C3.1 R4(e): Perform & document a pharmacokinetic interpretation (OTHER drug)

Clinical Pharmacy Note RE: Lithium

ID: 64 yo male admitted for hypoxemic respiratory failure secondary to aspiration pneumonia (also has R sided petroclival meningioma)

S/O:

  • RASS 0 to -1. AO x3 (to month and year)
  • Squeezed writer’s hand when asked if feeling confused, seeing and feeling things that are not there, feeling very tired, as well as, for dry mouth and increased thirst which is new fo rhim today (Lasix IV BID stopped today and had ++ oral secretions earlier today)
  • Currently on Lithium 300mg PO HS for query bipolar/mood disorder
    • Dose was reduced from 600mg PO HS in ICU due to AKI
    • Lithium level (Mar 13): <0.2 mmol/L, eGFR 97mL/min (stable)
  • According to P’net, was on Lithium 600mg PO HS
    (?compliance as last filled 7 days supply in Dec 2016)
  • Spoke to psych regarding indication and plan for lithium:
    • Psych spoke to his community psychiatrist who did not think the diagnosis for bipolar/mood disorder was strong. According to community psychiatrist, patient was kept on lithium 600mg PO HS in community as patient has failed multiple antidepressants in the past and patient felt that there was some benefit from lithium.
    • Given his clinical state and unclear history of indication and efficacy of lithium, psych suggests continuing on current dose of lithium and reassessing when patient is more stable.

A:

  1. Level drawn appropriately ~12 hours post dose and at steady state
  2. At his current subtherapeutic level, lithium is likely not effective for his query bipolar/mood disorder. However, given his clinical situation (also currently managing his delirium), efficacy of lithium is challenging to assess
  3. If renal function continues to be stable, it is unlikely that levels will become therapeutic with current dose.
  4. There is a potential drug interaction where lithium may enhance neurotoxic effects and EPS symptoms with antipsychotics which is currently used being to manage his delirium. Risk is low as patient is on low doses of antipsychotics (Haldol 2.5mg NG PO Q6H, Nozinan 25mg PO daily at 2100h)

P: Suggest

  1. Continue lithium 300mg PO HS and reassess indication and efficacy of lithium when patient is out of critical care state
  2. When patient is out of critical care state and more stable (e.g. delirium resolved), reassess indication and efficacy of lithium for query bipolar/mood disorder
  3. Daily monitoring of side effects of lithium: ataxia, seizures, tremors, dry mouth, worsening of sialorrhea, N/V/D, and EPS symptoms: spasms, muscle contractions, motor restlessness, tremors
  4. Daily monitoring of renal function (sCr, eGFR) while in ICU

 

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