The FDA has issued a warning that the epileptic zonisamide (Zonegran) may cause a metabolic acidosis.
Apparently Zonegran is associated with a drop in serum bicarbonate and hyperchloremia (non-AG). The mechanism is unclear. It is also unclear whether an ABG (or VBG for that matter) was taken to ensure there was true acidemia ( a pet peeve of mine when equating a drop in serum bicarb to a metabolic acidosis).
The FDA warning comes after reviewing the data in 2 studies, one in children and another in adults. In the adult trial the incidence of [HCO3] <20 mEq/L ranged from 21% it pts taking the lowest dose of the medication up to 43% in those on 300 mg/d. However, a persistent serum bicarbonate of <17 mEq/L was <2% across all doses. Younger patients were found to be at an even higher risk than the adults.
It is recommended that patients on Zonegran be monitored and although there was no comment on CKD in particular it would be logical to assume that this may be even more of a consideration in our patient population... albeit, Zonegran is typically contraindicated in patients with CrCl < 50 ml/min.
2 comments:
Any comment on any other renal abnormality? Is this an RTA, as with tenofovir? Any hypophosphatemia or glucosuria?
Unfortunately not, I assume an RTA but unclear type.
The report was too vague.
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