Fast and Sensitive LC–MS/MS Assay for Quantification of Nortriptyline and its Active Metabolites E- and Z-10-Hydroxynortriptyline in Human Plasma

Abstract

Background: A fast and sensitive validated assay for nortriptyline, E-10-hydroxynortriptyline and Z-10-hydroxynortriptyline in plasma following a single oral dose of nortriptyline 25 mg was needed to support a clinical study. Results: Plasma samples were prepared by protein precipitation, separated on a C18 column with a mobile phase consisting of 0.1% formic acid in an acetonitrile gradient over 6 min and detected by ESI in the positive mode and MS/MS. Mean recoveries of at least 90% were achieved. The LLOQ was 0.2 ng/ml for nortriptyline and 0.5 ng/ml for the metabolites. The standard curve was linear within LLOQ to 40 ng/ml (r² ≥ 0.997), precision was under 7.1% coefficient of variance (<16% at LLOQ) and accuracy was 92–114%. Conclusion: A fast and sensitive assay for nortriptyline, E- and Z-10-hydroxynortriptyline in plasma was developed and validated. It has been applied successfully to a clinical study.

Ethical conduct of research

The authors state that they have obtained appropriate institutional review board approval or have followed the principles outlined in the Declaration of Helsinki for all human or animal experimental investigations. In addition, for investigations involving human subjects, informed consent has been obtained from the participants involved.

Financial & competing interests disclosure

The authors wish to acknowledge Canterbury Medical Research Foundation, New Zealand for financial support of this study. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Additional information

Funding

The authors wish to acknowledge Canterbury Medical Research Foundation, New Zealand for financial support of this study. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.