Lithium and valproate Flashcards
How is lithium eliminated
95% renal from the proximal tuble
List factors that can reduce the excretion of lithium
advanced age volume depletion decreased Na in diet low flow CHF diabetes insipidus Meds: thiazide diuretics, NSAIDs ACE-I/ARBs
What are side effects of Li at therapeutic doses
tremor, NVD, nephrogenic DI, hypoth, leukocytosis, conduction abN (rare)
Teratogenic
How does acute Li toxicity present?
GI: N/V/D
CNS: H/A, tremulousness, dystonia, hyperreflx, ataxia, agitation, lethargy, coma, sz,
CVS: ventricular dysrhythmias, sinus arrest, asystole
What permanent neurologic sequele can result from chronic Li toxicity
(SILENT [syndrome of irreversible lithium effectuated neuro toxicity]syndrome)
- Cognitive impairment
- Sensorimotor peripheral neuropathy
Cerebellar dysfunction
How does chronic Li toxicity present
less GI
Renal: nephrogenic DI, interstitial nephritis, renal failure
Mostly neuro: Parkinson syndrome, psychosis
CVS: myocarditis
Hypothyroid
aplastic anemia
What 2 syndromes is Li toxicity also assoc with
NMS
serotonin syndrome
How can Li be decontaminated?
WBI
does not bind to AC
What is the mainstay of Tx for Li toxicity
IV fluids and dialysis
What are the indications for dialysis in Li toxicity
acute level GT 4 mEq/L
Chronic level GT 2.5mEq/L
Clinical: neurotoxicity renal failure unable to tolerate volume shoch worsening despite max therapy
What is required for valproic acid metabolism
Carnitine and acetyl-Co-A. Depletion of carnitine halts metabolism through oxidation and can cause hyperammonemia
What are the clinical manifestations of VPA overdose?
CNS: lethargy to encephalopathy
CVS: hypocalcemia: can cause prolonged QT
HyperNa
pancytopenia
pancreatitis, hepatitis via aberrant FFA metabolism (not hypersensitivity)
ARF
What are the therapies for VPA overdose?
AC, HD
Carnitine if liver failure, coma, hyperammonemia (GT 100umol/L or 2xULN
