Biochemical reagent

Tris(hydroxymethyl)aminomethane hydrochloride is a biochemical reagent that can be utilized in research pertaining to life sciences as an organic compound or biological material.
THAM (trometamol; tris-hydroxymethyl aminomethane) is a biologically inert amino alcohol of low toxicity, which buffers carbon dioxide and acids in vitro and in vivo. At 37 degrees C, the pK (the pH at which the weak conjugate acid or base in the solution is 50% ionised) of THAM is 7.8, making it a more effective buffer than bicarbonate in the physiological range of blood pH. THAM is a proton acceptor with a stoichiometric equivalence of titrating 1 proton per molecule.[1]

In vivo, THAM supplements the buffering capacity of the blood bicarbonate system, accepting a proton, generating bicarbonate and decreasing the partial pressure of carbon dioxide in arterial blood (paCO2). It rapidly distributes through the extracellular space and slowly penetrates the intracellular space, except for erythrocytes and hepatocytes, and it is excreted by the kidney in its protonated form at a rate that slightly exceeds creatinine clearance. Unlike bicarbonate, which requires an open system for carbon dioxide elimination in order to exert its buffering effect, THAM is effective in a closed or semiclosed system, and maintains its buffering power in the presence of hypothermia. THAM rapidly restores pH and acid-base regulation in acidaemia caused by carbon dioxide retention or metabolic acid accumulation, which have the potential to impair organ function. Tissue irritation and venous thrombosis at the site of administration occurs with THAM base (pH 10.4) administered through a peripheral or umbilical vein: THAM acetate 0.3 mol/L (pH 8.6) is well tolerated, does not cause tissue or venous irritation and is the only formulation available in the US. In large doses, THAM may induce respiratory depression and hypoglycaemia, which will require ventilatory assistance and glucose administration. The initial loading dose of THAM acetate 0.3 mol/L in the treatment of acidaemia may be estimated as follows: THAM (ml of 0.3 mol/L solution) = lean body-weight (kg) x base deficit (mmol/L). The maximum daily dose is 15 mmol/kg for an adult (3.5L of a 0.3 mol/L solution in a 70kg patient). When disturbances result in severe hypercapnic or metabolic acidaemia, which overwhelms the capacity of normal pH homeostatic mechanisms (pH < or = 7.20), the use of THAM within a 'therapeutic window' is an effective therapy. It may restore the pH of the internal milieu, thus permitting the homeostatic mechanisms of acid-base regulation to assume their normal function. In the treatment of respiratory failure, THAM has been used in conjunction with hypothermia and controlled hypercapnia. Other indications are diabetic or renal acidosis, salicylate or barbiturate intoxication, and increased intracranial pressure associated with cerebral trauma. THAM is also used in cardioplegic solutions, during liver transplantation and for chemolysis of renal calculi. THAM administration must follow established guidelines, along with concurrent monitoring of acid-base status (blood gas analysis), ventilation, and plasma electrolytes and glucose.[1]

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In the controls, the decrease in VT from 6 to 3 ml/kg increased PaCO2 from 6.0±0.5 to 13.8±1.5 kPa and lowered pH from 7.40±0.01 to 7.12±0.06, whereas base excess (BE) remained stable at 2.7±2.3 mEq/L to 3.4±3.2 mEq/L. In the THAM groups, PaCO2 decreased and pH increased above 7.4 during the infusions. After discontinuing the infusions, PaCO2 increased above the corresponding level of the controls (15.2±1.7 kPa and 22.6±3.3 kPa for 1-h and 3-h THAM infusions, respectively). Despite a marked increase in BE (13.8±3.5 and 31.2±2.2 for 1-h and 3-h THAM infusions, respectively), pH became similar to the corresponding levels of the controls. PVR was lower in the THAM groups (at 6 h, 329±77 dyn∙s/m(5) and 255±43 dyn∙s/m(5) in the 1-h and 3-h groups, respectively, compared with 450±141 dyn∙s/m(5) in the controls), as were pulmonary arterial pressures.
Conclusions: The pH in the THAM groups was similar to pH in the controls at 6 h, despite a marked increase in BE. This was due to an increase in PaCO2 after stopping the THAM infusion, possibly by intracellular release of CO2. Pulmonary arterial pressure and PVR were lower in the THAM-treated animals, indicating that THAM may be an option to reduce PVR in acute hypercapnia.[2]

