Comparison of activated charcoal and ipecac syrup in prevention of drug absorption

Gastrointestinal decontamination for acute poisoning

Gastric decontamination remains an important element in the therapy of pediatric poisoning; however, several issues remain unresolved. Additional studies, particularly in the clinical setting, are necessary to establish optimal therapeutic recommendations. Based on the data presented in this review, the following general recommendations can be made for gastric decontamination in children: If it is necessary to remove an ingested toxin, ipecac syrup is the preferred method if contraindications to its use are not present. The dose should be 30 ml in children older than 1 year of age and 10 ml in children 6 to 12 months of age. Pending further studies, the use of emetics in children younger than 6 months of age cannot be generally recommended, particularly in the home setting. Gastric lavage should be considered to be of very limited use in pediatric patients. Lavage using small nasogastric tubes, except under special circumstances, is nonproductive and cannot be advocated. If it must be used, a large-bore orogastric hose should be used. Administration of activated charcoal prior to lavage should be considered. In situations in which prompt induction of emesis is not possible or contraindications to emesis exist, activated charcoal followed by, or mixed with, a cathartic (preferably sorbitol) should be used as an alternative to removal of gastric contents. Patients with significant symptoms from ingestion requiring hospitalization should receive repeat doses of charcoal and cathartic until symptoms resolve. Activated charcoal should be given in conjunction with other appropriate therapies. Although the data to substantiate this recommendation are limited, particularly in pediatric patients, it is a benign therapy that holds promise of increasing drug elimination.

Preserving the emetic effect of syrup of ipecac with concurrent activated charcoal administration: a preliminary study

Activated charcoal is reported to block the emetic effect of syrup of ipecac. Therefore, activated charcoal administration is commonly delayed until syrup of ipecac induced emesis is complete. The advantages of early administration of activated charcoal have been well documented. Preservation of the emetic effect of syrup of ipecac in the presence of activated charcoal may produce a synergistic effect by enhancing toxin elimination. A study was conducted in ten human volunteers to determine if activated charcoal prevents the emetic effect of syrup of ipecac when a temporal separation exists between administration of the two substances. Syrup of ipecac 60 ml plus water 480 ml was administered via an 18 French nasogastric tube followed by an aqueous slurry of activated charcoal 50 g five minutes later. Eight (80%) of the subjects had emesis in a mean time of 20.25 minutes (range 16-26 min). The total dose of activated charcoal was retained for a mean time of 6.75 minutes (range 0-17 min). Two subjects (20%) failed to have emesis. This study illustrates that activated charcoal may not completely block the emetic effect of syrup of ipecac.

In vitro adsorption of tilidine HCl by activated charcoal

In vitro studies were carried out in order to determine the adsorption of tilidine HCl, a narcotic analgesic, by activated charcoal (max. adsorption capacity 185.5 mg/g of charcoal). The path of the adsorption isotherms at pH 1.2 and 7.5 suggests that the in vivo adsorption of tilidine HCl may be increased when the drug passes from the stomach to the intestine, unless the intestinal content exerts a displacing effect. Nevertheless, the adsorption was dependent on the quantity of activated charcoal used, becoming more complete when the quantity of activated charcoal was increased. The effects of additives on the adsorption capacity of activated charcoal were also investigated in vitro. Ethanol, sorbitol and sucrose significantly reduced drug adsorption, while cacao powder, milk and starch had no effect on tilidine adsorption. At an acid pH, Federa Activated Charcoal significantly adsorbed more drug than either Norit A or Activated Charcoal Merck.

Gastrointestinal transit times of cathartics combined with charcoal

Oral activated charcoal usually is administered in toxic ingestions along with a cathartic. A study was done in volunteers to determine the rapidity of gastrointestinal transit when activated charcoal was administered with various cathartics. A control of activated charcoal was compared to the gastrointestinal transit times of activated charcoal plus the cathartics magnesium citrate, magnesium sulfate, or sorbitol. Activated charcoal alone produced a mean transit time of 23.5 hours; magnesium citrate catharsis occurred in 4.2 hours, magnesium sulfate catharsis occurred in 9.3 hours, and sorbitol catharsis occurred in 0.9 hours. Sorbitol clearly was the most rapidly acting cathartic.

Management of acutely poisoned patients without gastric emptying

During an 18-month period, 592 acute oral drug overdose patients were studied prospectively in a controlled, randomized fashion to determine the efficacy of gastric emptying procedures in altering clinical outcome. Patients presenting on even-numbered days had no gastric emptying procedures performed, and they were compared to patients presenting on odd-numbered days who received either syrup of ipecac or gastric lavage. Patients were carefully followed for evidence of subsequent clinical improvement or deterioration after initial management. Syrup of ipecac did not significantly alter the clinical outcome of patients who were awake and alert on presentation to the emergency department (ED). Gastric lavage in obtunded patients led to a more satisfactory clinical outcome (P less than .05) only if performed within one hour of ingestion. Gastric emptying procedures in the ED for initial treatment of drug overdose are generally not of benefit unless gastric lavage is performed within one hour of ingestion in obtunded patients.

