Millennium Research Institute, 16980 Via Tazon, San Diego, CA 92127, USA.
Clin Chim Acta. 2013 Feb 1;416:80-5. doi: 10.1016/j.cca.2012.11.020. Epub 2012 Nov 29.
Effective urine drug testing requires an understanding of the stability of medications, metabolites and other substances excreted in the urine matrix. When the testing results do not fit the clinical picture, physicians frequently request repeat testing of the original specimen in order to corroborate the results. We determined the stability in urine of various medications, metabolites, and illicit substances commonly requested for testing by physicians treating patients with pain and pain-related disorders.
Quantitative analyses of urine specimens were performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Two replicates at a high and low concentration were analyzed at time 0, and after 2, 3 and 6 months following storage at +4 °C and -20 °C. At each time interval, the percent difference from time 0 for each analyte was calculated and averaged for each storage condition.
For the majority of medications, the percent differences were within 20% of the original measurement for all 3 storage conditions. All were within 30% of the original measurement after 2, 3 and 6 months in all storage conditions, except for 7-amino-clonazepam, and carboxy-tetrahydrocannabinol.
The findings from the current study confirm that the majority of medications, metabolites, and illicit substances commonly requested for testing by physicians treating patients with pain and pain-related disorders are stable within 20% of the original concentration when stored refrigerated or frozen for up to 6 months. Thus, delayed testing, repeat testing, and add-on testing of urine specimens can yield reliable results for up to 6 months following the urine collection date.
有效的尿液药物检测需要了解药物、代谢物和其他在尿液基质中排泄的物质的稳定性。当检测结果与临床情况不符时，医生通常会要求重复检测原始标本，以证实检测结果。我们确定了治疗疼痛和疼痛相关疾病患者的医生经常要求检测的各种药物、代谢物和非法物质在尿液中的稳定性。
使用液相色谱-串联质谱（LC-MS/MS）对尿液标本进行定量分析。在 0 时间点分析了高浓度和低浓度的两个重复样本，然后在 +4°C 和 -20°C 下储存 2、3 和 6 个月后进行分析。在每个时间间隔，从时间 0 计算每个分析物的百分比差异，并对每个储存条件进行平均。
对于大多数药物，在所有 3 种储存条件下，所有分析物的百分比差异均在原始测量值的 20%以内。在所有储存条件下，所有分析物在 2、3 和 6 个月后的百分比差异均在原始测量值的 30%以内，除了 7-氨基氯硝西泮和羧基四氢大麻酚。
当前研究的结果证实，治疗疼痛和疼痛相关疾病患者的医生经常要求检测的大多数药物、代谢物和非法物质在冷藏或冷冻储存长达 6 个月时，其原始浓度的 20%以内是稳定的。因此，尿液标本的延迟检测、重复检测和附加检测可在尿液采集日期后长达 6 个月内产生可靠的结果。
