DESCRIPTION
Activated charcoal is a form of carbon processed to be riddled with small, low-volume pores that increase the surface area available for adsorption or chemical reactions.
Due to its high degree of microporosity, just one gram of activated carbon has a surface area in excess of 500 m².
CLASSIFICATION
"Polimer-coated activated carbon" is of medical interest in the treatment of drug overdose. Polimer-coated activated carbon is a process by which a porous carbon can be coated with a biocompatible polymer to give a smooth and permeable coat without blocking the pores. It is used in clinical practice as a haemoperfusion column containing activated charcoal coated with cellulose acetate.
INDICATIONS
Polimer-coated activated carbon is useful for treatment in overdose by one or more drugs, especially barbiturates.
- This is achieved with hemoperfusion, a treatment technique in which large volumes of the patient's blood are passed over an adsorbent substance, the polimer-coated activated carbon in order to remove toxic substances from the blood.
“Fixed-bed activated charcoal cartridges were used for hemoperfusion in the treatment of 54 patients with overdose of one or more drugs, including barbiturate, glutethimide, ethchloryvnol, meprobamate, methyprylon, methaqualone, salicylate, and diazepam. The most dramatic improvement was noticed in patients with phenobarbitol intoxication; they were admitted in stage 3-4 coma and were either awake or arousable by verbal communication at the end of 1 1/2 to 3 1/2 hours of hemoperfusion. Other intoxications improved slowly and required longer duration of treatment. The clearance rates of the drugs with hemoperfusion were greater than those usually achieved with hemodialysis. The data demonstrate the efficacy and usefulness of charcoal hemoperfusion for the management of drug overdose. Fixed-bed charcoal hemoperfusion. Treatment of drug overdose, 1978
- It seems also to be useful by oral administration also in acceleration of the body clearance of Phenobarbital, but only if the administration is immediate.
“The efficacy of administering a slurry of 100 g of activated charcoal (AC) via the gastric tube following lavage was assessed in 25 treated and 37 control patients presenting to the emergency room with chemical evidence of sedative-hypnotics or aspirin in the blood. Efficacy was evaluated as the ability of AC to prevent further absorption as determined by subsequent blood drug concentration changes. Although fewer patients in the AC group showed increased blood drug concentrations, the differences were not statistically significant. Comparison of the mean percent change in blood drug concentrations at various times following treatment produced similar results. Comparisons using subgroups of patients based on the individual drugs, the treatment delay time, and entering functional decompensation showed significant benefit from AC only in the less symptomatic patients. Comparing these results with other studies demonstrating the unequivocal efficacy of early (e.g., 30 min) treatment, it is concluded that the use of AC following lavage may often be too late to benefit most patients. The authors suggest that AC be given in the home, emergency vehicle, or immediately upon admission.”
Assessment of the efficacy of activated charcoal following gastric lavage in acute drug emergencies, 1982
“We investigated the effect of multiple oral doses of activated charcoal on the pharmacokinetics of intravenously administered phenobarbital in a randomized crossover trial. Six healthy men volunteered to take 200 mg of phenobarbital sodium per 70 kg of body weight intravenously on two separate occasions. On one occasion, each subject received oral activated charcoal (180 g) in divided doses over three days after the infusion of phenobarbital. Serum levels of phenobarbital were measured in all subjects up to 96 hours after the infusion, and urinary excretion of phenobarbital was measured in two subjects 24 to 96 hours after the infusion. A pharmacokinetic analysis showed that the charcoal decreased the serum half-life of phenobarbital form 110 +/- 8 to 45 +/- 6 hours (S.E.M.) (P less than 0.01), increased the total body clearance of phenobarbital from 4.4 +/- 0.2 to 12.0 +/- 1.6 ml per kilogram per hour (P less than 0.01), and increased the nonrenal clearance from 52 to 80 per cent of the total body clearance. We conclude that oral administration of activated charcoal enhances the nonrenal clearance of phenobarbital.
Acceleration of the body clearance of phenobarbital by oral activated charcoal, 1982
"Drug overdose is a growing problem among adolescents. Clinical severity depends on the drug and ingested amount, which in some cases may be life-threatening. We present a clinical case of a previously healthy teenage girl who ingested 16.4 g of carbamazepine and 14.5 g of valproic acid. She presented with profound disturbance of consciousness and toxic levels of both drugs, raised in the first hours after the ingestion. She was successfully treated with charcoal haemoperfusion followed by continuous venovenous hemodiafiltration. Overdose with the two drugs separately is common, but there are no reports of intoxication by simultaneous ingestion. High levels of carbamazepine and valproic acid can lead to severe systemic effects and management is made difficult by the absence of specific antidotes. Extracorporeal removal techniques are a good therapeutic option in these cases as they enhance the clearance by reducing the half-life of both drugs thereby preventing serious complications."
Overdose with antiepileptic drugs: the efficacy of extracorporeal removal techniques, 2014
MOLECULAR MECHANISM
Activated charcoal is good at trapping chemicals and prevents their absorption, thanks to its bewildering adsorption surface: in fact a gram of activated carbon can have a surface area in excess of 500 m², with 1500 m² being readily achievable.
SIDE EFFECTS
No side effects were reported, because the CA administered by the gastric tube isn't absorbed by the intestinal mucosa, neither the haemoperfusion column containing activated charcoal coated with cellulose acetate has any metabolic effects.
