Antidote

  

From Rx-wiki

Antidote, derived from the Greek antidoton where anti is a prefix that means against and doton means given. Therefore we can think of an antidote as being working against what has already been given. A more contemporary definition would be a remedy or other agent used to neutralize or counteract the effects of a poison or other deleterious agent.

There is a popular misconception that there is an antidote for every poison, whereas there are actually relatively few classes of toxins that have antidotes. The antidotes for some particular toxins are manufactured by injecting the toxin into an animal in small doses and extracting the resulting antibodies from the host animals' blood. This results in an antivenom that can be used to counteract poison produced by certain species of snakes, spiders, and other venomous animals. A number of venoms lack a viable antivenom, and a bite or sting from an animal producing such a toxin may result in death. Some animal venoms, especially those produced by arthropods (e.g. certain spiders, scorpions, bees, etc.) are only potentially lethal when they provoke allergic reactions and induce anaphylactic shock; as such, there is no "antidote" for these venoms because it is not a form of poisoning and anaphylactic shock can be treated (e.g., by the use of epinephrine).

Some other toxins have no known antidote. For example, the poison aconitine, a highly poisonous alkaloid derived from various aconite species has no antidote, and as a result is often fatal if it enters the human body in sufficient quantities.

Mechanical approaches

Ingested poisons are frequently treated by the oral administration of activated charcoal, which adsorbs the poison and flushes it from the digestive tract, thereby removing a large part of the toxin. Poisons which are injected into the body (such as those from bites or stings from venomous animals) are usually treated by the use of a constriction band which limits the flow of lymph and/or blood to the area, thus slowing circulation of the poison around the body. This should not be confused with use of a tourniquet which cuts off blood flow completely - often leading to the loss of the limb.

List of antidotes

In the table below some of the more common antidotes have been listed.

Antidote Poison(s) Usual Dosage
acetylcysteine acetaminophen Should be given within 8 hr of acetaminophen ingestion for maximum benefit; however effective even after 24 hours of ingestion.
atropine cholinesterase inhibitors (organophosphates, carbamates) IV: 0.03-0.05 mg/kg IV/IM/IO/ET q10-20min PRN to effect; then q1-4hr for at least 24 hours.
IM: 2 mg for mild reaction, quickly repeat with up to another 4 mg for initial dose if more severe reaction.
deferoxamine iron salts, aluminum 100 mg of deferoxamine can bind to about 10 mg of iron & 4.1 mg of aluminum
digoxin FAB antibodies digoxin and related cardiac glycosides Each vial of Digibind (38 mg of Fab) or DigiFab (40 mg of Fab) binds 0.5 mg digoxin.
dimercaprol arsenic, gold, lead, mercury Dosing depends on which poison the patient has been overexposed to.
edetate calcium disodium lead For asymptomatic blood lead of 20-70 mcg/dL give 1 g/m2 IV or IM.
flumazenil benzodiazepines Give 0.2 mg IV inj over 15-30 sec. If no response: then 0.3 mg over 15-30 sec 1 min later, if no response then again 0.5 mg IV over 15-30 sec to max cumulative dose of 3 mg/hr
fomepizole methanol & ethylene glycol Load 15 mg/kg IV infusion over 30 min, THEN 10 mg/kg IV q12hr x 4 doses, THEN increase to 15 mg/kg q12hr.
glucagon beta-blocker & calcium channel blocker toxicity Give a loading dose of 50-150 mcg/kg IVP over 1 minute, THEN 1-5 mg/hr IV infusion.
hydroxycobalamin cyanide Adults: 5 g administered as an intravenous (IV) infusion over 15 minutes.
Children: A dose of 70 mg/kg has been used to treat children.
leucovorin methotrexate, methanol, pyrimethamine, sulfadiazine, trimethoprim, and trimetrexate Give in a 1:1 ratio leucovorin to inadvertent methotrexate overdose within 1 hr initial IV, then may switch to IM q6h. Consult various other resources for treating other poisonings.
mesna ifosfamide & cyclophosphamide ifosfamide: 240 mg/sq.meter (if receiving 1.2 g/sq.meter ifosfamide dose) IVP 15 minutes before & 4 & 8 hours after ifosfamide admin OR 240 mg/sq.meter (if receiving 1.2 g/sq.meter ifosfamide dose) IVP 15 minutes before & 480 mg/sq.meter PO 2 & 6 hours after ifosfamide admin.
cyclophosphamide: 60-160% of cyclophosphamide daily dosage divided 3-5 doses IVP OR by continuous IV infusion.
naloxone opioids Give 0.4-2 mg IV/IM/SC/ET, repeat q2-3min PRN; no more than 10 mg (0.01 mg/kg).
penicillamine arsenic, lead, copper, & mercury arsenic: 100 mg/kg/day PO divided q6hr x5 days.
lead: 1-1.5 g qDay PO or divided BID-TID x1-6 months.
phentolamine dental anesthesia Dose based on amount of local anesthetic administered.
physostigmine anticholinergic Initially give 0.5-2 mg slow IVP (not to exceed 1 mg/min); keep atropine nearby for immediate use. If no response, repeat q20min PRN. If initial dose effective, may give additional 1-4 mg q30-60min PRN.
phytonadione warfarin If INR 5-9: 1-2.5 mg PO, once.
If INR 10-20: 3-5 mg PO, once.
If INR >20: 5-10 mg IV.
pralidoxime organophosphate, acetylcholinesterase inhibitor, insecticides and related nerve gases Consult various other resources for treating poisonings with pralidoxime.
protamine sulfate heparin and low molecular weight heparins 1 mg neutralizes an average of 100 USP units of heparin.

