Intermittent haemodialysis and sustained low-efficiency dialysis (SLED) for acute theophylline toxicity

EDTA salt modified carbon paste electrode for square wave voltammetric determination of theophylline in pharmaceutical tablet formulation

In this study, a square wave voltammetric method for determination of theophylline in tablet formulation based on EDTA salt modified carbon paste electrode is presented. CV, FT-IR, and EIS results confirmed modification of the carbon paste with EDTA salt. In contrast to the unmodified carbon paste electrode, the modified carbon paste electrode showed irreversible oxidation of theophylline with considerable current enhancement. Investigation of the effect of scan rate on the Ip and Ep response of the modified electrode for theophylline revealed predominantly diffusion controlled oxidation kinetics. Under the optimized conditions, square wave oxidative peak current of theophylline in pH 7.0 PBS showed linear dependence on concentration in the range 10–200 μM with determination coefficient (R²), limit of detection, and limit of quantification of 0.99782, 0.0257 μM, and 0.0857 μM, respectively. Detection of an amount of theophylline in the analyzed tablet formulation with 1.85% error from its nominal content (120 mg/tablet) confirmed the accuracy of the developed method. Spike and interference recovery results of 98.59%, and 95.7–100%, respectively validated the applicability of the developed method for determination of theophylline content in tablet samples.

Dialysis and Extracorporeal Therapies for Enhanced Elimination of Toxic Ingestions and Poisoning

Poisoning and toxic ingestions cause significant morbidity and mortality worldwide. Extracorporeal therapies such as dialysis, haemoperfusion and plasma exchange are selectively applied to patients with severe intoxications unresponsive to standard interventions and can be lifesaving. Extracorporeal therapies are a complex but fundamental aspect of the practice of nephrology. Without high-quality evidence to guide implementation, an understanding of toxicokinetics and the physiochemical principles of the enhanced elimination techniques is especially important. This review provides a comphrensive, user-friendly outline of the application of extracorporeal therapy in the poisoned patient.

Extracorporeal Treatment for Gabapentin and Pregabalin Poisoning: Systematic Review and Recommendations From the EXTRIP Workgroup

Toxicity from gabapentin and pregabalin overdose is commonly encountered. Treatment is supportive, and the use of extracorporeal treatments (ECTRs) is controversial. The EXTRIP workgroup conducted systematic reviews of the literature and summarized findings following published methods. Thirty-three articles (30 patient reports and 3 pharmacokinetic studies) met the inclusion criteria. High gabapentinoid extracorporeal clearance (>150mL/min) and short elimination half-life (<5 hours) were reported with hemodialysis. The workgroup assessed gabapentin and pregabalin as "dialyzable" for patients with decreased kidney function (quality of the evidence grade as A and B, respectively). Limited clinical data were available (24 patients with gabapentin toxicity and 7 with pregabalin toxicity received ECTR). Severe toxicity, mortality, and sequelae were rare in cases receiving ECTR and in historical controls receiving standard care alone. No clear clinical benefit from ECTR could be identified although major knowledge gaps were acknowledged, as well as costs and harms of ECTR. The EXTRIP workgroup suggests against performing ECTR in addition to standard care rather than standard care alone (weak recommendation, very low quality of evidence) for gabapentinoid poisoning in patients with normal kidney function. If decreased kidney function and coma requiring mechanical ventilation are present, the workgroup suggests performing ECTR in addition to standard care (weak recommendation, very low quality of evidence).

The use of sustained low efficiency dialysis (SLED) in massive paracetamol overdose

CONTEXT

Massive paracetamol ingestion causing mitochondrial dysfunction is uncommon. Use of sustained low-efficiency dialysis (SLED) to improve acidaemia and enhance paracetamol elimination has not been previously described.

CASE DETAILS

A 44-year-old male presented to the emergency department 2.5 hours post overdose of 200 g (2.5 g/kg) of paracetamol. Examination revealed a BP 85/60 mmHg, pulse 112 bpm, temperature 33.9 °C and blood glucose of 13.9 mmol/l. Venous blood gas 5.5-hours post-ingestion showed a pH 6.9, pCO₂ 58 mmHg, HCO₃ 13 mmol/l and lactate 14 mmol/l. Fifty-grams of nasogastric activated charcoal and double-strength intravenous acetylcysteine were administered. Paracetamol concentration peaked at 4207 µmol/l six hours post-ingestion. SLED was commenced nine-hours post ingestion and acetylcysteine dose was doubled again during dialysis. Paracetamol extraction ratio was 47-52%. Plasma paracetamol clearance was steady throughout SLED (53-58 ml/min). Hepatotoxicity did not develop and the patient recovered.

DISCUSSIONS

Intermittent hemodialysis (IHD) is more efficient than SLED or continuous renal replacement therapy for enhancing paracetamol elimination and clearance. IHD plasma clearance is reported to range from 36 to 215 ml/min compared with endogenous clearance of 224 ml/70 kg/min.

CONCLUSIONS

SLED improved acidaemia with only moderate overall increase in paracetamol plasma clearance. Lack of development of hepatotoxicity was likely the result of early administration of acetylcysteine rather than any effect of SLED on paracetamol elimination.