Updated: Mar 24, 2009
Poisoning from sympathomimetic agents occurs secondary to the use of prescription and nonprescription agents. The public commonly uses prescription sympathomimetic agents, especially for treating diseases such as asthma and narcolepsy. Examples of nonprescription sympathomimetic agents include the over-the-counter cold agents (containing ephedrine), illegal street drugs (eg, cocaine, amphetamines, methamphetamine), dietary supplements (eg, ephedra alkaloids), and the very popular illicit designer drugs (eg, 3,4-methylenedioxy methamphetamine [MDMA, "ecstasy"]).
Cocaine is one of the most commonly abused drugs in the United States, especially in urban areas. Methamphetamine is frequently made and abused throughout the United States. Recent reports state that methamphetamine use has been linked to a rise in HIV transmission. In 2007, approximately 46,000 cases of sympathomimetic and street drug exposures were reported to the American Association of Poison Control Centers.1 Even more alarming are the number of out-of-hospital cardiac arrests secondary to sympathomimetic toxicity reported in the Seattle area and the number of deaths nationally secondary to sympathomimetics. Cocaine, methamphetamine, and ecstasy are 3 of the most common drug-related causes of emergency department visits in the United States. Methamphetamine use in trauma patients has increased significantly and has been associated with a financial burden on trauma centers.2
The many different sympathomimetic agents produce their physiologic and toxicologic properties through several different mechanisms. Toxicity secondary to these agents typically presents with classic sympathomimetic signs and symptoms that include tachycardia, hypertension, diaphoresis, hyperthermia, agitation, and combativeness.
The general treatment for preventing the potentially significant end-organ damage that is possible after overdose is similar for the sympathomimetic agents because their clinical presentation of toxicity is similar. Most sympathomimetic agents produce central stimulation following overdose. When central stimulation occurs in patients, the most important treatment involves physical and, more importantly, pharmacological control of their agitation.
Sympathomimetic agents produce their physiologic and toxic effects by 5 different mechanisms, as follows:
The pathophysiology of sympathomimetic toxicity is much more involved than what was just listed. To explore these mechanisms in more detail, references for further reading are provided in the reference section. An important clinical point is that the signs and symptoms produced by these 5 different mechanisms are very similar. In most cases, clinical poisoning by one sympathomimetic agent is indistinguishable from that of a second sympathomimetic agent with a different mechanism of action.
Sympathomimetic poisoning continues to be a very common toxicologic emergency. The 2007 Annual Report of the American Association of Poison Control Centers' National Poison Data System reported approximately 46,000 sympathomimetic and street drug exposures and approximately 180 fatalities.1 This category includes exposures to amphetamines, cocaine, and methamphetamine.
In 2007, the AAPCC reported approximately 180 deaths from stimulants and street drugs.1
The exact number of stimulant deaths in 2006 is unknown but is expected to be greater than the number reported by the AAPCC.
No scientific data have demonstrated that outcomes of sympathomimetic exposure are dependent on race.
No scientific data have demonstrated that outcomes of sympathomimetic exposure are dependent on sex.
Adult sympathomimetic toxicity produces typical adrenergic signs and symptoms, some of which can be deadly.
| Alcohol and Substance Abuse Evaluation | Scorpion Envenomations |
| Delirium Tremens | Toxicity, Amphetamine |
| Hypertensive Emergencies | Toxicity, Cocaine |
| Hyperthyroidism, Thyroid Storm, and Graves
Disease | Toxicity, Methamphetamine |
| Hyponatremia | Toxicity, Phencyclidine |
| Panic Disorders | Toxicity, Thyroid Hormone |
Alcohol-sedative withdrawal presents in a manner similar to that of sympathomimetic poisoning. In addition to the above listed differential, sympathomimetic poisoning can present in a manner similar to sedative-hypnotic withdrawal and monoamine oxidase inhibitor poisoning.
Treatment of sympathomimetic toxicity is focused on controlling agitation, managing seizure activity, and treating hypertension unresponsive to sedation. The most accepted pharmacologic option for controlling agitation is the use of benzodiazepines. Butyrophenones lower the seizure threshold, increase the risk of hyperthermia, and may prolong the QT interval (eg, droperidol); the use of butyrophenones is NOT recommended. Sympathomimetic-induced seizures should be treated with benzodiazepines or barbiturates (eg, phenobarbital). Hypertension should be managed with a short-acting, easily titrated agent (eg, nitroprusside) if it is not controlled with benzodiazepine-induced sedation.
