A sensitive and rapid HPLC-MS/MS method for the quantitative determination of trace amount of bromocriptine in small
Qingce Zang1, Yang Liu2, Jiuming He1
1State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100050, China.
Abstract:
Usually, insufficient intratumoral concentration of therapeutic drugs is one of the reasons for tumor treatment failure. However, little is known about intratumoral distribution of bromocriptine in non-responding prolactinomas because of extremely low drug concentration and small prolactinoma tissue samples. In this study, a sensitive, rapid and high-throughput quantitative bioanalytical method has been established by using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for the determination of bromocriptine at trace level in human prolactinoma tissue. As little as 20 mg (wet weight) tissue sample was required and total analysis time was 6 min in this method. The assay quantifies over a linear range of 50 fg/mg to 5 pg/mg, and has a 25 fg/mg limit of detection at a signal/noise ratio of 3. This validated method was successfully used to quantitatively determine bromocriptine in clinical post-operative bromocriptine-sensitive and -resistant prolactinomas. The results revealed bromocriptine concentration in resistant prolactinomas (0.49-1.25 pg/mg) was significantly higher than that in sensitive prolactinomas (0.057-0.47 pg/mg). These results provided direct evidence to demonstrate the reseaon for failure of bromocriptine treatment in some patients with prolactinoma was "intrinsic" tumor (cell) resistence, rather than insufficient drug concentration in tumor tissue. Additionaly, this HPLC-MS/MS method has been shown to be suitable for bromocriptine analysis in small amount tissue sample and could be adapted for therapeutic drug monitoring of other clinical medicine.
Insights
Bromocriptine resistance in prolactinomas is intrinsic, not due to low drug levels. A new HPLC-MS/MS method accurately measures bromocriptine in tiny tumor samples, revealing higher drug concentrations in resistant tumors.
Area of Science:
- Pharmacology
- Analytical Chemistry
- Oncology
Background:
- Insufficient drug concentration is a common cause of tumor treatment failure.
- Intratumoral bromocriptine distribution in non-responding prolactinomas is poorly understood due to low drug levels and small sample sizes.
Purpose of the Study:
- To establish a sensitive, rapid, and high-throughput bioanalytical method for quantifying bromocriptine in human prolactinoma tissue.
- To investigate the intratumoral concentration of bromocriptine in both sensitive and resistant prolactinomas.
Main Methods:
- Development and validation of a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method.
- Quantification of bromocriptine in minimal tissue samples (as low as 20 mg) with a 6-minute analysis time.
- Analysis of clinical post-operative bromocriptine-sensitive and -resistant prolactinoma samples.
Main Results:
- The HPLC-MS/MS method demonstrated high sensitivity (25 fg/mg limit of detection) and a wide linear range.
- Bromocriptine concentrations were significantly higher in resistant prolactinomas (0.49-1.25 pg/mg) compared to sensitive prolactinomas (0.057-0.47 pg/mg).
Conclusions:
- Treatment failure in some prolactinomas is due to intrinsic tumor resistance, not insufficient drug concentration.
- The validated HPLC-MS/MS method is suitable for analyzing small tissue samples and can be adapted for therapeutic drug monitoring.
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