Concomitant use of activated charcoal and N-acetylcysteine

Activated charcoal is a safe, effective, inexpensive adjunct in the management of most toxic ingestions. It has the ability to adsorb a wide variety of drugs and chemicals, one of which is acetaminophen. N-acetylcysteine (NAC) is the specific antidote available for serious overdoses of acetaminophen. Current management of acetaminophen overdose, however, does not recommend the concomitant oral administration of these two useful agents because adsorption and inactivation of NAC by charcoal is believed to occur. Our study was designed to help evaluate the effect of activated charcoal on N-acetylcysteine absorption. Ten healthy male volunteers were each given in the first, or control, phase of the study an oral dose of 140 mg/kg NAC, and venous blood samples were obtained. In the second phase, after a washout period, each subject received 60 g activated charcoal orally followed immediately by 140 mg/kg NAC. NAC serum levels were measured using gas-liquid chromatography, and levels were compared with and without the concomitant administration of charcoal. Although only a small number of the subjects completed the study, the results showed that in both phases there were no significant differences in the peak NAC levels, the plasma half-life of NAC, or the calculated area under the curve. We recommend that NAC and activated charcoal not be used clinically until further studies are completed.

Effect of two antacids on the bioavailability of paracetamol

The effect of two antacids on the bioavailability of paracetamol has been investigated in 12 young healthy volunteers. Following a random cross over design, each subject swallowed, on three separate occasions, one weak apart, 500 mg paracetamol alone, or together with two different aluminium hydroxide, magnesium hydroxide preparations (Dimalan and Maalox). Plasma paracetamol levels were measured by HPLC. The bioavailability of paracetamol was not altered by either antacid, but they both delayed the time to peak plasma concentration (0.85 h; 1.43 h; 1.25 h, without antacid, with Dimalan and with Maalox respectively). The peak plasma concentration was not affected by concurrent antacid administration.

Do gastric contents modify antidotal efficacy of oral activated charcoal?

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. 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. The serum concentrations and the cumulative excretion into urine of the drugs were followed for 48 h. 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. 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. 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.

Activated charcoal and syrup of ipecac in prevention of cimetidine and pindolol absorption in man after administration of metoclopramide as an antiemetic agent

The effects of activated charcoal and ipecac syrup by mouth on cimetidine and pindolol absorption were studied in seven subjects, who had ingested 20 mg metoclopramide 1 h earlier, and compared with the adsorption capacity of charcoal in vitro. Activated charcoal, 50 g, given 5 min after 400 mg cimetidine + 10 mg pindolol, reduced their absorption by 99% or more, based on AUC0-48h and the 48-h urinary excretion of the drugs. Syrup of ipecac caused emesis on each occasion. On the average, ipecac reduced the absorption of cimetidine and pindolol by 75% and 60%, respectively. Based on studies in vitro it seems probable that the adsorbing capacity of charcoal for cimetidine but not for pindolol will be saturated if 50 g charcoal is given after an overdose of about 100 fold the therapeutic dose. Because the use of ipecac allowed an absorption of the drugs at least 30 fold that allowed by charcoal, the immediate administration of activated charcoal, without preceding lavage or emesis, should be considered in such poisonings where the adsorption capacity of high charcoal doses will not be saturated.

Capacity of two forms of activated charcoal to adsorb nefopam in vitro and to reduce its toxicity in vivo

The adsorption of nefopam hydrochloride to two different charcoals was studied in vitro at pH 1.2 and 7.4. Both forms of activated charcoal effectively adsorbed nefopam, but the adsorption was significantly (p less than 0.001) more complete to PX-21 than to Norit A and the neutral pH favored adsorption over the acid pH. The unadsorbed fraction increased steeply when the charcoal-to-nefopam ratio was decreased below 5. In mice, the administration of Norit A and PX-21 (1700 mg/kg) significantly (p less than 0.001) increased the acute LD50 of nefopam hydrochloride, by 4.3 fold and 5.8 fold, respectively. The calculated amounts of free drug in the gastrointestinal tract are in good agreement with the observed LD50 values without charcoal when the free fractions at pH 1.2 and the corresponding charcoal-to-nefopam ratios in vitro are used in the calculations. The antagonism of charcoal to nefopam toxicity was confirmed in rats, too. At charcoal-to-nefopam ratios higher than those used in the present study, an even more effective reduction of toxicity is obvious. Therefore, immediate oral administration of a high dose (50-100 g) of activated charcoal is highly recommended to prevent nefopam absorption in acute intoxications in man, too.

Effect of activated charcoal on absorption of tolbutamide and valproate in man

The claim that activated charcoal should be ineffective or even contraindicated in intoxication due to tolbutamide is based only on limited in vitro studies. To test the claim, the effect of activated charcoal 50 g on the absorption of tolbutamide and, as a reference, of sodium valproate, was studied in 6 healthy volunteers. Each volunteer swallowed tolbutamide 500 mg and sodium valproate 300 mg with 50 ml water 1 h after a light breakfast, and within 5 min they took in randomized order either a suspension of activated charcoal or water. The absorption of tolbutamide, calculated as the peak concentration and the area under the serum drug concentration-time curve during 0-48 h, was reduced by 90% by charcoal (p less than 0.001). The absorption of valproate in these conditions was reduced on average by 65% (p less than 0.01). In each subject charcoal had a greater effect on the absorption of tolbutamide than of valproate. According to these findings and preliminary in vitro studies on other sulphonylureas high doses of activated charcoal can be recommended for the preventing the absorption of sulphonylureas in acute intoxications. The poor aqueous solubility of these substances at the gastric pH probably delays their gastrointestinal absorption, so that they may be adsorbed on to charcoal even given several hours later.