Tromethamine

Tromethamine (THAM / Tris)

1. Identity: Chemical Names, Structure, and Common Forms

Tromethamine, also known as tris(hydroxymethyl)aminomethane, or THAM, is an organic compound with the formula (HOCH₂)₃CNH₂. It is referred to as Tromethamine in the United States Pharmacopeia (USP) and as Trometamol in the European Pharmacopoeia (EP). The compound is also widely known in biochemical research contexts simply as "Tris" or "Tris buffer."

Tromethamine, USP (sometimes called "tris" or "tris buffer") is chemically designated 2-amino-2-(hydroxymethyl)-1,3-propanediol, a solid readily soluble in water, also classified as an organic amine buffer.

Key chemical and physical characteristics include:

• Molecular formula: C₄H₁₁NO₃
• pKa: Tromethamine has a pKa of 7.8, making it an effective buffer in the physiological pH range.
• Structural features: Contains three hydroxyl groups and one primary amine, exhibiting low biological toxicity. The compound is non-hygroscopic, non-volatile, and demonstrates excellent physical and chemical stability in storage.
• Biochemical reactivity: It is extensively used in biochemistry and molecular biology as a component of buffer solutions; it contains a primary amine and thus undergoes reactions associated with typical amines (e.g., condensations with aldehydes), and also complexes with metal ions in solution.

Tromethamine is a widely used pH buffer with applications spanning the chemical, cosmetic, and biopharmaceutical industries.

Common Pharmaceutical Forms and Preparations

Tromethamine is available in several pharmaceutical forms:

• Intravenous (IV) solution (THAM Solution): The 0.3 mol/L preparation of THAM base (pH 10.2), first used clinically for the correction of acidaemia, was replaced in the US in 1977 by a 0.3 mol/L solution titrated with acetic acid to pH 8.6 (THAM acetate).
• Pharmaceutical salt excipient: As an inactive ingredient, tromethamine (C₄H₁₁NO₃) is used in the synthesis of surface-active agents and pharmaceuticals; as an emulsifying agent for cosmetic creams and lotions, mineral oil and paraffin wax emulsions, as a biological buffer, and used as an alkalizer.
• Cosmetic and topical formulation: Tromethamine appears as a pH-adjusting agent in topical formulations, including eye creams, sunscreens, and lipsticks, functioning at typical usage rates as a neutralizer.
• mRNA vaccine excipient: Tromethamine is a commonly used excipient in various approved parenteral medicinal products, including the mRNA COVID-19 vaccines produced by Pfizer/BioNTech and Moderna.

2. Natural Source and Origin

Tromethamine is a fully synthetic organic compound. It does not occur naturally in plants, animals, or microorganisms. Tromethamine has played a significant role in the medical and nutritional fields since its introduction in the mid-20th century, and was originally synthesized for use as a laboratory buffer. It is produced industrially through chemical synthesis and has no botanical, mineral, or animal source. Its classification as a "natural ingredient" in some supplement or cosmetic contexts refers solely to its simple amino-alcohol structure and low mammalian toxicity profile, not to any natural origin.

3. Historical and Traditional Use

Tromethamine has no history of traditional or folk medicine use in any culture or time period, as it is a product of 20th-century synthetic chemistry. Its history is entirely one of modern scientific and pharmaceutical development.

Tromethamine has been widely used in clinical medicine since its introduction in 1959 as an in vivo carbon dioxide buffer. There are over 2,000 references to THAM in MEDLINE from 1966 to 1997, and several hundred articles before 1966.

Historically, tromethamine was embraced as a remedy for metabolic acidosis—a condition where the body produces too much acid or the kidneys are not removing enough acid from the body. Its buffering capacity enabled physicians to stabilize patients with kidney failure, diabetic ketoacidosis, or cardiac arrest, offering a life-saving alternative to sodium bicarbonate, especially when sodium load needed to be minimized.

Currently, sodium bicarbonate and THAM are the only available alkali therapy agents FDA-approved for these indications.

4. Key Constituents and Active Compounds

Tromethamine is itself the sole active constituent; it is a single small-molecule organic compound rather than a complex extract containing multiple phytochemicals. Its activity arises entirely from its own chemical structure. There are no secondary metabolites, alkaloids, terpenes, or flavonoids associated with it.