A one-hit injury ARDS model was established by repeated lung lavages in 18 piglets. After ventilation with VT of 6 ml/kg to maintain normocapnia, VT was reduced to 3 ml/kg to induce hypercapnia. Six animals received THAM for 1 h, six for 3 h, and six serving as controls received no THAM. In all, the experiment continued for 6 h. The THAM dosage was calculated to normalize pH and exhibit a lasting effect. Gas exchange, pulmonary, and systemic hemodynamics were tracked. Inflammatory markers were obtained at the end of the experiment.[2]

Absorption, Distribution and Excretion
Tromethamine is substantially eliminated by the kidneys. ... Ionized tromethamine (chiefly as the bicarbonate salt) is rapidly and preferentially excreted in urine at a rate that depends on the infusion rate. The manufacturer states that urinary excretion continues over a period of 3 days; 75% or more appears in the urine after 8 hours. In some studies, 50-75% of an iv dose was recovered in urine within 24 hours, but another study reported recovery in healthy adults to be 64% and 77% after 2 and 3 days, respectively.

It is not known whether tromethamine is distributed in human milk.

Ionized tromethamine is excreted by kidney, so the effect is that of excretion of hydrogen ions. Elimination of drug from body is entirely by renal excretion. Excretion of tromethamine is accompanied by osmotic diuresis, since clinical doses of drug considerably add to osmolarity of glomerular filtrate.

In rats of different age (5 to 240 days old) the renal excretion of Trishydroxymethylaminomethane (THAM) was studied. In 5 and in 240 days old rats the renal excretion of THAM was slower than in rats of other age groups. Stimulation of diuresis by i.p. injection of mannitol, thiazide or by oral water load resulted in an increase in THAM excretion in 5 and in 240 days old rats. The renal excretion of THAM was also increased by repeated administration of THAM in all age groups, except in new born rats. Possible mechanisms of action are discussed. PMID:240333

The distribution of 14C labelled THAM (tris-hydroxymethylaminomethane) was determined between intra- and extracellular space of nephrectomized Sprague-Dawley rats as a function of time at constant plasma pH of 7.4. The following results were obtained: An equilibrium in the distribution of THAM between ECS and ICS will not occur before 6-12 hours after administration. This indicates that THAM permeates very slowly into the intracellular compartment, which is in contrast to the general assumption that it quickly diffuses into the intracellular space to restore the intracellular acidosis. THAM disappears from the extracellular space in a multiexponential fashion, indicating that it equilibrates with the different body tissues at largely variable rates. The equilibrium which occurs between both body compartments 6-12 hours after THAM application does not agree with the values which are expected for transfer of only the nonionised substance. At plasma pH 7.4 and a "mean whole body pHi" of 6.88, THAM is distributed with a distribution ratio of 4 (ICS/ECS), a value quite different from the value of 11 which would be expected for exclusive nonionic diffusion. Thus THAM is also transferred across the cell membrane in ionized form. These results indicate that the influx of THAM into the intracellular space is too slow (when compared to the renal elimination kinetics) to influence intracellular pH significantly by direct buffer action. Moreover, only a fraction of THAM enters the intracellular space in the nonionized form, thus reducing (to an even greater extent) the direct effect of THAM on the intracellular acid-base equilibrium. PMID:6711774

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Metabolism / Metabolites
Tromethamine is not metabolized appreciably.

Human Toxicity Excerpts
/HUMAN EXPOSURE STUDIES/ In studies of tromethamine administration in healthy individuals, the ventilatory rate remained constant, but a reduced tidal volume produced a decrease in minute ventilation and in carbon dioxide output; arterial oxygen saturation decreased by an average of about 5%.

/SIGNS AND SYMPTOMS/ Too rapid administration and/or excessive amounts of tromethamine may cause alkalosis, hypoglycemia, overhydration or solute overload.

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Non-Human Toxicity Excerpts
/LABORATORY ANIMALS: Acute Exposure/ Even after neutralization, large oral doses in lab animals cause weakness, collapse, & coma (without convulsions). Injections of high doses in animals produce hypoglycemia, but concurrent administration of glucose does not prevent death.

