Pharmacobezoars: the challenges of gastric lavage for a patient with drug overdose

Drug overdose is a common reason for emergency department admissions. Although pharmacobezoars due to drug overdose are rare, they can increase the length of hospital stay and risk of mortality.[1] Currently, no clear procedure for the management of gastric pharmacobezoars exists. We report a case of a patient with pharmacobezoars caused by high-dose oral drug poisoning. The patient recovered completely after gastroscopy, gastric lavage, and symptomatic treatments.

A 16-year-old female with a history of schizophrenia presented to the emergency department by ambulance owing to “ingestion of multiple medications one hour ago.” She had ingested 200 tablets of sodium valproate (40 g), 120 sustained-release capsules of venlafaxine hydrochloride (9 g), and 60 tablets of quetiapine fumarate (6 g). Upon examination, the patient was conscious with no significant neurological symptoms, a blood pressure of 96/57 mmHg (1 mmHg=0.133 kPa), a heart rate of 110 beats/min, a respiratory rate of 16 breaths/min, and an oxygen saturation rate of 96%. Blood gas analysis revealed the following results: pH 7.265, PaCO₂ 70.6 mmHg, PaO₂ 127.06 mmHg (oxygen by oxygen nasal prongs: 41%), K⁺ 4.2 mmol/L, and Lacate 2.6 mmol/L. Blood drug concentrations indicated valproic acid at 265 μg/mL (reference range 50–100 μg/mL), quetiapine at 2.68 μg/mL (reference range <1 μg/mL), and venlafaxine at 0.50 μg/mL (reference range <1.8 μg/mL). Other blood examination results, including those of routine blood, liver and renal function tests, were normal. Chest and abdominal radiography revealed no significant abnormalities. The patient ingested the drugs less than 6 h before arrival. There was no clear contraindication for gastric lavage. Gastric lavage was performed immediately. The patient suddenly developed respiratory weakness and lapsed into a coma, with a blood pressure of 70/28 mmHg, a heart rate of 129 beats/min, a respiratory rate of 11 breaths/min, and an oxygen saturation level of 95%. The patient was in shock. Endotracheal intubation was performed and ventilator support was provided. Laxatives, enemas, continuous renal replacement therapy and hemoperfusion, fluid therapy, and diuresis were immediately administered (Supplementary Figure 1). Owing to the presence of a high number of capsules and medication residue in the stomach after the first gastric lavage, as evident on the abdominal computed tomography (CT) scan (Figure 1 A–C), gastric lavage was repeated on day 1. Subsequent blood test showed the levels of valproic acid at 183 μg/mL, quetiapine at 1.00 μg/mL, and venlafaxine at 2.64 μg/mL. On day 3, she had one epileptiform seizure that resolved with symptomatic treatment. Bedside gastric ultrasonography revealed a large amount of drugs in the stomach (Figure 1D). However, a high amount of drug was still found in the stomach by ultrasonography after the third gastric lavage. Gastroscopy examination revealed pharmacobezoars in the stomach, and most of these were concurrently cleared (Figure 2). On day 4, the blood drug concentration returned to normal, and blood purification was stopped. The patient gradually awakened and was weaned off mechanical ventilation on day 7. On day 8, the patient was discharged. She underwent a follow-up assessment of normal organ function one week later. She had no particular discomfort. Routine blood, liver, kidney, electrolyte, and coagulation tests were normal.

Figure 1.

Abdominal computed tomography images of the drugs in the stomach and intestine (A–C), and gastric ultrasonography of concretions in the stomach (D), STo: stomach; PHa: pharmacobezoar; INt: intestine.

Figure 2.

The pharmacobezoars observed and removed by gastroscopy. A: gastroscopy findings of the pharmacobezoars in the stomach; B: removal of the broken pharmacobezoars with a mesh pouch; C: the removed broken pharmacobezoars; D: the stomach after the pharmacobezoars was removed.

Herein, we describe a case of drug overdose resulting in gastric pharmacobezoars. The patient underwent treatments, including gastric lavage, endoscopic removal of pharmacobezoars, and blood purification, and achieved complete recovery. Until now, there has been no clear procedure for managing gastric pharmacobezoars in patients with drug overdoses.[2]

A gastric bezoar is caused by the accumulation of foreign bodies in the stomach. The main types are phytobezoars (vegetable matter), trichobezoars (hair), and pharmacobezoars (ingested drugs). Pharmacobezoars are drug-based concretions that form and persist in the gastrointestinal tract.[3] They can be formed from various oral drug formulations, especially after the overdose of extended-release tablets or capsules.[4] Several factors may have contributed to the pharmacobezoar formation in our patient, including massive tablet ingestion and the characteristics of the sustained-release formulation (Supplementary Table 1). The reduced surface area of these hard drug masses led to a prolonged dissolution time and delayed attainment of the maximum drug absorption concentration. In such cases, the active substances of drugs or toxins may be released slowly, causing persistent or recurrent poisoning.[5]

Gastric lavage is one of the most important treatments for the removal of unabsorbed toxins from the gastrointestinal tract.[6,7] However, the timing and significance of this procedure remain controversial, and it is also associated with many complications, including aspiration pneumonia, laryngeal spasm, arrhythmia, and perforation of the esophagus and stomach.[8] Alternative gastric decontamination methods should be considered. Several studies have shown that using a particular gastric lavage solution, such as paraffin oil or cola, may yield better results for a specific poison.[9,10] The modified gastric lavage procedures may improve the effect or reduce the risk of gastric lavage. Some previous study has suggested that modified gastric lavage may be beneficial for patients with gastric poisoning.[11] Moreover, gastric lavage guided by ultrasound or combined with gastroscopy, are of great value for evaluating gastric poisoning residues and have shown good outcomes.[12,13]

Our case suggests that conventional gastric lavage has limitation for clearing pharmacobezoars, whereas gastroscopy was able to remove the masses completely. However, gastroscopy has potential risks, including gastrointestinal bleeding and gastric ulcers, perforation, and lacerations;[14] therefore, its application should be evaluated.

In conclusion, pharmacobezoars can cause persistent or recurrent poisoning. Conventional gastric lavage has a limited capacity for removing these concretions. Abdominal CT and ultrasonography are important for diagnosing pharmacobezoars, and gastroscopy following gastric lavage should be considered for removal of concretions, especially in patients who have ingested lethal toxins that have no specific antidotes.

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