Limited efficacy of gastrointestinal decontamination in severe slow-release carbamazepine overdose

Management of acute carbamazepine poisoning: A narrative review

Standard management protocols are lacking and specific antidotes are unavailable for acute carbamazepine (CBZ) poisoning. The objective of this review is to provide currently available information on acute CBZ poisoning, including its management, by describing and summarizing various therapeutic methods for its treatment according to previously published studies. Several treatment methods for CBZ poisoning will be briefly introduced, their advantages and disadvantages will be analyzed and compared, and suggestions for the clinical treatment of CBZ poisoning will be provided. A literature search was performed in various English and Chinese databases. In addition, the reference lists of identified articles were screened for additional relevant studies, including non-indexed reports. Non-peer-reviewed sources were also included. In the present review, 154 articles met the inclusion criteria including case reports, case series, descriptive cohorts, pharmacokinetic studies, and in vitro studies. Data on 67 patients, including 4 fatalities, were reviewed. Based on the summary of cases reported in the included articles, the cure rate of CBZ poisoning after symptomatic treatment was 82% and the efficiency of hemoperfusion was 58.2%. Based on the literature review, CBZ is moderately dialyzable and the recommendation for CBZ poisoning is supportive management and gastric lavage. In severe cases, extracorporeal treatment is recommended, with hemodialysis as the first choice.

Clinical and Forensic Aspects of Pharmacobezoars

BACKGROUND

Pharmacobezoars are specific types of bezoars formed when medicines, such as tablets, suspensions, and/or drug delivery systems, aggregate and may cause death by occluding airways with tenacious material or by eluting drugs resulting in toxic or lethal blood concentrations.

OBJECTIVE

This work aims to fully review the state-of-the-art regarding pathophysiology, diagnosis, treatment, and other relevant clinical and forensic features of pharmacobezoars.

RESULTS

Patients of a wide range of ages and of both sexes present with signs and symptoms of intoxications or more commonly gastrointestinal obstructions. The exact mechanisms of pharmacobezoar formation are unknown but are likely multifactorial. The diagnosis and treatment depend on the gastrointestinal segment affected and should be personalized to the medication and the underlying factor. A good and complete history, physical examination, image tests, upper endoscopy, and surgery through laparotomy of the lower tract are useful for diagnosis and treatment.

CONCLUSION

Pharmacobezoars are rarely seen in clinical and forensic practice. They are related to controlled or immediate-release formulations, liquid, or non-digestible substances, in normal or altered digestive motility/anatomy tract, and in overdoses or therapeutic doses, and should be suspected in the presence of risk factors or patients taking drugs which may form pharmacobezoars.

Extracorporeal treatment for carbamazepine poisoning: systematic review and recommendations from the EXTRIP workgroup

Context. The Extracorporeal Treatments in Poisoning (EXTRIP) workgroup was created to provide evidence and consensus-based recommendations on the use of extracorporeal treatments (ECTRs) in poisoning. Objectives. To perform a systematic review and provide clinical recommendations for ECTR in carbamazepine poisoning. Methods. After a systematic literature search, the subgroup extracted the data and summarized the findings following a pre-determined format. The entire workgroup voted via a two-round modified Delphi method to reach a consensus on voting statements, using a RAND/UCLA Appropriateness Method to quantify disagreement. Anonymous votes were compiled, returned, and discussed in person. A second vote determined the final recommendations. Results. Seventy-four articles met inclusion criteria. Articles included case reports, case series, descriptive cohorts, pharmacokinetic studies, and in-vitro studies; two poor-quality observational studies were identified, yielding a very low quality of evidence for all recommendations. Data on 173 patients, including 6 fatalities, were reviewed. The workgroup concluded that carbamazepine is moderately dialyzable and made the following recommendations: ECTR is suggested in severe carbamazepine poisoning (2D). ECTR is recommended if multiple seizures occur and are refractory to treatment (1D), or if life-threatening dysrhythmias occur (1D). ECTR is suggested if prolonged coma or respiratory depression requiring mechanical ventilation are present (2D) or if significant toxicity persists, particularly when carbamazepine concentrations rise or remain elevated, despite using multiple-dose activated charcoal (MDAC) and supportive measures (2D). ECTR should be continued until clinical improvement is apparent (1D) or the serum carbamazepine concentration is below 10 mg/L (42 the μ in μmol/L looks weird.) (2D). Intermittent hemodialysis is the preferred ECTR (1D), but both intermittent hemoperfusion (1D) or continuous renal replacement therapies (3D) are alternatives if hemodialysis is not available. MDAC therapy should be continued during ECTR (1D). Conclusion. Despite the low quality of the available clinical evidence and the high protein binding capacity of carbamazepine, the workgroup suggested extracorporeal removal in cases of severe carbamazepine poisoning.

Successful treatment of severe carbamazepine toxicity with 5% albumin-enhanced continuous venovenous hemodialysis

Carbamazepine overdose is a common, toxic ingestion, manifesting as central nervous system (CNS) and respiratory depression. Carbamazepine is highly protein bound with a large volume of distribution and, therefore, inefficiently removed by conventional hemodialysis. We describe the successful use of continuous venovenous hemodialysis (CVVHD) with 5% albumin enhanced dialysate in a 31-year-old female who developed CNS depression, hypotension and respiratory failure, requiring mechanical ventilation, after an intentional ingestion of approximately 10 g of extended release carbamazepine, Tegretol CR(®). The peak drug level was 26 mcg/ml, therapeutic range 8-12 mcg/ml, with toxicity often developing a level above 15 mcg/ml. Normal half-life of drug elimination is 35-60 h in carbamazepine naïve patients. In contrast, with albumin-enhanced dialysis, we observed a drug half-life of 18 h. She was extubated on day two and was transferred to inpatient psychiatry by day 3 without significant neurologic sequelae. In vitro studies have been done with bovine blood demonstrating significant carbamazepine removal using CVVHD with albumin-enhanced dialysate. There has been very limited experience using albumin-enhanced CVVHD in an adult patient with carbamazepine toxicity.

Gastrointestinal decontamination in the acutely poisoned patient

Objective

To define the role of gastrointestinal (GI) decontamination of the poisoned patient.

Data Sources

A computer-based PubMed/MEDLINE search of the literature on GI decontamination in the poisoned patient with cross referencing of sources.

Study Selection and Data Extraction

Clinical, animal and in vitro studies were reviewed for clinical relevance to GI decontamination of the poisoned patient.

Data Synthesis

The literature suggests that previously, widely used, aggressive approaches including the use of ipecac syrup, gastric lavage, and cathartics are now rarely recommended. Whole bowel irrigation is still often recommended for slow-release drugs, metals, and patients who "pack" or "stuff" foreign bodies filled with drugs of abuse, but with little quality data to support it. Activated charcoal (AC), single or multiple doses, was also a previous mainstay of GI decontamination, but the utility of AC is now recognized to be limited and more time dependent than previously practiced. These recommendations have resulted in several treatment guidelines that are mostly based on retrospective analysis, animal studies or small case series, and rarely based on randomized clinical trials.

Conclusions

The current literature supports limited use of GI decontamination of the poisoned patient.