Medical Faculty, Ondokuz Mayis University, Department of Pediatrics, Samsun, Turkey
Sir,
Adolescents may turn to suicide as a solution to psychological and environmental problems, and medication overdose is the prominent method in this age group. However, the toxic threshold doses for most drugs and profiles toxic manifestations for paediatric exposures have not been well established [1].
Case
A 16-year-old male adolescent was brought to the emergency room because of drowsiness and confusion. His family members mentioned that he had quarrelled with his girl friend and that he might have ingested (based upon pill counts of empty boxes) phenprobamate 37 tablets (14.8 g), ranitidine 45 tablets (6.75 g), opipramol 10 tablets (5 g), paroxetine 7 tablets (0.14 g), naproxen 10 tablets (5 g), hydroxizine 15 tablets (0.375 g), roxithromycine 10 tablets (3 g), methylprednisolone 10 tablets (0.16 g), chlordiazepoxide 5 tablets (0.025 g) and pipenzolate bromide 5 tablets (0.0125 g) about 2 h before admission.
Physical examination revealed an unconscious patient and superficial respiration (distinguishable with difficulty), a respiration rate of 10 breaths/min, a blood pressure of 80/40 mmHg, a pulse rate of 80 beats/min, a temperature of 36°C, body weight 60 kg and height 167 cm. There was no response to light of his midriatic pupils, no response to verbal and painful stimuli, and no gag reflex. His skin was pale and cold on the extremities and there were no bowel sounds. He was intubated immediately and ventilated in IMV mode, gastric lavage was performed carefully but activated charcoal could not be given as it was not available. His biochemistry and urinalysis were normal on admission. A chest X-ray showed mild bilateral alveolar oedema. Unfortunately, serum levels of drugs could not be determined. Blood pressure, cardiac rhythm and urinary output were monitored immediately. Cardiopulmonary arrest developed during the second hour of admission following bradycardia. Normal heart beat was restored following intravenous adrenaline at a dose of 0.01 mg/kg. While he was ventilated in the first hour, activated charcoal haemoperfusion was started and performed three times for a period of 3 h utilizing a fresh cartridge (haemoperfusion with the Gambro® Adsorba® 150 C) each time and there were 6 h between the periods. After the first haemoperfusion, his level of consciousness and respiration improved. Several days later, he recovered completely and could be discharged on the 5th hospital day.
Comment
Phenprobamate (CAS 673-31-4) is a centrally acting skeletal-muscle relaxant. There are only two studies in the literature concerning the pharmacokinetics of phenprobamate in man [2]. Overdose with phenprobamate produces symptoms similar to those of barbiturate overdose. There may be hypotension, tachycardia, and cardiac arrythmias [3]. It has been reported that two children aged 2 and 2.5 years recovered with conservative management alone following overdose of meprobamate, another carbamate [4]. Electroencephalographic silence may be observed after carbamate intoxication [5]. Although there have been patients that ingested 40 g phenprobamate and responded to therapy, a dose of over 10 g may be lethal [4,5]. The highest dose the present patient had ingested was of phenprobamate. However, his EEG was normal and many of his symptoms could be explained by phenprobamate. Although the patient responded to haemoperfusion and supportive care therapy, we do not know how it modified the pharmacokinetics of these xenobiotics because we could not determine serum levels of these drugs. In conclusion, we think that early haemoperfusion and supportive care in phenprobamate poisoning and polypharmacy ingestion may be life saving in addition to general supportive measures.
Notes
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References