Validated method for determination of mazindol in human plasma by liquid chromatography/tandem mass spectrometry

Validation and application of a liquid chromatography-electrospray ionization mass spectrometric method for determination of mazindol in human plasma and urine

INTRODUCTION

Even after removal of some stimulants, like fenproporex, amfepramone and mazindol, from Brazilian market, the use of these substances is still high, especially by drivers. Mazindol is the second most used anorectic agent in the world acting as an indirect sympathomimetic agonist, having stimulatory action on central nervous system. Plasma is a good matrix to monitor since it reflects the psychomotor effects of these drugs, but unlike urine has an invasive collection; drug levels and detection time are quite low.

METHOD

The method involved a liquid-liquid extraction of the samples and a LC-MS analysis was fully validated. Method was used to analyze samples of urine and plasma collected from health volunteers in a period of 24h. Metabolite of mazindol was synthesized using alkaline conditions.

RESULTS

After validation the method proved to be adequate to analyze samples collected from health volunteers. Method was linear in the concentration range of 0.1-10ng/mL (r=0.9982) for plasma and 5-50ng/mL (r=0.9973) for urine.

DISCUSSION

Analysis of the samples showed that mazindol can be detected after 1h of administration and that concentration levels in urine were always higher than in plasma. Mazindol metabolite was detected only in urine.

Pilot Phase II study of mazindol in children with attention deficit/hyperactivity disorder

OBJECTIVE

Mazindol has been proposed as a potential treatment of children with attention deficit/hyperactivity disorder (ADHD). The purpose of this pilot study was to assess its pharmacokinetics, short-term efficacy, and safety.

SUBJECTS AND METHODS

A total of 24 children (aged 9-12 years) with ADHD (according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, text-revision criteria) received a daily dose of 1 mg for 7 days and were followed for 3 additional weeks. Pharmacokinetic samples were collected after the first administration. ADHD symptoms were assessed using the ADHD Rating Scale (RS)-IV, Conners' Parent Rating Scale - Revised: Long (CPRS-R:L) at screening, baseline, and the end of the study. The Clinical Global Impression - Severity (CGI-S) scale was assessed at baseline, and the CGI - Improvement (CGI-I) scale was assessed at subsequent visits.

RESULTS

Twenty-one subjects (aged 10±1 years) were analyzed. Pharmacokinetic data were described by a one-compartment model with first-order absorption, elimination, and lag time. The typical apparent clearance and apparent volume of distribution were 27.9 L/h and 234 L, and increased with fat-free mass and age, respectively. The mean change in score in ADHD RS-IV after 1 week of mazindol was -24.1 (P<0.0001), greater than a 90% improvement from baseline. Reduction of CPRS-R:L and CGI-S scores were -52.1 (P<0.0001) and -2.5 (P<0.01), respectively. Adverse events were mild to moderate, decreased appetite and upper abdominal pain being the most common.

CONCLUSION

This preliminary study shows that mazindol might be an effective, well-tolerated, and long-acting (more than 8 hours) agent for the treatment of ADHD in children.