- Start Date
- Expiration Date
- Largactil, Ormazine, Thorazaine, Thorazine Spansule
- CPT Codes
- Reference Test
- ATLAS Test Code
Red top (serum) or Lavender, EDTA
- Transport Info
Centrifuge and immediately transfer serum or plasma to separate plastic tube
- Fasting Required?
- Patient Instructions
- Reference Range
Adult Therapeutic: 50-300 ng/mL
Toxic: > 500 ng/mL
Child Therapeutic: 30-80 ng/mL
Toxic: > 200 ng/mL
Quantitative Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Evaluate toxicity; monitor therapeutic levels.
Although intestinal absorption is complete, the oral bioavailability is 32%±19% because of variable metabolism in the intestinal wall and liver (marked first-pass effect). Time to peak plasma concentration is two to four hours. After intramuscular administration, peak plasma concentrations are four to 10 times higher than after oral administration; onset of action occurs within 20-30 minutes, and the peak levels are noted in two to three hours. Volume of distribution (21±9 L/kg) is high and plasma binding (95% to 98%) is extensive. Clearance after intramuscular administration is 8.6±2.9 mL/minute/kg. Less than 1% of the drug is excreted unchanged by the kidney. The nominal elimination plasma half-life is 30±7 hours; however, some metabolites are eliminated slowly (months) in the urine. Hepatic enzyme induction with increased clearance usually is a minor effect that varies considerably among individuals.
At least 100 metabolites of chlorpromazine appear in humans; most are minor. Several, including 7-hydroxychlorpromazine, 11- hydroxychlorpromazine, norchlorpromazine, and possibly chlorpromazine N-oxide are neuropharmacologically active.