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Non-Human Toxicity Values
LD50 Rat iv 2300 mg/kg
LD50 Rat oral 5900 mg/kg
LD50 Mouse iv 3500 mg/kg

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Environmental Fate / Exposure Summary
Tromethamine's production and use as an emulsifying agent, in the synthesis of surface-active agents and vulcanization accelerators may result in its release to the environment through various waste streams. If released to air, an estimated vapor pressure of 2.2X10-5 mm Hg at 25 °C indicates that tromethamine is expected to exist in both the vapor and particulate phase in the ambient atmosphere. Vapor-phase tromethamine is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 11hours. Particulate-phase tromethamine is removed from the atmosphere by wet and dry deposition. Tromethamine does not contain chromophores that absorb at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight. If released to soil, an estimated Koc value of 1 indicates that tromethamine is expected to possess very high mobility in soil. The pKa of tromethamine is 8.07. Thus, this compound will partially exist in cation form in the environment and cations generally adsorb to organic carbon and clay more strongly than their neutral counterparts. As a result, tromethamine may have greater adsorption and less mobility than its estimated Koc value indicates. Volatilization from moist soil is not expected since cations do not volatilize and the estimated Henry's Law constant for the neutral species (free base) of tromethamine is 8.7X10-13 atm cu m/mol. Tromethamine is not expected to volatilize from dry soil surfaces based upon its estimated vapor pressure. Tromethamine yielded no oxygen uptake when incubated with pure cultures of different strains of bacteria, indicating biodegradation may be slow in the environment. If released to water, tromethamine is not expected to adsorb to suspended solids and sediment based upon the estimated Koc. However, based on the pKa of 8.07, it should exist partially as a cation under environmental conditions (pH 5-9). As a result, tromethamine may have greater adsorption to suspended to solids and sediment than its estimated Koc value indicates. Volatilization from water surfaces will not be an important fate process since cations do not volatilize and given the estimated Henry's Law constant for the neutral species. An estimated BCF of 3 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions. Occupational exposure to tromethamine may occur through inhalation and dermal contact with this compound at workplaces where tromethamine is produced or used. (SRC)

[1]. Guidelines for the treatment of acidaemia with THAM. Drugs. 1998 Feb;55(2):191-224.

[2]. THAM reduces CO2-associated increase in pulmonary vascular resistance - an experimental study in lung-injured piglets. Crit Care. 2015 Sep 17;19(1):331.

Low tidal volume (VT) ventilation is recommended in patients with acute respiratory distress syndrome (ARDS). This may increase arterial carbon dioxide tension (PaCO2), decrease pH, and augment pulmonary vascular resistance (PVR). We hypothesized that Tris(hydroxymethyl)aminomethane (THAM), a pure proton acceptor, would dampen these effects, preventing the increase in PVR.[2]

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Mechanism of Action
Tromethamine is an alkalinizing agent which acts as a proton (hydrogen ion) acceptor. Tromethamine is a weak base; following IV injection, it attracts and combines with hydrogen ions and their associated acid anions and the resulting salts are excreted in urine. Tromethamine can combine with lactic, pyruvic, and other metabolic acids and with carbonic acid. ... At pH 7.4, approximately 70% of the tromethamine present in plasma is in the ionized (protonated) form; if pH is decreased from pH 7.4, the ionized fraction of the drug is increased. In contrast to the ionized fraction of tromethamine, which upon administration reacts only with acid in the extracellular fluids, the fraction of the dose which remains un-ionized at physiologic pH is thought to be capable of penetrating the cell membrane to combine with intracellular acid. Since administration of tromethamine reduces hydrogen ion concentration, there is a decrease in proton donor and an increase in proton acceptor concentrations in body buffers. In the bicarbonate:carbonic acid buffer, the concentration of dissolved carbon dioxide is decreased (at least until regulatory mechanisms compensate) and the concentration of bicarbonate is increased. The reduction of carbon dioxide tension removes a potent stimulus to breathing and may result in hypoventilation and hypoxia. McEvoy, G.K. (ed.). American Hospital Formulary Service. AHFS Drug Information. American Society of Health-System Pharmacists, Bethesda, MD. 2007., p. 2647 Hazardous Substances Data Bank (HSDB) Tromethamine ... acts as a weak, osmotic diuretic, increasing the flow of alkaline urine containing increased amounts of electrolytes. McEvoy, G.K. (ed.). American Hospital Formulary Service. AHFS Drug Information. American Society of Health-System Pharmacists, Bethesda, MD. 2007., p. 2647 Hazardous Substances Data Bank (HSDB) By removing protons from hydronium ions, ionization of carbonic acid is shifted so as to decrease pCO2 and to increase bicarbonate. Excess bicarbonate is then gradually excreted in kidney. /Tromethamine is an/ especially useful way to manage excessively high pCO2 in respiratory acidosis...

