Effects of emetic and cathartic agents on the gastrointestinal tract and the treatment of toxic ingestion

Drugs and pharmaceuticals: management of intoxication and antidotes

The treatment of patients poisoned with drugs and pharmaceuticals can be quite challenging. Diverse exposure circumstances, varied clinical presentations, unique patient-specific factors, and inconsistent diagnostic and therapeutic infrastructure support, coupled with relatively few definitive antidotes, may complicate evaluation and management. The historical approach to poisoned patients (patient arousal, toxin elimination, and toxin identification) has given way to rigorous attention to the fundamental aspects of basic life support--airway management, oxygenation and ventilation, circulatory competence, thermoregulation, and substrate availability. Selected patients may benefit from methods to alter toxin pharmacokinetics to minimize systemic, target organ, or tissue compartment exposure (either by decreasing absorption or increasing elimination). These may include syrup of ipecac, orogastric lavage, activated single- or multi-dose charcoal, whole bowel irrigation, endoscopy and surgery, urinary alkalinization, saline diuresis, or extracorporeal methods (hemodialysis, charcoal hemoperfusion, continuous venovenous hemofiltration, and exchange transfusion). Pharmaceutical adjuncts and antidotes may be useful in toxicant-induced hyperthermias. In the context of analgesic, anti-inflammatory, anticholinergic, anticonvulsant, antihyperglycemic, antimicrobial, antineoplastic, cardiovascular, opioid, or sedative-hypnotic agents overdose, N-acetylcysteine, physostigmine, L-carnitine, dextrose, octreotide, pyridoxine, dexrazoxane, leucovorin, glucarpidase, atropine, calcium, digoxin-specific antibody fragments, glucagon, high-dose insulin euglycemia therapy, lipid emulsion, magnesium, sodium bicarbonate, naloxone, and flumazenil are specifically reviewed. In summary, patients generally benefit from aggressive support of vital functions, careful history and physical examination, specific laboratory analyses, a thoughtful consideration of the risks and benefits of decontamination and enhanced elimination, and the use of specific antidotes where warranted. Data supporting antidotes effectiveness vary considerably. Clinicians are encouraged to utilize consultation with regional poison centers or those with toxicology training to assist with diagnosis, management, and administration of antidotes, particularly in unfamiliar cases.

Pediatric gastrointestinal decontamination in acute toxin ingestion

The appropriate implementation of the various modalities of gastrointestinal (GI) decontamination is critical in the management of the pediatric patient who is examined in the emergency department or private office after an acute ingestion. Gastrointestinal decontamination includes gastric lavage, syrup of ipecac, activated charcoal, and whole bowel irrigation. Clinical studies have delineated the role and efficacy of these procedures. Trends in GI decontamination place less emphasis on ipecac and gastric lavage and more emphasis on activated charcoal alone in the patient with a mild overdose. Gastric lavage is indicated in serious ingestion and is most effective if done soon after the exposure. Whole bowel irrigation is the newest addition and has important clinical use in the treatment of serious iron ingestions as well as in older adolescent cocaine body suffers and packers. Indications and contraindications of the various forms of GI decontamination are discussed and relevant clinical studies are reviewed.

Whole bowel irrigation in an acute oral lead intoxication

An 89-year-old man acutely ingested approximately three ounces of a ceramic glaze preparation with a 30% lead oxide content. A blood lead level of 18 micrograms/mL was reported from a sample drawn within 1 hour of ingestion and just prior to gastric lavage. Following lavage, an abdominal radiograph demonstrated lead throughout the small intestine. Whole bowel irrigation was then undertaken and subsequent x-rays demonstrated clearing of all lead in the small bowel. At 16 and 24 hours post-ingestion, blood lead levels rose to 39 micrograms/dL and 42 micrograms/dL, respectively, and the patient then underwent a 5-day course of chelation therapy. This is the first reported case of the use of whole bowel irrigation in an acute lead ingestion. The use of decontamination techniques in acute lead ingestions is reviewed.

