Which different groups of hallucinogenic drugs are known? 

1. The arylcyclohexylamine drugs = glutamate NMDA receptor antagonists

   • Phencyclidine (PCP) / aka ‘angel dust’ 

   • Ketamine / aka ‘special K’ 

2. Miscellaneous hallucinogens = 5-HT2A agonists 

   • Lysergic acid diethylamide (LSD) 

   • Mescaline

   • Psilocybin (the active ingredient of ‘shrooms’) 

Hallucinogenic effects can also be seen with Scopolamine and other lipophilic anticholinergic drugs. 

Name a few typical effects of the hallucinogens and discuss the clinical profile of a patient who had taken them: 

PCP is presumably the most dangerous of the hallucinogenic drugs and usually causes psychosis; along with the psychotic reactions, impaired judgement seen with PCP use often leads to reckless & life-threatening behaviours. PCP ought to be classified as a psychotomimetic drug.

The miscellaneous hallucinogens cause effects on the CNS that have been defined as “psychedelic” & “mind-revealing” and they also induce sensory distortion (especially visual = shape and colour distortion). Along with the psychedelic effects, they also cause somatic side effects like nausea, weakness & paraesthesia. These drugs also cause panic reactions and “bad trips” in some people. 

Patient clinical profile: 

PCP & Ketamine: 

• Psychedelic effects lasts roughly 1 hour post-consumption 

• These effects entail impaired memory function, visual alterations and increased blood pressure 

• Unpleasant dreams and vivid hallucinations

• In ↑ doses, these drugs may precipitate unpleasant “out-of-body” and “near-death” experiences 

Miscellaneous:

• Psychoactive effects 30 minutes post-consumption and can last up to 12 hours

• During that period of psychosis-like manifestations, patients appear incapable of making rational judgements and to understand common dangers – leading to increased risks for personal injury or accidents 

How is an overdose of LSD dealt with? 

Pre-hospital care: as in any drug overdose instance emergency medical responders should be contacted with an LSD overdose. In the meantime before they arrive, it is best to reassure & calm the patient down and remove any dangerous / distracting objects or removing the patient from a stressful environment, since sensory overload is a large contributor to “bad trips” experienced in overdose. Sometimes the person needs to be isolated from others to prevent any harmful behaviour – since the real danger of LSD use/overdose is the person’s own actions. 

Medications: Benzodiazepines can be administered to treat agitation, neuroleptic drugs such as haloperidol are not recommended since they may exacerbate psychotomimetic effects. Sometimes massive ingestions of LSD require additional supportive care such as respiratory support and endotracheal intubation; cardiotoxicities are treated symptomatically. 

How is an overdose of anticholinergics dealt with? 

Pre-hospital care involves transporting the patient to the closest ER with advanced life support capabilities, avoid ipecac syrup and ensure that the patient’s airway is open and breathing is present and can be maintained. 

Medical care: provide oxygen to the patient and intubate if severe CNS suppression is present. If the patient is agitated – pharmacological intervention with physostigmine / benzodiazepines can be used. Activated charcoal can be useful for GIT decontamination especially when sustained release anticholinergic agents were used; however usefulness significantly declines more than 1 hour post-ingestion of anticholinergics. 

Medications: pharmacological treatment for overdose of anticholinergic drugs consists of anticonvulsants, antitachydysrhythmics, sodium bicarbonate, physostigmine and sedatives. The recommended physostigmine initial dose for adults is 0.5-1mg by slow IV-push – higher doses can lead to cholinergic toxicity. Wait 15 minutes before re-dosing physostigmine.