Drug Level Monitoring

DrugTherapeutic rangeLabs
Antipsychotics ---▪Baseline/yearly: CBC, CMP, Hba1c, TSH, Lipid panel
▪Monitor weight
▪Consider Baseline EKG
▪Yearly AIMS*
Clozapine ---▪Same as above (except CBC scheduling)
▪CBC (ANC) Schedule:
Check at baseline, weekly for 6 months, then biweekly for 6 months, then monthly after 1 year
Lithium▪Acute: 0.8-1.2mEq/L▪Baseline/2-3x per year: CBC, Cr, BUN, TSH, CMP
▪Chronic: 0.50-0.75mEq/L▪Consider baseline EKG in pts >50yo
▪Monitor weight
▪Check Li levels after 4-5 half lives (blood should be collected prior to next dose)
▪Recheck Li levels after dose changes, addition of other drugs, or if suspecting toxicity
Valproic acid▪ 45-125ug/ml▪Baseline/q6-12mos: CBC, LFTs, Electrolytes, TSH
(Manic patients may require/ tolerate higher levels)
Carbamazepine ---▪Baseline: Na, CBC, BUN, Cr, LFTs, TSH
▪Monitor weight
▪Follow CBC and Na q2-4wks for 8 wk then q3-6mos
▪Follow BUN, Cr, LFTs, and TSH q6-12mos
SNRIs, Bupropion, TCAs, MAOIs---▪Monitor blood pressure & HR

*(—) No definitive evidence correlating levels with efficacy 

Clozapine ANC Monitoring

Benzodiazepine Equivalents

 Dosage Equivalency (mg)Onset of Action (hrs)Duration of Action (hrs)Half-Life (hrs)
Alprazolam (Xanax)0.50.5-13.0-4.011.0-16.0
Chlordiazepoxide (Librium)10.0-25.01.0-2.0---5-200 (with active metabolite)
Clonazepam (Klonopin)0.25-0.514.0-8.020-80
Diazepam (Valium)50.54.0-6.0>100
Lorazepam (Ativan)10.5-14.0-6.010.0-20.0
Temazepam (Restoril)15-300.5-14.0-6.09.0-18.0

Lithium Toxicity

Lithium ToxicityCausesPresentation Treatment
OverdoseNauseaHold/Discontinue Lithium
DehydrationVomitingMonitor lithium levels every 2-4 hours
Hyponatremia (low sodium)DiarrheaIntravenous (IV) Fluids
Low GFR (Glomerular Filtration Rate)AtaxiaHemodialysis recommended if Lithium level >2.5 mEq/L with signs of neurotoxicity
Renal Impairment/Failure/DiseaseConfusionHemodialysis recommended if no improvement with IV fluids
Drug InteractionsTremorHemodialysis recommended if Lithium level >4.0 mEq/L
Diuretics (except loop diuretics)Slurred Speech
NSAIDs (except aspirin)Seizures
ACE Inhibitors Abnormal Movements

Lithium Level Monitoring

Lithium MonitoringTarget Lithium LevelRecommended Labs
Acute Mania0.8-1.2mEq/LBaseline: CBC, CMP, Cr, BUN, TSH, Weight, EKG (in pts>50yo or with cardiac disease)
Maintenance0.6-1.0 mEq/LAfter 1 week, 1 month, 6 months, and 12 months of starting lithium: Lithium Level, TSH, BUN/Cr, Electrolytes, monitor weight
Every 6-12 months: Lithium Level, TSH, BUN/Cr, Electrolytes, monitor weight
NOTE: Check Lithium levels after 4-5 half lives (blood should be collected prior to next dose); Also check lithium levels after dosage changes, addition of other drugs, or if suspecting toxicity