Extracorporeal removal of drugs and toxins

5-Hydroxytryptophan toxicity successfully treated by haemodialysis in a dog

OBJECTIVE

To describe a case of 5-hydroxytryptophan (5-HTP) toxicity successfully treated with haemodialysis in a dog.

CASE SUMMARY

A 3-year-old, male neutered Labrador Retriever, weighing 28.2 kg, presented to the emergency department approximately 4-5 h after ingesting a human supplement containing 200 mg of 5-HTP. The amount of 5-HTP ingested was estimated between 980 and 1988 mg (35-71 mg/kg). At presentation, the dog demonstrated progressive neurologic abnormalities consistent with serotonin syndrome, including altered mentation and ataxia. Due to the magnitude of the ingested dose and progression of clinical signs, extracorporeal blood purification with intermittent haemodialysis was chosen to expedite clearance of 5-HTP. High-efficiency haemodialysis was initiated, and the dog showed continued clinical improvement throughout the 5-h treatment. Clinical signs resolved completely within 12 h. Sequential blood and urine samples were obtained to document levels of both 5-HTP and serotonin. The dog was discharged 24 h after presentation with complete resolution of clinical signs.

NEW OR UNIQUE INFORMATION

This is the first report documenting the serial changes in 5-HTP concentrations during treatment with haemodialysis.

Pharmacokinetics of immunosuppressive agents during hemoperfusion in a sheep model

Introduction

Hemoadsorption shows promising signals in organ preservation and post lung transplantation. However, its potential impact on the pharmacokinetics of immunosuppressant drugs (ID) is still unknown.

Methods

In this interventional study, CytoSorb® hemoperfusion was tested in healthy sheep (n = 5) against a sham extracorporeal circuit (n = 3). Seven different ID (tacrolimus (TAC), cyclosporin A (CYA), mycophenolate mofetil (MMF), everolimus (EVER), basiliximab (BAS), methylprednisolone (MP) and prednisolone (PRED)) were administered in clinically relevant doses and combinations. Their levels were measured repeatedly in blood samples from the extracorporeal circulation over 6 h following administration. Population pharmacokinetic modeling analysis (NONMEM® 7.5) was performed.

Results

Negligible clearance was observed for PRED and BAS. For all other substances, a saturable adsorption sub-model with linear decrease of the adsorption effect over the adsorbed amount best described the measured concentrations. The maximum absolute adsorbed amounts (95% CI) for TAC, CYA, MMF, EVER, and MP were 0.040 (0.028-0.053), 1.15 (0.39-1.91), 4.17 (2.00-6.35), 0.0163 (0.007-0.026), and 53.4 mg (20.9-85.9), respectively, indicating an adsorption of less than 5% of the daily administered dosages for all investigated substances.

Discussion

In this large animal model, CytoSorb® hemoperfusion appears to have a limited effect on the clearance of tested ID.

Extracorporeal blood purification in acutely intoxicated veterinary patients: A multicenter retrospective study (2011-2018): 54 cases

OBJECTIVE

To investigate the clinical outcome and complications associated with extracorporeal blood purification (EBP) using either hemodialysis (HD), hemodialysis and hemoperfusion (HD + HP), or therapeutic plasma exchange (TPE) for the management of acute toxin ingestion in small animals.

DESIGN

Retrospective, multicenter study from January 2011 to July 2018.

SETTING

One university teaching hospital and one private specialty hospital.

ANIMALS

Fifty-one dogs and 3 cats with a history of acute toxin exposure that could lead to severe morbidity and mortality, managed with different EBP techniques.

MAIN RESULTS

Nonsteroidal anti-inflammatory drugs (38/54, 52%), baclofen (8/54, 15%), and ethylene glycol (7/54, 13%) were the most common toxicities treated with EBP. Membrane-based TPE was used most commonly (22/54, 40.7%), followed by HD (17/54, 31.5%) and then HD + HP (15/54, 27.8%). There was an 83.3% (45/54) overall survival, with 88.9% (8/9) of nonsurvivors having clinical signs prior to therapy. One third (18/54) of the patients never developed clinical signs of toxicity. Treatment complications occurred in 44.4% (24/54) of the animals, although only 18.5% (10/54) of these complications, such as mild hypotension, thrombocytopenia secondary to the HP cartridge, facial swelling after plasma transfusion for TPE, bleeding from catheter size secondary to heparinization, or clotting of the system, could be attributed to the EBP treatment. None of the nonsurvivors died because of EBP complications.

CONCLUSIONS

Early initiation of EBP therapy might be considered as an alternative route of decontamination in severe acute toxicities with high potential for significant morbidity and mortality. The survival rate in small animals undergoing EBP is high despite exposure to potential lethal doses of toxins, and survival appears to be more likely if clinical signs of toxicity are not present at the time of EBP. Continued research is warranted with randomized controlled clinical trials to further evaluate the clinical efficacy and benefit of EBP.

