Toxicology (main)
(Redirected from Drugs and toxins)
Background
Epidemiology
- In 2014, ~2.2million human exposures reported to US poison control centers
- Top 5 substance classes:
- analgesics (11%)
- cosmetics/personal care products (8%)
- household cleaning substances (8%)
- sedatives/hypnotics/antipsychotics (6%)
- antidepressants (4%)
- 1,835 human exposures resulted in death
Autonomic Nervous System Receptors and Their Effects
- Parasympathetic - ACh is transm
- Muscarinic
- receptors in heart, eye, lung, GI, skin and sweat glands
- Bradycardia
- Miosis
- Bronchorrhea / Bronchospasm
- Hyperperistalsis (SLUDGE)
- Sweating
- Vasodilation
- Nicotinic
- receptors in both sympathetic and parasympathetic nervous systems
- fasciculations, flaccid paralysis
- ?Mild bradycardia, hypotension
- Muscarinic
- Sympathetic
- Alpha effects (vessels, eye, skin)
- Mydriasis, hypertension, sweating
- Beta effects (heart, lungs)
- Tachycardia, bronchodilation
- Alpha effects (vessels, eye, skin)
Clinical Features
Toxidrome Chart
| Finding | Cholinergic | Anticholinergic | Sympathomimetic | Sympatholytic^ | Sedative/Hypnotic |
| Example | Organophosphates | TCAs | Cocaine | Clonidine | ETOH |
| Temp | Nl | Nl / ↑ | Nl / ↑ | Nl / ↓ | Nl / ↓ |
| RR | Variable | Nl / ↓ | Variable | Nl / ↓ | Nl / ↓ |
| HR | Variable | ↑ | ↑ (sig) | Nl / ↓ | Nl / ↓ |
| BP | ↑ | ↑ | ↑ | Nl / ↓ | Nl / ↓ |
| LOC | Nl / Lethargic | Nl, agitated, psychotic, comatose | Nl, agitated, psychotic | Nl, Lethargic, or Comatose | Nl, Lethargic, or Comatose |
| Pupils | Variable | Mydriatic | Mydriatic | Nl / Miotic | |
| Motor | Fasciculations, Flacid Paralysis | Nl | Nl / Agitated | Nl | |
| Skin | Sweating (sig) | Hot, dry | Sweating | Dry | |
| Lungs | Bronchospasm / rhinorrhea | Nl | Nl | Nl | |
| Bowel Sounds | Hyperactive (SLUDGE) | ↓ / Absent | Nl / ↓ | Nl / ↓ |
- ^Consider Sympatholytic when looking at Sedative OD or someone who doesn't respond to Narcan
- Withdrawal from substances have the opposite effect
Differential Diagnosis for Specific Signs
Hyperthermia
- Altered Metabolism
- Aspirin (Salicylate) Toxicity
- Withdrawal states (e.g. baclofen withdrawal
- Thyroid hormones
- Dinitrophenols
- Increased Muscle Activity
- Withdrawal, sympathomimetics
- MAOI Toxicity
- PCP, LSD
- Lithium
- Serotonin Syndrome
- Impaired Heat Dissipation
- Anticholinergics
- Antihistamines
- Antipsychotics, TCAs
- Phenothiazines, Lithium, LevoDopa
- Malignant Hyperthermia
- Anesthetics
- Neuroleptic Malignant Syndrome
Hypothermia
- Exposure
Increased Respiratory Rate
- Direct stimulation
- Aspirin (Salicylate) Toxicity
- Metabolic Acidosis
- Dinitrophenol, pentachlorophenol
- hepatic/renal failure
- CNS stimulants (cocaine, amphetamine, theophylline)
- Tissue Hypoxia
Respiratory Depression
- Central Depression
- Antipsychotics
- Chlorinated hydrocarbons
- Sedative/Hypnotics (Ethanol Toxicity, glycols)
- Tricyclic (TCA) Toxicity
- Lomotil toxicity
- Opioids
- Marijuana
- Muscle Failure
- Organophosphates
- Marine Toxins
- Nicotine
- Strychnine
- Botulism
- Mojave rattlesnake, Cobra
Bradycardia
PACED
- Propranolol/beta-blockers, poppies (opiates), propoxyphene,
- Anticholinesterases, antiarrhythmics
- Clonidine, calcium channel blockers
- Ethanol or other alcohols
- Digoxin, digitalis
Tachycardia
FAST
- Free base or other forms of cocaine
- Anticholinergics, antihistamines, antipsychotics, amphetamines, alcohol withdrawal
- Sympathomimetics (cocaine, caffeine, amphetamines, PCP), solvent abuse, strychnine
- Theophylline, TCA, thyroid hormones
Hypotension
CRASH
- Clonidine, calcium channel blockers
- Rodenticides (with arsenic, cyanide)
- Antidepressants, aminophylline, antihypertensives
- Sedative/Hypnotics
- Heroin or other opioids
Hypertension
CT SCAN
- Cocaine
- Thyroid supplements
