Glutamine (symbol Gln or Q) is an α-amino acid that is used in the biosynthesis of proteins. Its side chain is similar to that of glutamic acid, except the carboxylic acid group is replaced by an amide. It is classified as a charge-neutral, polar amino acid. It is non-essential and conditionally essential in humans, meaning the body can usually synthesize sufficient amounts of it, but in some instances of stress, the bodys demand for glutamine increases, and glutamine must be obtained from the diet. It is encoded by the codons CAA and CAG. In human blood, glutamine is the most abundant free amino acid.The dietary sources of glutamine include especially the protein-rich foods like beef, chicken, fish, dairy products, eggs, vegetables like beans, beets, cabbage, spinach, carrots, parsley, vegetable juices and also in wheat, papaya, Brussels sprouts, celery, kale and fermented foods like miso. Functions
Glutamine plays a role in a variety of biochemical functions:

Protein synthesis, as any other of the 20 proteinogenic amino acids
Lipid synthesis, especially by cancer cells. Regulation of acid-base balance in the kidney by producing ammonium
Cellular energy, as a source, next to glucose
Nitrogen donation for many anabolic processes, including the synthesis of purines
Carbon donation, as a source, refilling the citric acid cycle
Nontoxic transporter of ammonia in the blood circulation. Integrity of healthy intestinal mucosa, though small randomized trials have shown no benefit in Crohn’s disease. Roles in metabolism and cancer
Cancer cells rely on glutamine metabolism as carbon and nitrogen sources.
In 1998 NTI amended its agreement with Childrens to allow Merz to take over development.In 2000, Merz partnered with Forest to develop the drug for Alzheimers disease in the U.S. under the name Namenda.In 2000, Merz partnered with Suntory for the Japanese market and with Lundbeck for other markets including Europe; the drug was originally marketed by Lundbeck under the name Ebixa.Sales of the drug reached $1.8 billion for 2014. The cost of Namenda was $269 to $489 a month in 2012.In February 2014, as the July 2015 patent expiration for memantine neared, Actavis, which had acquired Forest, announced that it was launching an extended release (XR) form of memantine that could be taken once a day instead of twice a day as needed with the then-current "immediate release" (IR) version, and that it intended to stop selling the IR version in August 2014 and withdraw the marketing authorization. This is a tactic to thwart generic competition called "product hopping". However the supply of the XR version ran short, so Actavis extended the deadline until the fall. In September 2014 the attorney general of New York, Eric Schneiderman, filed a lawsuit to compel Actavis to keep selling the IR version on the basis of antitrust law.In December 2014, a judge granted New York State its request and issued an injunction, preventing Actavis from withdrawing the IR version until generic versions could launch.