Journal of Pharmaceutical and Biomedical Analysis 47 (2008) 882–887 Contents lists available at ScienceDirect Journal of Pharmaceutical and Biomedical Analysis journal homepage: www.elsevier.com/locate/jpba HPLC analysis of the antidepressant trazodone and its main metabolite m-CPP in human plasma Laura Mercolini a , Carolina Colliva a , Mario Amore b , Salvatore Fanali c , Maria Augusta Raggi a,∗ a Laboratory of Pharmaco-Toxicological Analysis, Department of Pharmaceutical Sciences, Alma Mater Studiorum – University of Bologna, Via Belmeloro 6, 40126 Bologna, Italy b Department of Neurosciences, University of Parma, Strada del Quartiere 2, 43100 Parma, Italy c Institute of Chemical Methodologies, National Research Council, 00016 Monterotondo Scalo, Rome, Italy article info Article history: Received 16 January 2008 Received in revised form 23 February 2008 Accepted 25 February 2008 Available online 4 March 2008 Keywords: Trazodone m-CPP HPLC Solid-phase extraction Human plasma Therapeutic drug monitoring abstract The present paper deals with the development of a rapid and feasible high-performance liquid chromatographic method for the determination of trazodone and its main active metabolite 3-(1- clorophenyl)piperazine (m-CPP) in human plasma. Trazodone is a second-generation antidepressant with serotonin antagonist activity. The metabolite seems to be involved in the onset of some side effects of tra- zodone therapy, thus its determination is very important during therapeutic drug monitoring. Separation was achieved using a C8 reversed-phase column and a mobile phase composed of aqueous phosphate buffer (70%), containing triethylamine, at pH 3.5 and acetonitrile (30%). The UV detector was set at 255 nm and loxapine was used as the internal standard. An original pre-treatment procedure of plasma samples was developed, based on solid-phase extraction with C8 reversed phase cartridges (50 mg, 1 mL). The obtained extraction yields values were higher than 90% and precision, expressed as R.S.D., was lower than 5.6%. The method was successfully applied to plasma samples from depressed patients undergoing therapy with trazodone; accuracy results were satisfactory (recovery >91%). Thus, the method seems to be suitable for the therapeutic drug monitoring of trazodone and its main active metabolite in depressed patients’ plasma. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Trazodone (2-[3-[4-(3-chlorophenyl)-1-piperazinyl]propyl]- 1,2,4-triazole[4,3-a]pyridin-3(2H)-one, TRZ, Fig. 1a) is a weak inhibitor of monoamine reuptake and its major mechanism of action seems to be the antagonism at serotonin 5-HT 2 /5-HT 1C receptors [1]. TRZ is used for the treatment of major depres- sion, sometimes in conjunction with selective serotonin reuptake inhibitors (SSRIs), like fluoxetine [2], or to control sleep disturbance symptoms when using serotonin and norepinephrine reuptake inhibitors (SNRIs) [3]. TRZ (Desyrel, Molipaxin, Trittico, Thombran and Trialodine) is commercially available as tablets, long-acting tablets, oral solutions and solutions for injection [4]. Treatment should be started with a dose of 25–50mg daily, which may be increased slowly to a maxi- mum of 300 mg daily in ambulatory patients or to 600 mg daily in hospitalised patients. ∗ Corresponding author at: Laboratory of Pharmaco-Toxicological Analysis, Department of Pharmaceutical Sciences, Via Belmeloro 6, 40126 Bologna, Italy. Tel.: +39 051 2099700; fax: +39 051 2099740. E-mail address: mariaaugusta.raggi@unibo.it (M.A. Raggi). TRZ is mainly metabolised in the liver by the cytochrome isoform CYP3A4. The most important metabolite thus formed is 3-(1- clorophenyl)piperazine (m-CPP, Fig. 1b) [5], which is a serotonergic agonist with a long half-life [6]. Plasma levels in patients treated with TRZ at therapeutic doses usually range between 130 ng mL -1 and 2 g mL -1 for the parent drug [7], while m-CPP concentrations are typically less than 20% of those of TRZ [8]. The main side effects associated with TRZ administration are: nausea, insomnia, agitation, dry mouth, constipation, headache, hypotension, blurred vision and confusion [9]. Some of these effects can be attributed to m-CPP, which has well-known pro- headache activity and hallucinogenic properties; in fact, due to this latter action it is also used on its own as a recreational drug [10]. From short-term studies, TRZ seems to increase the risk of suicide in children and adolescents with depression [11]; though this assertion is still a matter for debate [12], the FDA requires that package inserts of this drug report a warning that TRZ should be used with caution in children and adolescents and the patients kept under appropriate surveillance [13]. For these reasons, it is evident that a reliable therapeutic drug monitoring (TDM) of patients treated with TRZ could greatly improve their quality of life and that the determination of m-CPP should be an integral part 0731-7085/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jpba.2008.02.028