Use of pralidoxime without atropine in rivastigmine (carbamate) toxicity

Abstract

<jats:p> Some experimental models suggest that the use of pralidoxime in carbamate toxicity is deleterious. Although pretreatment with atropine minimizes the adverse effect of pralidoxime reported in these models, concerns over the risks of pralidoxime in humans with carbamate poisoning continue. We present a unique case of carbamate toxicity treated successfully with pralidoxime alone. An 80-year-old woman with Alzheimer’s dementia presented to the emergency department with 3-4 days of lightheadedness, vomiting, diarrhea, and bilateral lower extremity muscle pain. Extensive review of systems was otherwise negative. Her vital signs were BP, 207/85 mmHg; pulse, 101 beats/min; rectal temperature, 36.6<jats:sup> °</jats:sup>C; respirations, 18/min; and SpO<jats:sub>2</jats:sub>, 95% breathing room air. Her bedside glucose measurement was 6.7 mmol/L. Physical examination revealed a confused, diaphoretic, ill-appearing woman with miosis and fasciculations of the tongue, eyelids, gastrocnemius and quadriceps bilaterally. The heart, lung, abdominal and head, eyes, ears, nose and throat examinations were otherwise unremarkable. Nine 5-cm<jats:sup>2</jats:sup> rivastigmine patches (9.5 mg/24-hour) were found adherent to her torso and lower extremities. The patches were immediately removed and underlying skin cleansed with soap and water. Laboratory values including complete blood count, basic metabolic panel, calcium, magnesium, phosphorus, troponin, coagulation studies and urinalysis were unremarkable. Due to the absence of pulmonary muscarinic findings, no atropine was administered. However, 1 g of pralidoxime was administered intravenously over 30 min to treat fasciculations. Within 30 min of this treatment, there was significant improvement in symptoms and resolution of fasciculations. She was admitted to the hospital, required no further pralidoxime therapy and was discharged after 3 days. Rivastigmine is a reversible (carbamate) cholinesterase inhibitor used to treat dementia. In overdose, cholinergic crisis is expected and in this case was precipitated by patch overuse. We believe there was a causal relationship between pralidoxime administration and the prompt resolution of symptoms and fasciculations. This case of apparently safe and effective pralidoxime use without concomitant atropine administration in a patient with carbamate toxicity reinforces recent data demonstrating the potential safety of pralidoxime in carbamate toxicity. </jats:p>

Characteristics of Pediatric Exposures to Antidementia Drugs Reported to a Poison Control System

“…14 Adult case reports report significant morbidity and death from rivastigmine exposure. [15][16][17] Our findings of higher rates of reported symptoms and health care facility evaluations with rivastigmine exposures are consistent with the increased morbidity seen in these prior case reports, and merit attention to more exposures from this drug in the years ahead.…”

Treatment rationale for dogs poisoned with aldicarb (carbamate pesticide) : clinical review

“…However, due to the fact that the temporary AChE-carbamate bond is rapidly reversed, this test must preferably be performed immediately, seeing that the diagnostic test results could become inconclusive if the test is not performed within a few hours 27 . A blood sample may be collected prior to initiating the treatment and the AChE concentration determined as soon as possible.…”

“…In contrast to organophosphate toxicity, the carbamate-induced inhibition of AChE is rapidly reversible with hydrolysis of the carbamylated complex often occurring within an hour 31 . The use of oximes in carbamate poisoning is controversial 5,12,29,55 or even contraindicated 27,50 and is therefore not recommended for the treatment of aldicarb poisoning in dogs. Many studies have indicated that the treatment of carbamate poisonings in animals with oximes has resulted in a protective ratio of less than 1 (i.e.…”

“…Potential toxicity of oximes when used in the treatment of carbaryl (carbamate) poisoning has been reported 55 . However, recent data suggest that this concern may be unwarranted 27,55 . If uncertainty exists as to whether the poisoning is due to an organophosphate or carbamate, the veterinarian may choose to include an oxime in the treatment protocol.…”

Medication errors related to transdermal opioid patches: lessons from a regional incident reporting system

“…The American Food and Drug Administration (FDA) states that opioids poses the highest risk of harm and death, among approved transdermal patches, because of their risk to cause respiratory depression [7] and has, along with other organizations, issued warnings regarding unsafe use of these patches [8,9]. There are also previous reports of serious and fatal cases due to erroneous administration of multiple patches of rivastigmine, an anticholinergic drug used to treat dementia [4,10]. Prevalence and characteristics of medications errors related to transdermal opioid patches has not been systematically compiled and presented in the scientific literature and such information is needed to develop effective preventive measures.…”