See also

Five rights
MedWatch
Drug recalls
Vaccine Adverse Event Reporting System
Five rights
Tallman lettering
Medication errors
Barcoding technologies
Medication safety

References

  1. The Free Dictionary, antidotes, http://www.thefreedictionary.com/antidotes
  2. Wikipedia, Antidotes, http://en.wikipedia.org/wiki/Antidotes
  3. Medscape, acetylcysteine (Antidote), http://reference.medscape.com/drug/acetadote-n-acetylcysteine-antidote-acetylcysteine-antidote-343740
  4. Medscape, atropine (IV, IM), http://reference.medscape.com/drug/atropen-atropine-iv-im-343093#0
  5. Medscape, digoxin immune FAB (Antidote), http://reference.medscape.com/drug/digibind-digifab-digoxin-immune-fab-antidote-343725
  6. Medscape, edetate calcium disodium, http://reference.medscape.com/drug/calcium-disodium-versenate-edetate-calcium-disodium-343729
  7. Medscape, flumazenil, http://reference.medscape.com/drug/romazicon-flumazenil-343731
  8. Medscape, fomepizole, http://reference.medscape.com/drug/antizol-fomepizole-343713
  9. Medscape, glucagon, http://reference.medscape.com/drug/glucagen-glucagon-342712
  10. Facts & Comparisons eAnswers, hydroxycobalamin, http://online.factsandcomparisons.com/MonoDisp.aspx?monoID=fandc-hcp17888&quick=949633%7c21&search=949633%7c21&isstemmed=True#firstMatch
  11. Medscape, leucovorin, http://reference.medscape.com/drug/fusilev-levoleucovorin-leucovorin-343736
  12. Medscape, mesna, http://reference.medscape.com/drug/mesnex-mesna-342126
  13. Medscape, naloxone, http://reference.medscape.com/drug/narcan-naloxone-343741
  14. Medscape, penicillamine, http://reference.medscape.com/drug/cuprimine-depen-penicillamine-343728
  15. Medscape, phentolamine, http://reference.medscape.com/drug/regitine-oraverse-phentolamine-342392
  16. Medscape, physostigmine, http://reference.medscape.com/drug/physostigmine-343743
  17. Medscape, phytonadione, http://reference.medscape.com/drug/vitamin-k-mephyton-vitamin-k1-phytonadione-344424
  18. Medscape, pralidoxime, http://reference.medscape.com/drug/protopam-2pam-antidote-pralidoxime-343744
  19. Medscape, protamine, http://reference.medscape.com/drug/protamine-343746
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