Ciguatera Toxicity Medication

Updated: Dec 29, 2015
  • Author: Thomas C Arnold, MD, FAAEM, FACMT; Chief Editor: Asim Tarabar, MD  more...
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Medication

Medication Summary

Medications used to treat ciguatera poisoning include the following:

  • Activated charcoal
  • Antihistamines
  • Amitriptyline
  • Mannitol
  • Analgesics
  • Nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Gabapentin
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Antidotes, Other

Class Summary

Gastrointestinal (GI) decontamination with oral activated charcoal is selectively used in the emergency treatment of poisoning caused by some drugs and chemicals. The network of pores present in activated charcoal adsorbs 100-1000 mg of drug per gram of charcoal. Activated charcoal does not dissolve in water.

Activated charcoal achieves its maximum effect when administered within 30 minutes after ingestion of a drug or toxin. However, decontamination with activated charcoal may be considered in any patient who presents within 4 hours after the ingestion.

Activated charcoal (Actidose-Aqua, EZ-Char, Kerr Insta-Char)

Activated charcoal is used for emergency treatment in poisoning caused by drugs and chemicals, and is the drug of choice when gastric decontamination is being considered. A network of pores adsorbs 100-1000 mg of drug per gram of charcoal. Activated charcoal prevents absorption by adsorbing the drug in the intestine; multidose charcoal may interrupt enterohepatic recirculation and enhance elimination by enterocapillary exsorption.

In theory, by constantly bathing the GI tract with charcoal, the intestinal lumen serves as a dialysis membrane for reverse absorption of the drug from the intestinal villous capillary blood into the intestine. Activated charcoal does not dissolve in water.

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Antihistamines, 1st Generation

Class Summary

These agents are used to reduce pruritus.

Cyproheptadine

Cyproheptadine is a seratonin and histamine antagonist that competitively inhibits the H1 receptor, mediating bronchial constriction, smooth-muscle contraction, edema, hypotension, CNS depression, and cardiac arrhythmias. It prevents histamine release in blood vessels and is more effective in preventing histamine response than in reversing it; nevertheless, it is reported to ameliorate pruritus in ciguatera toxicity.

Diphenhydramine (Benadryl, Diphen, Altaryl, Anti-Hist)

Diphenhydramine is a histamine H1-receptor antagonist of effector cells in the respiratory tract, blood vessels, and GI smooth muscle. It has moderate to high anticholinergic and antiemetic properties. This agent is used for relief of symptoms caused by release of histamine in pruritus.

Hydroxyzine (Vistaril)

Hydroxyzine is H1-receptor antagonist with low to moderate antihistaminic properties; it inhibits respiratory, vascular, and GI smooth-muscle constriction. It has moderate to high anticholinergic and antiemetic properties. Antagonism of H1 receptors in the periphery mediates antipruritic effects.

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Antidepressants, TCAs

Class Summary

The anticholinergic and antihistaminic effects of these agents decrease pruritus. They are also used to treat associated neurologic pain.

Amitriptyline

Amitriptyline has been reported to relieve pruritus and dysesthesias in patients with acute ciguatera toxicity, and to diminish the severity of residual symptoms (ie, chronic pain syndromes). This agent is most effective for chronic neurologic symptoms that often follow ciguatera poisoning. In this setting, amitriptyline may act by blocking fast sodium channels that have been activated by ciguatoxin.

Imipramine (Tofranil)

These agents have been suggested to act by inhibiting reuptake of noradrenaline at synapses in central descending pain modulating pathways located in the brainstem and spinal cord.

Doxepin (Silenor)

Doxepin increases the concentration of serotonin and norepinephrine in the CNS by inhibiting their reuptake by the presynaptic neuronal membrane. It inhibits histamine and acetylcholine activity and has proven useful in treatment of various forms of depression associated with chronic and neuropathic pain.

Nortriptyline (Pamelor)

Nortriptyline has demonstrated effectiveness in the treatment of chronic pain.

Desipramine (Norpramin)

This is the original TCA used for depression. These agents have been suggested to act by inhibiting the reuptake of noradrenaline at synapses in central descending pain modulating pathways located in the brainstem and spinal cord.

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Diuretics, Osmotic Agents

Class Summary

These agents are used empirically to treat neurologic symptoms associated with ciguatera poisoning. The toxic effect of ciguatoxin results from the opening of sodium channels in excitable tissues such as nerve and muscle. Mannitol produces osmotic inhibition of water transport in the proximal tubule and a subsequent decreased gradient for passive sodium absorption in the ascending limb of the loop of Henle.

Mannitol (Osmitrol, Resectisol, Aridol)

Mannitol is an osmotic diuretic that has become the mainstay of acute treatment in recent years. Mannitol has been reported to dramatically diminish or prevent neurologic symptoms associated with ciguatera poisoning. Mannitol is most effective when given early in course of treatment, but somewhat effective even after several days of symptoms. Neurologic symptoms often decrease within minutes of mannitol administration and may resolve completely within 2 days.

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Anticonvulsants, Other

Class Summary

Used to manage pain and provide sedation in neuropathic pain.

Gabapentin (Neurontin)

Gabapentin is a membrane stabilizer, a structural analogue of inhibitory neurotransmitter gamma-amino butyric acid (GABA), which paradoxically is thought not to exert effect on GABA receptors. It appears to exert action via the alpha2delta1 and alpha2delta2 auxiliary subunits of voltage-gaited calcium channels. It is used to manage pain and provide sedation in neuropathic pain.

Pregabalin (Lyrica)

Pregabalin is a structural derivative of GABA; its mechanism of action unknown. Pregabalin binds with high affinity to the alpha2-delta site (a calcium channel subunit), and, in vitro, pregabalin reduces the calcium-dependent release of several neurotransmitters, possibly by modulating calcium channel function.

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Analgesics, Other

Class Summary

These agents are used to provide pain relief.

Acetaminophen (Tylenol, Acephen, Cetafem, Valorin)

Acetaminophen is a clinically proven analgesic and antipyretic that produces analgesia by elevating the pain threshold and reduces fever through its action on the hypothalamic heat-regulating center. It equals aspirin in analgesic and antipyretic effectiveness and is unlikely to produce many of the adverse effects associated with aspirin and aspirin-containing products.

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NSAIDs

Class Summary

NAIDs are used for patients with mild to moderate pain. These agents inhibit inflammatory reactions and pain by decreasing prostaglandin synthesis.

Ibuprofen (Advil, Caldolor, Addaprin, Motrin)

Ibuprofen is the drug of choice for patients with mild to moderate pain. It inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis. The intravenous form (Caldolor) is available only for hospital use and is indicated for pain or fever.

Ketoprofen

Ketoprofen is used for relief of mild to moderate pain and inflammation. Small dosages initially are indicated in small and elderly patients and in those with renal or liver disease. Doses over 75 mg do not increase therapeutic effects. Administer high doses with caution and closely observe patient for response.

Naproxen (Aleve, Anaprox, Naprosyn)

Naproxen is used for relief of mild to moderate pain; it inhibits inflammatory reactions and pain by decreasing the activity of cyclooxygenase, which is responsible for prostaglandin synthesis. NSAIDs decrease intraglomerular pressure and decrease proteinuria.

Diclofenac (Voltaren, Cataflam XR, Zipsor, Cambia)

Diclofenac inhibits prostaglandin synthesis by decreasing cyclooxygenase activity, which, in turn, decreases the formation of prostaglandin precursors.

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