Usage
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L-Histidine is an essential amino acid, meaning it is not synthesized by the human body and must be obtained through diet. While L-Histidine hydrochloride itself isn’t typically prescribed as a standalone medication in the traditional sense, it’s used as a component in various solutions, including parenteral nutrition and some infant formulas. It also available as a dietary supplement. L-Histidine plays a role in growth and repair of tissues, and is involved in various metabolic processes.
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Pharmacological Classification: It can be classified as a nutrient replenisher when used in parenteral nutrition.
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Mechanism of Action: L-Histidine is crucial for protein synthesis, and is a precursor to histamine, a neurotransmitter and mediator in immune responses. It is also involved in the formation of carnosine, a dipeptide that acts as a buffer and antioxidant in muscle tissue.
Alternate Names
- L-Histidine hydrochloride monohydrate, L-α-Amino-β-(4-imidazolyl)propionic acidmonohydrochloride.
- Brand names vary depending on the manufacturer and formulation. It is commonly found as a generic supplement.
How It Works
- Pharmacodynamics: L-Histidine, once absorbed, participates in protein synthesis and acts as a precursor to histamine. Histamine plays a role in various physiological processes, including immune response, gastric acid secretion, and neurotransmission. Carnosine, synthesized from L-histidine and beta-alanine, has antioxidant and pH-buffering properties in muscle tissue.
- Pharmacokinetics: The absorption of L-histidine from the gut is efficient. Once absorbed it is metabolized in the body, with some being converted to histamine or carnosine. Elimination primarily occurs through renal excretion.
- Mode of Action: At the cellular level, L-Histidine is incorporated into proteins during translation. Its conversion to histamine is catalyzed by histidine decarboxylase.
- Receptor Binding/Enzyme Inhibition/Neurotransmitter Modulation: Histamine, a metabolite of L-Histidine, acts on histamine receptors (H1, H2, H3, H4), mediating its diverse physiological effects.
- Elimination Pathways: It is primarily excreted in the urine along with other amino acids and nitrogenous waste products.
Dosage
Dosage recommendations for L-Histidine supplementation vary greatly due to differences in product formulations. There is no established standard dosage for L-histidine. It is essential to follow the instructions provided by the manufacturer of the specific product being used. General recommendations:
Standard Dosage
Adults:
- Supplemental doses of up to 4 grams per day have been used in some studies.
Children:
- Pediatric dosing guidelines have not been well-established. Consult a healthcare professional before giving L-Histidine supplements to children.
Special Cases:
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Elderly Patients: Start with a lower dose and increase gradually as needed.
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Patients with Renal Impairment: Dose adjustment may be necessary. Consult a healthcare professional.
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Patients with Hepatic Dysfunction: No specific dosage adjustments are typically recommended.
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Patients with Comorbid Conditions: Exercise caution and consult a healthcare professional.
Clinical Use Cases
The following dosage guidelines pertain to L-histidine as a component of parenteral nutrition and not for standalone L-Histidine supplementation. Dosage recommendations for L-histidine hydrochloride for specific medical situations can differ significantly.
- Intubation, Surgical Procedures, Mechanical Ventilation, ICU Use, Emergency Situations: In these contexts, L-Histidine is typically provided as part of a parenteral nutrition regimen, and its dosage will be determined by the overall nutritional needs of the patient.
Dosage Adjustments
Dosage adjustments should be made under the guidance of a healthcare professional. Considerations include:
- Renal/hepatic function, concurrent medication, overall clinical picture, and the specific formulation being used.
Side Effects
Common Side Effects
- L-Histidine supplementation is generally well-tolerated at recommended doses. Some individuals might experience mild gastrointestinal discomfort.
Rare but Serious Side Effects
- Serious side effects are rare with standard dosages.
Long-Term Effects
- Long-term effects of high doses are unknown and more research is needed.
Adverse Drug Reactions (ADR)
- Rare but potential ADRs may include allergic reactions.
Contraindications
- Folic acid deficiency: L-Histidine can interfere with folic acid metabolism.
- Hypersensitivity to L-Histidine.
Drug Interactions
- Limited information is available on specific drug interactions with L-Histidine. Consult a doctor if taking other medications.
Pregnancy and Breastfeeding
- The safety of supplemental L-Histidine during pregnancy and breastfeeding hasn’t been definitively established. Consult a healthcare professional before use.
Drug Profile Summary
- Mechanism of Action: Essential amino acid; precursor to histamine and carnosine; involved in protein synthesis.
- Side Effects: Generally well-tolerated; potential for mild gastrointestinal discomfort.
- Contraindications: Folic acid deficiency, hypersensitivity.
- Drug Interactions: Limited information available.
- Pregnancy & Breastfeeding: Consult a healthcare professional before use.
- Dosage: Varies widely; up to 4g/day in some studies for adults.
- Monitoring Parameters: Monitor for allergic reactions and gastrointestinal issues.
Popular Combinations
- Not typically used in drug combinations as a primary therapeutic agent.
Precautions
- General Precautions: Consult a healthcare professional before starting L-Histidine supplementation.
- Specific Populations: Caution advised during pregnancy and breastfeeding. Consult with a doctor if you have pre-existing medical conditions or are taking other medications.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for L-Histidine Hydrochloride?
A: There’s no officially established recommended dosage for L-Histidine hydrochloride supplementation. Follow product label instructions and consult a healthcare provider.
Q2: Is L-Histidine safe during pregnancy?
A: The safety of L-Histidine supplementation during pregnancy and breastfeeding is not yet confirmed. Consult a healthcare professional before use.
Q3: What are the signs of L-Histidine deficiency?
A: Deficiency is rare but may manifest as growth retardation in children.
Q4: What foods are rich in L-Histidine?
A: Meat, poultry, fish, dairy products, eggs, and some plant-based proteins like beans and lentils.
Q5: Can L-Histidine help with eczema?
A: Some studies suggest a potential benefit, but more research is needed.
Q6: Does L-Histidine interact with any medications?
A: Drug interactions are not fully understood. It is always advised to check with a physician before starting any supplements alongside medication.
Q7: Can L-Histidine be used in parenteral nutrition?
A: Yes, it is frequently included in parenteral nutrition formulations to ensure adequate protein synthesis.
Q8: Are there any long-term risks associated with L-histidine supplementation?
A: Long-term effects of high-dose supplementation are not well studied.
Q9: What should I do if I experience side effects from L-Histidine?
A: Discontinue use and consult a healthcare professional.
