Indications
L-Glutamine is indicated for use as a nutritional supplement to address dietary deficiencies or imbalances. Additionally, it is prescribed to reduce acute complications in individuals with sickle cell disease, applicable to both adults and pediatric patients aged 5 years and older.
Pharmacodynamics
As an integral amino acid, L-glutamine plays a vital biochemical role in protein composition and nitrogen metabolism. It is essential in the conversion of glutamic acid to glutamine via the enzyme glutamine synthetase, facilitating assimilation of ammonia from nitrogen fixation into organic compounds. L-glutamine serves as a nitrogen donor for the biosynthesis of various compounds, including amino acids, purines, and pyrimidines, and contributes to enhancing nicotinamide adenine dinucleotide (NAD) redox potential.
Absorption
L-Glutamine is absorbed efficiently through an active transport mechanism. Following a single dose, the time to reach maximum concentration (Tmax) is approximately 30 minutes. The absorption kinetics for multiple dosing regimens have not yet been fully characterized.
Metabolism
The metabolism of exogenously administered L-glutamine is expected to follow the same metabolic pathways as endogenously produced L-glutamine. These pathways involve the formation of glutamate, proteins, nucleotides, and amino acid sugars.
Mechanism of Action
L-Glutamine plays a significant role in maintaining and enhancing the immune function, particularly through its actions in the gastrointestinal tract. It is essential for preserving the integrity of the large intestine by serving as the preferred respiratory fuel for enterocytes, colonocytes, and lymphocytes. During catabolic states, the demand for L-glutamine significantly increases, surpassing the supply provided by skeletal muscle, which is the primary reservoir for this amino acid. Supplementation with L-glutamine under such conditions may help maintain muscle stores and prevent the translocation of Gram-negative bacteria from the large intestine. It supports the maintenance of secretory IgA, crucial for inhibiting bacterial adhesion to mucosal surfaces, and is required for the proliferation of stimulated lymphocytes, as well as the production of interleukin-2 and interferon-gamma. Moreover, L-glutamine enhances phagocytic activity in neutrophils and monocytes and contributes to increased synthesis of glutathione in the intestine, thereby mitigating oxidative stress and supporting mucosal integrity. While the precise mechanism of its immunomodulatory effects is not fully understood, it likely exerts significant impact at the intestinal level, potentially interacting directly with intestinal lymphoid tissue to enhance immune response. Additionally, L-glutamine may improve the redox potential by increasing reduced glutathione levels, which helps reduce oxidative damage in sickle cell patients. This reduction in oxidative stress can decrease chronic hemolysis and vaso-occlusive events.