Used for controlling sympathomimetic-induced agitation.
Depresses all levels of CNS (eg, limbic and reticular formation), possibly by increasing activity of GABA.
Individualize dosage and increase cautiously to avoid adverse effects. Easily titrated with a long half-life.
0.2 mg/kg IV at 2 mg/min; not to exceed 20 mg (as a single dose); may repeat
0.2-0.5 mg/kg IV
<5 years: not to exceed 5 mg
>5 years: not to exceed 10 mg
Increases toxicity of benzodiazepines in CNS with coadministration of phenothiazines, cimetidine, barbiturates, alcohols, and MAOIs
Documented hypersensitivity; narrow-angle glaucoma
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Caution with other CNS depressants, low albumin levels, or hepatic disease (may increase toxicity); monitor for respiratory depression and hypotension
Sedative hypnotic with short onset of effects and relatively long half-life.
By increasing the action of GABA, a major inhibitory neurotransmitter in the brain, may depress all levels of CNS, including limbic and reticular formation.
Excellent when patient requires sedation for more than 24 h.
0.044 mg/kg (2-4 mg) IV; titrate to effect
Status epilepticus: 4 mg IV over 2-5 min; may repeat second dose in 10-15 min if prn; not to exceed 8 mg/dose
Infants and children: 0.1 mg/kg IV slowly over 2-5 min; repeat in 10-15 min at 0.05 mg/kg prn; not to exceed 4 mg/dose
Adolescents: 0.07 mg/kg IV slowly over 2-5 min; repeat in 10-15 min prn; not to exceed 4 mg/dose
Toxicity of benzodiazepines in CNS increases when used concurrently with alcohol, phenothiazines, barbiturates, and MAOIs
Documented hypersensitivity; preexisting CNS depression, hypotension, and narrow-angle glaucoma
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Caution in renal or hepatic impairment, myasthenia gravis, organic brain syndrome, or Parkinson disease; monitor for respiratory depression with high or repeated doses; contains benzyl alcohol, which may be toxic to infants in high doses
Used as alternative in termination of refractory status epilepticus. Because water soluble, takes approximately 3 times longer than diazepam to peak EEG effects. Thus, clinician must wait 2-3 min to fully evaluate sedative effects before initiating procedure or repeating dose. Has twice the affinity for benzodiazepine receptors than diazepam. May be administered IM if unable to obtain vascular access.
0.01-0.05 mg/kg (usually 0.5-4 mg; up to 10 mg) IV slowly over several min; may repeat q10-15min until adequate response achieved
<32 weeks: 0.5 mcg/kg/min IV infusion
>32 weeks: 1 mcg/kg/min IV infusion
Children: 0.05-0.2 mg/kg IV over 2-3 min, followed by 1-2 mcg/kg/min continuous infusion
Status epilepticus (refractory to standard therapy), >2 months and children: 0.15 mg/kg IV, followed by continuous infusion of 1 mcg/kg/min IV; titrate upward q5min until seizures controlled
Sedative effects may be antagonized by theophyllines; narcotics, cimetidine, ethanol, and erythromycin may accentuate sedative effects because of decreased clearance; reduce dose of thiopental by 15% when using together
Documented hypersensitivity; preexisting hypotension, narrow-angle glaucoma, and sensitivity to propylene glycol (diluent)
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Caution in congestive heart failure, pulmonary disease, renal impairment, hepatic failure, neuromuscular disease, hypotension, and patients >60 y; monitor for respiratory depression with high or repeated doses; consider lower dosages with organic brain syndrome and patients who may have inhibition of benzodiazepine metabolism and clearance (eg, using nicotine, taking cimetidine)
Interferes with transmission of impulses from thalamus to cortex of brain. Used for sympathomimetic-induced seizure unresponsive to diazepam.
