Clinical Pharmacy Note RE: Valproic Acid (VPA) Level *My notes
ID: 55 yo male with psychosis (wt = 50kg)
prescribed valproic acid as augmentation to his antipsychotic for persistent symptoms of agitation
- Sept 23 Labs:
AST: 64 ↑ ALT: 109 ↑ GGT: 268 ↑ ALP: 71 Total bilirubin: 10 Alb: 35g/L
Patient is also hepatitis C+.
- Sept 14 Labs (was on Divalproex 500mg BID):
AST: 76 ↑ ALT: 123 ↑ GGT: 441 ↑ ALP: 75
- VPA level: 515 (reference range: 350- 835 umol/L)
valproic acid monitoring to assess for toxicity and to assess if room to grew for efficacy if clinically indicated. CPS: A good correlation has not been established between daily dose, total serum valproate concentration and therapeutic effect
– drawn at 1000 hr on Sept 26, 2016 (12 hours after 2200 hr dose on Sept 25)
– valproic acid was ↑ from 1500mg PO HS to 1750mg PO HS on September 21, 2016
(Max dose: 60mg/kg/day = 3000mg)
- All doses were given on time
- Level was taken at steady state (half-life increases in hepatic impairment but questionable clinical significance, as per UofK PK manual)
Lexi-comp: Half-life in adults: 9-19 hours (5 half-lives: ~1.875-3.95 days)
University of Kentucky Pharmacokinetic Manual: Protein binding decreases in patients with hepatic impairment
In order to do free VPA level at SPH: physician needs to fill a form stating reason for monitoring.
- Level was drawn on time appropriately.
University of Kentucky Pharmacokinetic Manual:
– trough levels (within 30 mins prior to dose)
– preferably before AM dose, due to effects of diurnal variation on clearance
St. Paul’s reference range: based on 12 hours post-dose
Handbook of psychiatric drugs (2004 edition) : “Serum drug levels should be drawn 12 hours after the previous dose and are usually drawn in the morning before AM dose.”
- Valproic acid level is within normal reference range.
- Currently unsuitable to interview, as per nurses about side effects and efficacy
- Continue valproic acid 1750mg PO HS
?frequency of valproic acid – Lexicomp: >250mg should be in divided doses.
?Compliance issues as patient has frontal lobe syndrome and refusing meds in hospital. Half-life is 9-19 hours but longer in hepatic impairment. Patient appears to be tolerating medication and psychosis seems to be improving. Difficult to assess patient’s baseline cognitive function (MOCA on admission: 8/30)
- Monitor for side effects: ataxia, abnormal gait, nausea, vomiting, anorexia and hepatotoxicity (e.g. jaundice)
- Monitor LFTs, INR, albumin and bilirubin regularly every 6 months
- Look at the patient’s whole clinical picture (e.g. size, weight, age, fragility, clinical stability)
- Look at all the medications patients are on
- Look to see if there are any recent medication and clinical changes (poly-pharmacy)
- The Safety of Valproic Acid Use for Patients With Hepatitis C Infection