Amino Acid

Approved (Labeled Uses):

• Nutritional support in infants (including preterm and low‑birth‑weight) and children when enteral feeding is contraindicated or insufficient, as part of total parenteral nutrition (TPN).
• Correction of negative nitrogen balance in adults when oral or enteral nutrition is not feasible.

Clinically Accepted Off‑Label Uses:

• Critically ill adults and children in catabolic states: trauma, burns, sepsis, major surgery, ICU care.
• Patients with malabsorption syndromes (e.g., Crohn’s disease, short bowel syndrome) intolerant of enteral feeding.
• Chronic liver disease (e.g., hepatic encephalopathy): use of BCAA‑enriched amino acid formulations to support protein needs and minimize encephalopathy.
• Chronic renal failure patients on dialysis requiring higher protein needs.

Adults (maintenance and stress states):

• Base protein requirement: 0.8–1.0 g/kg/day (ideal body weight).
• Mild stress: 1.0–1.2 g/kg/day.
• Moderate stress (e.g. postoperative, trauma): 1.2–1.5 g/kg/day.
• Severe stress/burn/injury: 1.5–2.0 g/kg/day, occasionally up to 2.5 g/kg/day in dialysis patients.

Renal Impairment:

• Non‑dialysis chronic renal failure: 0.6–0.8 g/kg/day initially.
• Intermittent hemodialysis: 1.2–1.8 g/kg/day, up to 2.5 g/kg/day in hypercatabolic state.
• Continuous renal replacement therapy: same dosing as above.

Hepatic Impairment:

• Without encephalopathy: 1.0–1.5 g/kg/day.
• With encephalopathy: reduce to 0.6–1.0 g/kg/day using BCAA‑enriched formulations.

Pediatric/Neonatal:

• Extremely low‑birth‑weight infants (<1 kg): start 1.0–1.5 g/kg/day, advance to ~3.5–3.85 g/kg/day as tolerated.
• Term infants (≥1 kg): initiate ~2.5 g/kg/day, goal ~3.0 g/kg/day.
• Infants <1 month: 3.0–4.0 g/kg/day.
• Children 1 month to <1 year: 2.0–3.0 g/kg/day.
• Children 1–11 years: 1.0–2.0 g/kg/day.
• Adolescents (≥11 years): 0.8–1.5 g/kg/day.

Pregnancy Support (2nd/3rd trimester):

• Additional 10–14 g/day of protein via amino acid infusion when oral intake insufficient.

Administration:

• Intravenous infusion only (via central or appropriately selected peripheral line) as part of a combined TPN regimen (amino acids, dextrose, lipids, electrolytes, vitamins, minerals).
• Rate titrated to avoid metabolic complications; infuse gradually over hours.

Dose Adjustments:

• Adjust for renal or hepatic dysfunction, severity of catabolic state, and fluid restriction requirements.
• Monitor electrolytes, fluid balance, nitrogen status, serum ammonia, liver enzymes, and renal function regularly.

Amino acid solutions deliver a mixture of essential and non‑essential amino acids intravenously, providing substrates needed for protein synthesis while decreasing endogenous protein catabolism. This supports nitrogen balance, enhances tissue repair, preserves lean body mass, bolsters immune function, and maintains metabolic reserve during periods like critical illness, surgical recovery, or prolonged fasting when enteral nutrition is not possible.

• Absorption: Delivered directly into the bloodstream; bypasses gastrointestinal tract.
• Distribution: Amino acids rapidly distribute into total body water and intracellular compartments; preferential uptake by liver and muscle.
• Metabolism: Amino acids undergo transamination, deamination, and incorporation into protein or energy pathways; excess nitrogen converted to urea. Minimal involvement of CYP450.
• Excretion: Nitrogenous waste excreted primarily as urea via kidneys; unused amino acids may be excreted intact in urine.
• Onset/Half-Life: Therapeutic effect coincides with continuous infusion; individual amino acid half-lives vary (minutes to hours)—no distinct elimination half-life for the mixture as a whole.

Pregnancy:

• No formal FDA pregnancy category applies. Amino acid injections are considered nutritional support and used when necessary in pregnancy, especially when enteral intake is inadequate. Benefits generally outweigh theoretical risks in malnourished or hypermetabolic pregnant patients.

Lactation:

• Amino acids are expected to be metabolized with minimal secretion into breast milk. No documented adverse effects in breastfed infants when used appropriately. Use with caution if maternal renal or metabolic impairment exists. Adequate maternal nutrition remains essential.

• Primary Class: Nutritional support agent.
• Subclass: Parenteral amino acid solution, used as a core component in total parenteral nutrition.

• Hypersensitivity to any component of the amino acid formulation or excipients used.
• Known inborn errors of amino acid metabolism (e.g., maple syrup urine disease, isovaleric acidemia).
• Severe hepatic coma or anuria without access to specialized renal formulations.
• Severe oliguric renal failure when a renal-specific solution is unavailable.
• Pulmonary edema or uncompensated cardiac insufficiency where fluid load is contra-indicated.

• High-Risk Groups: Neonates (especially preterm), elderly, patients with hepatic or renal dysfunction, fluid-restricted individuals, or those with cardiac compromise.
• Major Risks: Fluid overload, electrolyte imbalance, metabolic acidosis, hyperammonemia (in hepatic dysfunction), aluminum toxicity (notably in preterm infants and renal failure), catheter-related infection or thrombosis.
• Monitoring: Frequent assessments of electrolytes, renal/liver function tests, serum ammonia, acid-base balance, nitrogen balance, glucose, fluid status, weight, and catheter site integrity.
• Early Warning Signs: Mental status changes, sudden edema or weight gain, tachycardia, respiratory distress, nausea/vomiting, signs of infection at infusion site.

Common (often related to infusion rate or electrolyte imbalances):

• Nausea, vomiting.
• Local phlebitis or infusion site irritation.
• Mild electrolyte shifts (e.g. sodium, potassium, chloride).

Serious / Rare:

• Fluid overload, pulmonary edema.
• Metabolic acidosis, hyperammonemia.
• Aluminum toxicity (in premature infants, patients with renal failure).
• Sepsis or bloodstream infection from catheter.
• Hypersensitivity reactions—rare, but may include rash or anaphylaxis.

Onset is usually during or soon after infusion; many effects—especially serious ones—are dose and rate-dependent.

• Interactions primarily within components of TPN (e.g. electrolytes, dextrose, lipid emulsions); compatibility must be verified before mixing.
• Cofactor vitamins (especially B-complex vitamins)—particularly B6, B2, B3—may be required to optimize amino acid metabolism.
• No direct drug–drug interactions via CYP450 enzymes.
• No known interactions with food or alcohol (IV administration).

• No major changes in labeled indications.
• Nutrition guidelines increasingly emphasize tailored protein targets based on stress level and underlying organ dysfunction.
• BCAA‑enriched amino acid solutions are recommended in cases of hepatic encephalopathy when standard formulations may exacerbate ammonia accumulation.
• Emerging practice protocols advocate early initiation of tailored amino acid infusion in surgical recovery, burn care, and sarcopenia, though regulatory labeling remains unchanged.

• Store unopened vials/solutions at 20 °C to 25 °C (room temperature), protecting from extreme heat and direct sunlight.
• Do not freeze; discard if crystallization or cloudiness appears.
• Follow aseptic technique when mixing or admixing.
• Prepared TPN bags: refrigerate at 2 °C to 8 °C until use; use within 24 hours of preparation; discard remaining solution after that period.
• Warm to room temperature before infusion; gently invert or swirl to ensure homogeneity (do not shake vigorously).