Effect of activated charcoal on aspirin absorption in man Part I

The effect of charcoal‐drug ratio on the antidotal efficacy of oral activated charcoal was studied in six healthy volunteers in a randomized cross‐over study and compared with the adsorption capacity of activated charcoal in vitro. Aminosalicylic acid (PAS) 1 g and 5 g were ingested on an empty stomach in 30 ml of water. Immediately afterwards the subjects ingested 50 g of activated charcoal in 300 ml of water or 300 ml of water only. PAS 10 g 20 g were only given with 50 g of activated charcoal administered immediately afterwards. The plasma concentrations and the cumulative excretion of PAS into urine were measured for 48 h. Increasing the dose of PAS from 1 g to 20 g reduced the antidotal efficacy of activated charcoal: at a charcoal‐drug ratio of 50:1 under 5% of the dose was absorbed but at a ratio of 2.5:1 about 37%. These data correlated well to the saturation of adsorption capacity of charcoal in vitro. To minimize the possibility of saturation of the adsorption capacity of charcoal in acute intoxications where the amount and type of drug taken is usually unknown, large doses (50‐100 g) of activated charcoal should be used.

Section: Introduction Methodsmentioning

confidence: 99%

Effect of charcoal‐drug ratio on antidotal efficacy of oral activated charcoal in man.

Olkkola¹

1985

“…Different food components can have different effects, and food may interact in opposite ways, even with drugs that are chemically related (Melander, 1978). Therefore, the net effect of food and activated charcoal on In man it has been demonstrated that food reduces the inhibiting effect of charcoal on aspirin absorption: the percentage of a 1 g aspirin dose recovered in the urine, when 10 g activated charcoal was given immediately after the aspirin, was about 60% for fasted subjects and 75% for subjects who had eaten a standard -I I .E 2. breakfast 15 min prior to the test (Levy & Tsuchiya, 1972). In dogs, however, the opposite effect was observed when they had been fed 1 h before the test (Atkinson & Azarnoff, 1971).…”

Section: Discussionmentioning

confidence: 99%

Do gastric contents modify antidotal efficacy of oral activated charcoal?

Olkkola¹,

Neuvonen²

1984

1 The effect of food on the antidotal efficacy of activated charcoal was studied in six healthy volunteers, who ingested aspirin 1000 mg, mexiletine 200 mg and tolfenamic acid 400 mg in a randomized cross-over study. 2 Activated charcoal 25 g, suspended in water, was administered 5 min or 60 min after the drugs were taken on an empty stomach or after a standard meal. 3 The serum concentrations and the cumulative excretion into urine of the drugs were followed for 48 h. 4 When the drugs were taken on an empty stomach, activated charcoal given 5 min or 60 min afterwards reduced the bioavailability of the drugs by 75-98% or 10-60%, respectively. 5 Food moderately weakened the effect of activated charcoal administered 5 min after the drugs, but when the charcoal was given 1 h later the effect was still practically the same, the reduction of absorption varying in both cases in the range of 45-85%. Thus the efficacy of charcoal given 60 min after the drugs was better after a standard meal than on an empty stomach. 6 Presence of food in the stomach of patients with drug overdosage modifies the efficacy of activated charcoal and gives it more time to adsorb drugs in the gastrointestinal canal, possibly by slowing gastric emptying rate.

“…Firstly, it has been shown that scaling down procedures underestimate the adsorption of drug to charcoal for both aspirin and paracetamol (Levy & Houston, 1976;Levy & Tsuchiya, 1972). This has been attributed to non-specific competition of gastric contents for adsorption on charcoal, the relative effect of which diminishes as the absolute dose of charcoal increases even though the ratio of drug to charcoal is kept constant.…”

Section: Methodsmentioning

confidence: 99%

The effect of activated charcoal and hyoscine butylbromide alone and in combination on the absorption of mefenamic acid.

el‐Bahie¹,

Allen²,

Williams³

et al. 1985

Mefenamic acid 500 mg orally was administered to nine healthy volunteers on four occasions 7 days apart. On two occasions allocated at random, activated charcoal (2.5 g of medicoal) was administered 1 h after the drug. Hyoscine butylbromide (20 mg intramuscularly) was given immediately after mefenamic acid on one of these occasions, and on one occasion after mefenamic acid without charcoal. Hyoscine significantly delayed the time to maximum mefenamic acid concentrations but did not affect the area under the plasma concentration-time curve. Charcoal reduced the area under the plasma concentration curve by 36% and charcoal and hyoscine reduced the area under the plasma concentration curve by 42% from their respective control values. We conclude that early charcoal administration in a ratio of 5 g to 1 g of drug effectively reduces the area under the plasma concentration-time curve after oral mefenamic acid administration. Early charcoal administration may be of value therefore in reducing the toxicity of mefenamic acid after deliberate or accidental overdosage.