[Torsades de pointes caused by cetirizine overdose]. / Torsades de pointes induites par surdosage en cétirizine: à propos d'un cas.

Several therapeutic substances can cause torsades de pointes, especially if they prolong the QT interval and/or if there is an associated hypokalaemia. Certain second generation H1 antihistamines have been incriminated in the occurrence of such ventricular arrhythmias, such as terfenadine and astezimole, which have been withdrawn. Cetirizine, widely used in the treatment of allergic reactions, is a second generation H1 antihistamine with as yet no precautions of use regarding rhythm disturbances. No documented case of arrhythmia attributable to this drug has been reported. We report the case of a dialysed patient with chronic renal failure who had symptomatic episodes of torsades de pointes in the context of hypokalaemia and cetirizine overdose. In the light of this observation it would appear that the prescription of cetirizine is contra-indicated under such conditions.

Long-term follow up of ionic plasma fluoride level in patients receiving hemodialysis treatment.

The elimination half-life of fluoride is significantly increased in patients with chronic renal failure. This led us to conduct a study of variations of its plasma levels in 35 patients receiving dialysis treatment. In this population, there is a gaussian distribution of the values before and after the hemodialysis session, with a significant decrease in the averages. Furthermore, there is a highly significant correlation between fluoride levels before and after the dialysis session (P < 0.00001), and also between the amount of time in hemodialysis (in months) and the average fluoride level before dialysis (r = 0.624; P = 0.008). The presence of a group of patients consuming fluoride waters such as Vichy St-Yorre Water was easily identified by their excessive fluoride levels (above 100 micrograms/l), which could have a tendency to increase the risks of this group.

Hyperkalemia risks in hemodialysed patients consuming fluoride-rich water.

In order to observe the consequences of chronic ingestion of high fluoride-rich water on plasma potassium levels of hemodialysed subjects, we have conducted a retrospective study on 25 patients with chronic renal failure, treated with a substitute method, six of whom (consumers group, group C) were drinkers of a bicarbonate (about 4500 mg/l) and fluoride-rich (9 mg/l) mineral water, the Vichy Saint-Yorre water. With respect to sodium polystyrene sulfonate consumption (n = 17), there was no significant difference between group C and NC (non-consumers group). A significant correlation between plasma fluoride and potassium levels was observed only before dialysis (P < 1 x 10(-7)) but not after dialysis. A group by group analysis revealed that this correlation was linked to group C (P < 5 x 10(-6)), in which kalemia before dialysis was higher than that observed in group NC (P < 0.005). Moreover, it appeared that the higher fluoride levels were, the higher the kalemia was inclined to be. Thus, the risks of hyperkalemia in dialysed patients, who also drink Vichy St-Yorre water or other fluoride-rich waters, are more important, while not forgetting the risk of fluorosis. The mechanisms by which chronically administered fluoride could increase kalemia are also discussed.

Investigation of fluoride elimination during a dialysis session.

We have conducted a study of the elimination kinetics of fluoride ions by a log linear regression analysis of plasma levels obtained during a bicarbonate hemodialysis session, with a dialyzer in polymercaprin for six patients with chronic renal failure. Using plasma fluoride levels of 35 patients studied for 20 months, we have validated these kinetics for hemodialysis with sodium bicarbonate, acetate-free biofiltration, hemodiafiltration with low flow rate and other dialyzers. Our results show that the decrease in plasma fluoride levels is statistically significant only after the first hour, and the fall reaches approximately 30% after a 4 h dialysis session. We propose that post-dialysis measurements of plasma fluoride are now not necessary if levels before dialysis are known.