Primary Structural and Functional Features

• Primary amine group (–NH₂): This is the proton-accepting moiety responsible for buffering activity. The amine accepts a hydrogen ion (H⁺) and becomes protonated (–NH₃⁺), thereby removing the proton from solution.
• Three hydroxymethyl groups (–CH₂OH): These confer high water solubility and modulate the compound's pKa to a value near physiological pH. They also limit membrane permeability to a degree, while a significant fraction of the molecule remains non-ionized at physiological pH and can enter cells.

5. Mechanisms of Action

5.1 Proton Buffering (Non-CO₂-Generating)

When administered intravenously as a 0.3 M solution, tromethamine acts as a proton acceptor and prevents or corrects acidosis by actively binding hydrogen ions (H⁺). It binds not only cations of fixed or metabolic acids, but also hydrogen ions of carbonic acid, thus increasing bicarbonate anion (HCO₃^–).

THAM acts by proton buffering without generating carbon dioxide (CO₂), which may be a problem with bicarbonate therapy. THAM is non-ionic and penetrates cell membranes, reducing acidosis—unlike bicarbonate, which may exacerbate intracellular acidosis.

THAM is sodium-free and does not cause hypernatremia.

5.2 Intracellular Buffering

A significant fraction of tromethamine (30% at pH 7.40) is not ionized and therefore is capable of reaching equilibrium in total body water. This portion may penetrate cells and may neutralize acidic ions of the intracellular fluid. This is a pharmacological distinction from sodium bicarbonate, which is largely confined to the extracellular space.

5.3 Osmotic Diuresis

Tromethamine also acts as an osmotic diuretic, increasing urine flow, urinary pH, and excretion of fixed acids, carbon dioxide, and electrolytes.

5.4 Metabolism and Elimination

Tromethamine is not metabolized appreciably. The drug is rapidly eliminated by the kidney; 75% or more appears in the urine after eight hours. Urinary excretion continues over a period of three days.

5.5 Advantage Over Sodium Bicarbonate in CO₂-Sensitive Situations

Sodium bicarbonate, the most widely used buffer, has limitations including CO₂ generation, risk of hypernatremia, fluid overload, and paradoxical intracellular acidosis that have spurred interest in alternative agents. THAM is a biologically inert amino alcohol with a pKa of 7.8 that buffers hydrogen ions without producing CO₂ and partially penetrates the intracellular space.

THAM is often used in place of sodium bicarbonate because it lacks the carbon-dioxide-producing effects of bicarbonate. THAM is capable of buffering both metabolic and respiratory acids, leading to an increase in extracellular and intracellular pH without carbon dioxide generation.

6. Scientific Evidence by Area of Use

6.1 Metabolic Acidosis (Primary Approved Indication)

THAM Solution (tromethamine injection) is indicated for the prevention and correction of metabolic acidosis. In the following conditions it may help to sustain vital functions and thus provide time for treatment of the primary disease: metabolic acidosis associated with cardiac bypass surgery.

THAM (tromethamine injection, solution) is a parenteral systemic alkalizer and fluid replenisher indicated for the prevention and correction of metabolic acidosis, including metabolic acidosis associated with cardiac bypass surgery, correction of acidity of ACD blood in cardiac bypass surgery, and metabolic acidosis associated with cardiac arrest.

Clinical evidence: Published clinical data on THAM usage is somewhat limited. One study examined 15 patients undergoing major surgical procedures with metabolic acidosis, defined as pH <7.2 or base excess (BE) <–5 mmol/L. All patients had indwelling arterial catheters for blood sampling. After developing metabolic acidosis, patients were given THAM via a central vein in a dose of 1.1 × BE × weight (kg) mL of 0.3 M solution.

A pediatric observational study also reported on THAM in children: the study included 50 children aged 12 months to 16 years with metabolic acidosis after surgery-associated hemorrhage; patients received 3.66% THAM infusion, with dosage calculated as negative standard BE (mmol/L) × kg body weight, not to exceed 1.5 mL/kg body weight every 24 hours.

The safety and effectiveness of THAM Solution in pediatric patients is based on over 30 years' clinical experience documented in the literature and on safety surveillance. THAM Solution has been used to treat severe cases of metabolic acidosis with concurrent respiratory acidosis because it does not raise PCO₂ as bicarbonate does in neonates and infants with respiratory failure.

