patients and health care providers managing these often debilitating pain conditions.”
The efficacy and safety of Lyrica CR in PHN  was established in a randomized placebo-controlled clinical trial conducted in a total of 801 patients with PHN who entered single-blind treatment with Lyrica CR. As both pDPN and PHN are peripheral neuropathic pain conditions, the PHN data was supportive of both the pDPN and PHN indications. The randomized trial included a six-week single-blind, dose optimization phase followed by a 13-week double-blind phase. In the PHN study, 73.6 percent of patients in the Lyrica CR group achieved at least 50 percent improvement in pain intensity compared with 54.6 percent in the placebo group.
The most common adverse reactions reported with Lyrica CR were dizziness, somnolence, headache, fatigue, peripheral edema, nausea, blurred vision, dry mouth and weight gain.
Please see the full prescribing information and Medication Guide for Lyrica CR (pregabalin) extended-release tablets 
Ref :  http://www.pfizer.com/products/product-detail/lyrica

FDA Approves Lyrica CR (pregabalin) Extended-Release Tablets for Neuropathic Pain Conditions