Elimination profile of low-dose chlortalidone and its detection in hair for doping analysis-Implication for...

Area of Science:

• Pharmacology
• Sports Science
• Analytical Chemistry

Background:

• Chlortalidone (CLT) is a diuretic used for edema and hypertension.
• Diuretics are prohibited by WADA, with a 20 ng/mL threshold for some due to contamination.
• A recent case questioned unintentional doping from CLT contamination in other drugs.

Purpose of the Study:

• To investigate the potential for unintentional doping via CLT contamination.
• To analyze CLT and hydrochlorothiazide (HCTA) co-elimination in urine and hair.
• To assess the risk of adverse analytical findings from low-dose CLT intake.

Main Methods:

• Co-administration of low-dose CLT and HCTA to two volunteers for five days.
• Analysis of urine samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS).
• Examination of CLT incorporation into scalp hair.

Main Results:

• HCTA was rapidly excreted in high urine concentrations.
• CLT exhibited significantly slower elimination (12x longer half-life) and lower urine concentrations (45-53 ng/mL).
• Higher CLT incorporation was observed in hair when co-administered with HCTA.

Conclusions:

• Sub-therapeutic CLT intake from contamination could lead to adverse analytical findings.
• The slower CLT elimination and hair incorporation highlight risks for athletes.
• This research is crucial for understanding doping control and unintentional violations.