Fly Agaric (Amanita Muscaria)

Amanita muscaria is a member of the Basidiomycete group of fungi [6] and is the classic toadstool depicted in literature and art with a red or orange cap that is often mottled with white spots. When dry these specimens have an orange/brown colour but the mottled spotting is still clearly visible (Fig. 14.1) and NPS samples are sold as bagged-up whole basidia (caps). Figure 14.1. Cap of Amanita muscaria showing the distinctive mottled spots characteristic of this species.

Figure 14.2 shows a NPS product purchased on the Internet and disingenuously labelled ‘not for consumption’, despite there being no rational reason other than for research purposes for possession of this material. Figure 14.2. A legal high purchase of Amanita muscaria (Fly Agaric) ‘labelled not for consumption’.

Within this genus there are a number of poisonous relatives including the panther (Amanita pantherina), the death cap (Amanita phalloides) and the delightfully termed destroying angel (Amanita verna) [6].

Fly agaric has a long history of use as a sedative material and the main psychoactive compounds within these species are thought to be analogues of the neurotransmitter gamma-aminobutyric acid (GABA) and glutamic acid, notably muscimol and ibotenic acid, respectively [7] (Fig. 14.3). Figure 14.3. Structures of Gamma amino butyric acid (GABA), muscimol, ibotenic acid, and muscarine.

The natural products muscimol and ibotenic acid are isoxazole alkaloids and possess some structural similarity with GABA and both act at various parts of the GABA receptor. Muscimol is derived from ibotenic acid by decarboxylation [8]. Muscarine is a cholinergic agonist and was thought to contribute to the overall psychoactivity of A. muscaria. However, it was reported later that the mushroom contained only trace amount of muscarine so it is unlikely to be responsible for the psychoactive effect [9].

The use of this material is steeped in history and it has been suggested that fly agaric is Soma, the vedic drug consumed by the Indo-Iranians. Poisoning by this species has been described as the ‘pantherina–muscaria’ syndrome and is ‘atropine like’ and comparatively rare. Symptoms can manifest between 30 minutes and two hours and include dizziness, confusion, tiredness, and increased sensitivity to visual and auditory stimuli. The ‘atropine-like’ effects also include dryness of mouth, pupil dilation and followed by drowsiness with a deep sleep [10,11]. Effects have been compared to alcohol consumption but with hallucinations, incoherent speech, possible seizures, vomiting, transient deep sleep or coma and persistent headache [4]. Treatment of toxicity associated with A. muscarina includes gut decontamination and in severe cases the use of benzodiazepines; some authors have suggested that the use of a cholinesterase inhibitor such as physostigmine may need to be considered [12]. In some countries fly agaric is consumed as food stuff but the red skin is removed and the mushroom is soaked or boiled and the resulting water is discarded, and this would presumably have an effect on reducing the concentrations of the isoxazoles, and therefore reduce the risk of psychotropic effects. A few case studies have been reported with one example of a 48- year-old male having consumed fly agaric, vomited and fell asleep 30 minutes after consumption, being found later comatose and having a seizure-like episode. Four hours after admission he was still comatose and was administered activated charcoal and awoke 10 hours after ingestion. At 18 hours his condition deteriorated with paranoid psychosis and visual and auditory hallucinations which persisted for five days. This case report suggested that a delay can occur with the onset of poisoning and that psychosis may last several days [13].

One case report has shown respiratory and cardiovascular depression with ingestion of fly agaric with myoclonus, flushing and mydriasis and treatment included the use of intravenous atropine, diazepam and mechanical/assisted ventilation [14].