Tromethamine

Pronunciation: troe-METH-a-meen
Class: Alkalinizing agents

Trade Names

Tham
- Injection, solution 18 g (150 mEq) per 500 mL

Pharmacology

Acts as a proton acceptor and prevents or corrects acidosis by actively binding hydrogen ion. Also acts as an osmotic diuretic, increasing urine flow, urinary pH, and excretion of fixed acids, carbon dioxide, and electrolytes.

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Pharmacokinetics

Elimination

Rapidly eliminated by the kidneys; 75% or more appears in the urine after 8 h. Urinary excretion continues over a period of 3 days.

Indications and Usage

Prevention and treatment of metabolic acidosis, including metabolic acidosis associated with cardiac bypass surgery, cardiac arrest, and neonatal respiratory distress syndrome; correction of acidity of absolute cardiac dullness (ACD) blood in cardiac bypass surgery.

Contraindications

Anuria; uremia; chronic respiratory acidosis and salicylate intoxication (neonates only).

Dosage and Administration

Adults

The following formula is intended as a general guide to estimating the dosage:

Tromethamine solution (mL of 0.3 M) required = body weight (kg) × base deficit (mEq/L) × 1.1

Factor of 1.1 accounts for an approximate reduction of 10% in buffering capacity due to the presence of sufficient acetic acid to lower pH of the 0.3 M solution to approximately 8.6.

Metabolic acidosis associated with cardiac arrest

IV If the chest is open, tromethamine 2 to 6 g (62 to 185 mL of a 0.3 M solution) is injected directly into the ventricular cavity. Do not inject into the cardiac muscle. If the chest is not open, tromethamine 3.6 to 10.8 g (111 to 333 mL of a 0.3 M solution) should be injected immediately into a larger peripheral vein. Additional amounts may be required to control acidosis persisting after cardiac arrest is reversed.

Metabolic acidosis associated with cardiac bypass surgery

IV 9 mL/kg (324 mg/kg) has been used in clinical studies. Total single dose of 500 mL (150 mEq) is considered adequate for most adults. Larger single doses (up to 1,000 mL) may be required in unusually severe cases. Repeated determinations of pH and other clinical observations should be used as a guide to the need for repeat doses. Do not exceed individual doses of 500 mg/kg IV over at least 1 h. Thus, for a 70 kg (154 lb) patient, the dose should not exceed 35 g per hour (1,078 mL of a 0.3 M solution).

Correction of acidity of ACD blood in cardiac bypass surgery

0.5 to 2.5 g (15 to 77 mL of a 0.3 M solution) added to each 500 mL of ACD blood used for priming the pump-oxygenator. Clinical experience indicates that 2 g (62 mL of a 0.3 M solution) added to 500 mL of ACD blood is usually adequate.

Infants and neonates Metabolic acidosis associated with neonatal respiratory distress syndrome

IV Initial dose should be based on initial pH and birth weight amounting to approximately 1 mL per kg for each pH unit below 7.4. Further doses have been given according to changes in PaO 2 , pH, and PCO 2 .

General Advice

  • Administer slowly through the largest antecubital vein available. Do not inject into the cardiac muscle.
  • IV catheters are recommended.
  • Adjust dosage to maintain blood pH in a normal range (7.35 to 7.45). Avoid overtreatment (alkalosis).
  • Limit administration to 1 day, except in life-threatening situations.
  • Some additives may be incompatible. When introducing additives, mix thoroughly and do not store.

Storage/Stability

Store between 68° and 77°F. Protect from freezing.

Drug Interactions

None well documented.

Adverse Reactions

Hepatic

Hepatocellular necrosis with infusions via low-lying umbilical venous catheters.

Local

Chemical phlebitis; infection at injection site; local tissue damage and subsequent sloughing may occur if extravasation occurs; phlebitis extending from site of injection; venospasm.

Metabolic

Transient depression of blood glucose.

Respiratory

Respiratory depression.

Miscellaneous

Febrile response; hypervolemia; venous thrombosis.

Precautions

Monitor

Monitor blood pH, PCO 2 , bicarbonate, glucose, and electrolytes before, during, and after administration. In patients with renal disease or reduced urinary output, monitor potassium.


Pregnancy

Category C .

Lactation

Undetermined.

Children

Hypoglycemia may develop when products are used in premature and even full-term neonates.

Elderly

Use with caution. Because of the risk of reduced renal function, take care in dose selection; renal function monitoring may be useful.

Renal Function

Use with caution in patients with renal disease or reduced urinary output because of potential hyperkalemia and decreased excretion of tromethamine. Monitor ECG and frequently check serum potassium.

Extravasation

Exercise caution to prevent perivascular infiltration. Signs/symptoms may include inflammation, necrosis, and sloughing of tissue. Venospasm and IV thrombosis can be minimized by ensuring that the injection needle is in the largest available vein and that solutions are slowly infused. IV catheters are recommended. If perivascular infiltration occurs, institute appropriate countermeasures.

Fluid/Solute overload

May cause fluid and/or solute overloading, resulting in dilution of serum electrolyte concentrations, overhydration, congested states, or pulmonary edema.

Hypoglycemia

Overdosage in terms of total drug and/or too-rapid administration may cause hypoglycemia of a prolonged duration (several hours).

Respiratory depression

Large doses may depress ventilation as a result of increased blood pH and reduced CO 2 . Adjust dosage to maintain blood pH within a normal range. May be used with mechanical ventilation assistance in patients with concomitant respiratory acidosis.

Overdosage

Symptoms

Alkalosis, hypoglycemia, overhydration, solute overload.

Patient Information

  • Advise patient that medication will be prepared and administered by a health care provider in a hospital setting.

Copyright © 2009 Wolters Kluwer Health.

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