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14 Cards in this Set
- Front
- Back
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What is the mechanism of action of lithium as a mood-stabilizing agent?
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Uncertain. May relate to intercellular signalling.
It increases serotonin release and serotonin receptor sensitivity while inhibiting norepi and dopamine release from nerve terminals |
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What are the relevant pharmacodynamics of lithium?
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D - 2 compartment model (extracellular fluid --> tissues slowly over 24 hours)
E - 95% renally excreted - excretion slows with decreased GFR and hyponatremia |
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What are complications of chronic lithium therapy?
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Nephrogenic diabetes insipidus
Hypothyroidism |
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How is lithium toxicity classified?
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Acute
Acute-on-chronic Chronic |
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Describe acute lithium toxicity.
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OD in a patient without lithium stores
Predominantly GI - N/V/D Also: Neuro - delayed neurotoxicity ECG changes - long QT, bradycardia but few arrhythmias |
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Describe chronic lithium toxicity.
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Chronic lithium user with increased absorption or decreased elimination
Predominently neurotoxicity - drowsy, hyperreflexia, clonus, coma, seizures, extrapyramidal signs, tremor Also: Nephrotoxicity |
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What is SILENT?
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The Syndrome of Irreversible Lithium-Effectuated Neurotoxicity
Persistent neurologic dysfunction due to lithium toxicity that persists for >2 months following lithium cessation Presents with cerebellar dysfunctionextrapyramidal syndromes, brainstem dysfunction and dementia. |
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Describe acute-on-chronic lithium toxicity
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Mix of acute and chronic toxicity
Gastrointestinal and neurologic csymptoms |
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How does lithium relate to NMS and SS?
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It can contribute to the development of BOTH.
All 3 should be on the differential of a febrile, confused patient that is on lithium. |
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What particular laboratory tests should be assessed for lithium toxicity and why?
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Serum lithium
Creatinine (nephrotoxicity and clearance) Sodium (elevated in DI) Anion gap (low in lithium toxicity) ECG (long QT, brady) TSH (hypothyroid) |
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Are AC/GL/WBI indicated for lithium OD?
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AC - Doesn't absorb lithium
GL - IR Lithium is absorbed too rapidly and emesis has often already occurred. SR tablets are too big for OG tubes. WBI - Only for Sr preparation |
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How can renal clearance of Lithium be maximized?
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Fluid resuscitation with NaCl to correct hyponatremia and dehydration and encourage diuresis., Ren at 2x maintenance.
NOTE: Diuretics and HCO3 do not consistently increase excretion and can lead to other problems. Not recommended. |
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What is the role of hemodialysis in Lithium toxicity?
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No evidence that it prevents SILENT or mortality. Effectively clears lithium by increasing clearance from 20mL/min to 100mL/min.
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When is hemodialysis indicated?
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Clinical deterioration
Inadequate endogenous lithium clearance (renal insufficiency) Inability to enhance renal elimination (CHF, cirrhosis, etc) Levels: Chronic >4.0mEq/L; Acute >2.5mEq/L |
