GHRP-2 abuse detectable up to 4 hours post-injection using dried blood spot anti-doping tests
Background
Anti-doping agencies face significant logistical and financial challenges with traditional blood and urine sampling, including collection, transport, and cold storage. Dried blood spot (DBS) sampling offers a promising alternative due to its simplicity and cost-effectiveness. However, before DBS can be widely adopted for routine testing, its suitability must be validated for each specific performance-enhancing drug. This is particularly crucial for substances like growth hormone-releasing peptides (GHRPs), which are prohibited in sports. This study focuses on validating a DBS-based detection method for GHRP-2, a representative member of this peptide family, to establish a reliable and practical testing protocol for sports authorities.
Study Design
Researchers developed and validated an analytical procedure to detect GHRP-2 and its main metabolite (AA-3) from DBS samples. The method used liquid chromatography-tandem mass spectrometry (LC-MS/MS). To test its real-world application, an administration study was conducted where a single 100 μg intravenous dose of GHRP-2 was given. DBS samples were collected from both venous and capillary blood over time to determine the detection window and compare concentrations between blood sources. The procedure's specificity and identification capabilities were assessed according to official anti-doping guidelines.
Results
The analytical method successfully detected GHRP-2 with a limit of detection (LoD) of 50 pg/ml. The peptide demonstrated excellent long-term stability in DBS samples, remaining detectable for over 2 years. Following a single 100 μg IV administration, GHRP-2 was consistently detected for up to 4 hours post-injection. Interestingly, GHRP-2 concentrations were found to be higher in venous blood DBS compared to capillary blood DBS.
Despite the concentration differences between venous and capillary sources, a similar detection window of up to 4 hours was achieved regardless of the blood type used.
While the method was robust for the parent compound, the levels of the main metabolite, AA-3, found in the DBS samples were too low for effective application and determination.
Key Findings
- GHRP-2 was detectable in dried blood spots for up to 4 hours after a single 100 μg intravenous dose.
- The limit of detection (LoD) for GHRP-2 in DBS was established at 50 pg/ml.
- GHRP-2 demonstrated long-term stability in DBS samples for over 2 years.
- GHRP-2 concentrations were higher in venous blood DBS compared to capillary blood DBS.
- The metabolite AA-3 was found at levels too low for effective determination using this DBS method.
Why It Matters
This study provides strong evidence that dried blood spot testing is a viable, stable, and effective method for detecting GHRP-2 abuse. For anti-doping organizations, this validates a simpler, cheaper, and less invasive collection method that could increase testing frequency and reach. For athletes using GHRP-2, this means the window of detection via this method is approximately 4 hours post-intravenous administration. The established long-term stability (>2 years) of GHRP-2 in DBS samples is a significant logistical advantage for storing evidence for future re-analysis. This work paves the way for the inclusion of GHRP-2, and likely other similar peptides, in routine DBS-based anti-doping screening panels, making evasion more difficult.
