Absorption of iron after experimental overdose of chewable vitamins

Antidote Use in the Critically Ill Poisoned Patient

The proper use of antidotes in the intensive care setting when combined with appropriate general supportive care may reduce the morbidity and mortality associated with severe poisonings. The more commonly used antidotes that may be encountered in the intensive care unit ( N-acetylcysteine, ethanol, fomepizole, physostigmine, naloxone, flumazenil, sodium bicarbonate, octreotide, pyridoxine, cyanide antidote kit, pralidoxime, atropine, digoxin immune Fab, glucagon, calcium gluconate and chloride, deferoxamine, phytonadione, botulism antitoxin, methylene blue, and Crotaline snake antivenom) are reviewed. Proper indications for their use and knowledge of the possible adverse effects accompanying antidotal therapy will allow the physician to appropriately manage the severely poisoned patient.

Iron intoxication in a dog consequent to the ingestion of oxygen absorber sachets in pet treat packaging

Oxygen absorbers are commonly used in packages of dried or dehydrated foods (e.g., beef jerky, dried fruit) to prolong shelf life and protect food from discoloration and decomposition. They usually contain reduced iron as the active ingredient although this is rarely stated on the external packaging. Although reduced iron typically has minimal oral bioavailability, such products are potential sources of iron poisoning in companion animals and children. We present a case of canine ingestion of an oxygen absorber from a bag of dog treats that resulted in iron intoxication necessitating chelation therapy. A 7-month-old female Jack Russell terrier presented for evaluation of vomiting and melena 8-12 h after ingesting 1-2 oxygen absorber sachets from a package of dog treats. Serum iron concentration and ALT were elevated. The dog was treated with deferoxamine and supportive care. Clinical signs resolved 14 h following treatment, but the ALT remained elevated at the 3-month recheck. The ingestion of reduced iron in humans has been reported to cause mild elevation of serum iron concentration with minimal clinical effects. To our knowledge, no cases of iron intoxication following the ingestion of oxygen absorbers have been reported. The lack of ingredient information on the packaging prompted analysis of contents of oxygen absorber sachets. Results indicate the contents contained 50-70% total iron. This case demonstrates that iron intoxication can occur following the ingestion of such products. Human and veterinary medical personnel need to be aware of this effect and monitor serum iron concentrations as chelation may be necessary.

Iron Ingestion: an Evidence-Based Consensus Guideline for Out-of-Hospital Management

From 1983 to 1991, iron caused over 30% of the deaths from accidental ingestion of drug products by children. An evidence-based expert consensus process was used to create this guideline. Relevant articles were abstracted by a trained physician researcher. The first draft of the guideline was created by the primary author. The entire panel discussed and refined the guideline before its distribution to secondary reviewers for comment. The panel then made changes in response to comments received. The objective of this guideline is to assist poison center personnel in the appropriate out-of-hospital triage and initial management of patients with suspected ingestions of iron by 1) describing the manner in which an ingestion of iron might be managed, 2) identifying the key decision elements in managing cases of iron ingestion, 3) providing clear and practical recommendations that reflect the current state of knowledge, and 4) identifying needs for research. This guideline applies to ingestion of iron alone and is based on an assessment of current scientific and clinical information. The expert consensus panel recognizes that specific patient care decisions may be at variance with this guideline and are the prerogative of the patient and the health professionals providing care, considering all of the circumstances involved. The panel's recommendations follow; the grade of recommendation is in parentheses. 1) Patients with stated or suspected self-harm or who are victims of malicious administration of an iron product should be referred to an acute care medical facility immediately. This activity should be guided by local poison center procedures. In general, this should occur regardless of the amount ingested (Grade D). 2) Pediatric or adult patients with a known ingestion of 40 mg/kg or greater of elemental iron in the form of adult ferrous salt formulations or who have severe or persistent symptoms related to iron ingestion should be referred to a healthcare facility for medical evaluation. Patients who have ingested less than 40 mg/kg of elemental iron and who are having mild symptoms can be observed at home. Mild symptoms such as vomiting and diarrhea occur frequently. These mild symptoms should not necessarily prompt referral to a healthcare facility. Patients with more serious symptoms, such as persistent vomiting and diarrhea, alterations in level of consciousness, hematemesis, and bloody diarrhea require referral. The same dose threshold should be used for pregnant women, however, when calculating the mg/kg dose ingested, the pre-pregnancy weight of the woman should be used (Grade C). 3) Patients with ingestions of children's chewable vitamins plus iron should be observed at home with appropriate follow-up. The presence of diarrhea should not be the sole indicator for referral as these products are often sweetened with sorbitol. Children may need referral for the management of dehydration if vomiting or diarrhea is severe or prolonged (Grade C). 4) Patients with unintentional ingestions of carbonyl iron or polysaccharide-iron complex formulations should be observed at home with appropriate follow-up (Grade C). 5) Ipecac syrup, activated charcoal, cathartics, or oral complexing agents, such as bicarbonate or phosphate solutions, should not be used in the out-of-hospital management of iron ingestions (Grade C). 6) Asymptomatic patients are unlikely to develop symptoms if the interval between ingestion and the call to the poison center is greater than 6 hours. These patients should not need referral or prolonged observation. Depending on the specific circumstances, follow-up calls might be indicated (Grade C).

