1. Clinical Overview
Amino Acids (NA) refers to a sterile, non-antigenic, hypertonic solution of essential and non-essential crystalline amino acids for intravenous infusion. It is a nitrogen source for protein synthesis and is used for parenteral nutrition in patients unable to meet their nutritional requirements via the enteral route. In the Indian context, these are critical care medicines, often used in hospital settings for patients with severe malnutrition, post-surgical recovery, burns, trauma, or gastrointestinal disorders preventing adequate oral intake.
| Onset | Duration | Bioavailability |
|---|---|---|
| Immediate upon initiation of intravenous infusion. | Duration is dependent on the infusion rate and the metabolic utilization of amino acids; effects persist during and for a short period after the infusion stops, as amino acids are rapidly incorporated into metabolic pathways. | 100% via intravenous administration. |
2. Mechanism of Action
Provides a balanced mixture of essential (cannot be synthesized by the body) and non-essential amino acids. These serve as the fundamental building blocks for the synthesis of structural and functional proteins (e.g., enzymes, hormones, antibodies, albumin). They provide nitrogen for the synthesis of other nitrogenous compounds (e.g., purines, pyrimidines). They can also be used as a substrate for energy production via gluconeogenesis or oxidation in the Krebs cycle, sparing body protein from catabolism.
3. Indications & Uses
- Total Parenteral Nutrition (TPN) in patients with non-functioning gastrointestinal tract (e.g., intestinal obstruction, fistulas, short bowel syndrome)
- Severe protein-calorie malnutrition where enteral nutrition is not possible or insufficient
- Pre-operative and post-operative nutritional support in major surgery
4. Dosage & Administration
Adult Dosage: Individualized based on nitrogen balance, metabolic rate, and clinical condition. Typical range: 0.8 to 1.5 grams of amino acids per kg of body weight per day. For severely catabolic patients, may go up to 2.0 g/kg/day. Infused over 12-24 hours as part of TPN.
Administration: For central venous administration only (preferred). Can be given via large peripheral vein with adequate dilution if central access is not possible, but risk of phlebitis is high. Must be mixed with other TPN components (dextrose, lipids, electrolytes) in a single container (all-in-one or 3-in-1 admixture) or infused separately via a Y-connector. Infusion rate must be controlled by an infusion pump. Do not administer simultaneously with blood products through the same line.
5. Side Effects
Common side effects may include:
- Nausea
- Vomiting
- Fever (pyrogenic reaction)
- Local reactions at injection site: pain, erythema, thrombophlebitis
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Tetracyclines | May complex with calcium in TPN, reducing antibiotic efficacy. Separate administration. | Moderate |
| Warfarin | Amino acid infusion may alter protein binding and vitamin K status, affecting INR. Monitor closely. | Moderate |
| Insulin | Required to manage hyperglycemia from concomitant dextrose infusion. Dose adjustment is mandatory. | High |
| Corticosteroids | Increase protein catabolism and hyperglycemia, counteracting anabolic effect and increasing insulin needs. | Moderate |
7. Patient Counselling
- Do report any pain, redness, or swelling at the infusion site immediately.
- Do inform the healthcare team of any chills, fever, nausea, or headache during the infusion.
- Don't attempt to adjust the infusion pump rate.
- Don't use the IV line for amino acid infusion for any other purpose unless instructed.
8. Toxicology & Storage
Overdose: Symptoms of overdose/too rapid infusion include: nausea, vomiting, fever, chills, headache, hyperglycemia, hyperosmolar state, electrolyte imbalances, metabolic acidosis/alkalosis, hyperammonemia (in susceptible individuals), and pulmonary edema.
Storage: Store at room temperature (not exceeding 25°C). Protect from freezing and direct sunlight. Do not use if the solution is cloudy, contains particulate matter, or if the container is leaking. Once the bag/bottle is spiked for administration, use immediately. Follow manufacturer's instructions for shelf-life after admixing.