Drug overdose — reducing the load

OBJECTIVE

To review available information about various methods for reducing gastrointestinal absorption of a poison or drug.

DATA SOURCES

Articles on overdose and accidental poisoning generated by the Australian Medlars Service and concentrating on the period between 1985 and 1990 were surveyed. Earlier studies were included if relevant.

STUDY SELECTION AND DATA EXTRACTION

English language articles with an emphasis on studies using objective methods to measure individual and comparative efficacy of gastrointestinal decontamination techniques were selected. A total of 65 articles were reviewed.

DATA SYNTHESIS

Gastric emptying procedures (gastric lavage or emesis caused by syrup of ipecac) are only effective if performed within one hour of drug ingestion. Gastric lavage is superior to syrup of ipecac. Oral administration of activated charcoal is more effective than either gastric emptying procedure, and is recommended for most cases of poisoning. Cathartics (sorbitol) can be used with activated charcoal. Whole bowel lavage with polyethylene glycol is indicated in selected cases of potentially lethal overdose where the toxic substance cannot be absorbed by charcoal and has passed the pylorus.

CONCLUSIONS

Children--syrup of ipecac can be given at home to children older than 12 months. Most children who reach hospital can be treated by charcoal alone. ADULTS--Most patients are managed with supportive care and, in the absence of contraindications, a single dose of activated charcoal if seen within four hours of ingestion of the poison or drug. Gastric lavage is used if the patient presents within one hour of ingestion and has clinical features of toxicity.

Hypermagnesemia. A potential complication during treatment of theophylline intoxication with oral activated charcoal and magnesium-containing cathartics

Toxic reaction to theophylline compounds is common. Oral activated charcoal (OAC) is a widely accepted mode of therapy for management of moderate to severe cases of theophylline toxicity. Magnesium-containing cathartics are generally recommended in conjunction with OAC in the treatment of drug or toxin ingestions. We report two cases of hypermagnesemia complicating the treatment of theophylline toxicity with OAC and magnesium citrate. In both patients, the hypermagnesemia contributed significantly to morbidity or mortality. In light of these cases and after review of the literature, we suggest that sorbitol be considered the cathartic agent of choice in the treatment of theophylline toxicity with OAC.

Effects of activated charcoal and sorbitol on sodium pentobarbital absorption in the rat

Three activated charcoals were tested for their ability to reduce the oral absorption of sodium pentobarbital (SP) in rats. Fasted adult, male rats were given 40 mg/kg of C-14 labelled SP by gavage (2 ml). Five minutes after drug administration, the animals were given 40 mg of either Darco (G-60), United States Pharmacopeia (USP) or SuperChar (SC) activated charcoals. The charcoals were administered as a slurry in either 1 ml of water, or 1 ml of 70 percent (w/v) sorbitol solution. Water (control) and sorbitol given alone were tested separately. Various pharmacokinetic parameters were calculated from the plasma concentration of SP determined at various time intervals after drug administration. When given in water, only SC significantly (p less than .01) reduced the peak plasma concentration and oral bioavailability of SP. Sorbitol given alone produced diarrhea but did not affect drug absorption. However, sorbitol selectively enhanced the effectiveness of G-60 and USP charcoals and, as a result, all charcoals significantly reduced SP absorption when given along with the cathartic. The results suggest that when given in water, charcoal antidotal effectiveness is proportional to absorptive surface area, and that sorbitol may enhance the antidotal effectiveness of some charcoals but not others.

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.

Advances in clinical toxicology

New data are reviewed in two areas in the management of the acute overdose: gastrointestinal decontamination and systemic antidotes. The mechanism and effectiveness of Ipecac syrup, gastric aspiration and lavage, activated charcoal, gastrointestinal dialysis, and saline cathartics are discussed. Special problems posed by disc batteries and packet ingestion of cocaine (in transporting contraband) are highlighted. The pharmacology and uses of pyridoxine and naloxone as antidotes are detailed.

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.