Understanding and Managing Matrix and Solvent Instability for Olanzapine Diane Ly (Presenter) ARUP Laboratories

Authors: Diane Ly 1 and Kamisha L. Johnson-Davis 1,2
1. ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, Utah, USA 2. University of Utah Health Sciences Center, Department of Pathology, Salt Lake City, Utah, USA

Abstract Summary:

Olanzapine is an atypical antipsychotic drug that is clinically monitored to maintain therapeutic levels and confirm compliance. A literature search for the reported stability of olanzapine in matrix and solvent showed contradicting information about olanzapine’s light and temperature sensitivities. In some published papers, olanzapine is reported as light and temperature sensitive due to oxidization susceptibility during storage and extraction. In other papers, olanzapine is not described as having stability problems. For papers showing stability issues, the addition of ascorbic acid is hypothesized to reduce the amount of oxidation (Nielsen et al. 2008). To evaluate and manage matrix and solvent stability, light, temperature, and long term storage stability (at -80 °C) were tested using human plasma untreated and treated with ascorbic acid. Spiking solutions made in acetonitrile were also tested. The results presented here show ascorbic acid addition protects olanzapine in plasma samples from oxidizing at room temperature and light conditions. The spiking solutions made in acetonitrile were not impacted by light and room temperature conditions. Long-term stability for treated plasma, untreated plasma, and spiking solutions in acetonitrile are similar (up to three weeks). Additional testing will be presented showing extended long-term matrix stability.

Problem:

It has been observed in the clinical lab that olanzapine is not stable in matrix or solvent under white light or room temperature conditions. Olanzapine also does not have long term stability in matrix or solvent, thereby complicating calibrator/control manufacture and storage. A robust method is necessary to confidently report olanzapine concentrations in serum and plasma samples. Providing appropriate specimen handling instructions to the client is also critical.

Method Information:

• 50 µL of serum/plasma was extracted with Solid Phase Extraction (SPE)

• Agilent 6470

• Agilent 1260 Binary Pumps

• MPA: 10 mM Ammonium Acetate pH 9.0 in water

• MPB: Acetonitrile

• 3.70 minute gradient LC program, 0.500 mL/min flow rate

• Column: Agilent InfinityLab Poroshell 120 EC-C18, 2.1 x 50 mm, 2.7 µm

• Column oven temperature: 30°C

• Injection volume: 10 µL

• Quantitative MRM acquisition

Troubleshooting Steps:

Light sensitivity tests were completed by subjecting spiking solutions, treated (0.25% ascorbic acid) matrix, and untreated matrix on ice to wide spectrum artificial light for two hours. Temperature sensitivity tests were completed by storing spiking solutions, treated matrix and untreated matrix in amber vials on the benchtop for 24 hours. Long term stability was conducted at -80 °C using treated and untreated matrix.

Outcome:

Untreated human plasma spiked with olanzapine showed more than 30% negative bias under light and room temperature conditions. Human plasma treated with 0.25% ascorbic acid showed ≤10% bias under light and room temperature conditions. Spiking solutions were not impacted by light conditions and room temperature conditions. Long-term matrix stability was established for 3 weeks for both untreated, treated, and spiking solutions made in acetonitrile, additional testing will be completed to extend long term matrix stability.

Problem

Method Information

Troubleshooting Steps

Outcome