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wikitox:enhanced_elimination [2024/04/29 00:15] – kharriswikitox:enhanced_elimination [2025/02/24 21:25] (current) – kharris
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- <font 36px/inherit;;#c12b04;;inherit>Enhanced Elimination</font> +====== Enhanced Elimination ======
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 ===== Overview ===== ===== Overview =====
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 ===== Multi-dose Activated Charcoal ===== ===== Multi-dose Activated Charcoal =====
  
-Multi dose activated charcoal (MDAC) enhances elimination through the interruption of enterohepatic recirculation (binding of drugs excreted into the bile before they are reasorbed further along the GI tract) and gastrointestinal dialysis (where lipid soluble, low molecular weight drugs move from gut capillaries back into the lumen down their concentration gradient and bind to charcoal, which in turn maintains the gradient).+Multi dose activated charcoal (MDAC) enhances elimination through the interruption of enterohepatic recirculation (binding of drugs excreted into the bile before they are reabsorbed further along the GI tract) and gastrointestinal dialysis (where lipid soluble, low molecular weight drugs move from gut capillaries back into the lumen down their concentration gradient and bind to charcoal, which in turn maintains the gradient).
  
 MDAC can be considered for a potentially toxic overdose of a drug with a long half-life but small volume of distribution. Complications include constipation, aspiration, and obstruction. MDAC can be considered for a potentially toxic overdose of a drug with a long half-life but small volume of distribution. Complications include constipation, aspiration, and obstruction.
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 Alkalinisation of the urine increases urinary excretion of weak acids (e.g. salicylates, phenobarbitone). This occurs because the two different forms of the acid have different lipid solubility and therefore are reabsorbed by the renal tubules to a greater or lesser extent. As an acid loses a hydrogen ion it becomes ionised and less lipid soluble (HA equilibrates with H+ and A -). Alkalinisation of the urine, by reducing the concentration of free hydrogen ions, causes more of the acid to dissociate to the ionised form to maintain an equilibrium. As the ionised form has low lipid and high water solubility it remains 'trapped' in the renal tubules and is excreted in the urine. Alkalinisation of the urine increases urinary excretion of weak acids (e.g. salicylates, phenobarbitone). This occurs because the two different forms of the acid have different lipid solubility and therefore are reabsorbed by the renal tubules to a greater or lesser extent. As an acid loses a hydrogen ion it becomes ionised and less lipid soluble (HA equilibrates with H+ and A -). Alkalinisation of the urine, by reducing the concentration of free hydrogen ions, causes more of the acid to dissociate to the ionised form to maintain an equilibrium. As the ionised form has low lipid and high water solubility it remains 'trapped' in the renal tubules and is excreted in the urine.
  
-Drugs amenable to urinary alkalinisation should be weak acids (pKa > 3), undergo substantial renal elimination and result in clinically significant toxicity. Urinary Alkalinisation is used in the management of salicylate and chlorphenoxy herbicide poisoning. \\ +Drugs amenable to urinary alkalinisation should be weak acids (pKa > 3), undergo substantial renal elimination and result in clinically significant toxicity. 
-To alkalinise the urine, give 1 mmol/kg (up to 100mmol) sodium bicarbonate bolus followed by an infusion of 25 mmol/h. Place an indwelling urinary catheter and monitor urinary pH q2h, aiming for a pH > 7.5.+ 
 +Urinary Alkalinisation is used in the management of salicylate and chlorphenoxy herbicide poisoning. 
 + 
 +To alkalinise the urine, give **1 mmol/kg (up to 100mmol) sodium bicarbonate bolus followed by an infusion of 25 mmol/h**. Place an indwelling urinary catheter and monitor urinary pH q2h, aiming for a pH > 7.5.
  
 Complications include hypokalaemia, hypocalcaemia, hypernatraemia and fluid overload. Complications include hypokalaemia, hypocalcaemia, hypernatraemia and fluid overload.