The genera Rhododendron which belongs to Ericaceae family contains grayanotoxin which is also known as rhodotoxin or dromedotoxin or acetyandromedol. Grayanotoxin I is the major toxic isomer that is responsible for most of the symptoms [6]. The toxins are found in leaves, petals and nectar. There is an evidence of phenotypic correlation between toxin and herbivore defense [7]. The toxins have been studied in animal models as well. A study showed that the goats developed symptoms of poisoning when fed with rhododendron branches [8]. In an experiment, pigs also showed similar results [9].
Grayanotoxins bind to voltage gated sodium channels. This binding stabilizes the channel’s activated (open) state. This leads to increased sodium permeability and persistent depolarization in excitable tissues like brain, heart, gastrointestinal tract and muscles [10]. This action is similar to that of aconite poisoning. Due to their shared mechanism, both toxins produce comparable effects. Aconite is also found in higher altitude like Rhododendron [11]. However, appearance of plant and its flower can easily help to distinguish them. Poisoning presents with symptoms involving multiple organs; cardiac (bradycardia, hypotension), CNS (altered mental status, seizure), respiratory (shortness of breath, chest tightness), muscular (tremors, weakness) [5].
A case was reported in rural Nepal in a man presenting with dizziness and bradycardia after consuming dried white rhododendron flowers [6]. Similar case was also reported in Manang after consumption of wild honey consuming grayanotoxin [12]. Consumption of honey imported from Turkey developed similar symptoms in a patient in US [4]. Poon W et al. also reported a case of grayanotoxin poisoning in infants from Hongkong [13]. However, poisoning following ingestion of fresh flower has not been reported.
Mainstay of treatment for poisoning with rhododendron is supportive therapy. IV fluids for hypotension, atropine for bradycardia and occasionally vasopressors are required to maintain blood pressure. Prognosis is good and patients usually recover fully within 24 to 48 h [6, 11]. In this case, patient well responded to iv fluid bolus. Hence, Atropine and vasopressors were not considered.
Based on these findings, patient presenting with bradycardia, hypotension, and chest discomfort in the background of consumption of plants or plant products in high altitude, rhododendron intoxication should be suspected. However, not all species of rhododendron are toxic. Thus, laboratory evaluation is needed to confirm the presence of toxin in vivo and in vitro. In this case, laboratory confirmation was not possible due to unavailability of resources. The case was reported to Public Health Office, Dolakha.
WHO recommends established center to be provided expertise to manage the cases of poisoning. Prevention of poisoning is one of the important indicators of sustainable development goals [14]. It is vital to create public awareness regarding consumption of rhododendron products. This also calls for training needs for health care providers to manage locally relevant toxicity.