Acetazolamide poisoning in a toddler

Acetazolamide ingestion and its sequelae have not been previously reported in children. A 12-month-old girl, weighing 10 kg, developed metabolic acidosis following ingestion of between 500 and 1250 mg of acetazolamide. The maximum base deficit recorded was 11.6. She was treated with sodium bicarbonate and recovered completely. Accidental poisoning should be included in the differential diagnosis of a child presenting with metabolic acidosis.

Chronic acetazolamide intoxication

Severe acidosis associated with acetazolamide therapy is rare. We report the first case in which plasma and whole blood acetazolamide concentrations were measured. A 61 year-old patient receiving oral acetazolamide for treatment of glaucoma presented with a 7 day history of declining mental status. The patient was lethargic and oriented only to name. The respiratory rate was 36 per minute in a Kussmaul pattern with arterial blood gases revealing a pH of 7.23, pO2 68 mmHg, paCO2 14 mmHg and bicarbonate 6 mEq/L. Serum creatinine was 3.1 mg%, Cl 126 mEq/L, and anion gap 15. Urine pH was 6.0. Infection and other causes of acidosis and bicarbonate loss were excluded, and he was discharged with normal mental status and improving acid-base balance 18 days after admission. Acetazolamide concentrations four days after the last dose were 26.38 mcg/ml and 38.84 mcg/ml in serum and whole blood, respectively. The serum half-life was 34 hours, compared to a range of 1.5 to 6 hours in subjects with normal renal function. Monitoring acetazolamide concentrations may be useful in adjusting dosage and preventing toxicity in patients with decreased renal function.

Hemodialyzability of acetazolamide

Because the dialyzability of acetazolamide is not known, we undertook a study to determine the in vivo dialysance of this drug and found it to average 22 ml per minute. The quantity of the drug removed by four hours of dialysis was approximately 30% of the dose administered intravenously one half hour before dialysis. Accordingly, considerable amounts of the drug are removed by dialysis, despite its high intraerythrocytic distribution and plasma protein binding properties. Therefore, hemodialysis may be effective in the management of acetazolamide overdose, particularly when complicated by the presence of renal failure. The dialysance can vary under different dialyzing conditions. An acetazolamide/urea nitrogen extraction ratio of 0.16 established in this study can be used to predict the acetazolamide dialysance in various dialyzing conditions.