Comparison with sodium bicarbonate: THAM has not been documented to be clinically more efficacious than bicarbonate. Evidence suggests THAM may be particularly advantageous in patients with limited ventilatory reserve, elevated intracranial pressure, hypernatremia, and severe metabolic or mixed acidosis. A Phase 4 randomized controlled trial at the Mayo Clinic comparing THAM and sodium bicarbonate in cardiac surgery patients is currently registered and underway, indicating the evidence base is still evolving.

Evidence strength: The approval of THAM for metabolic acidosis is primarily based on decades of clinical use, pharmacological characterization, and smaller observational and uncontrolled studies rather than large randomized controlled trials (RCTs). High-quality, adequately powered head-to-head RCTs against sodium bicarbonate in humans remain limited.

6.2 Respiratory Distress Syndrome (RDS) in Neonates and Infants

The initial dose of THAM Solution in neonates with RDS should be based on initial pH and birthweight, amounting to approximately 1 mL per kg for each pH unit below 7.4, with further doses given according to changes in PaO₂, pH, and PCO₂.

Changes in arterial pH (pHa), partial pressure of CO₂, and oxygen in arterial blood following THAM administration have been documented in neonates with infant respiratory distress syndrome.

Evidence strength: Use in neonatal RDS is based on long clinical experience and pharmacokinetic rationale (avoidance of CO₂ load), but controlled trial data specific to this population are sparse and largely older.

6.3 Elevated Intracranial Pressure (ICP) and Traumatic Brain Injury (TBI)

Tromethamine (THAM) is a non-CO₂-generating buffer solution that has been utilized for a variety of clinical applications, including the control of intracranial pressure (ICP). Cerebral lactic acidosis after injury has been linked to edema formation and is postulated to be a major contributor to elevated intracranial pressures. Attenuation of such acidosis via non-CO₂ buffer compounds such as THAM can allow stability in ICP and an overall reduction in pressure.

Systematic review evidence: A systematic review published in Neurocritical Care (2014) examined THAM specifically for ICP control: the goal was to perform a systematic review of the literature on the use of tromethamine (THAM) and its effects on intracranial pressure (ICP) in patients with neurological illness, searching all articles from MEDLINE, BIOSIS, EMBASE, Global Health, HealthStar, Scopus, and the Cochrane Library. Two reviewers independently identified all manuscripts pertaining to the administration of THAM in human patients that recorded effects on ICP. Secondary outcomes of effect on cerebral perfusion pressure, mean arterial pressure, patient outcome, and adverse effects were recorded.

Twelve articles, nine manuscripts, and three meeting proceedings were considered for the review, with all utilizing THAM while documenting ICP in neurosurgical patients. All studies were prospective. Across all studies, there were a total of 488 patients studied, with 263 receiving THAM and 225 serving as controls in a variety of heterogeneous studies. All but one study documented a decrease in ICP with THAM administration, with both bolus and continuous infusions. One study documented a reduction in cerebral perfusion pressure. No significant renal dysfunction, hepatocellular injury, or hypoglycemia were reported. Three prospective randomized control trials displayed trends toward improved outcome in severe traumatic brain injury (TBI) patients with THAM administration.

An earlier randomized clinical trial in TBI reported: this study was based on the hypothesis that following brain trauma, brain tissue acidosis develops which may contribute to prolongation of coma and neurologic deficit. Tromethamine (THAM), a safe and low-toxicity agent which buffers in major part by causing a hypocapnic alkalosis, was selected for trial. Patients admitted with GCS <8 were randomized into one of three arms: control; THAM plus hyperventilation; or hyperventilation alone. Each regimen was maintained for 5 days post-injury. The analysis of 3 and 6 months Glasgow Outcome Scores showed that prophylactic hyperventilation retards recovery, and the use of THAM overcomes the apparent deleterious effects of hyperventilation.

A case-series analysis at a single center further suggested: early administration of THAM for ICP control could potentially lead to the avoidance of other ICP-directed therapies. Prospective studies of early THAM administration are warranted.

Evidence strength: The systematic review identified consistent ICP-lowering effects across prospective studies, but the overall evidence base was graded as limited by study heterogeneity and relatively small sample sizes. Large, adequately powered RCTs specifically powered for neurological outcomes remain lacking.

