Usage
- L-Glutamine, not L-Glutamate, is prescribed for short bowel syndrome (SBS) in patients receiving specialized nutritional support, particularly when used in conjunction with recombinant human growth hormone. It is also used for sickle cell disease. L-Glutamate itself is not typically prescribed as a medication but is used in some specific clinical situations (e.g., during intubation or surgery) or as part of compounded parenteral nutrition.
- L-Glutamine is classified as a non-essential amino acid, though it becomes conditionally essential during metabolic stress. L-Glutamate is classified as an excitatory neurotransmitter.
- L-Glutamine’s mechanism of action in SBS involves regulating gastrointestinal cell growth, function, and regeneration. In sickle cell disease, it reduces oxidative stress and improves erythrocyte hydration. L-Glutamate’s mechanism of action pertains to its role as a neurotransmitter, mediating excitatory signals in the central nervous system via various glutamate receptors.
Alternate Names
- L-Glutamine: Glutamine, Glutaminol
- L-Glutamate: Glutamic acid, Glutamate, monosodium glutamate (MSG)
- Brand Names (L-Glutamine): Endari, GlutaSolve, NutreStore, SYMPT-X G.I.
How It Works
L-Glutamine:
- Pharmacodynamics: In SBS, glutamine promotes enterocyte proliferation and reduces intestinal permeability. In sickle cell disease, it acts as an antioxidant and improves red blood cell deformability.
- Pharmacokinetics: Orally administered glutamine is absorbed in the small intestine via active transport. It’s metabolized primarily in the small intestine, liver, and kidneys, where it’s converted to glutamate and ammonia. It’s eliminated renally, primarily as urea.
- Mode of Action (SBS): Glutamine serves as a primary energy source for intestinal cells, promoting cell growth and repair.
- Mode of Action (Sickle Cell Disease): Glutamine reduces oxidative stress by increasing the levels of glutathione, an important antioxidant. It also improves erythrocyte hydration by increasing intracellular water content.
L-Glutamate:
- Pharmacodynamics: As a neurotransmitter, L-Glutamate binds to various ionotropic (NMDA, AMPA, kainate) and metabotropic glutamate receptors, mediating excitatory synaptic transmission. Excessive L-Glutamate can lead to excitotoxicity.
- Pharmacokinetics: Glutamate is absorbed from the small intestine via active transport. It’s metabolized in the liver and other tissues, primarily through conversion to glutamine. It’s eliminated primarily by renal excretion.
- Mode of Action: L-Glutamate binds to its receptors, leading to depolarization of postsynaptic neurons and propagation of nerve impulses.
- Receptor Binding: NMDA, AMPA, kainate receptors, mGluRs.
- Elimination Pathways: Primarily renal excretion.
Dosage
Standard Dosage
Adults (L-Glutamine):
- Short Bowel Syndrome: 30 g/day orally divided into six doses (5 g every 2-3 hours while awake) for up to 16 weeks.
- Sickle Cell Disease: >65 kg: 15 g orally twice daily; 30-65 kg: 10 g orally twice daily; <30 kg: 5 g orally twice daily.
Children (L-Glutamine):
- Short Bowel Syndrome: Safety and efficacy not established.
- Sickle Cell Disease: Dosing as described above based on weight. For children under 5, dosing should be determined by a doctor.
Special Cases (L-Glutamine):
- Elderly Patients: No specific dosage adjustment guidelines are available. Caution is advised due to potential age-related decline in renal function.
- Patients with Renal Impairment: Use with caution. Monitor renal function.
- Patients with Hepatic Dysfunction: Use with caution. Monitor liver function.
- Patients with Comorbid Conditions: Use with caution in patients with diabetes, bipolar disorder, seizure disorders, or MSG sensitivity.
Clinical Use Cases (L-Glutamate): Dosages for L-Glutamate in clinical situations like intubation, surgical procedures, or ICU use should be individualized and based on patient needs and clinical context. It’s typically administered intravenously as part of a compounded parenteral nutrition solution.
Dosage Adjustments (L-Glutamine): Dose adjustments should be based on patient tolerance, clinical response, and renal or hepatic function.
Side Effects
Common Side Effects (L-Glutamine):
- Constipation, nausea, headache, abdominal pain, cough, extremity pain, back pain, chest pain.
Rare but Serious Side Effects (L-Glutamine):
- Allergic reactions (rash, itching, swelling).
Long-Term Effects (L-Glutamine): Limited data available.
Contraindications
- L-Glutamine: Severe renal impairment, severe hepatic impairment, hypersensitivity to glutamine, Reye’s syndrome, multi-organ failure.
- L-Glutamate: Hypersensitivity to glutamate.
Drug Interactions
- L-Glutamine: May decrease the efficacy of lactulose.
- L-Glutamate: May interact with amphetamines, decreasing their serum concentrations.
Pregnancy and Breastfeeding
- L-Glutamine: Pregnancy Category C. Use with caution during pregnancy and breastfeeding only if the potential benefit justifies the potential risk to the fetus or infant.
- L-Glutamate: Limited information. Exercise caution.
Drug Profile Summary
(Refer to earlier sections for detailed explanations.)
Popular Combinations
L-Glutamine is often used in combination with growth hormone in SBS.
Precautions
(Refer to the Side Effects and Contraindications sections.)
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for L-Glutamine in SBS?
A: 30 g/day orally divided into six doses (5 g every 2-3 hours while awake) for up to 16 weeks.
Q2: What is the recommended dosage for L-Glutamine in Sickle Cell Disease?
A: Dose depends on weight: >65kg: 15g BID; 30-65kg: 10g BID; <30kg: 5g BID.
Q3: What are the common side effects of L-Glutamine?
A: Constipation, nausea, headache, abdominal pain, cough, extremity pain, and back pain.
Q4: What are the contraindications to L-Glutamine use?
A: Severe renal or hepatic impairment, hypersensitivity to glutamine, Reye’s syndrome, multi-organ failure.
Q5: Does L-Glutamine interact with other medications?
A: It may decrease the effectiveness of lactulose.
Q6: Can L-Glutamine be used during pregnancy and breastfeeding?
A: Pregnancy Category C. Use with caution only if the potential benefit outweighs the potential risk.
Q7: How should L-Glutamine be administered?
A: Orally, dissolved in water or other beverages, with meals or snacks every 2-3 hours.
A: Primarily in the small intestine, liver, and kidneys; converted to glutamate and ammonia.
Q9: What is the role of L-Glutamate in the nervous system?
A: It’s the primary excitatory neurotransmitter in the CNS.
Q10: What is the difference between L-Glutamate and L-Glutamine?
A: While both are amino acids, L-Glutamate acts as a neurotransmitter, whereas L-Glutamine serves as a metabolic fuel and has various clinical uses.
