Overdoses Flashcards
How do amphetamines work?
Amphetamine exerts its behavioral effects by altering the use of epinephrine and norepinephrineas neuronal signals in the brain, primarily incatecholamine neurons in the reward and executive function pathways of the brain
What type of drugs are amphetamines?
Amphetamines are CNS and cardiovascular stimulants
What do amphetamine overdoses lead to?
Agitation, tachycardia, hypertension, widely dilated pupils, trismus and sweating
What detrimental processes can happen in severe amphetamine overdose?
In more severe cases, hyperthermia, disseminated intravascular coagulation, rhabdomyolysis, acute kidney injury and hyponatraemia predominate
How long are amphetamines detectable?
Amphetamines are detectable in the urine for 2-3 days
How would you manage an amphetamine overdose?
Agitation is controlled by diazepam 10–20 mg i.v. or chlorpromazine 50–100 mg i.m.
The peripheral sympathomimetic actions of amfetamines are antagonized by β- adrenoceptor blocking drugs.
If hyperthermia is present, dantrolene 1 mg/ kg body weight i.v. is used.
How do benzodiazepines work?
Benzodiazepines enhance GABA, decreasing the excitability of neurons
What does a benzodiazepine overdose lead to?
Benzodiazepines produce drowsiness, ataxia, dysarthria and nystagmus. Coma and respiratory depression develop in severe intoxication.
How would you manage benzodiazepine intoxication?
If respiratory depression is present in patients who have severe benzodiazepine poisoning, flumazenil 0.5–1.0 mg i.v. is given in an adult and this dose often needs repeating.
Flumazenil use often avoids ventilation.
It is contraindicated in mixed tricyclic antidepressant (TCA)/benzodiazepine poisoning and in those with a history of epilepsy because it may cause convulsions.
How do cannabis overdoses present?
Intravenous injection leads to watery diarrhoea, tachycardia, hypotension and arthralgia.
Heavy users suffer impairment of memory and attention and poor academic performance. There is an increased risk of anxiety and depression
How would you manage cannabis intoxication?
Reassurance is usually the only treatment required, although sedation with intravenous diazepam 10–20 mg i.v. in an adult or chlorpromazine 50–100 mg i.m. in an adult is sometimes required.
Hypotension requires i.v. fluids.
How does cocaine work?
Blockade of noradrenaline (norepinephrine), reuptake produces tachycardia, and inhibition of serotonin reuptake induces hallucinations
Cocaine also enhances CNS arousal by potentiating the effects of excitatory amino acids
Cocaine is also a powerful local anaesthetic and vasoconstrictor
How does a cocaine intoxication present?
After initial euphoria, cocaine produces agitation, tachycardia, hypertension, sweating, hallucinations, convulsions, metabolic acidosis, hyperthermia, rhabdomyolysis and ventricular arrhythmias
Dissection of the aorta, myocarditis, myocardial infarction, dilated cardiomyopathy, subarachnoid haemorrhage, and cerebral haemorrhage and infarction also occur
If a young person present with stroke or an MI, what do you have to check?
If they use cocaine
How would you manage a cocaine overdose?
Diazepam 10–20 mg i.v. is used to control agitation and convulsions
Active external cooling should be used for hyperthermia
How does GHB intoxication present?
Poisoning with GHB is characterised by aggressive behaviour, ataxia, amnesia, vomiting, drowsiness, bradycardia, respiratory depression and apnoea, seizures and characteristically coma, which is short-lived
How would you manage a GHB intoxication?
In a patient who is breathing spontaneously, the management of GHB poisoning is primarily supportive with oxygen supplementation and the administration of atropine for persistent bradycardia, as necessary
Those who are severely poisoned will require mechanical ventilation, although recovery is usually complete within 6–8 hours
How does a lithium overdose present?
Features of intoxication include thirst, polyuria, diarrhoea and vomiting and in more serious cases impairment of consciousness, hypertonia and convulsions; irreversible neurological damage occurs
Acute massive overdose may produce concentrations of 5 mmol/L (34.7 mg/L) without causing toxic features, whereas chronic toxicity is associated with neurological features at concentrations >1.5 mmol/L (6.94 mg/L).
How would you manage a lithium overdose?
Forced diuresis with sodium chloride 0.9% is effective in increasing elimination of lithium, though haemodialysis is far superior and should be undertaken particularly if neurological features are present
How does an opioid overdose present?
Cardinal signs of opiate poisoning are pinpoint pupils, reduced respiratory rate and coma
Hypothermia, hypoglycaemia and convulsions are occasionally observed in severe cases.
In severe heroin overdose, non-cardiogenic pulmonary oedema has been reported.
How would you manage an opioid overdose?
Naloxone 1.2–2.0 mg i.v. will reverse at least partially severe respiratory depression and coma
The duration of action of naloxone is often less than the drug taken in over dose, e.g. methadone, which has a very long half-life; infusion of naloxone is often required
In what people is a paracetamol overdose partially dangerous?
People with pre-existing liver disease, those suffering from acute or chronic starvation (patients not eating for a few days for example due to a recent febrile illness or dental pain), those suffering from anorexia nervosa and other eating disorders, those receiving enzyme inducing drugs, and those with HIV infection should be considered to be at greater risk and given treatment at plasma paracetamol concentrations lower than those normally used for interpretation
How does a paracetamol overdose present?
Following the ingestion of an overdose of paracetamol, patients usually remain asymptomatic for the first 24 hours or at the most develop anorexia, nausea and vomiting
Liver damage is not usually detectable by routine liver function tests until at least 18 hours after ingestion of the drug
Liver damage usually reaches a peak, as assessed by measurement of alanine transferase (ALT) activity and prothrombin time (INR), at 72–96 hours after ingestion
How would you manage a paracetamol overdose?
The treatment protocol is dependent on the time of presentation
Acetylcysteine (antioxidant) has emerged as an effective protective agent provided that it is administered within 8–10 hours of ingestion of the overdose (Can administer later, but efficacy goes down)
What is the risk of Acetylcysteine treatment?
Up to 15% of patients treated with intravenous acetyl cysteine (20.25h regimen) develop rash, angio-oedema, hypotension and bronchospasm
These reactions, which are related to the initial bolus, are seldom serious and discontinuing the infusion is usually all that is required
How do salicylate overdoses present?
Salicylates stimulate the respiratory centre, increase the depth and rate of respiration, and induce a respiratory alkalosis
Compensatory mechanisms, including renal excretion of bicarbonate and potassium, result in a metabolic acidosis
Thus, tachypnoea, sweating, vomiting, epigastric pain, tinnitus and deafness develop
How would you manage a salicylate overdose?
Fluid and electrolyte replacement is required and special attention should be paid to potassium supplementation. Severe metabolic acidosis requires at least partial correction with the administration of sodium bicarbonate intravenously.
Patients whose plasma salicylate concentrations are in excess of 500 mg/L (3.62 mmol/L) should receive urine alkalinisation
Haemodialysis is the treatment of choice for severely poisoned patients (plasma salicylate concentration >700 mg/L; >5.07 mmol/L)
