DIABACT UBT Tablet Ref.[28028] Active ingredients: Urea ¹³C

Pharmacotherapeutic group: Other diagnostic agents
ATC code: V04CX05

Mechanism of action

After oral ingestion, ¹³C-urea labelled urea tablets will rapidly disintegrate on reaching the stomach. In the case of infection with H. pylori, ¹³C-urea is metabolised by the enzyme urease of H. pylori.

The carbon dioxide which is liberated diffuses into the blood vessels and is transported as bicarbonate to the lungs where it is then liberated as ¹³CO₂ in exhaled air. Infection with H. pylori will significantly change the ¹³C/¹²C – carbon isotope ratio. The proportion of ¹³CO₂ in the breath samples is determined by isotope-ratio-mass spectrometry (IRMS) or by another suitably-validated method carried out by any qualified laboratory and stated as an absolute difference (excess) in the value between a pre-urea and post-urea breath sample (see section 6.6).

The cut off point for discriminating between H. pylori positive and negative patients is based on a study with 885 patients. Values below 1.5‰, i.e. ≤1.5‰ are diagnosed as negative and values above i.e. >1.5‰ are diagnosed as positive.

In order to determine test performance and to fulfil lack of direct comparison vs Standard of Truth (SoT) at the registered dose, a simulation analysis was carried out based on two comparative studies: the sensitivity was 94.3% (95% CI = [85.1%-98.5%]) and specificity was 97.1% (95% CI = [92.4%-99.2%]). The accuracy was 96.2% (95% CI = [92.2-98.5%]) and with the PPV (positive predicted value) of 94.0% (95% CI = [84.6-98.3%]) and NPV (negative predicted value) 97.3% (95% CI = [92.7-99.3%]).