THAM
Clinical safety rating: caution
Comprehensive clinical and safety monograph for THAM (THAM).
THAM (tromethamine) is a proton acceptor that buffers hydrogen ions, treating metabolic acidosis by increasing blood pH and bicarbonate buffering capacity.
| Metabolism | THAM is not metabolized; it is excreted unchanged primarily by the kidneys. |
| Excretion | Renal: >95% excreted unchanged in urine. Biliary/fecal: negligible (<5%). |
| Half-life | Terminal half-life: 1-2 hours in patients with normal renal function; prolonged up to 6-8 hours in renal impairment. |
| Protein binding | No significant protein binding; effectively 0%. |
| Volume of Distribution | Vd: 0.3-0.4 L/kg; distributes primarily in extracellular fluid. |
| Bioavailability | IV: 100% (only route used). Oral: negligible (not absorbed). |
| Onset of Action | IV: Onset within 5-10 minutes. No other routes clinically relevant. |
| Duration of Action | Duration: 30-60 minutes for buffer effect; clinical effect (pH correction) lasts hours depending on dose and metabolic rate. |
Intravenous administration of 300-500 mL of 0.3 M THAM solution (approximately 1-2 mEq/kg) over 30-60 minutes, repeated as needed based on blood pH and base deficit.
| Dosage form | SOLUTION |
| Renal impairment | Contraindicated in patients with anuria or severe renal impairment (GFR < 30 mL/min) due to risk of hyperkalemia and volume overload. For GFR 30-60 mL/min, reduce dose by 50% and monitor serum electrolytes and pH closely. |
| Liver impairment | No specific Child-Pugh based dose adjustments are established; however, caution is advised in severe hepatic impairment due to potential for electrolyte disturbances and acid-base imbalance. |
| Pediatric use | Intravenous dose of 1-2 mEq/kg (as a 0.3 M solution) administered over 30-60 minutes, repeated based on pH and clinical response. Use with caution in neonates due to risk of hyperosmolality and rapid correction of acidosis. |
| Geriatric use | Use with caution due to age-related decline in renal function; consider lower initial doses and monitor electrolytes, renal function, and fluid status. Dose reduction may be necessary. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for THAM (THAM).
| Breastfeeding | Excretion into breast milk is unknown. Due to potential for severe adverse effects (respiratory depression, alkalosis) in the infant, use with caution only if clearly needed. M/P ratio not available. |
| Teratogenic Risk | There is no adequate data on developmental risks in pregnant women; animal studies have not been conducted. THAM is used in life-threatening metabolic acidosis; risk may be justified compared to potential fetal harm from maternal acidosis. Generally, consider benefit-risk. First trimester: unknown risk, avoid unless necessary. Second and third trimesters: no known teratogenicity, but monitor for electrolyte disturbances in the newborn. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to tromethamine","Anuria or severe oliguria","Uremia (relative contraindication)"]
| Precautions | ["Avoid extravasation due to risk of tissue necrosis and phlebitis","Use with caution in patients with renal impairment or anuria","May cause respiratory depression due to carbon dioxide reduction","Monitor serum electrolytes, especially potassium (hypokalemia risk)","Risk of hyperosmolality with large doses"] |
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| Fetal Monitoring | Monitor maternal acid-base status, electrolytes (potassium, calcium), serum glucose, respiratory rate, and ECG during infusion. Fetal monitoring (heart rate, acid-base status) if indicated by maternal condition. |
| Fertility Effects | No data available on effects on fertility in humans or animals. |