tromethamine

tromethamine /tro·meth·amine/ (tro-meth´ah-mēn) a proton acceptor used as an alkalizer in the treatment of metabolic acidosis; also used to make buffer solutions.

---

tro·meth·a·mine (tr-mth-mn)

n.

A weakly basic compound used as an alkalizing agent and as a buffer in enzymatic reactions.

---

tromethamine

Tham

Pharmacologic class: Protein substrate

Therapeutic class: Systemic alkalizer

Pregnancy risk category C

Action

Combines with hydrogen ions to form bicarbonate and a buffer, correcting acidosis. Also shows some diuretic activity.

Availability

Injection: 18 g/500 ml

⊘Indications and dosages

➣ Metabolic acidosis associated with cardiac bypass surgery

Adults: 9 ml/kg (0.32 g/kg) by slow I.V. infusion; 500 ml (18 g) is usually adequate. Maximum single dosage is 500 mg/kg infused over at least 1 hour.

➣ Metabolic acidosis associated with cardiac arrest

Adults: 3.6 to 10.8 g by I.V. injection into large peripheral vein if chest isn't open, or 2 to 6 g I.V. directly into ventricular cavity if chest is open. After reversal of cardiac arrest, patient may need additional amounts to control persistent acidosis.

➣ To correct acidity of acid-citrate-dextrose (ACD) blood in cardiac bypass surgery

Adults: 0.5 to 2.5 g added to each 500 ml of ACD blood used for priming pump-oxygenator. Usual dosage is 2 g.

Dosage adjustment

• Elderly patients

Contraindications

• Hypersensitivity to drug
• Anuria
• Uremia

Precautions

Use cautiously in:
• renal disease, severe respiratory disease, respiratory depression
• pregnant patients
• infants.

Administration

☞ Keep intubation equipment nearby in case respiratory depression occurs.
• For metabolic acidosis associated with cardiac bypass surgery, give by slow I.V. infusion through large-bore I.V. catheter into large antecubital vein. Elevate arm after infusion.
• If extravasation occurs, discontinue drug and infiltrate affected area with 1% procaine hydrochloride (containing hyaluronidase).
• Be aware that in cardiac arrest, drug is used with standard resuscitative measures. When giving by direct I.V. injection into open chest, never inject into cardiac muscle.

Route	Onset	Peak	Duration
I.V	Immediate	Immediate	Unknown

Adverse reactions

GU: oliguria

Hepatic: hemorrhagic hepatic necrosis

Metabolic: metabolic alkalosis, transient hypoglycemia, fluid-solute overload, hyperkalemia

Respiratory: respiratory depression

Other: fever; I.V. site infection; extravasation with venous thrombosis or phlebitis, inflammation, necrosis, and sloughing

Interactions

Drug-diagnostic tests. Glucose: decreased level

Potassium: increased level

Patient monitoring

• Maintain continuous cardiac monitoring.
• Monitor arterial blood gas levels. Watch for alkalosis and signs and symptoms of respiratory depression.
• Assess liver function tests. Stay alert for signs and symptoms of hepatic impairment.
• Monitor glucose and potassium levels. Watch for hypoglycemia and hyperkalemia.
• Closely monitor fluid intake and output. Check for fluid and electrolyte imbalances and oliguria related to hyperkalemia.

Patient teaching

• Explain drug therapy to patient. Assure him he'll be monitored continuously.
• As appropriate, review all significant and life-threatening adverse reactions and interactions, especially those related to the tests mentioned above.