Why sorbitol in activated charcoal

Activated charcoal in either water or sorbitol is usually sold as 50 grams charcoal in ml total volume. Activated charcoal is often recommended in a dose by weight that is ten times the weight of the estimated drug or poison ingested, to a maximum single dose of grams in adults. The precise appropriate dose of charcoal in any given ingestion is, however, unknown. The charcoal to drug ratio is based on multiple studies looking at the ability of activated charcoal to retard absorption when given at varying charcoal to toxin ratios.

In one such study, Chin 4 used a rat model to investigate the effectiveness of charcoal:drug ratios of , , and for exposures to phenobarbital, chloroquine and isoniazid. It is far easier to achieve a ratio of charcoal to drug for overdoses of medicines usually prescribed in microgram quantities, i. It would be hard to find a digoxin overdose for which the administration of 50 grams of charcoal would not achieve at least a ratio, as 5 grams of digoxin equals a dose of 20, tablets of 0.

On the other hand, grams of charcoal would be optimal for aspirin ingestions of just 10 grams or less, yet ASA overdoses often involve a much higher dose. For this reason, repeat dosing of activated charcoal may be needed to approach the desired ratio. Additional doses of charcoal can be given at intervals of hours.

Drugs that are removed by this method either undergo extensive entero-hepatic reabsorption or are drugs that have an unusual affinity for charcoal, and can be attracted across the capillary-gut interface for adsorption. Activated charcoal is effective at adsorbing experimentally a wide variety of pharmaceutical and toxic agents. Generally, most medications undergo some adsorption by charcoal. Alcohols, metals including iron and lithium, and strong acids and bases are poorly adsorbed.

Clinical use has been predicated on the belief that adsorption to charcoal prevents systemic absorption of the drug or poison, and can thus positively affect outcome, doing so in a manner which is safe. What do we really know about the clinical benefit and risk of activated charcoal? Unfortunately, we have insufficient scientific studies addressing the use of gastrointestinal decontamination. In , In , only 2. By , ipecac use was down to 0. It is not a simple matter to study the effectiveness of any modality of gastrointestinal decontamination, nor to apply the body of collected science to a given patient.

The decision to employ a GI decontamination procedure involves a large number of variables germane to the specific case, and this has made relevant, generalizable, study difficult if not impossible. At a minimum, the effectiveness of decontamination involves: 1 the drug or poison ingested, 2 the dose, 3 patient weight, 4 time since ingestion, 5 the medical status of the patient at the time decontamination is contemplated, 6 the binding affinity of the drug or poison to charcoal, 7 operator skill and 8 patient cooperation.

When confronted with the need to treat an altered patient who ingested 1, mg diphenhydramine 2 hours ago, it is highly unlikely that you will be able to find a study describing the benefit of charcoal in your particular patient. There are 4 lines of inquiry in the medical literature addressing the potential utility of activated charcoal in the treatment of poisoned patients. In vitro studies document that charcoal can adsorb a large number of substances in the test tube, and this evidence has generated enthusiasm over many years that adsorption could be used to decrease absorption, and thus to improve outcome.

Human case reports provide testimony that charcoal has been used successfully here and there, but do little to prove efficacy. Human volunteer studies, in which subjects were given subtoxic dose of a marker drug followed by activated charcoal after a delay of 5, 10 or 60 minutes, show reduced systemic absorption of the drug.

However, because the doses given were subtoxic, it is difficult to extrapolate to an overdose. Phenobarbital and theophylline are examples of toxins which can be eliminated more rapidly by this method. There are no known absolute contraindications to the use of activated charcoal, however, it is not an equally effective adsorbent for all toxins. It should be used with caution, if at all, in patients who have ingested corrosive agents since the activated charcoal may obscure endoscopic visualization of esophageal and gastric lesions produced by the corrosive.

The use of a cathartic with activated charcoal may not be advised if a patient has significant fluid or electrolyte abnormalities. Young children should not receive cathartic doses of sorbitol unless hospitalized and under the immediate care of a physician. Safe use during pregnancy and lactation has not been established. No teratogenic effects have been noted in rabbits or rats.

Prior to the use of activated charcoal, proper basic life support measures must be implemented as well as the appropriate gastric emptying technique if indicated. These stools may be diarrhetic and may persist for several hours. A study conducted in healthy adult human volunteers who ingested therapeutic amounts of activated charcoal and sorbitol resulted in severe prolonged diarrhea, but no significant changes were noted in serum electrolytes or osmolality, BUN, or the metabolic profile as compared to the control.

Gastrointestinal obstruction from activated charcoal may occur as a consequence of toxin-induced antiperistaltic effects. Bowel sounds should be frequently monitored to assess peristaltic action, especially in patients undergoing multiple dose activated charcoal therapy.

Activated charcoal with sorbitol has produced severe hypernatremic dehydration when used in excessive amounts in pediatric patients. Aspiration of activated charcoal has been reported to produce airway obstruction and a limited number of fatalities have occurred. Gastrointestinal obstruction associated with the use of multiple dose activated charcoal therapy has been reported. If possible call a Poison Control Center, emergency medical facility, or health professional for help before using this product.

If help cannot be reached quickly, follow directions under this label. Read label warnings and directions upon buying this product. Write emergency phone numbers in space provided. Keep this and all drugs out of the reach of children. Adults over 12 yrs. Clinical Pharmacokinetics. Am J Emerg Med. Poisindex Information System, Micromedix, Denver, J Pediatrics. Diabetes Care. Clinical Toxicology.

Medical Toxicology. New York, Elsevier, Clinical Management of Poisoning and Drug Overdose. Phase 2 was identical except that 1. The mean amount of aspirin absorbed without the use of sorbitol was 1. The difference is significant at P less than.

This study demonstrates that the addition of sorbitol significantly decreases drug absorption in a simulated drug overdose model.