6.4 Acute Lung Injury / Permissive Hypercapnia

Preclinical evidence consistently suggests that THAM may outperform sodium bicarbonate in settings of impaired ventilation, high ICP, or profound metabolic acidosis, while sodium bicarbonate remains effective in isolated extracellular acidosis with preserved ventilation.

THAM has been described in clinical reports for use in patients with acute lung injury managed with permissive hypercapnia (a strategy that allows CO₂ to rise in order to use lower, less injurious ventilator pressures). The CO₂-sparing property of THAM makes it pharmacologically rational for this application. However, published controlled human trial data for this specific indication remain limited.

Evidence strength: Primarily case reports and small observational series. This constitutes preliminary, low-certainty evidence in humans.

6.5 Cardiac Arrest

By correcting acidosis, THAM Solution has caused the arrested heart to respond to resuscitative efforts after standard methods alone had failed. In these cases, tromethamine was given intraventricularly.

An animal study compared THAM and sodium bicarbonate in cardiac resuscitation: Tris(hydroxymethyl)aminomethane (tromethamine or THAM) has been suggested as an effective substitute for sodium bicarbonate (NaHCO₃) in the treatment of metabolic acidosis accompanying cardiac arrest; a double-blind study compared in 36 dogs the effectiveness of 0.6 M THAM, 0.3 M THAM, and NaHCO₃ to correct metabolic acidosis produced during cardiac fibrillation followed by cardiac compression. Both THAM and NaHCO₃ were equally effective in correcting metabolic acidosis. Initially, 0.6 M THAM produced a more pronounced elevation of blood pH, but this effect was not sustained. It was concluded that adequate ventilation and effective cardiac compression are still the chief criteria on which final outcome depends, and that either THAM or NaHCO₃ can be used with comparatively equivalent effect.

Evidence strength: Animal data demonstrating equivalence with sodium bicarbonate; direct human RCT evidence in cardiac arrest is absent.

6.6 Cystic Fibrosis Airway Disease (Emerging/Investigational)

In cystic fibrosis (CF), loss of CFTR anion channel activity causes airway surface liquid (ASL) pH to become acidic, which impairs airway host defenses. One potential therapeutic approach is to correct the acidic pH in CF airways by aerosolizing bicarbonate and/or nonbicarbonate pH buffers.

Tromethamine (THAM) is a buffer with a long serum half-life used as an IV formulation to treat metabolic acidosis. Researchers found that THAM aerosols increased airway surface liquid pH in vivo for at least 2 hours and enhanced bacterial killing. THAM alkalinizes serum with an effect that persists for 16–48 hours.

Evidence strength: This is early-stage preclinical and proof-of-concept research in pigs and humans, published in 2016. Large-scale clinical trials in CF have not yet been completed. This represents an emerging, investigational area with preliminary (low certainty) evidence.

6.7 Role as a Pharmaceutical Excipient and Salt-Forming Agent

Tromethamine's role as a pharmaceutical salt-former is a significant and well-established area of its use, even though the therapeutic effects belong to the active drug rather than the tromethamine moiety itself.

• Fosfomycin tromethamine: Fosfomycin is available in two oral formulations — fosfomycin tromethamine (a soluble salt with improved bioavailability over fosfomycin), which is synthetically prepared, and fosfomycin calcium. Fosfomycin tromethamine is the preferred formulation for oral administration. The use of tromethamine salt, an alkalizer, delays acid-catalyzed hydrolysis from gastric acid and improves bioavailability. In the US, fosfomycin is only available in an oral tromethamine salt form and approved only for adult female uncomplicated cystitis; the tromethamine acts as a basic buffer protecting fosfomycin from stomach acid degradation.
• Ketorolac tromethamine: Tromethamine serves as the salt counterion in ketorolac tromethamine (Toradol), a widely used injectable and oral NSAID analgesic. In this context, tromethamine improves the solubility and stability of ketorolac in aqueous formulations.
• Carboprost tromethamine (HEMABATE): HEMABATE Sterile Solution, an oxytocic, contains the tromethamine salt of the (15S)-15-methyl analogue of naturally occurring prostaglandin F_2α in a solution suitable for intramuscular injection.
• COVID-19 mRNA vaccines: Tromethamine is a component in certain COVID-19 vaccine formulations and is a commonly used excipient in various approved parenteral medicinal products, including the mRNA COVID-19 vaccines produced by Pfizer/BioNTech and Moderna.

