Toxicology Flashcards
Explain the GABA receptor mechanism behind alcohol withdrawal
Chronic alcoholics GABA receptors lose sensitive due to overstimulation. Therefore, in withdrawal. In response glutamate (excitatory is produced in excess. In withdrawal, there is a removal of that inhibitor, and an imbalance leading to over-excitation
Symptoms of alcohol withdrawal
6-12h: tremor, sweating, headache, craving, anxiety.
12-24h- hallucination
24-48h: seizure
24-72h: delirium tremens
Treatment of alcohol withdrawal
Give thiamine. If CIWA >10, give a benzodiapine. In alcohol withdrawal without delirium tremens or seizures, give chlordiazepoxide. If delirium tremens or seizures, give short acting like lorazepam. Preferably symptom based approach.
Treatment of delirium tremens.
High dose diazepam or lorazepam + antipsychotics if not controlled after >130 mg chlordiazepoxide in 1h give antipsychotics (haloperidol or olanzapine)
Classic triad wernickes encephalopathy
Ataxia, oculomotor dysfunction, acute encephalopathy
Korsakoff syndrome causes
Chronic alcoholism, malabsorption, glucose infusion
Triad of korsakoff syndrome
Confabulation, irreversible anterograde and retrograde amnesia
Signs of opioid overdose
Needle track marks, pinpoint pupils, bradypnoea
Opioid overdose treatment
Naloxone
Effect of TCA by different blocking mechanisms
Anticholinergic: mydriasis, confusion, dry mucous membranes, hot and flushed
Serotonin reuptake inhibitor: seizures
Alpha-adrenergic blockade (present in arteries): hypotension due to vasodilation
Na channel blockade: widened QRS and dominant R wave in AVr
Management of TCA toxicity
If <2h, activated charcoal
If hypotension, arrhythmia or acidosis, IV sodium bicarbonate
Symptoms and management of benzodiazepine overdose
Main features are extreme sedation, unremarkable vital signs and anterograde amnesia. In severe cases in can progress to coma and respiratory depression.
Management - supportive mainly and can give flumazenil in non-benzo dependent ppl but not to benzo dependent due to risk of seizure
Explain physiology of aspirin overdose
Initially, aspirin stimulates the brain stem causing tachypnoea - respiratory alkalosis.
Then, uncoupling of oxidative phosphorylation causes buildup of acid products leading to a metabolic acidosis.
Symptoms of salicylate poisoning and management
Tachypnoea, confusion, coma,convulsions, N&V
Management includes activated charcoal if patient presents within 1h, , supportive measures, management of fluids and hypokalaemia.
Blood results in paracetamol overdose (LFTs, PT, INR, lactate)
LFTs: deranged
Lactate: high with acidosis
PT: prolonged
INR: high
Management of paracetamol overdose
<8h
Activated charcoal if within 1h
Take paracetamol conc at 4h. If warranted treat with acetylcystein until INR <1.4
> 8h
Take paracetamol conc STAT and start acetylcystein if indicated.
When to give acetylcystein immediately
When >150mg/kg and cannot get a paracetamol concentration within 8h of overdose. Or anytime after 24 with hepatic issues
Given as 150mg/kg over 1h, then 50mg over 4h, then 100mg over 16h.
Diagnostic ABG finding of CO poisoning and management
Carboxyhaemoglobin>20%. 100% oxygen via mask, hyperbaric oxygen if available.
Cocaine overdose symptoms
Hyper adrenergic state: agitation, anxiety, dilated pupil, diaphoresis, hyperreflexia, hyperthermia, hallucination…
When can you safely discharge a patient with paracetamol overdose
And at the end of the 24 hour treatment ALT is less than two times the upper limit of normal and a ALT is not more than double the admission measurement and I and our is 1.3 or less
A pattern of substance use that is causing damage or harm to the user
Harmful use. Can be physical, psychological or social.
A cluster of symptoms that occur after repeated substance use where taking the substance takes over aspects of life. Leads to tolerance, compulsion, withdrawal.
Dependency
Classical Pavlovian conditioning
Cravings become associated with cues
Operant conditioning
Drug makes you feel good so you want to do it again.
