15 – Stimulants Flashcards
Toxidromes
- Toxic syndromes
- Cluster of clinical signs characteristic of a group of agents
- Recognition of the toxidrome important even when exact agent is unknown
- *Symptomatic and supportive care is generally the same
- *Symptomatic and supportive care is generally the same
Cholinergic toxidrome
- Consider OP/carbamate poisoning
Anticholinergic toxidrome
- Atropine overdose
Opioid/sedative toxidrome
- CNS depressants in general
Sympathomimetic toxidrome
- Many stimulant drugs
- Mechanism: overstimulation of adrenergic, dopaminergic and/or serotonergic receptors
o NE, DA, 5-HT = vasoconstriction, increased cardiac contractility, CNS excitation - Ex. cocaine, amphetamines, MDMA, ecstasy, high dose serotonergic drugs, methylxanthines, ephedrine, bath salts
**What are the clinical presentations you see with sympathomimetic toxidrome?
- Mydriasis
- Tachycardia, hypertension, arrythmias
- Tachypnea
- Altered mental state: hyperexcitable, agitated, anxious (maybe seizures)
- Sweating, hyperthermia
- Increased GI motility
Antidepressants
- Widely used in human medicine
- Use in vet med: behaviour modification, anxiety, aggression
- Various categories
Antidepressants: mechanism and target organs
- Overstimulation of serotonin, dopamine and/or NE receptors
- **CNS and CV
- Variable toxicity (ex. SSRI seems to be more common)
Antidepressants: onset
- As early as 30 minutes post-exposure
o Signs can be delayed up to 12-24 hrs
Antidepressants: mild overdose clinical features
- Lethargy
- Ataxia
Antidepressants: moderate to severe overdoses clinical features
- *SEROTONIN SYNDROME
- Hypersalivation, vomiting, diarrhea
- Hyperexcitability, ataxia, agitation, tremors, seizures, hyperthermia
- Tachycardia, hypertension, arrythmias
- (TCAs: ileus, urinary retention=anticholinergic toxidrome)
What are other drugs that contribute to serotonin syndrome?
- Amphetamines
- 5HTP
- Tramadol
- Fentanyl, cocaine, bath salts
- CYP inhibitors
Antidepressants: management
- Decontamination if not contraindicated
- **Antidote for serotonin syndrome: CYPROHEPTADINE
- Sedation: acepromazine
- Supportive care
- IVFT, methocarbamol
- Correction of acid-base abnormalities
- Frequent monitoring
Antidepressants: diagnosis
- History of exposure, compatible clinical signs
Antidepressants: prognosis
- Generally excellent with prompt medical care
Beta-2 receptor agonists
- Blue rescue inhaler (contains salbutamol (albuterol))
- Vet med: relief of bronchoconstriction
o Equine and feline asthma - Difficult to establish toxicity
Beta-2 receptor agonists: exposure scenario
- Chewed inhaler
o Owners report hearing a ‘hiss’
o Dogs - Iatrogenic overdose is possible
Beta-2 receptor agonists: mechanism
- Overstimulation of beta receptors
o Loss of beta-2 selectivity = stimulation of beta 1 receptors
Beta-2 receptor agonists: target organ
- CV
- CNS
Beta-2 receptor agonists: onset
- Peracute
Beta-2 receptor agonists: clinical features
- *cardiovascular/respiratory
o Weakness, tachypnea, dyspnea
o Vasodilation, hypotension=reflex tachycardia
o Loss of beta-2 selectivity ( beta-1 effects: increased cardiac contractility, sinus tachycardia)
o Severe: myocardial hypoxia - *CNS: anxiety, restlessness, agitation, tachypnea, muscle tremors
- “burns” at back of mouth: pain control
Beta-2 receptor agonists; clinical pathology
- *hypokalemia
o Weakness, PU/PD, decreased urine concentrating ability, ECG abnormalities
o Mechanism: stimulates intracellular K+ shifting
Beta-2 receptor agonists: management
- Decontamination NOT possible
- *antidote: BETA-BLOCKERS
- *Correction of hypokalemia: potassium supplement
- Supportive care and monitoring
Beta-2 receptor agonists: diagnosis
- Chewed inhaler
- Sympathomimetic toxidrome
Beta-2 receptor agonists: prognosis
- Generally good with medical care
o Guarded: severe tachycardia
Cocaine
- Alkaloid from coca plant
- Therapeutic use (humans): local anesthetic
- Common drug abuse
- Mechanism: blocks reuptake of NE, 5HT, DA=increased catecholamine released=**SYMPATHOMIMETIC
- *target organs: *CNS, CV
Amphetamines
- Medications that contain it: ADHD medications, narcolepsy medications, weight loss
- Exposure scenarios: access to owner drugs/medications
- Mechanism: increased 5HT, DA, NE
Cocaine and Amphetamines: onset
- Within 30mins of ingestion
Cocaine and Amphetamines: clinical features
- Sympathomimetic toxidrome
- Severe cases: development of seizures, hyperthermia drives further progression
o Arrythmias, DIC, coma
Cocaine and Amphetamines: management
- No true antidote
- Symptomatic and supportive care
o Sedation: acepromazine
o Tremors/seizures control
o CV: beta-blockers, ECG, BP
o Blood gas
o IVLE
Cocaine and Amphetamines: diagnosis
- History of exposure
- Sympathomimetic toxidrome
- Urine drug screen
Cocaine and Amphetamines: prognosis
- Depends on severity of clinical signs and response to supportive care
What are the toxic differentials for sympathomimetics?
- Ephedrine, pseudoephedrine
- First generation antihistamines
- PCP, LSD, bath salts
- Methylxanthines (chocolate: caffeine, theobromine)
- Tremorgenic mycotoxins
- Strychnine, fluroacetate, metaldehyde
- Nicotine
- Water hemlock
- Lead, salt
- OP/carbamate insecticides, organochlorine insecticides
