Specific Considerations II (Murray 2.8- 2.22) Flashcards
What is serotonin syndrome?
Clinical manifestation of excessive stimulation of serotonin receptors in the CNS. Occurs when excess serotonin accumulates in the CNS due to pharmacological mechanisms.
What is the serotonin syndrome triad?
Mental status changes, autonomic stimulation and neuromuscular excitation
Discuss the features of serotonin syndrome.
Neuromuscular excitation: clonus, hyperreflexia, increased tone, myoclonus, rigidity, tremor. ANS stimulation: diarrhoea, flushing, hypertension, hyperthermia, mydiasis, sweating, tachycardia. Mental state: apprehension, anxiety, agitation, confusion
If undetected what are the life-threatening complications of serotonin syndrome?
Rhabdomyolysis, renal failure, DIC and death
Describe the diagnostic algorythm for serotonin syndrome.
Ingestion or overdose –> spontaneous clonus (if yes then = toxicity, if no then…) —> inducible clonus/ocular clonus (if yes + agitation or diaphoresis or hypertonia and hyperpyrexia = toxicity, if no then…) —> tremor (if yes + hyperreflexia then = toxicity, if no then…) —> not clinically significant toxicity. You can also have clonus + hyperreflexia as a combination = toxicity.
Describe some scenarios in which serotonin syndrome may develop.
(1) No washout between changing drugs, (2) Introduction of new drug, (3) Drug interaction/stacking, (4) Interaction with illicit or herbal drugs, (5) Deliberate self-poisoning
What is the most common and most severe life-threatening combination of drugs that cause serotonin syndrome?
MAOI and SSRI combination
List the drugs/agents implicated in the development of serotonin syndrome.
Analgesia/antitussives (tramadol, pethidine, fentanl, dextromethorphan), Antidepressants (TCAs), Ilicit drugs (amphetamines, MDMA), Herbals (spirulina, St John’s wort), Lithium, MAOIs, SSRIs, SNRI, tryptophan
List the important differentials for serotonin syndrome.
NMS, anticholinergic syndrome and malignant hyperthermia
Differentiate serotonin syndrome, NMS, anticholinergic syndrome and malignant hyperthermia
Obs discussed in a separate question. Onset over days for NMS but minutes-24 hours for MH. <12 hours SS and ACS. Mydriasis in all but MH (= normal). Sweaty and pale in all but ACS (hot, red, dry). Increased tone/rigidity in all but ACS. NMS results in mutism/bradykinesia but the others all in agitated delirium. Pts are hyporeflexic in MH, normal reflexes in ACS, bradyreflexic in NMS and hyperreflexic + clonic in SS.
What drug causes malignant hyperthermia?
Inhaled anaesthetics
What drugs cause neuroleptic malignant syndrome?
Dopamine antagonists
Compare and contrast the obs for serotonin syndrome, NMS, anticholinergic syndrome and MH.
HR, BP, RR and temp are increased in all 4
What is a possible antidote for serotonin syndrome? What dose?
Cyprohepatadine, give orally/NGT - 8 mg every 8 hours for 24 hours. Others: olanzapine, chlorpromazine
What is cyprohepatadine?
An antihistamine with anti-serotonergic effects
How long should patients with mild serotonin syndrome be observed for?
At least 8 hours (12 hours if slow-release). If any ALOC/delirium then admit for up to 24 hours and then discharge.
What is anticholinergic syndrome best described as?
Agitated delirium with variable signs of peripheral muscarinic blockade
What are the clinical features of anticholinergic syndrome?
Central Features: agitated delirium, fidgeting, picking at the air, restless, mumbling/slurred speech, disruptive behaviour, tremor, myoclonus, coma, seizures. Peripheral Features: mydriasis, tachycardia, dry mouth, dry skin, flushing, hyperthermia, sparse/absent bowel sounds, urinary retention
List 10 classes of drugs with anticholinergic effects.
Antiparkinsonian drugs (amantadine, benztropine), antihistamines, antitussives, antidepressants (TCAs), antipsychotic agents (butyrophenones, phenothiazines - droperidol, haloperidol, chlorpromazine), atypical antipsychotics (olanzapine, quetiapine), anticonvulsant agents (carbamazapine), motion sickness agents (hyoscine), antimuscarinic agents (atropine, glycopyrrolate), topical eye agents (tropicamide), urinary antispasmodic agents (oxybutynin), muscle relaxants, plants/herbals
List the differential diagnosis of anticholinergic syndrome.
Encephalitis, hypoglycaemia, hyponatraemia, ictal phenomenon, NMS, neurotrauma, sepsis, serotonin syndrome, SAH, Wernicke’s encephalopathy
What is the antidote for anticholinergic syndrome?
Physostigmine
What is cholinergic syndrome?
Result of increased acetylcholine at central and peripheral muscarinic and nicotinic receptors
How does cholinergic syndrome arise?
Either acetylcholinesterase enzyme inhibition or direct agonist action at muscarinic or nicotinic receptors
What are most clinically significant cholinergic syndromes caused by?
Organophosphate or carbamate poisonings