Management of severe baclofen toxicosis using hemodialysis in conjunction with mechanical ventilation in a cat with chronic kidney disease

Case summary

A 2-year-old castrated male domestic shorthair cat was presented for evaluation of acute and progressive neurologic signs 2-4 h after exposure to baclofen. The suspected ingested dose was 2.1 mg/kg. On admission, the cat was tetraplegic with stuporous mentation, and venous blood gas analysis showed mild hypercapnia (PvCO₂ 43.4 mmHg) raising concern for hypoventilation. Owing to the acute nature of the ingestion, severity of the clinical signs and reported history of chronic kidney disease, hemodialysis was recommended to remove the toxin. A 5 h hemodialysis session was performed using an intermittent platform without hemoperfusion. At the beginning of hemodialysis, worsening hypoventilation and hypercapnia (PvCO₂ 88.6 mmHg) required endotracheal intubation and manual ventilation initially, followed by mechanical ventilation. At the end of the dialysis session, the cat was breathing spontaneously and disconnected from the ventilator. The cat was ambulatory and alert 1 h after the end of dialysis. After an additional 12 h of monitoring, the cat had full return of neurologic function and was discharged from hospital. Serum baclofen concentration measured prior to, during and after hemodialysis showed a 77.7% reduction in baclofen levels immediately after hemodialysis.

Relevance and novel information

This is the first report of baclofen toxicity in a cat successfully treated with hemodialysis and mechanical ventilation simultaneously. Treatment with hemodialysis therapy and mechanical ventilation could be considered in cases of acute baclofen toxicosis to improve outcome and reduce the length of the hospital stay.

Therapeutic nanoreactors for detoxification of xenobiotics: Concepts, challenges and biotechnological trends with special emphasis to organophosphate bioscavenging

The introduction of enzyme nanoreactors in medicine is relatively new. However, this technology has already been experimentally successful in cancer treatments, struggle against toxicity of reactive oxygen species in inflammatory processes, detoxification of drugs and xenobiotics, and correction of metabolic and genetic defects by using encapsulated enzymes, acting in single or cascade reactions. Biomolecules, e.g. enzymes, antibodies, reactive proteins capable of inactivating toxicants in the body are called bioscavengers. In this review, we focus on enzyme-containing nanoreactors for in vivo detoxification of organophosphorous compounds (OP) to be used for prophylaxis and post-exposure treatment of OP poisoning. A particular attention is devoted to bioscavenger-containing injectable nanoreactors operating in the bloodstream. The nanoreactor concept implements single or multiple enzymes and cofactors co-encapsulated in polymeric semi-permeable nanocontainers. Thus, the detoxification processes take place in a confined space containing highly concentrated bioscavengers. The article deals with historical and theoretical backgrounds about enzymatic detoxification of OPs in nanoreactors, nanoreactor polymeric enveloppes, realizations and advantages over other approaches using bioscavengers.

Extracorporeal Therapies in the Emergency Room and Intensive Care Unit

Extracorporeal treatments create opportunity for removing disease causing solutes within blood. Intoxications, renal failure, and immune-mediated diseases may be managed with these treatments, often providing new hope for patients with severe or refractory disease. Understanding solute pharmacokinetics and the limitations of each type of extracorporeal technique can allow for the selection of the optimal treatment modality.

Efficacy of a single session in-series hemoperfusion and hemodialysis in the management of carprofen overdose in two dogs

OBJECTIVE

To describe the efficacy of in-series hemoperfusion and hemodialysis in 2 dogs with carprofen overdose.

CASE SUMMARY

This report describes the treatment of 2 dogs following accidental carprofen overdoses who underwent a single in-series hemoperfusion and hemodialysis session. Serial serum carprofen concentrations were measured before, during, and after the session. The first patient's session lasted 5 hours, with the largest decrease in serum carprofen concentrations occurring during the first hour of treatment. The carprofen clearance during the following 4 hours of treatment decreased substantially compared to the first hour and was not different from the patient's intrinsic clearance of carprofen after the session was completed. Based on the findings from the first case, the second patient was treated with a 1 hour single hemoperfusion and hemodialysis session. Our results support the hypothesis that carprofen is not effectively removed by conventional hemodialysis and the efficacy of hemoperfusion is short lived due to rapid saturation of the charcoal filter. Once filter saturation occurs, the extracorporeal session is no longer efficacious. Using in-series hemoperfusion and hemodialysis is of benefit to correct the side effects seen with hemoperfusion alone, and hourly charcoal filter replacement may extend the efficacy of treatment in removing carprofen.

NEW OR UNIQUE INFORMATION PROVIDED

This is the first published report of in-series hemoperfusion and hemodialysis being used to treat carprofen overdose in a dog. In these 2 cases, the intrinsic clearances of the patients were shown to be equivalent to that of standard hemodialysis alone, indicating that hemodialysis does not produce any advantage in carprofen clearance. In this limited report, we suggest that the efficacy of hemoperfusion in removing carprofen is short-lived, and extending the treatment beyond the first hour does not produce any therapeutic benefit. In order to extend the efficacy of hemoperfusion, hourly replacement of the charcoal filter should be considered.

