Pediatric case of accidental oral overdose of methotrexate

Toxicological Aspects of Methotrexate Intoxication: Concentrations in Postmortem Biological Samples and Autopsy Findings

The aim of this study was the establishment of a UHPLC-QqQ-MS/MS method to determine methotrexate in postmortem biological samples and quantify the postmortem distribution of methotrexate in a case of fatal intoxication of this drug. A volume of 100 μL or 100 mg of postmortem specimens was precipitated with 400 μL of cold methanol and then analyzed using UHPLC-QqQ-MS/MS. The validation parameters of the method were as follows: limit of quantification: 0.1−1.0 ng/mL or ng/g, coefficient of determination: >0.998 (R2), matrix effect, intra- and inter-day accuracies and precisions: not greater than 13.6%, 14.8% and 17.4%, respectively. The recoveries were: 89.0−113.6%. The postmortem distribution studies revealed methotrexate concentrations as follows: blood—7.2 ng/mL, vitreous humor—0.8 ng/mL, liver—43.7 ng/g, kidney—20.6 ng/g, bone marrow—29.9 ng/g, lumbar vertebra—20.0 ng/g. The highest concentrations of methotrexate after poisoning were found in the tissues with the most rapidly dividing cells. The method described is simple, precise and selective. Methotrexate concentrations can be routinely determined in postmortem specimens. Determination of methotrexate in the postmortem biological material is possible after a few days of intensive treatment.

Use of charcoal hemoperfusion and hemodialysis in the treatment of methotrexate toxicosis in a dog

OBJECTIVE

To describe the successful use of charcoal hemoperfusion (HP) and hemodialysis (HD) in a dog in the treatment of methotrexate (MTX) toxicosis.

CASE SUMMARY

An American Pit Bull Terrier accidentally ingested 56.8 mg/m² of MTX. The patient's initial serum MTX concentration was 0.11 μmol/L. At this dosage, myelosuppression and gastrointestinal epithelial necrosis have been reported. Charcoal HP and HD in series were used to enhance elimination of MTX. Serial serum samples were obtained during the session at 0, 30, 60, 90, 120, 150, and 180 minutes and 12 hours after the session. These were later analyzed for MTX concentrations. Clearance of MTX was 73% and extraction ratio was 63% within the first 30 minutes of HP/HD. A 3-hour session eliminated all detectable traces of MTX. The dog tolerated the session well and did not develop any clinical signs of MTX toxicosis.

NEW OR UNIQUE INFORMATION PROVIDED

HP and HD together were highly effective in enhancing elimination of MTX from this patient. The prompt use of extracorporeal techniques decreased toxic concentrations of MTX to safer values, which prevented myelosuppression and gastrointestinal injury. HP and HD in conjunction or in place of traditional therapy may be a viable option for the treatment of acute toxic exposures to MTX.

A Large Case Series of Acute Pediatric Methotrexate Ingestions: Significant Clinical Effects Are Rare

OBJECTIVE

Significant adverse effects after acute pediatric methotrexate (MTX) exposures have been limited to parenteral exposures. Treatment recommendations for pediatric MTX exposures do not differentiate between routes of exposure. We report the incidence of significant clinical effects and drug-specific treatments reported in a large series of acute, pediatric MTX ingestions.

METHODS

Poison center records of all MTX ingestions by patients younger than 17 years during 2000 to 2005 were collected from 6 poison centers. The cases included all MTX ingestions including those with additional substances. One trained reviewer, blinded to the study purpose, used a standardized data collection form to extract study data. Missing or conflicting data were reconciled with predetermined process.

RESULTS

Forty-seven cases were documented for 6 years, 42 (89%) of which were unintentional. Thirty-six percent (17/47) were male. The mean age for the unintentional ingestions was 3.7 years (range, 20 days-17 y; median, 2 y). Five cases (11%) were intentional suicidal ingestions in teenagers. The mean dose in acute, unintentional ingestions (AUIs) in all children and in children younger than 6 years was the same, 8 mg (range, 2.5-17.5 mg). Eleven patients (23%) had follow-up greater than 12 hours. No patient with an AUI developed MTX-induced sedation, hepatotoxicity, renal insufficiency, seizures, or bone marrow suppression. Three patients with an AUI received folinic acid, but no patients in this group received sodium bicarbonate or hemodialysis. One patient with an intentional suicidal exposure developed hepatotoxicity, but the patient also ingested a toxic dose of acetaminophen and valproate. Hemodialysis was performed once on this patient. No patient died.

CONCLUSIONS

Acute pediatric MTX ingestion is uncommon. Methotrexate-induced seizure, renal failure, hepatic injury, and sedation were not documented in our series. Supportive care and observation only should be considered the mainstay of treatment of pediatric AUIs. Prospective verification of our findings is warranted.

