Introduction
Sotalol is a non-selective beta blocker with class III antiarrhythmic properties. It is not protein bound and is mostly excreted unchanged in the urine. Both peritoneal dialysis [1] and haemodialysis [2] have been successful in treating Sotalol-induced arrhythmias in the prescence of renal failure. Clearance of Sotalol by continuous venovenous haemofiltration (CVVH) is not described. We report a case of massive Sotalol overdose in which CVVH was successfully used.
Patient
A 53-year-old lady presented following a deliberate overdose of Sotalol tablets. She was admitted to the ITU in multiple organ failure requiring mechanical ventilation, vasopressors and renal replacement therapy. CVVH was commenced 15 hours after the overdose using an exchange of 6000 ml/hour (approximately 70 ml/kg/hour) on a Baxter 'Aquarius' machine. High-flow CVVH was continued for 48 hours before reducing to 3000 ml/hour. CVVH was required for 21 days in total. The patient was discharged home without significant morbidity 2 months after admission.
Methods
Paired plasma and filtrate samples were collected at intervals during the first 24 hours of CVVH. These were analysed for Sotalol concentration using a HPLC assay. Plasma clearance was estimated using the formula C = UV / P, where C = clearance (ml/min), U = filtrate concentration (mg/ml), V = filtrate volume (ml/min) and P = plasma concentration (mg/ml).
Results
See Table 1. Mean clearance = 67.00 ± 6.64 ml/min.
Table 1.
| Time | Plasma concentration | Filtrate concentration | Clearance |
|---|---|---|---|
| 15:30 | 0.0235 | 0.013 | 55.32 |
| 17:30 | 0.0156 | 0.0111 | 71.15 |
| 21:30 | 0.0177 | 0.0121 | 68.36 |
| 01:30 | 0.0142 | 0.0105 | 73.94 |
| 05:30 | 0.0114 | 0.0082 | 71.93 |
| 09:30 | 0.011 | 0.0074 | 67.27 |
| 13:30 | 0.01 | 0.0061 | 61.00 |
Conclusion
Clearance of Sotalol by CVVH is significant and should be considered as an adjunct in cases of Sotalol toxicity and renal insufficiency. CVVH is likely to cause less cardiovascular instability than the previously described methods [1,2] of increasing drug clearance.
Acknowledgements
The authors would like to thank Guy's and St Thomas' Medical Toxicology Unit for their assistance with the Sotalol assay.