Experimental model for removal of snake venom via hemoperfusion in rats

OBJECTIVE

To examine the efficiency of hemoperfusion in removing South American rattlesnake (Crotalus durissus terrificus) venom from rats compared with neutralization by antivenom.

DESIGN

An exploratory experimental investigation in rats involving the injection of snake venom with or without subsequent hemoperfusion or antivenom administration.

SETTING

Basic animal research laboratory in a private university.

ANIMALS

Normal, healthy male Wistar rats (0.29-0.40 kg, 3-6 months old) from a commercial breeder.

INTERVENTIONS

Four experimental groups of randomly allocated rats (n = 3/group) were studied: Group 1: rats were injected with a single dose of venom (5 mg/kg, IM, in the right thigh) with no other treatment; blood samples were collected minutes before death to determine leukocyte, platelet, and erythrocyte counts; Group 2 (Control): rats underwent hemoperfusion alone for 60 min using a hemoperfusion cartridge designed for protein adsorption (by granulated charcoal) and protein precipitation (by tannic acid); Group 3 (Venom + antivenom): rats were injected with venom (5 mg/kg, IM) and, 10 min later, were treated with antivenom at the venom:antivenom ratio recommended by the manufacturer; Group 4 (Venom + hemoperfusion): Rats were injected with venom (5 mg/kg, IM) and, 10 min later, were hemoperfused for 60 min. In groups 2-4, blood samples were collected for leukocyte, platelet, and erythrocyte counts 24 h after venom.

MEASUREMENTS AND MAIN RESULTS

Rats injected with venom alone (Group 1) developed signs of neurotoxicity and ataxia and died in 9.0 ± 0.43 h but showed no changes in leukocyte or erythrocyte counts. In contrast, there were no deaths in groups 2-4. The lack of deaths in Groups 3 and 4 indicated that antivenom and hemoperfusion, respectively, protected against the lethal effects of the venom.

CONCLUSIONS

Hemoperfusion with a double-action hemoperfusion cartridge capable of protein adsorption and precipitation protected rats against C. d. terrificus venom.

Clinical Practice Guidelines: An Opinion of the Legal Implication to Veterinary Medicine

The strengthening of the bond between humans and animals has changed the landscape of the veterinary profession. This has, in turn, led the legal system to assess damages in veterinary malpractice and liability cases more carefully, paying attention to the possibility of using clinical practice guidelines (CPGs) to prove whether the defendant veterinarian contravened or not the standard of care. In this era of evidence-based veterinary medicine, CPGs are becoming an integral part of many aspects of veterinary practice, even if CPGs do not have the force of law and are situated halfway between ethical rules and legal requirements. Although guidelines have been used for several years, there seems to be a general lack of recognition of the medical and legal ramifications of CPGs for veterinarians. This creates ambiguity and inconsistency in the care that veterinary practitioners provide, compromises the care animals receive, and prevents the courts from assessing veterinarian competence in a systematic and rational way. On the basis of these considerations, this article discusses the legal implications of CPGs in veterinary medicine for dogs and cats and explores how the law may treat CPGs in the future. Redefining the CPGs should be a priority for veterinary profession. NOTE: The authors chose to use the terms "companion animal," "pet," and "small animal" interchangeably throughout this article, as all three are commonly in use and refer to the same animals (dogs and cats).

Surface-Engineered Blood Adsorption Device for Hyperphosphatemia Treatment

Correspondence: Melanie S. Joy, PharmD, PhD, University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences, Department of Pharmaceutical Sciences, Mail Stop C238, Room V20-4108, 12850 East Montview Blvd, Aurora, CO 80045. Email: Melanie.Joy@ucdenver.edu The research employed surface engineering methods to develop, optimize, and characterize a novel textile-based hemoadsorption device for hyperphosphatemia in hemodialysis-dependent end-stage kidney disease. Phosphate adsorbent fabrics (PAFs) were prepared by thermopressing alumina powders to polyester filtration fabrics and treatment with trimesic acid (TMA). For static experiments, phosphate adsorption capacity in buffer solution, plasma, and blood were evaluated by submersing the PAFs in 100 ml. For dynamic experiments, PAFs were equipped in a device prototype and incorporated in a pump-driven circuit. Phosphates were determined by a colorimetric assay and an Ortho Clinical Diagnostics Vitros 5600 Integrated analyzer. The maximum loading amount of TMA-alumina on PAFs was approximately 35 g/m under 260°C processing temperature. Phosphate adsorption capacity increased with initial concentration. Adsorption isotherms from buffer demonstrated a maximum phosphate adsorption capacity of approximately 893 mg/m at 37.5°C, pH 7.4, with similar results from plasma and whole blood. Measured phosphate concentrations during simulations demonstrated a 42% reduction, confirming the high capacity of the PAFs for removing phosphate from whole blood. Results from the current study indicated that an alumina-TMA treated PAF can dramatically reduce phosphate concentrations from biological samples. The technology could potentially be used as a tunable adsorbent for managing hyperphosphatemia in kidney disease.