15-20 mg/kg IV load
Administer as in adults
May decrease effects of chloramphenicol, digitoxin, corticosteroids, carbamazepine, theophylline, verapamil, metronidazole, and anticoagulants (patients stabilized on anticoagulants may require dosage adjustments if added to or withdrawn from their regimen); coadministration with alcohol may produce additive CNS effects and fatality; chloramphenicol, valproic acid, and MAOIs may increase toxicity; rifampin may decrease effects; induction of microsomal enzymes may result in decreased effects of oral contraceptives in women (must use additional contraceptive methods to prevent unwanted pregnancy); menstrual irregularities also may occur
Documented hypersensitivity; severe respiratory disease, marked impairment of liver function, and nephritic patients
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
In prolonged therapy, evaluate hematopoietic, renal, hepatic, and other organ systems; caution in fever, hyperthyroidism, diabetes mellitus, and severe anemia because adverse reactions can occur; caution in myasthenia gravis and myxedema; monitor for respiratory depression and hypotension
Control sympathomimetic-induced hypertension.
Rapidly acting, easily titrated antihypertensive. Produces vasodilation and increases inotropic activity of the heart. At higher dosages, may exacerbate myocardial ischemia by increasing heart rate.
0.3 mcg/kg/min IV; titrate to effect
Administer as in adults
None reported
Documented hypersensitivity; subaortic stenosis, idiopathic hypertrophic and atrial fibrillation or flutter; sildenafil (Viagra) use within previous 24 h
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Caution in increased intracranial pressure, hepatic failure, severe renal impairment, and hypothyroidism; in renal or hepatic insufficiency, nitroprusside levels may increase and can cause cyanide toxicity; sodium nitroprusside has the ability to lower blood pressure and, thus, should be used only in patients with mean arterial pressures >70 mm Hg
Causes relaxation of vascular smooth muscle by stimulating intracellular cyclic guanosine monophosphate production, resulting in a decrease in blood pressure.
May administer bolus of 12.5-25 mcg before continuous infusion.
Initial infusion rate of 10-20 mcg/min may be increased 5-10 mcg/min q5-10min until desired clinical or hemodynamic response is achieved.
Infusion rates of 500 mcg/min have occasionally been required.
400 mcg SL or 5 mcg/min IV; titrate to effect
Not established
Aspirin and indomethacin may increase nitrate serum concentrations; marked symptomatic orthostatic hypotension may occur with coadministration of calcium channel blockers (dose adjustment of either agent may be necessary); concurrent use with DHE may increase toxicity of both agents
Documented hypersensitivity; severe anemia, hypovolemia, constrictive pericarditis or pericardial effusion, hypertrophic cardiomyopathy, shock, postural hypotension, head trauma, closed-angle glaucoma, cerebral hemorrhage, and sildenafil (Viagra) use within previous 24 h
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Caution in coronary artery disease, low systolic blood pressure, glaucoma, hepatic disease, and hyperthyroidism
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sympathomimetic agents, sympathomimetics toxicity, ephedrine, asthma, narcolepsy, over-the-counter agent, over-the-counter medication, over-the-counter drug, OTC, OTC agent, OTC medication, OTC drug, pseudoephedrine, illegal street drug, cocaine, amphetamines, methamphetamine, meth, dietary supplement, ephedra alkaloids, ephedra, designer drug, 3, 4-methylenedioxy methamphetamine, MDMA, ecstasy, cardiac arrest
Paul Kolecki, MD, FACEP, Associate Professor, Department of Emergency Medicine, Thomas Jefferson University Hospital, Director of Undergraduate Emergency Medicine Student Education, Jefferson Medical College, Philadelphia, PA, Consultant, Philadelphia Poison Control Center, Philadelphia, PA
Paul Kolecki, MD, FACEP is a member of the following medical societies: Alpha Omega Alpha and American College of Emergency Physicians
Disclosure: Nothing to disclose.
Mark S Slabinski, MD, FACEP, FAAEM, Vice President, EMP Medical Group
Mark S Slabinski, MD, FACEP, FAAEM is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, and Ohio State Medical Association
Disclosure: Nothing to disclose.
John T VanDeVoort, PharmD, Regional Director of Pharmacy, Sacred Heart & St. Joseph's Hospitals
John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists
Disclosure: Nothing to disclose.
Fred Harchelroad, MD, FACMT, FAAEM, FACEP, Chair, Department of Emergency Medicine, Director of Medical Toxicology - Allegheny General Hospital, Associate Professor, Department of Emergency Medicine, Drexel University College of Medicine
Disclosure: Nothing to disclose.
John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.
Asim Tarabar, MD, Assistant Professor, Department of Surgery, Section of Emergency Medicine, Yale University School of Medicine; Consulting Staff, Department of Emergency Medicine, Yale-New Haven Hospital
Disclosure: Nothing to disclose.
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