Whole bowel irrigation (WBI) in acute iron poisoning — case report

Objective: In theory, WBI (whole bowel irrigation) is indicated in iron poisoning, but the existing data are still insufficient to support or exclude its efficacy.

Case report: A 46 year-old female admitted to the Toxicology Department due to suicidal ingestion of 5000 miligrams of elemental iron (57 mg/kg) in sustained-release preparation. WBI was instituted at 2 hours after ingestion, because abdominal X-ray showed mass of tablet material inside stomach and past pylorus. After 3-hour WBI subsequent X-ray revealed residual opacities in small intestine. Levels of serum iron were increasing 289 μg/dL on admission, (1,5 h post ingestion) 408 μg/dL (6 h after ingestion), 424 μg/dL (after 12 h). WBI was continued within 7 hours, until there was no radiographic evidence of toxin remaining in the gastrointestinal tract and clear rectal effluent was apparent. Subsequent serial serum iron concentrations were as follows: 389 μg/dL (after 14 h), 239 μg/dL (after 21 h), 119 μg/dL (after 36 h). Since the patient was asymptomatic did not undergo deferoxamine therapy. Patient recovered without sequelae.

Conclusion: WBI seems to be beneficial in early stage of iron intoxication ensuring rapid and effective cleansing of gut, and decreasing toxin absorption. Authors believe that the use of early WBI allows to provide supportive care and avoid deferoxamine treatment.

Management of drug-induced liver disease

The treatment and prevention of drug-induced liver injury starts with the recognition of hepatotoxicity at the earliest possible time so that the suspected drug can be discontinued expeditiously. Both liver enzyme monitoring and vigilance for signs of hypersensitivity involving the liver are useful strategies for many agents known to cause hepatocellular necrosis leading to liver failure. Specific antidotes to prevent or limit hepatic damage exist for only a few drugs, the most important being N-acetylcysteine for the treatment of acetaminophen hepatotoxicity. Corticosteroids are of unproven benefit in the setting of fulminant failure. Ursodiol may be helpful in instances of cholestatic injury. For other agents, supportive measures and the increasing use of liver-assist devices as well as emergency liver transplantation are available when drug injury evolves into irreversible liver failure. It is hoped that a better understanding of hepatotoxicity mechanisms will lead to the development of more specific and effective forms of therapy in the near future.

Efficacy of the cation exchange resin, sodium polystyrene sulfonate, to decrease iron absorption

BACKGROUND

Iron is not bound by charcoal; therefore, a method of binding iron in the gastrointestinal tract to prevent absorption in iron overdose is needed. This study investigated the efficacy and safety of sodium polystyrene sulfonate to prevent absorption of iron in human volunteers.

METHODS

Six adult volunteers completed this prospective crossover trial. Following an oral dose of elemental iron 10 mg/kg, each subject received sodium polystyrene sulfonate 30 g or water as control. Baseline and serial serum iron samples were drawn to determine pharmacokinetic parameters.

RESULTS

A trend toward increased time to peak following sodium polystyrene sulfonate compared to the control arm (5.7 vs 3.6 hours) was observed but was not statistically significant (p = 0.517). A trend toward smaller area-under-the-curve for the sodium polystyrene sulfonate was evident but was not statistically significant (p = 0.77). Iron concentration increased on average 298 mcg/dL and 370 mcg/dL above baseline in the treatment and control arms (p = 0.44). Sodium polystyrene sulfonate is not an effective method of decontamination for iron overdose.

Usefulness of the total iron binding capacity in the evaluation and treatment of acute iron overdose

The ingestion of iron-containing products is a potential toxicologic emergency. The total iron binding capacity (TIBC) has been used widely as a predictor of end-organ toxicity and a guide to the need for deferoxamine therapy. When the TIBC is greater than the serum iron concentration (SIC), it is held that no free iron is present to cause toxicity. The TIBC fails as a marker of toxicity for several reasons. First, the laboratory methods used to measure TIBC are inaccurate in the setting of iron overload. Second, the presence of deferoxamine, the antidote for iron poisoning, has been shown to make the TIBC measurement inaccurate. Third, TIBC measurements have been shown to be variable. Finally, studies and case reports demonstrate toxicity even when the TIBC is greater than the SIC. These shortcomings of the TIBC invalidate it as a predictor of toxicity in iron poisoning.

The effect of oral deferoxamine on iron absorption in humans

Acute iron overdose is a serious cause of morbidity and mortality, however, optimal gastric decontamination procedures in iron overdose are unclear. In order to determine the effectiveness of oral deferoxamine mesylate solution in humans to prevent the absorption of iron in acute exposures, the following prospective case control crossover study was designed. Seven informed adult human volunteers were given an oral dose of 5 mg/kg elemental iron alone in a control phase and again in an experimental phase followed by a single equimolar dose of oral buffered deferoxamine solution. Plasma iron concentrations were determined spectrophotometrically for eight hours following administration of iron alone and following doses of iron with deferoxamine. There was no significant difference in peak iron concentration, time to peak iron concentration or area-under-the-curve between the two groups. Based on our results, equimolar doses of oral deferoxamine do not appear to decrease the absorption of low doses of oral iron in humans.