Abstract: SA-PO295
A Case of Phenobarbital Overdose - Managed by High Flux Hemodialysis
Session Information
- Trainee Case Reports - VI
October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Trainee Case Reports
- 1700 Pharmacology (PharmacoKinetics, -Dynamics, -Genomics)
Author
- Chen, Huiwen, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States
Introduction
Intentional and accidental drug overdose result in approximately 10, 000 death per year. While some overdose can be managed with antidote, others might require more invasive care. Although techniques such as charcoal hemoperfusion have gone obsolete, hemodialysis ( HD) has become the new standard to remove drugs that are moderately protein bound but small in size. We present a case of phenobarbital (PB) overdose corrected by HD.
Case Description
A 52 year old female with a history of seizure on PB who was brought to the hospital because of unresponsiveness secondary to an apparent suicide attempt via medication overdose. Ingestions occurred more than 24 hours prior to arrival.
Vitals:T 36.8C, BP 106/82, HR 113, RR 40, Sat: 96% on non-rebreather. GCS< 8 She was breathing spontaneously and pupils were small but reactive to light. She was intubated for airway protection.
Serum chemistry was within normal limits. Urine drug screening was positive for PB, benzodiazepine, and opioids. The rest of the toxicology workup was negative. Urine PB level was 147.9 ug/ml and therapeutic range is between 30 to 40 ug/ml. CT brain did not show cerebral pathology. EEG was consistent with cortical irritability and potential for seizure. Given that there was a national shortage of bicarbonate solution, serum and urine alkalization were not performed. One session of four-hour hemodialysis (HD) was initiated. Initial post-HD PB level was 54.2 ug/ml. Two hour post-HD PB level was 35.6 ug/ml. Patient was able to open her eyes the following day with drug level 43 ug/ml. No further dialysis was required.
Discussion
The therapeutic level of PB for seizure disorder is 30-40 ug/ml. A concentration above 60 ug/ml is considered toxic. The half life of PB in adults is between 50 to 140 hours depends on patients’ age. Although PB is 20-45 percent protein bound, its plasma volume of distribution is large, between 0.6-1.0 L/kg, and the molecular size is only 232 daltons, making elimination of the drug easily with HD. The calculated time for this patient to reach non-toxic level of drug concentration with native renal clearance would be at least 100 hours. However, it took less than 24 hours to reach similar level with the help of HD.
Take home message:
While PB overdose can be treated with supportive care, in patients who are intubated, implementation of HD can effectively reduce the serum drug level and potentially reduce ventilator time.