A phenobarbital overdose: a case report

Background: Phenobarbital is a long-acting barbiturate, responsible for many cases of poisoning, from unintentional overdose or attempted suicide. We report a case of phenobarbital overdose in a patient with history of depression. Patients and Methods: A 60 year old woman was admitted to our Internal Medicine Unit for drowsiness, irritability, difficulties in the maintenance of an upright position, dysphasia and weakness. She was suffering from depression and epilepsy and treated with phenobarbital 150 mg/die. Results: At the admittance, she had high fever and neck stiffness; phenobarbital serum levels were 71.2 mcg/ml (3 times u.n.l.); aminotransferases were 12-17u.n.l. Arterial blood pressure was 80/50 mmHg. An inflammatory meningeal process was excluded by lumbar puncture; a brain and spinal cord CT scan excluded spine bone lesions and ischemic stroke. In the suspect of an overdose, a protocol of urine alkalinization was applied resulting in a reduction of phenobarbital levels below the therapeutic range in about 6 days, with state of consciousness, cognitive and behavioral functions improvement. A rapid normalization in aminotransferases levels was noted and serology for hepatitis viruses (HAV, HBV, CMV, EBV, HSV) resulted negative. Conclusions: In our patient phenobarbital was responsible for stupor, hypotension, hypertonicity and aminotransferases elevation, whereas fever was due to a concomitant pulmonary inflammatory process resolved after antibiotic therapy. Despite the use of these drugs has been progressively reduced, the number overdose reports remains still high