Repeat-dose activated charcoal

Haemoperfusion is effective for phenobarbitone (> 100-150 mg/1, but repeat-dose activated charcoal by mouth appears to be as effective, see above) and other barbiturates, ethchlorvynol, glutethimide, meprobamate, methaqualone, theophylline, trichloroethanol derivatives. 

F. Repeat-dose activated charcoal. Repeated doses of activated charcoal (20-30 g or 0.5-1 g/kg every 2-3 hours) are given orally or via gastric tube. The presence of a slurry of activated charcoal throughout several meters of the intestinal lumen reduces blood concentrations by intermpting enterohep-atic or enteroenteric recirculation of the dmg or toxin, a mode of action quite distinct from simple adsorption of ingested but unabsorbed tablets. This technique is easy and noninvasive and has been shown to shorten the half-life of phenobarbital, theophylline, and several other dmgs (Table 1-41). However, it has not been shown in clinical trials to alter patient outcome. Caution Re-peat-dose charcoal may cause serious fluid and electrolyte disturbance secondary to large-volume diarrhea, especially if premixed charcoal-sorbitol suspensions are used. Also, It should not be used in patients with ileus or obstmction. 

TABLE Ml. SOME DRUGS REMOVED BY REPEAT-DOSE ACTIVATED CHARCOAL ... 

Dapsone undergoes enterohepatic recirculation and is mote rapidly eliminated with repeat-dose activate charcoal (see p 57). 

D. Enhanced elimination. Hemodialysis, hemoperfusion, peritoneal dialysis, and repeat-dose activated charcoal are not effective in removing antihistamines. 

Repeat-dose activated charcoal has been shown to decrease the half-life of phenobarbital, but it has not been shown to actually shorten the duration of coma. 

D. Enhanced elimination. Repeat-dose activated charcoal (see p 57) may enhance caffeine elimination. Seriously intoxicated patients (with multiple seizures, significant tachyarrhythmias, or intractable hypotension) may require hemodialysis or charcoal hemoperfusion (see p 55). 

D. Enhanced elimination. Owing to extensive protein binding, dialysis and he-moperfusion are not effective. Repeat-dose activated charcoal has not been evaluated, but may serve as an adjunct to gastrointestinal decontamination after overdose with sustained-release preparations. 

Repeat-dose activated charcoal is effective and may increase clearance by up to 50%. However, it may be difficult to perfonn safely in a patient with obtundation and ileus, and there is no demonstrated benefit on morbidity or mortality. 

Because of its large volume of distribution, digoxin is not effectively removed by dialysis or hemoperfusion. Repeat-dose activated charcoal may be useful in patients with severe renal insufficiency, in whom clearance of digoxin is markedly diminished. 

Repeat-dose activated charcoal or cholestyramine resin may be administered to enhance elimination by interrupting enterohepatic circulation. 

Repeat-dose activated charcoal interrupts enterohepatic recirculation and is very effective, reducing the half-life from 77 to 13.5 hours in one report. Continue charcoal for at least 48-72 hours. Do not use charcoal/sor-bitol suspension (see p 57). 

D. Enhanced elimination. Hemodialysis is not indicated for disulfiram overdose, but it may remove ethanol and acetaldehyde and has been reported to be effective in treating the acute disulfiram-ethanol interaction. This is not iikeiy to be necessary in patients receiving adequate fluid and pressor support. There are no data to support the use of repeat-dose activated charcoal for any of the disulfiram syndromes. 

D. Enhanced elimination. Dialysis and hemoperfusion are not effective. Repeat-dose activated charcoal has not been studied. 

Repeat-dose activated charcoal may trap small quantities of amatoxin undergoing enterohepatic recirculation. 

Repeat-dose activated charcoal therapy may enhance the elimination of meloxicam, oxyphenbutazone, phenylbutazone, and piroxicam. 

D. Enhanced elimination. Enhanced removal methods are generally not effective because of the large volume of distribution of these lipid-soluble compounds. Hexachlorophene is excreted in the bile, and repeat-dose activated charcoal (see p 57) may possibly be effective in increasing its clearance from the gut. 

Repeat-dose activated charcoal therapy effectively reduces the semm salicylate half-life, but it is not as rapidly effective as dialysis, and frequent stooling may contribute to dehydration and electrolyte disturbances. 

D. Enhanced elimination. Symptoms usually abate within several hours and can be managed effectively with intensive supportive care, so there is little to be gained from accelerated drug removal by dialysis or hemoperfusion. The use of repeat-dose activated charcoal has not been studied. 

D. Enhanced elimination. Repeat-dose activated charcoal may enhance fecal elimination by binding thallium secreted into the gut lumen or via the biliary system, interrupting enterohepatic or enteroenteric recirculation. Forced diuresis, dialysis, and hemoperfusion are of no proven benefit. 

D. Enhanced elimination (see p 54). Theophylline hers a small volume of distribution (0.5 L/kg) and is efficientty remov by hemodialysis, charcoal hemop-erfusion, or repeat-dose activated charcoal. 

Repeat-dose activated charcoal. Theoretically, repeated doses of charcoal may enhance clearance by interruption of enterohepatic recirculation, but no controlled data exist to confirm or quantify this benefit. Another benefit is enhanced gastrointestinal decontamination after large or massive ingestion, since single doses of charcoal are inadequate to adsorb all ingested drug. 

D. Enhanced elimination. There is no clinical experience with extracorporeal drug removal for these agents. Terazosin and doxazosin are long-acting and eliminated 60% in feces thus, repeat-dose activated charcoal may enhance their elimination. 

B. Theoretical (unproved) use to stimulate bowel activity in patients with ileus who require repeat-dose activated charcoal or whole-bowel irrigation. 

C. Extracorporeal removal techniques (eg, hemodialysis, hemoperfusion, and repeat-dose activated charcoal see p 54) may enhance the clearance of phenobarbital, possibly requiring supplemental dosing to maintain therapeutic levels. 

B. Extracorporeal removal methods (eg, hemoperfusion and repeat-dose activated charcoal) will enhance phenytoin clearance. Supplemental dosing may be required during such procedures to maintain therapeutic levels. 

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