- Sympathomimetics
- Caffeine
- Anticholinergics, amphetamines
- Nicotine
Miosis
COPS
- Cholinergics, clonidine, carbamates
- Opioids, organophosphates
- Phenothiazines, pilocarpine, pontine hemorrhage
- Sedative/Hypnotics
Mydriasis
SAW
- Sympathomimetics
- Anticholinergics
- Withdrawal syndromes
Coma
LETHARGIC
- Lead, lithium
- Ethanol, ethylene glycol
- TCA, thallium, toluene
- Heroin, hemlock, hepatic encephalopathy, heavy metals, hydrogen sulfide, hypoglycemics
- Arsenic, antidepressants, anticonvulsants, antipsychotics, antihistamines
- Rohypnol, risperidone
- GHB
- Isoniazid, insulin
- Carbon monoxide, cyanide, clonidine
Seizures
OTIS CAMPBELL
- Organophosphates, oral hypoglycemics (e.g. sulfonylurea)
- TCA, theophylline, tramadol
- Isoniazid, Insulin
- Sympathomimetics, salicylates, strychnine
- Camphor, carbon monoxide, cyanide, chlorinated hydrocarbons, cocaine
- Anticholinergics (antihistamines), amphetamines, antidepressants (citalopram, TCAs, bupropion)
- Methanol, Methylxanthines (theophylline, caffeine), MAOI
- PCP, propranolol
- Benzodiazepine withdrawal, bupropion, botanicals (hemlock, nicotine), GHB
- ETOH withdrawal, ethylene glycol
- Lead, lithium
- Lidocaine, lindane (pesticide, scabies)
Skin findings
Diaphoresis
SOAP
- Sympathomimetics
- Organophosphates
- Acetylsalicylic acid and other salicylates
- PCP
Dry skin
Bullous lesions/blisters
Flushed/red appearance
- Anticholinergics
- Niacin
- Boric acid
- Carbon monoxide
- Cyanide
Cyanosis
- Benzocaine and other local anesthetics
- Cyanokit, nitrites, nitrates, well water (nitrates)
- Antimalarials
- Quinolones
- Dapsone (used to treat leprosy, PCP pneumonia, toxoplasmosis, dermatitis herpetiformis, brown recluse bite)
- Aniline dyes
- Phenazopyridine[1]
- Nitrates, nitrites
- Ergotamine toxicity|Ergotamine]]
Acneiform rash
- Bromides
- Chlorinated aromatic hydrocarbons
Evaluation
Toxicological Exam
- All vital signs (Temp, RR, HR, BP) + bedside glucose
- Neurologic exam
- Level of consciousness
- Pupillary exam
- Motor response
- DTRs
- Skin Exam - moisture, temp, evidence of injection drug abuse
- Lung Exam
- Bowel Sounds
- ECG (ie. look for QT prolongation, QRS prolongation, etc)
- Consider CBC, BMP, urinalysis (with ẞ-HCG if appropriate), urine toxicology screen, serum alcohol concentration, VBG
- The urine screen is a qualitative test -> positivity ≠ acute toxicity
- It can be falsely positive due to cross-reactivity
- It can be falsely negative if the substance ingested does not cross-react with the tested analyte
- The diagnosis of intoxication is clinical!!!
Management
- Depends on agent
- See antidotes
- "Coma cocktail" when suspecting toxic ingestion (mnemonic = "DONT")
- Dextrose (50mg IV)
- Oxygen
- Naloxone (0.2-0.4mg IV/IM, repeat dose 1-2mg)
- Empiric opioid ingestion treatment
- Thiamine (50-100mg)
- Treat or avoid Wernicke encephalopathy
- Though some suggest giving thiamine prior to dextrose, do NOT let this delay treatment of hypoglycemia!
- Case reports of dextrose precipitating Wernicke's involved thiamine-deficient patients receiving prolonged course of IV glucose, NOT with single bolus[2][3]
Disposition
- Depends on agent
See Also
- Altered mental status
- Traditional chinese medicine toxicology
- Drug Levels
- Antidote
- Camphor toxicity
- In-Training Exam Review
References
- ↑ Jeffery WH, Zelicoff AP, Hardy WR. Acquired methemoglobinemia and hemolytic anemia after usual doses of phenazopyridine. Drug Intell Clin Pharm. 1982 Feb;16(2):157-9.
- ↑ Donnino MW, Vega J, Miller J, Walsh M. Myths and misconceptions of Wernicke's encephalopathy: what every emergency physician should know. Ann Emerg Med. 2007;50(6):715-21.
- ↑ Gussow, L. Myths of Toxicology: Thiamine Before Dextrose. Emergency medicine news. 2007;29(4):3-11.