Metformin-associated lactic acidosis is a life-threatening condition characterized by an elevation in serum lactate level in patients with metformin exposure. Here we report a case of lactic acidosis due to metformin overdose, who underwent early introduction of intermittent hemodialysis and successful clinical improvement. An adult patient who had treated diabetes was transferred to our emergency center because of metformin overdose 8 hours before. The patient took a total 54.5 g of metformin and 7.5 mg of repaglinide, and lactic acidosis (pH of 7.299 and lactate levels of 10.4 mmol/L) was determined on hospital arrival. Renal dysfunction and hyperkalemia were also determined and we diagnosed the patient as lactic acidosis caused by metformin overuse. After hospital admission, lactate was continuously increased and we decided to introduce intermittent dialysis 6 hours later on admission because we concerned the exacerbation of lactic acidosis caused by metformin overuse. Successful clinical improvement of the patient was observed because of two times of intermittent dialysis. We concluded that early introduction of intermittent dialysis should be considered as one of the treatment options of lactic acidosis caused by metformin overuse.

We herein report on a man in his thirties with delayed neurological sequelae (DNS) associated with carbon monoxide (CO) intoxication. He was found to be in a deep coma state in his room and subsequently transferred to our emergency department. His mental status gradually improved over the next 29 days, however, neuropsychological examinations revealed he had neurocognitive impairments. On day 29, he was found to be in disturbance of consciousness again, and at that time, we diagnosed he had DNS due to CO poisoning. He had been in a deep coma state for 12 weeks, but his symptoms remarkably improved after the sustained immunosuppressive therapy, mainly methylprednisolone and rehabilitation. We had routinely checked up on myelin basic protein (MBP) levels in his cerebrospinal fluid, which showed monotonical improvements. Our presented case suggested that impaired consciousness levels would recover with persistent corticosteroid therapy in a patient with DNS associated with CO poisoning, and MBP would be a useful biomarker, which reflects the severity of demyelination in central nervous systems.

We report a case of a 78-year-old woman who was treated with 1,500 mg of metronidazole after burr hole drainage for a brain abscess caused by headache. About two months after drainage, she was admitted to our hospital with the recurrence of headache, vomiting, muscle weakness, difficulty in retention, and dysarthria. Brain MRI FLAIR showed a high signal in the bilateral dentate nuclei. Based on these findings, metronidazole-induced encephalopathy was diagnosed, and metronidazole was discontinued. Serum concentrations of metronidazole and its metabolite, hydroxymetronidazole, were measured on admission and after discontinuation of the drug (41.5 μg/mL and 15.9 μg/mL, respectively). After discontinuation of the drug, serum concentrations of metronidazole and hydroxymetronidazole decreased rapidly, and symptoms improved. Brain MRI revealed that cerebellar dentate nucleus lesions had disappeared. These results suggest that metronidazole and hydroxymetronidazole may be involved in metronidazole-induced encephalopathy. Serum concentrations of metronidazole and hydroxymetronidazole may or be useful for preventing the onset of encephalopathy or predicting the clinical course of the disease.

Compared to other illegal drugs, there are very few cases in Japan where cocaine is positive in urinary drug screening. We report the detection of cocaine and its metabolites by mass analysis in the urine and serum of patients with cardiopulmonary arrest who tested positive for cocaine in urinary drug screening. Detection of benzoylecgonine and cocaine, or benzoylecgonine and ecgonine methyl ester is desirable for proof of cocaine. Instrumental analysis denied false positives for cocaine, and it was possible to report to the clinician that day that drug addiction might be a factor leading to cardiopulmonary arrest. It is probable that cocaine could be detected because the time from the onset of symptoms to the start of sample processing was within 1 hour. One of the major factors is that the night shift worker on the day was an engineer who could handle analytical instruments in detail about addiction.

An 18-year-old male who abused several over-the-counter (OTC) drugs, mainly diphenhydramine, was admitted to the emergency department. He presented with tachycardia, delirium, tremor, and tonic convulsions. He was treated with diazepam, tracheal intubation, and activated charcoal. His symptoms appeared to be caused by diphenhydramine poisoning. In addition, we suspected that the combined use of diphenhydramine, alcohol, and an anticholinergic agent exacerbated the poisoning symptoms. His symptoms improved with time and he was discharged on day 6.

In recent years, the routes for obtaining drugs and information are becoming more diverse. While OTC drugs are often readily available, we need to be aware that certain types of medication can cause serious symptoms.