Review of Experience of a Statewide Poison Control Center With Pediatric Exposures to Oral Antineoplastic Drugs in the Nonmedical Setting

The use of oral antineoplastic agents in nonmedical settings continues to increase. There are limited data available on pediatric exposures to these agents. We sought to identify characteristics of such exposures. We performed a retrospective review of database of a statewide poison system from 2000 to 2009 for all cases of pediatric exposures to oral antineoplastic agents, which took place in a nonmedical setting. Data collected include gender, age, agent of exposure, dose, drug concentration, reason for exposure, symptoms, outcomes, interventions, and length of hospital stay. There were a total of 328 patients. The mean average age was 4.1 years. Eighty-nine percentage (n = 293) was unintentional. Exposures to 21 different antineoplastic agents were identified. Methotrexate (n = 91) and 6-mercaptopurine (n = 47) were the most common agents encountered. Two hundred ninety-nine (91%) cases had no symptoms reported. When reported, gastrointestinal symptoms (n = 17) and central nervous system sedation (n = 6) were most common. One case of pancytopenia was reported. No deaths were reported in this series. Sixty-seven percent (n = 220) were managed at home, whereas 19 (6%) were admitted to a health care facility. Cases were followed by the poison control center for 0.34 days (SD = 1.40). In this study, exposures to oral antineoplastics were primarily unintentional, asymptomatic, and managed at home. Study limitations include possible reporting bias, inability to objectively confirm exposures, and limited duration of monitoring by the poison control center. In this retrospective review, no significant morbidity or mortality was reported from pediatric exposures to oral antineoplastic drugs in the nonmedical setting.

Accidental methotrexate ingestion in a 19-month-old child

The authors present the youngest reported case of a single oral overdose of methotrexate in an otherwise well 19-month-old child who was treated with delayed folinic acid rescue. Initial history revealed possible ingestion of up to 10 tablets, each containing 2.5 mg of methotrexate. The peak methotrexate level was 0.67 µmol/l measured 8 h following ingestion. Depending on the protocol, methotrexate levels that remain greater than 0.05-0.1 µmol/l for 24-48 h are associated with risk of toxicity. No adverse sequelae were noted during hospital admission despite delayed folinic acid rescue and there was no evidence of myelosuppression for up to 3 weeks following the overdose.

Use of calcium folinate in the management of accidental methotrexate ingestion in two dogs

CASE DESCRIPTION

2 English Pointers were suspected of having consumed toxic doses of methotrexate, a dihydrofolate reductase inhibitor frequently used in human and veterinary chemotherapeutic protocols.

CLINICAL FINDINGS

Potentially toxic plasma concentrations of methotrexate were detected in both dogs. Results of physical examination, a CBC, blood gas analysis, and serum biochemical analysis were predominantly unremarkable, although 1 dog had mild hyponatremia (1372 mmol/L; reference range, 140 to 153 mmol/L) and mild hypocalcemia (1.03 mmol of ionized calcium/L; reference range, 1.13 to 1.33 mmol of ionized calcium/L).

TREATMENT AND OUTCOME

Point-of-care determination of plasma methotrexate concentrations was not available; thus, palliative care was provided. Emesis was induced in both dogs by SC administration of apomorphine, and 3 doses of a suspension of activated charcoal with sorbitol were administered orally over a 6-hour period. Fluid diuresis was initiated in both dogs by administration of a compound sodium lactate solution, and N-acetylcysteine was administered IV to both dogs as a hepatoprotectant. A solution of calcium folinate (also known as leucovorin) was administered IV to both dogs to mitigate the effects of ingested methotrexate. No adverse effects associated with calcium folinate administration were identified, and no clinical or pathological evidence of methotrexate intoxication was detected.

CLINICAL RELEVANCE

IV administration of calcium folinate appeared to prevent the pathological sequelae of methotrexate intoxication without adverse effects. Administration of calcium folinate is recommended for the treatment of dogs with suspected or confirmed methotrexate overdose.

Four-year experience with methotrexate exposures

INTRODUCTION

Unintentional methotrexate (MTX) acute oral overdose is rarely reported.

METHODS

We conducted a retrospective chart review of all human exposure calls (>150,000 charts) for MTX ingestions reported to our Poison Center during 2000-2003.

RESULTS

Thirteen patients met the criteria. The average amount of MTX ingested was 13.03 mg (data from 7 cases), and the average patient age was 43 years (20 months to 80 years). No significant toxicities occurred.

DISCUSSION

Although intravenous MTX toxicity can be severe, this does not appear to be a phenomenon associated with either acute unintentional or suicidal oral ingestion.

Iatrogenically-related, fatal methotrexate intoxication: A series of four cases

Since the early eighties, the folic antagonist methotrexate (MTX) has been used in long-term treatment of rheumatoid arthritis. Because of the high toxic potential clinical and laboratory controls at regular intervals and patient education in order to avoid misadventure is of overriding importance. We present four cases of fatal MTX intoxication due to medical malpractice from the Tübingen Institute of Forensic Medicine autopsy material, which show the severe consequences of MTX overdose. It becomes evident that among non-rheumatologists there still is need for information about toxicity and dose limitation in MTX low-dose treatment.