Gastric bezoar following venlafaxine overdose

Gastric bezoar following venlafaxine overdose

To the Editor:

Venlafaxine (Effexor) is a nonselective inhibitor of serotonin, dopamine, and norepinephrine reuptake (1) marketed for severe major depressive disorder and generalized anxiety disorder. Major recognized side effects in cases of overdose are serotonin syndrome, seizures, sedation, and QRS and QT prolongation (1–3). This case report describes the formation of a tenacious gastric drug bezoar following intentional venlafaxine overdose.

A 47-year-old woman presented to a tertiary care emergency department (ED) with a history of new onset seizures and a depressed level of consciousness. One self-limited seizure was witnessed in the ED. History revealed no recent febrile episodes, medication changes, or confirmed ingestions. Physical exam revealed a woman who was drowsy with otherwise normal vital signs. Laboratory exams showed normal range electrolytes and non-toxic levels of acetaminophen, ASA, ethanol, and normal anion gap and osmol gap. The results of a lumbar puncture were normal. Computed tomography of the head showed no acute changes. An intentional ingestion was suspected.

Following observation in the ED, it was felt that the patient was safe for admission to a general medical floor. Twelve hours later she seized and suffered respiratory arrest after apnea and aspiration. Emergent intubation and admission to the Critical Care Unit (CCU) followed. Her husband later confirmed that he had found numerous empty bottles of sustained release venlafaxine (Effexor SR) at their home, making possible a total ingestion of 15 grams. Upon admission to the CCU, she developed acute respiratory distress syndrome, hemodynamic instability, and acute renal failure requiring continuous renal replacement therapy. Gastric residuals during feeding attempts remained high throughout the first five days of her CCU stay. A gastroscopy was performed. A gelatinous mass of partially dissolved tablets was found coating the entire greater curvature of the stomach. The decision was made to try to remove the bezoar and gastric lavage was performed (4). Repeat gastroscopy showed little to no overall effect. Whole bowel irrigation was also futile (5). Eventually, multiple gastroscopies using basket extraction was needed to clear the bezoar. Unfortunately, complications from cerebrovascular infarcts resulted in persistent vegetative condition, and request for withdrawal of care by family.

Venlafaxine ingestions and related toxicity are usually attributed to seizure activity and serotonin syndrome (1,2,6). Abrupt discontinuation of venlaflaxine has also been related to adverse effects, such as serotonin withdrawal reactions (6,7). However, no reported cases of bezoar formation have been previously described, and delayed toxicity from such bezoars is unknown. The approach to removal of such tenacious bezoars is also unclear.

This patient's massive bezoar formation after venlafaxine overdose is the first reported occurrence of its kind. However, with the gelatinous covering of the sustained release preparation, it is not unreasonable to suggest that this adverse effect of intentional ingestion may occur in future cases. Overdose of sustained release venlafaxine that causes repeated seizures may necessitate direct visualization of the stomach to ensure no bezoar and slow leach of medication is occurring, especially for critical ingestions. Collation of such events is recommended, and could result in Venlafaxine SR being added to the list of toxicologic ingestions that may benefit from early whole bowel irrigation.