Rebound metabolic acidosis following intentional amygdalin supplement overdose.

Introduction: Amygdalin, marketed misleadingly as supplement "Vitamin B17," is a cyanogenic glycoside. When swallowed, it is hydrolyzed into cyanide in the small intestine, which causes histotoxic hypoxia via inhibition of cytochrome c oxidase. It remains available for purchase online despite a ban from the US Food and Drug Administration. We report a case of massive intentional amygdalin overdose resulting in recurrent cyanide toxicity after initial successful antidotal therapy.Case summary: A 33-year-old woman intentionally ingested 20 g of "apricot POWER B17 Amygdalin" supplements. She presented five hours post-ingestion with vital signs: P 127 bpm, BP 112/65 mmHg, RR 25/min, temperature 98.1 °F, and SpO2 98% RA. She was in agitated delirium, diaphoretic, and mydriatic. Her VBG was notable for a pH of 7.27 (rr 7.32-7.42) and lactate 14.1 mmol/L (rr 0.5-2.2), with ECG demonstrating QTc 538 ms (normal <440 ms). She was empirically treated with hydroxocobalamin and supportive care, but worsened clinically, requiring intubation and additional hydroxocobalamin and sodium thiosulfate, which resolved her toxicity. Twelve hours later, she developed recurrent hypotension, acidemia, and QTc prolongation that resolved with repeat hydroxocobalamin and sodium thiosulfate dosing.Discussion: Our case demonstrates rebound metabolic acidosis after massive amygdalin overdose. Toxicity was associated with prolonged QTc, which warrants further investigation into clinical significance. Redosing of combination antidotal therapy suggested efficacy without adverse effects.

Severe cyanide poisoning from an alternative medicine treatment with amygdalin and apricot kernels in a 4-year-old child.

BACKGROUND: The use of complementary and alternative medicine (CAM) is widespread in children with cancer and is poorly regulated. PATIENTS AND METHODS: Case report. RESULTS: We describe a case of severe cyanide poisoning arising from CAM use. A severely agitated, encephalopathic, unresponsive 4-year-old boy (initial Glasgow Coma Scale of 3) with a history of metastatic ependymoma was brought to our emergency department by ambulance services. Initial blood gas analysis demonstrated severe metabolic/lactic acidosis. On detailed questioning of the parents, the use of CAM including intravenous and oral "vitamin B 17" (amygdalin) and oral apricot kernel was reported. After administering sodium thiosulfate, rapid improvement in his medical condition with complete recovery without need for further intensive care treatment was seen. Serum cyanide level was markedly elevated. CONCLUSIONS: Cyanide poisoning can be the cause of severe encephalopathy in children receiving CAM treatment with substances containing cyanogenic glycosides.

Severe cyanide toxicity from 'vitamin supplements'.

The use of alternative medicines is increasing and poorly regulated. We describe a case of severe cyanide poisoning arising from amygdalin, a putative vitamin supplement. A 32-year-old woman arrived in the emergency department by ambulance unresponsive, shocked and with fixed dilated pupils. She was hypothermic and tachycardic but was breathing spontaneously. Despite her age, she had documented breast cancer with hepatic metastases. Conventional treatment having failed, she only took 'vitamin supplements' bought on the Internet, her father said. Over the next 6 h she required mechanical ventilation and increasing doses of inotropes. Diabetes insipidus developed. As the appropriateness of further treatment was considered, a relative arrived with her medications including 'vitamin B 17' or amygdalin. An Internet search identified this as a debunked cancer remedy and cyanogen. Serum thiocyanate level was markedly elevated. She recovered fully over 8 h. While various antidotes to cyanide exist, in this case supportive therapy alone proved effective.

Unproven methods of cancer management. Laetrile.

"Laetrile" is used interchangeably with "amygdalin" to designate natural substances, derived primarily from apricots and almonds, that can release cyanide, which is lethal to living organisms. In the 1920s, Dr. Ernst T. Krebs, Sr., formulated a theory that amygdalin could kill cancer cells. His theory was inconsistent with biochemical facts and has since been modified at least twice by his son, Ernst T. Krebs, Jr. Extensive work has been done by cancer scientists to test the claim that Laetrile fights cancer. Many animal experiments in the 1970s showed a complete lack of tumor killing by Laetrile. Reviews of the medical records of patients whose cancers were claimed to be reduced or cured after Laetrile treatment found insufficient medical evidence to judge Laetrile's efficacy. Finally, in a clinical trial in cancer patients reported in 1982, Laetrile neither caused shrinkage of tumors, nor increased survival time, nor alleviated cancer symptoms, nor enhanced well-being. Several reports in the medical literature document instances in which Laetrile has caused serious, life-threatening toxicity when taken in large doses in the manner prescribed by Laetrile advocates. In light of the lack of efficacy of Laetrile and its demonstrated ability to cause harm, Laetrile should not be used to treat cancer.

Clinical toxicology of cyanide.

Cyanide poisoning causes a high incidence of severe symptomatology and fatality. There are numerous sources of potential cyanide exposure. Without the history of cyanide exposure, diagnosis is often difficult. Treatment with supportive measures and available specific and efficacious antidotes frequently allows survival. The toxicology of cyanide, including sources, clinical features, diagnosis, and treatment, is reviewed.

Laetrile--an overview.

The original theory in the 1920s on the mode of action of Laetrile is described along with the research that followed in light of this theory. For over 40 years, studies were conducted, using test animals, in an attempt to substantiate the theory. All of these studies have shown Laetrile does not preferentially kill cancer cells. In spite of these studies, the misconception persists that Laetrile prevents and cures cancer. The legal and socioeconomic implications of Laetrile are examined and the role of health education in combating this problem is explored.

The current status of laetrile.

Amygdalin at various concentrations and with numerous impurities is the most common cyanogenic glycoside found in laetrile samples. Its chemical properties were first described in 1837, and pharmacologic studies have shown that ultimately it is broken down to HCN, benzaldehyde, and glucose by enzymes found in gut bacteria but not intracellularly in humans. Fatal and nonfatal toxicities to orally ingested cyanogenic glycosides have been reported worldwide. We review here the signs and symptoms of acute cyanide toxicity and its treatment. Substantial in-vitro and in-vivo testing in animal tumor systems has shown that amygdalin is entirely devoid of significant anticancer activity. Control animals often have lived longer than those treated with various doses and schedules of amygdalin. Acceptable clinical studies in humans are lacking, but such ventures would appear to be contraindicated from animal studies and observed human toxicities. We also discuss current legal-judicial aspects of laetrile therapy for cancer.