Risk factors for rhabdomyolysis following doxylamine overdose

When Overdose of Doxylamine Leads to Severe Rhabdomyolysis and Renal Failure That Requires Hemodialysis: A Case Report and Literature Review

A 52-year-old male with acute onset right-sided weakness, numbness, and buttock pain after consuming 30 tablets of doxylamine antihistamine the night prior. Laboratory tests showed elevated creatinine kinase, blood urea nitrogen, creatinine, troponins, liver transaminases, and phosphate. The patient was admitted to the medical intensive care unit for severe rhabdomyolysis, acute liver failure, and acute kidney injury secondary to doxylamine intoxication. Studies describe symptoms of severe doxylamine intoxication, such as impaired consciousness (coma), grand mal seizures, and cardiopulmonary arrest. Circulating myoglobin causes oxidative injury to the kidney through the formation of F2-isoprostanes leading to renal vasoconstriction. One study explained drug-induced rhabdomyolysis via two mechanisms: direct drug injury to the striated muscle and local muscle compression in seizure, coma, and metabolic abnormality. Treatment involves aggressive hydration with monitoring of serum electrolytes and renal function. Aggressive volume expansion via intravenous fluids remains critical in preventing rhabdomyolysis-associated nephrotoxicity and myoglobin-induced acute renal failure. Alkalinization of urine may prevent renal vasoconstriction resulting in enhanced excretion of the toxic metabolites of doxylamine and myoglobin via renal tubules, thereby reducing peak serum concentration time and preventing direct renal tissue damage.

Risk factors for delayed-onset rhabdomyolysis in doxylamine succinate intoxication patients

Background and Objectives:

Patients who overdose on doxylamine, hypnotic agent, usually exhibit good outcomes, but some experience serious complications. Some patients who present with normal creatinine phosphokinase levels in the emergency department later develop rhabdomyolysis during observation. We investigated factors associated with delayed-onset rhabdomyolysis in patients with doxylamine overdoses.

Methods:

Our investigation period was between 1 January 2011 and 29 February 2016. The initial blood samples were obtained for arterial blood gas analysis and measurements of the levels of electrolytes, creatinine phosphokinase, blood urea nitrogen, creatinine, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. Urine analyses including pH and occult blood analyses were performed. Follow-up samples were obtained at 6 and 12 h after admission. Delayed-onset rhabdomyolysis was defined by a follow-up serum creatinine phosphokinase level greater than fivefold the upper limit of normal (>1000 IU/L). Comparisons of categorical variables between groups were performed using either the χ2 or Fisher exact tests. Continuous variables were compared between groups using the Mann–Whitney U test.

Results:

A total of 337 patients were enrolled. The large amount of ingested doxylamine (odds ratio = 7.002), tachycardia (odds ratio = 2.809), low arterial blood gas analysis pH (odds ratio = 2.267), and presence of occult blood in the urine (odds ratio = 2.048) were significant associated with delayed-onset rhabdomyolysis.

Conclusion:

Laboratory follow-up examinations were required for patients, ingested more than 18 mg/kg doxylamine poisoning, who had pulses exceeding 120 beats/min, had arterial blood gas analysis pH values below 7.3 on blood and urine testing, and/or exhibited the presence of occult blood in the urine, even if the initial creatinine phosphokinase level was normal.

Accuracy of tablet counts estimated by members of the public and healthcare professionals

Objective

Intentional and accidental drug intoxication is commonly seen in the emergency department. When treating intoxicated patients, accessing the amount of the ingested drug is crucial albeit often difficult. We investigated the accuracy of estimating tablet counts when participants were asked to hold tablets in their fists and hands (semi-quantitative terms).

Methods

The widths and lengths of the participants’ hands were measured. Then, the subjects were asked to hold 5-mm round, 10-mm round, 10-mm oval, and 15-mm elliptical tablets using their hands and fists and to estimate the number of tablets they were holding. Differences between the estimated and actual numbers of tablets were examined.

Results

A total of 47 members of the public and 32 healthcare professionals were included in our study. In our analyses of the differences between the actual and estimated amounts of tablets held in the participants’ hands and fists, we found that the actual amount was higher than the estimated amount for all tablet types and in both groups. When participants held the tablets in the same manner (handful or fistful), the differences between the actual and estimated amounts were greater for 5- than 15-mm-sized tablets (P<0.05).

Conclusion

The treatment of patients presenting with drug overdoses to the emergency department should be based on the assumption that the actual amount of drugs the patients ingested is likely greater than the amount the patients state.

The associative factors of delayed-onset rhabdomyolysis in patients with doxylamine overdose

OBJECTIVES

The aim of this study was to investigate the associative factors of rhabdomyolysis in patients with doxylamine overdose who had normal creatine phosphokinase levels at admission.

METHODS

This study included 169 patients who visited the emergency department of a tertiary teaching hospital after doxylamine overdose between January 1, 1998, and March 31, 2009. Demographic information, clinical variables, and laboratory data were investigated for the associative factors of rhabdomyolysis.

RESULTS

Thirty-five (21%) of the 169 patients developed rhabdomyolysis. Patients who developed rhabdomyolysis differed from those who did not in the amount of doxylamine ingested, sex, heart rate, initial value of serum creatinine, and alanine aminotransferase. In the multivariate regression analysis, the only reliable predictors of rhabdomyolysis were the amount of doxylamine ingested (P = .004) and heart rate (P < .001).

CONCLUSION

Observation and laboratory follow-up are required for patients with large reported ingestions or tachycardia on admission, even if their creatine phosphokinase levels were normal.