Card Set Information
What are the common uses of lithium?
treatment of bipolar disorder
adjunctive treatment of depression
Is TDM of lithium necessary?
Classified by NCBOP as a NTI drug
Serious toxicity and death possible
Clear relationship between serum level and efficacy
What formulations are lithium available in?
IR tablets and capsules
What is the absorption/bioavailability of lithium?
What is the distribution of lithium?
does NOT bind to plasma proteins
crosses placenta and present in breast milk (category D)
How does the Vd in elderly compare to adults?
What is the metabolism of lithium?
Describe the elimination of lithium.
1. Primarily eliminated as free ion (not metabolized)
**95% renal clearance
**half-life ~24 hours
2. Renal clearance of lithium is approx 20% of CrCl
How does the clearance of lithium of older adults compare to that of normal adults?
clearance in older adults in ~2/3 of normal adults
What is the therapeutic range of lithium for the treatment of acute mania?
0.8 to 1.2 mEq/L
What is the prophylaxis therapeutic range of lithium?
0.5 to 0.8 mEq/L
When should lithium serum levels be measured?
12 hours post dose is generally recommended (for divided doses)
What is moderate lithium toxicity?
> 1.5 to 2.5 mEq/L
What is severe lithium toxicity?
> 2.5 mEq/L
What are the side effects of lithium?
:N/V, anorexia, diarrhea, abdominal pain, tremor
: polyuria, DI, interstitial nephritis, edema
: lethargy, fatigue, weakness, action tremor, cognitive slowing, memory disturbance
: coarse tremor, ataxia, confusion, visual changes, dysarthria (severe = ataxia, seizures, hallucinations, delirium, coma, death)
: hypothyroidism, arrhythmias, acne, psoriasis, benign leukocytosis, weight gain
What drug-drug interactions are there with lithium and what will they do to lithium levels?
thiazide diuretics, spironolactone, triamterene
NSAIDs, COX-2 inhibitors
ACE inhibitors, ARBs
They will increase lithium levels by 25-50%
What happens to lithium levels when a person experiences dehydration?
Lithium levels will go up 25-50%
What is "ideal" dosing of lithium?
What are the peak dose effects of lithium?
nausea and tremor
What is the typical dosing for a healthy young adult?
300mg = 1.0 mEq/L
What dose of lithium is given to a patient with a CrCl 10-50 ml/min?
50% to 75% of normal dose
What dose of lithium is given to a patient with a CrCl <10 ml/min?
25% to 50% of normal dose
What are the kinetic pearls of antidepressants (TCAs and SSRIs)?
Highly lipophilic, cross BBB
F~ 30% to 90%
Readily and completely absorbed but extensive 1st pass metabolism
Generally linear pharmacokinetics
Extensively bound to albumin and other proteins
Half-life = 6-88 hours [dosed daily]
List TDM for Amitriptyline, Nortriptyline, Imipramine/Desipramine and Desipramine.
Amitriptyline 100 to 200 mcg/L
Nortriptyline 50 to 150 mcg/L
Imipramine and desipramine 180 to 350 mcg/L
Desipramine 100 to 200 mcg/L
When should TCA levels be drawn?
12 hours post-dose
What is the half-life of SSRIs?
15-33 hours (fluoxetine = 4-6 days)
Generally allows for once daily dosing
What is the TDM of SSRIs?
Does not exist with the exception of monitoring for adherence
What are the pharmacodynamic considerations involving SSRIs?
Antidepressants and EtOH
What are the drug-drug interactions involving SSRIs?
fluoxetine and paroxetine - strong CYP2D6 inhibitors
Give the ADME of atypicals/antipsychotics.
Vd = large, highly bound to plasma proteins, can accumulate in tissues
Half-life 20-40 hours (usually dosed daily)
Higly lipophilic, crosses BBB
Describe the TDM of antipsychotics (atypicals).
Not commonly done
For most, there does appear to be a threshold serum level needed for response and a serum level-response relationship
What is the therapeutic range for clozapine?
**only antipsychotic that is really monitored**
What is the therapeutic range for risperidone?
What is the therapeutic range for olanzapine?
What kind of drug interaction occurs with cigarettes and psychotropics?
Olanzapine = need a lot more to get a good therapeutic dose
What kind of drug interaction occurs with antidepressants and psychotropics?
SSRI + antipsychotic = have to lower the dose of antipsychotic
What kind of drug interaction occurs with St. John's Wort and psychotropics?
3A4, 2D6 inducer
Will lower the levels of psychotropics (but not lithium)