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Drug Indication
For the prevention and correction of metabolic acidosis.

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Therapeutic Uses
Buffers; Excipients
/Tromethamine is indicated/ for the prevention and correction of metabolic acidosis. /Included in US product label/
Metabolic Acidosis Associated with Cardiac Bypass Surgery. Tromethamine solution has been found to be primarily beneficial in correcting metabolic acidosis which may occur during or immediately following cardiac bypass surgical procedures. /Included in US product label/
Correction of Acidity of ACD Blood in Cardiac Bypass Surgery. It is well known that ACD blood is acidic and becomes more acidic on storage. Tromethamine effectively corrects this acidity. Tromethamine solution may be added directly to the blood used to prime the pump-oxygenator. When ACD blood is brought to a normal pH range the patient is spared an initial acid load. Additional tromethamine may be indicated during cardiac bypass surgery should metabolic acidosis appear. /Included in US product label/

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Drug Warnings Local reactions associated with administration of tromethamine may include local irritation and tissue inflammation or infection at the site of injection, a febrile response, chemical phlebitis, venospasm, hypervolemia, and iv thrombosis. The drug should be administered through a large needle or indwelling catheter to minimize venous irritation by the highly alkaline tromethamine solution. Extravasation may result in inflammation, necrosis, and sloughing of overlying skin. If perivascular infiltration occurs, tromethamine administration should be discontinued immediately. Infiltration of the affected area with 1% procaine hydrochloride, to which hyaluronidase has been added, will often reduce venospasm and also will dilute any tromethamine remaining in the tissues locally. Local infiltration of an alpha-adrenergic blocking agent, such as phentolamine mesylate, into the vasospastic area has been recommended. If necessary, nerve block of autonomic fibers to the affected area may be performed.

Transient decreases in blood glucose concentration may occur during administration of tromethamine. When larger than recommended doses are used or when administration is too rapid, hypoglycemia may persist for several hours after the drug is discontinued.

Tromethamine should be slowly administered and in amounts sufficient only to correct the existing acidosis, in order to avoid overdosage and alkalosis. Determinations of blood glucose concentrations should be frequently performed during and following therapy.

Respiratory depression may occur in patients receiving large doses of tromethamine, as a result of increased blood pH and reduced carbon dioxide concentrations, and in those with chronic hypoventilation or those receiving other drugs that depress respiration. Dosage must be carefully adjusted so that blood pH does not increase above normal, and facilities for providing mechanical ventilation should be readily available during administration of tromethamine. Tromethamine may be used in conjunction with mechanical ventilatory support if respiratory acidosis is present concomitantly with metabolic acidosis.

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Reported Fatal Dose
3. 3= MODERATELY TOXIC: PROBABLY ORAL LETHAL DOSE (HUMAN) 0.5-5 G/KG, BETWEEN 1 OZ & 1 PINT FOR 70 KG PERSON (150 LB).

C4H12CLNO3

157.60

157.05

1185-53-1

77-86-1; 6850-28-8 (acetate)

93573

Typically exists as White to off-white solid at room temperature

1.05 g/mL at 20 °C

357ºC at 760 mmHg

150-152 °C

169.7ºC

5

4

3

9

54

0

Cl[H].O([H])C([H])([H])C(C([H])([H])O[H])(C([H])([H])O[H])N([H])[H]

QKNYBSVHEMOAJP-UHFFFAOYSA-N

InChI=1S/C4H11NO3.ClH/c5-4(1-6,2-7)3-8;/h6-8H,1-3,5H2;1H

2-amino-2-(hydroxymethyl)propane-1,3-diol;hydrochloride

1185-53-1; Tris hydrochloride; Tris(hydroxymethyl)aminomethane hydrochloride; 2-Amino-2-(hydroxymethyl)propane-1,3-diol hydrochloride; Tromethamine hydrochloride; TRIS HCl; Tris-HCl; Trometamol hydrochloride;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO: 250 mg/mL (1586.29 mM)
H2O: 50 mg/mL (317.26 mM)

Solubility in Formulation 1: ≥ 2.08 mg/mL (13.20 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.08 mg/mL (13.20 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.08 mg/mL (13.20 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)