Cathartics and laxatives. Do they still have a place in management of the poisoned patient?

Efficacy of Whole Bowel Irrigation Using Solutions with or without Adsorbent in the Removal of Paraquat in Dogs

1 The efficacy of whole bowel irrigation with a solution containing either polyethylene glycol (PEG) with electrolyte or an adsorbent (Kayexalate™) with a cathartic (sorbitol) was investigated in 18 dogs who had been given 250 mg kg -1 paraquat dichloride via a jejunal tube to eliminate the influence of gastric absorption.

2 Plasma paraquat concentrations 2 and 3 h after the initiation of bowel irrigation and at the end of the study (5 h later) were significantly lower in the bowel irrigation groups than in the control (no bowel irrigation) group.

3 The total body clearances of paraquat in the bowel irrigation groups were significantly greater than in the control group.

4 There were no significant differences between the two different irrigation solution groups in plasma paraquat concentration, the area under the plasma concentration time curve and the total body clearance.

5 In the PEG with electrolyte group, about 70% of the administered dose of paraquat was removed by means of bowel irrigation (n=4).

6 The adjunction of the adsorbent had no beneficial effects.

7 Haemodynamic changes associated with whole bowel irrigation were unremarkable except that right atrial and pulmonary arterial pressures were elevated in the latter part of the study.

Efficacy of magnesium citrate cathartic in pediatric toxic ingestions

STUDY OBJECTIVE

To investigate the efficacy of magnesium citrate in reducing gastrointestinal transit time of activated charcoal in children.

DESIGN

A prospective, randomized, clinical comparison of four magnesium doses.

SETTING

Urban children's hospital emergency department.

PARTICIPANTS

Children aged 1 month to 6 years who presented for management of an acute toxic ingestion.

INTERVENTION

Each child received 1 g/kg activated charcoal combined with a randomly assigned dose of a 6% solution of magnesium citrate: 0 mL/kg, 4 mL/kg (standard recommended dose), 6 mL/kg, or 8 mL/kg. The primary outcome measure was the interval to first activated charcoal-containing stool, which was determined by follow-up telephone call or review of the medical record.

RESULTS

Sixty-four children were enrolled. Median times to first charcoal stool were 19.5 hours (0 mL/kg), 13.0 hours (4 mL/kg), 14.0 hours (6 mL/kg), and 12.0 hours (8 mL/kg). Intergroup differences were significant by Kruskal-Wallis analysis of variance (P = .0035).

CONCLUSION

Magnesium citrate reduces gastrointestinal transit times of activated charcoal stools when administered to children who receive activated charcoal for a toxic ingestion. Further study is needed to determine the clinical value of this reduction.

Effect of saline cathartics on gastrointestinal transit time of activated charcoal

The effects of saline cathartics on the gastrointestinal transit time of activated charcoal were investigated in six healthy volunteers. The study shows that the mean gastrointestinal transit times of charcoal alone were 29.3 h and 24.4, 15.4, 17.3 and 17.5 h with sodium chloride, sodium sulphate, magnesium sulphate alone and Andrew's Liver Salt respectively. Some volunteers complained of slight abdominal discomfort in all the phases except the Andrew's Liver Salt phase.

The effect of activated charcoal on phenytoin pharmacokinetics

STUDY OBJECTIVES

To examine the effect of administration of oral activated charcoal with or without sorbitol on the elimination of phenytoin.

SETTING

Emergency department of a rural teaching institution.

TYPE OF PARTICIPANTS

Eight normal volunteers.

INTERVENTIONS

Subjects received 15 mg/kg phenytoin as an IV infusion. During the first phase of the study, oral activated charcoal was administered to a total dose of 140 g over a ten-hour period. During the second phase of the study, phenytoin alone was administered.

MEASUREMENTS AND MAIN RESULTS

Administration of activated charcoal resulted in a significant decrease in the area under the curve 0-inf (p = .008) and in total body clearance (P = .008). No difference in the effect on phenytoin pharmacokinetic parameters was noted when the charcoal was administered with or without sorbitol, but fewer gastrointestinal adverse effects were noted without sorbitol treatment.

CONCLUSION

Oral activated charcoal was shown to affect phenytoin pharmacokinetic parameters. Further pharmacokinetic/pharmacodynamic studies are warranted to determine if activated charcoal results in a faster recovery from phenytoin toxicity.

Serum magnesium concentrations after repetitive magnesium cathartic administration

Severe hypermagnesemia has been reported by several authors after multiple doses of magnesium-containing cathartic are administered during management of a toxic ingestion. To evaluate the frequency and magnitude of serum magnesium elevations after the use of repetitive magnesium catharsis, we prospectively evaluated 102 patients who received multiple doses of magnesium citrate as a part of treatment of an overdose. Commonly ingested substances for which repetitive cathartic was administered were tricyclic antidepressants in 47%, aspirin in 17%, and phenytoin in 10%. For each case, serial electrolytes, blood urea nitrogen, creatinine, calcium and magnesium were obtained. Mean initial serum magnesium concentration was 1.8 +/- .03 mEq/L. After a mean 960 mL of magnesium citrate (9.22 g magnesium), final mean serum magnesium concentration was 2.5 +/- .05 mEq/L. Forty-seven patients (47%) developed an elevated (greater than 2.4 mEq/L) serum magnesium concentration, with 12 greater than 3.0 mEq/L. No correlation was found between total quantity of magnesium citrate administered and the increment in serum magnesium concentration. Our data indicate that serum magnesium concentrations consistently rise after repetitive magnesium citrate use. However, the magnitude of this rise appears modest. The elevation in serum magnesium concentration does not correlate with the quantity of magnesium administered. We conclude that with close monitoring, repetitive magnesium citrate can be administered without inducing severe hypermagnesemia (serum magnesium concentration greater than 5.0 mEq/L).