7. Body Systems and Health Areas Associated with Tromethamine

• Acid-base regulation / Renal system: Tromethamine's primary clinical action is direct modulation of systemic and intracellular pH, operating through the kidneys for elimination. It is indicated whenever severe metabolic or mixed acidosis occurs.
• Cardiovascular system: Used during cardiac bypass surgery and cardiac arrest to prevent or correct life-threatening acidosis affecting myocardial function. THAM Solution has been found to be primarily beneficial in correcting metabolic acidosis which may occur during or immediately following cardiac bypass surgical procedures.
• Central nervous system / Neurocritical care: THAM has been utilized for control of intracranial pressure. Cerebral lactic acidosis after injury has been linked to edema formation and is postulated to be a major contributor to elevated intracranial pressures. Attenuation of such acidosis via non-CO₂ buffer compounds such as THAM can allow stability in ICP and an overall reduction in pressure.
• Respiratory system: Used in neonatal respiratory distress and in adult acute lung injury managed with permissive hypercapnia, where CO₂-sparing buffering is pharmacologically advantageous.
• Hematology / Blood banking: Used to reduce acidity in acid-citrate-dextrose (ACD) blood stored for cardiac bypass surgery. It is well known that ACD blood is acidic and becomes more acidic on storage.
• Urinary tract (as fosfomycin salt): Fosfomycin tromethamine is administered orally for uncomplicated urinary tract infections, where tromethamine serves as a bioavailability-enhancing carrier.

8. Dosage Forms and Dosages Reported in Clinical Studies

Note: The following dosages are those reported in authoritative sources and FDA-approved labeling. They reflect use in specific clinical/hospital settings only.

IV Systemic Administration (THAM Solution)

• Standard IV formulation concentration: The 0.3 mol/L (0.3 M) preparation, titrated with acetic acid to pH 8.6 (THAM acetate), is the standard US formulation.
• General dosing formula: A 70-kg patient with a buffer base deficit ("negative base excess") of 5 mEq/L would require 70 × 5 × 1.1 = 385 mL of THAM Solution containing 13.9 g (115 mEq) of tromethamine. The factor of 1.1 accounts for an approximate reduction of 10% in buffering capacity due to the presence of sufficient acetic acid.
• Cardiac bypass surgery: A dose of approximately 9.0 mL/kg (324 mg/kg) has been used in clinical studies with THAM Solution. This is equivalent to a total dose of 630 mL (189 mEq) for a 70-kg patient. A total single dose of 500 mL (150 mEq) is considered adequate for most patients.
• Neonates (RDS): The initial dose should be based on initial pH and birthweight, amounting to approximately 1 mL per kg for each pH unit below 7.4; further doses are given according to changes in PaO₂, pH, and PCO₂.
• Perioperative metabolic acidosis (one observational study): Patients were given THAM via a central vein in a dose of 1.1 × BE × weight (kg) mL of 0.3 M solution.
• Pediatric surgery-associated hemorrhage (observational study): Patients received 3.66% THAM infusion; the dose was calculated as negative standard BE (mmol/L) × kg body weight, and did not exceed 1.5 mL/kg body weight every 24 hours.

Route and Administration Notes

THAM Solution is administered by slow intravenous infusion, by addition to pump-oxygenator ACD blood or other priming fluid, or by injection into the ventricular cavity during cardiac arrest. For infusion by peripheral vein, a large needle should be used in the largest antecubital vein or an indwelling catheter placed in a large vein of an elevated limb to minimize chemical irritation of the alkaline solution during infusion. Catheters are recommended.

Because clinical experience has been limited generally to short-term use, the drug should not be administered for more than a period of one day except in a life-threatening situation.

9. Safety Considerations and Interactions

This section describes factual, source-backed adverse effects and pharmacological interactions associated with tromethamine as documented in regulatory labeling and peer-reviewed literature.

