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The cardiotoxicity of tricyclic antidepressants is a well-described phenomenon requiring serious consideration in patients who have taken an overdose. In patients who are at high risk for suicide attempts, selective serotonin reuptake inhibitors (SSRIs) were thought to constitute a safe alternative. However, evidence is accumulating that they, too, possess proarrhythmic properties, which must be reconciled in the setting of an overdose. An 82-year-old woman intentionally ingested citalopram 1.6 g. Several hours after presentation, she developed sinus arrest and junctional bradycardia that resolved after infusion of intravenous sodium bicarbonate solution. Thereafter, she demonstrated no further electrocardiographic abnormalities and was safely transferred to the psychiatry service without the need for a temporary transvenous pacemaker. The dramatic effect of the sodium bicarbonate on the arrhythmia represents a probable event according to the Naranjo probability scale. Intravenous sodium bicarbonate may serve as an effective antidote to SSRI-induced bradyarrhythmias.

It is now becoming common practice to co-administer H2-receptor antagonists and anti-reflux agents in the treatment of reflux oesophagitis. The mechanism by which anti-reflux agents achieve flotation requires a small amount of gastric acid to be present in the stomach. This study investigated whether an anti-reflux agent would remain effective after the decrease in acid secretion produced by a typical clinical dosage regimen of cimetidine (400 mg q.d.s., 7 days). Gastric distribution and residence of a meal and an anti-reflux agent were assessed in 12 normal subjects using gamma scintigraphy. The area under the gastric and fundal emptying curves demonstrated that Liquid Gaviscon (sodium alginate compound) had a significantly greater gastric residence than the meal, both during the control period and after cimetidine pretreatment, and that the majority of the Gaviscon was located in the fundus. The distribution of Gaviscon into the fundus was not affected by cimetidine pretreatment. Cimetidine pre-treatment slightly, but not significantly, increased the time for half the meal and the Gaviscon to empty from the stomach. The results suggest that the mechanism of action of Liquid Gaviscon is not compromised by concurrent H2-antagonist therapy.