Management of toxicoses

This article provides information on the detoxification of and supportive care for poisoned animals. Involved are measures to control life-threatening manifestations of toxicoses, to remove agents from the digestive tract, skin, or eyes, and to promote removal of systemically absorbed toxicants. The use of these methods is often of paramount importance in an effort to limit organ damage and to enable a poisoned animal to survive.

Magnesium toxicity secondary to catharsis during management of theophylline poisoning

Multiple doses of oral activated charcoal are used increasingly to promote elimination of toxins that have already reached the bloodstream; this is often referred to as gastrointestinal dialysis. Cathartics usually are used in conjunction to hasten transit of the charcoal-adsorbed toxin. In the present case, a regimen of activated charcoal and magnesium citrate was used to treat a patient with theophylline poisoning. It was effective in lowering the patient's serum theophylline concentration but produced an elevated magnesium level associated with decreased responsiveness, confusion, and diminished deep tendon reflexes. Magnesium citrate may not be the optimal cathartic for use in gastrointestinal dialysis, at least in selected patients. Sorbitol has been shown to produce a more rapid catharsis without disturbing magnesium serum concentrations. Therefore, the use of sorbitol in place of magnesium citrate, at least in selected patients, may be preferred.

Poisoning with sustained release potassium

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Oral activated charcoal in the treatment of intoxications. Role of single and repeated doses

Activated charcoal has an ability to adsorb a wide variety of substances. This property can be applied to prevent the gastrointestinal absorption of various drugs and toxins and to increase their elimination, even after systemic absorption. Single doses of oral activated charcoal effectively prevent the gastrointestinal absorption of most drugs and toxins present in the stomach at the time of charcoal administration. Known exceptions are alcohols, cyanide, and metals such as iron and lithium. In general, activated charcoal is more effective than gastric emptying. However, if the amount of drug or poison ingested is very large or if its affinity to charcoal is poor, the adsorption capacity of activated charcoal can be saturated. In such cases properly performed gastric emptying is likely to be more effective than charcoal alone. Repeated dosing with oral activated charcoal enhances the elimination of many toxicologically significant agents, e.g. aspirin, carbamazepine, dapsone, dextropropoxyphene, cardiac glycosides, meprobamate, phenobarbitone, phenytoin and theophylline. It also accelerates the elimination of many industrial and environmental intoxicants. In acute intoxications 50 to 100g activated charcoal should be administered to adult patients (to children, about 1 g/kg) as soon as possible. The exceptions are patients poisoned with caustic alkalis or acids which will immediately cause local tissue damages. To avoid delays in charcoal administration, activated charcoal should be a part of first-aid kits both at home and at work. The 'blind' administration of charcoal neither prevents later gastric emptying nor does it cause serious adverse effects provided that pulmonary aspiration in obtunded patients is prevented. In severe acute poisonings oral activated charcoal should be administered repeatedly, e.g. 20 to 50g at intervals of 4 to 6 hours, until recovery or until plasma drug concentrations have fallen to non-toxic levels. In addition to increasing the elimination of many drugs and toxins even after their systemic absorption, repeated doses of charcoal also reduce the risk of desorbing from the charcoal-toxin complex as the complex passes through the gastrointestinal tract. Charcoal will not increase the elimination of all substances taken. However, as the drug history in acute intoxications is often unreliable, repeated doses of oral activated charcoal in severe intoxications seem to be justified unless the toxicological laboratory has identified the causative agent as not being prone to adsorption by charcoal. The role of repeated doses of oral activated charcoal in chronic intoxication has not been clearly defined.(ABSTRACT TRUNCATED AT 400 WORDS)

Magnesium levels after magnesium-containing cathartics

To determine the effect on serum Mg++ levels of oral Magnesium-containing cathartics (MgCC) used in the treatment of suspected drug overdose, a prospective, non-randomized study of 24 cases of suspected drug overdose was conducted. Ten cases admitted to the observation unit were assigned to the single dose MgCC group. Fourteen cases admitted to either the ICU or the observation unit were assigned to the multiple dose MgCC group. Single dose cases received 30 gm of magnesium sulfate (MgSO4) at 0 hours. Multiple dose cases received 3 30 gm doses of MgSO4 at 0, 4, and 8 hours. Mg++ levels were measured prior to each MgSO4 dose and 1 and 4 hours after the final dose in both groups. In the single dose group, there was no difference between baseline Mg++ levels and post MgSO4 levels, and only 2/10 developed slightly elevated levels (2.2, 2.3 mEq/L). In the multiple dose group, levels increased and remained significantly higher than baseline after the second MgSO4 dose, and 9/14 developed elevated levels (2.2 to 5.0 mEq/L). All patients who developed elevated Mg++ levels had normal BUN and creatinine values. When the single and multiple dose groups were compared, baseline Mg++ levels were no different (1.68 +/- 0.21 vs 1.69 +/- 0.24, p = 0.952), but peak Mg++ levels were significantly higher in the multiple dose group (1.80 +/- 0.31 vs 2.61 +/- 0.86, p = 0.004). Cases that developed hypermagnesemia had slightly higher baseline Mg++ levels (1.78 +/- 0.22 vs 1.60 +/- 0.19 mEq/L, p = 0.041). In the multiple dose group, higher peak Mg++ levels were noted in cases involving ingestions of anticholinergic or opioid drugs (2.83 vs 1.98, p = 0.025). Hypermagnesemia developed in some cases with normal renal function, blood pressure, and urine output. We conclude that significant hypermagnesemia can occur rapidly after use of multiple dose Mg++ cathartics in standard doses in patients with normal renal function.