9.1 General Adverse Effects

Generally, side effects have been infrequent. The following specific adverse effects have been documented:

• Respiratory depression: Although the incidence of ventilatory depression is low, it is important to keep in mind that such depression may occur. Respiratory depression may be more likely to occur in patients who have chronic hypoventilation or those who have been treated with drugs which depress respiration.
• Alkalosis: Too rapid administration and/or excessive amounts of tromethamine may cause alkalosis, hypoglycemia, overhydration, or solute overload.
• Hypoglycemia: Transient depression of blood glucose may occur. Hypoglycemia may occur when this product is used in premature and even full-term neonates.
• Local tissue damage / extravasation: Extreme care should be taken to avoid perivascular infiltration. Local tissue damage and subsequent sloughing may occur if extravasation occurs. Chemical phlebitis and venospasm also have been reported.
• Hepatocellular necrosis: Infusion via low-lying umbilical venous catheters has been associated with hepatocellular necrosis. This is a risk specific to neonatal administration via umbilical venous catheters.
• Fluid and electrolyte overload: The intravenous administration of THAM Solution can cause fluid and/or solute overloading resulting in dilution of serum electrolyte concentrations, overhydration, congested states, or pulmonary edema.
• Febrile and injection-site reactions: Reactions which may occur because of the solution or the technique of administration include febrile response, infection at the site of injection, venous thrombosis or phlebitis extending from the site of injection, extravasation, and hypervolemia.

9.2 Contraindications and Special Populations

• Anuria/uremic states: Tromethamine is contraindicated in patients with anuria or uremia, as the drug depends on renal excretion for elimination.
• Renal impairment: This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions may be greater in patients with impaired renal function. Extreme caution is required in patients with renal disease or reduced urinary output because of potential hyperkalemia and the possibility of decreased excretion of tromethamine.
• Respiratory acidosis: In patients with associated respiratory acidosis, tromethamine should be administered with mechanical assistance to ventilation.
• Pregnancy: It is not known whether tromethamine can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Tromethamine should be given to a pregnant woman only if clearly needed.
• Lactation: It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when THAM Solution is administered to a nursing mother.
• Elderly patients: In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions may be greater.
• Carcinogenicity/mutagenicity/fertility: Studies with THAM Solution have not been performed to evaluate carcinogenic potential, mutagenic potential, or effects on fertility.

9.3 Known Drug Interactions

Specific pharmacokinetic drug–drug interactions with tromethamine as a standalone agent are not extensively characterized in the published literature. However, because tromethamine is a systemic alkalizer, it can affect the ionization state and renal elimination of other drugs:

• Quinidine: Alkalinization of the urine (a consequence of THAM administration) reduces the renal clearance of weakly basic drugs such as quinidine.
• Methenamine: Urinary alkalinization reduces the conversion of methenamine to formaldehyde, the active antimicrobial species, thus diminishing its antibacterial efficacy.
• Lithium: Altered urinary pH can affect lithium excretion.
• Stimulant medications: Alkaline urine decreases renal elimination of sympathomimetic amines and certain stimulants.

THAM also carries its own unique side effects, including hyperkalemia, hypoglycemia, ventilatory depression, extravasation risks, and hepatic necrosis in neonates.

9.4 Potential Allergic Concern with Vaccine Formulations

In the context of mRNA COVID-19 vaccine (mRNA-1273) adverse reactions, the involvement of tromethamine/trometamol contained in the vaccine in systemic allergic reactions has been considered plausible, but further studies would be necessary to investigate the role of tromethamine/trometamol in any such reactions. This remains an area requiring further research; no definitive causal link has been established.

10. Regulatory and Pharmacopeial Status

• Tromethamine is the official name in the United States Pharmacopeia (USP) and trometamol is the name used in the European Pharmacopoeia (EP).
• Sodium bicarbonate and THAM are the only available alkali therapy agents FDA-approved for treating metabolic acidosis.
• In medicine, tromethamine is occasionally used as a drug, given in intensive care for its properties as a buffer for the treatment of severe metabolic acidosis in specific circumstances.
• Tromethamine is listed as an inactive (excipient) ingredient by the US FDA when used as a pH-adjusting agent in cosmetics, topical drug formulations, and parenteral preparations. Its GRAS (Generally Recognized As Safe) status for excipient purposes reflects a long history of use and low intrinsic toxicity at the quantities present in finished drug products.

References

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