Relationship between Effect of Activated Charcoal on Drug Absorption in Man and Its Drug Adsorption Characteristics In Vitro

Tsuchiya, Tamehiro; Levy, Gerhard

doi:10.1002/jps.2600610419

Cited by 56 publications

(9 citation statements)

References 9 publications

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“…Consequently, aspirin (pKa 3.5) and other weak acids are more completely adsorbed at pH 1 ( fig. 1) than at a neutral or alkaline pH (Andersen, 1947;Boehm and Oppenheim, 1 ~77;Neuvonen and Alanen, 1981;Tsuchiya and Levy, 1972b). The adsorption of par aceta mol (acetaminophen; pKa 9.9) High charcoaldrug ratio Low charcoaldrug ratio …”

Section: Effect Of Phmentioning

confidence: 96%

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Clinical Pharmacokinetics of Oral Activated Charcoal in Acute Intoxications

Neuvonen

1982

Clinical Pharmacokinetics

152

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Activated charcoal has the ability to adsorb a wide variety of substances onto its sUrface. This property can be applied in preventing the absorption of various drugs and toxins from the gastrointestinal tract and in some cases to increase their rate of elimination. In vitro. the extent of adsorption depends mainly on the relative amounts oj the charcoal and the drug ingested. but the quality and formulation of the activated charcoal. as well as other Jactors such as the pH of the incubation medium also have an effect. Under optimum conditions the adsorption to charcoal is a rapid process but desorption from charcoal is possible due. for example. to competition by other substances or to changes in pH.In acute poisonings the most important determinants of the efficacy oj activated charcoal are the delay in the administration and the amount of activated charcoal given. Activated charcoal should be given as a water suspension as soon as possible. preferably within 30 minutes oJthe ingestion of the toxic agent. However. in acute intoxications the absorption of drugs may be considerably delayed and thus charcoal may be effective when administered 24 hours after drug ingestion. At a constant charcoal-drug ratio. the adsorption capacity oj charcoal increases with increasing doses because the competitive effect of gastrointestinal contents diminishes. Thus the amount oj charcoal should be as high as feasible. i.e. about 50 to lOOg in adults. This amount is able to adsorb lethal doses of many drugs. Significant desorption from charcoal and subsequent systemic absorption of a drug is possible if inadequate amounts of charcoal are used. The adsorption to charcoal is more complete in poisonings with potent drugs. i.e. where the charcoal-drug ratio is high (e.g. digitalis glycosides. tricyclic antidepressants. etc.). With some drugs the adsorption capacity may be exceeded, e.g. in aspirin poisonings, but even in these cases the charcoal may adsorb that fraction oj the drug which is dissolved in the gastrointestinal./luids.In experimental studies. the efficacy of charcoal in preventing systemic absorption oj many drugs has been of the same order or even better than that of emesis, but in certain poisonings the efficacy oj charcoal is inadequate, e.g. in those caused by ethanol, methanol or iron salts. Charcoal is rather ineffective and may even be contraindicated in poisonings caused by caustic alkalis or acids. Charcoal is non-toxic but, if administered too rapidly, patients may vomit.Some drugs and toxic agents have a long elimination half-life and are excreted into the gastrointestinal tract and then reabsorbed. With such agents multiple oral doses of activated charcoal, e.g. 20g every 6 hours Jor 1 or 2 days, can accelerate their elimination and shorten the duration of intoxication.

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Section: Effect Of Phmentioning

confidence: 96%

“…The absorption was about 7% when 2g of charcoal was administered in solution together with 50mg of phenylpropanolamine, but 2 I % when activated charcoal was given separately but immediately afterwards (Tsuchiya and Levy, 1972b).…”

Section: Phenylpropanolaminementioning

confidence: 99%

Clinical Pharmacokinetics of Oral Activated Charcoal in Acute Intoxications

Neuvonen

1982

Clinical Pharmacokinetics

152

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“…Phenylpropanolamine was used as the test drug because : (a) activated charcoal is an effective inhibitor of the absorption of this drug in man, and (6) the amount of charcoal required for this purpose is relatively small (2). A preliminary study was carried out with aspirin as the test drug, but the large number of charcoal tablets required (more than 20 per dose) made a continuation of that investigation impractical.…”

Section: Resultsmentioning

confidence: 99%

Drug Adsorption Efficacy of Commercial Activated Charcoal Tablets In Vitro and in Man

Tsuchiya

Levy

1972

Journal of Pharmaceutical Sciences

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“…Activated charcoal, due to its high adsorptive capacity, has long found use in the removal of colours from solutions [1,2], pyrogens from injections [3,4] and in the management of acute poisoning [5][6][7]. Though activated charcoal is so popular, clays are also known to have high adsorptive capacities due to their colloidal dimensions which result in high exposed surface areas; they also have high ion exchange capacities as a result of negative charges in solution.…”

Section: Introductionmentioning

confidence: 99%