Intoxicação por diquat / Diquat intoxication

O paraquat e o diquat são herbicidas de contacto do grupo dos bipiridilos, utilizados largamente para controlo de ervas daninhas. A importância deste grupo de herbicidas reside na sua utilização frequente para fins suicidas e pela inexistência de antídoto ou tratamento médico específico. O envenenamento com diquat é muito menos comum que com o paraquat e por isso existem poucos casos descritos na literatura. A dose letal de ambos é sobreponível, contudo o diquat é considerado menos tóxico devido ao menor dano pulmonar. Por outro lado, o diquat tem efeitos tóxicos graves sobre o sistema nervoso central. Por este motivo os sinais de neurotoxicidade pelo diquat são os mais relevantes e incluem sinais de parkinsonismo. O rim é a principal via excretora do diquat e a necrose tubular aguda é a lesão tipicamente identificada. A sobrevida depende de dois fatores: a concentração da substância no plasma e o tempo após a ingestão. O tratamento centra-se em três pontos essenciais: prevenção da absorção, rápida excreção e modificação dos efeitos tecidulares. A hemoperfusão é mais eficaz na clearance do diquat do que a hemodiálise e a sua utilização nas primeiras 12 horas de intoxicação pode reduzir a mortalidade.

Paraquat and diquat are contact herbicides from bipyridyl group, commonly used in weed control. The importance of this herbicide group is due to its frequent use with suicidal purpose and because there is neither an antidote nor a specific treatment. Poisoning with diquat is much less common that with paraquat, so there are few cases published in literature. The lethal dose of both is similar, however diquat is considered less toxic because it causes less lung damage. On the other side, diquat has severe toxic effects on central nervous system and neurotoxic signs are the more relevant, and include Parkinsonism. The kidney is the main excretory pathway of diquat and acute tubular necrosis is typical. Survival depends on two factors: plasma concentration and time of ingestion. Treatment focus in three key points: preventing absorption, rapid excretion and tissue effects. Hemoperfusion is more effective in diquat clearance than haemodialysis and its use in first 12 hours can reduce mortality.

Pharmacokinetics - based comparison among certain enhanced elimination procedures used in treatment of theophylline toxicity

Thirty patients with theophylline overdose were selected to study the pharmacokinetics of theophylline during continuous hemodialysis with and without filtration, charcoal hemoperfusion and intestinal dialysis using multiple-dose activated charcoal [MDAC]. Patients were classified into three equal groups; each comprised 10 patients. Group-1 started the enhanced elimination by continuous hemodialysis with filtration, Group-2 by charcoal hemoperfusion and Group-3 by continuous hemodialysis alone. The extracorporeal procedures in the three groups were initiated 2 hours post-admission and terminated when patient's vomiting had settled where MDAC was started. Serum theophylline concentrations peaked at 2 hours, for both hemofiltration and hemoperfusion groups, which is the time of initiating the extracorporeal procedures. For hemodialysis group, drug concentration peaked at 3 hours [1 hour post-initiating hemodialysis]. Following the peak, serum levels of patients in hemofiltration group showed significant greater decrease compared with patients in either charcoal hemoperfusion or hemodialysis groups. Also, charcoal hemoperfusion produced the same effects compared with hemodialysis alone. With respect to the pharmacokinetic parameters, there was a significant shorter half-life and a greater clearance for theophylline as a result of continuous hemodialysis with filtration [1.27 +/- 0.214 hours and 0.273 +/- 0.046 L/h/kg, respectively] versus charcoal hemoperfusion [1.86 +/- 0.335 hours and 0.186 +/- 0.034 Mg, respectively], continuous hemodialysis [3.73 +/- 1.087 hours and 0.093 +/- 0.031 L/h/kg, respectively] or gastrointestinal dialysis by MDAC [5.58 +/- 1.36 hours and 0.0621 +/- 0.0163 L/h/kg, respectively]. In conclusion, immediate continuous dialysis with filtration is an effective, rapid, and safe treatment of the life-threatening toxicity of theophyiline overdose. In combination with oral activated charcoal, hemofiltration is considered as a realistic and practical alternative to charcoal hemoperfusion