The Usefulness of Reduced Anion Gap and the Possibility of Pupillary Findings in the Treatment of Acute Bromvalerylurea Intoxication

Abstract

Bromvalerylurea is found as an over-the-counter analgesic and hypnotic drug in Japan and can be purchased at drugstores or over the Internet. Therefore, both acute poisoning due to large doses taken in suicide attempts and chronic poisoning due to continuous use for chronic pain have been observed. We report a case of acute BVU poisoning due to the use of an over-the-counter hypnotic sedative for a suicide attempt.A 34-year-old woman was referred to our ICU with unexplained disturbance of consciousness, respiratory failure, and shock. During ICU management, when her pupil diameter was measured with an automatic pupillometer to confirm her conscious state, the right pupil diameter was larger than the left, but one hour later, the left pupil diameter was larger than the right. The difference between right and left fluctuated with the time of day. After awakening, it was found that the patient had taken 108 tablets of Utt, an over-thecounter hypnotic sedative, and the possibility of acute poisoning by its component, BVU, was raised. Because a blood gas analysis at the time of admission showed metabolic acidosis with anion gap ≤1, a diagnosis of acute BVU poisoning was made. The patient's general condition stabilized, and she was transferred to the psychiatric ward.Symptoms of acute BVU poisoning include impaired consciousness and respiratory and circulatory depression, which may make it impossible to obtain a medical interview. When treating a patient with suspected drug intoxication who is unable to communicate, the clinician needs to include BVU poisoning in the differential when a reduced anion gap is observed. The clinician should also know that BVU poisoning can cause ocular manifestations such as anisocoria. This may lead to early diagnosis and therapeutic intervention.