HELICOBACTER Powder for oral solution Ref.[8561] Active ingredients: Urea ¹³C

Pharmacotherapeutic group: Other diagnostic agents
ATC code: VO4CX

For the amount of 75 mg ¹³C-urea, which is administered per unit in the course of the breath test, no pharmacodynamic activity is described.

After oral ingestion the labelled urea reaches the gastric mucosa. In the presence of Helicobacter pylori the ¹³C-urea is metabolised by the enzyme urease of Helicobacter pylori.

The carbon dioxide diffuses into the blood vessels. From there it is transported as bicarbonate into the lung and liberated as ¹³CO₂ with the exhaled air.

In the presence of bacterial urease the ratio of the ¹³C/¹²C-carbon isotopes is significantly changed. The portion of ¹³CO₂ in the breath samples is determined by isotope-ratio-mass-spectrometry (IRMS) and stated as an absolute difference (∆δ-value) between the 00-minute- and the 30-minute-values.

Urease is produced in the stomach only by Helicobacter pylori. Other urease producing bacteria were seldom found in the gastric flora.

The cut off point for discriminating Helicobacter pylori-negative and positive patients is determined to be ∆δ-value of 4‰, which means that an increase of the ∆δ-value by more than 4‰ indicates an infection. In comparison to bioptic diagnostics of an infection with Helicobacter pylori, the breath test achieved in clinical trials on 457 patients, a sensitivity in the range of 96.5% to 97.9% [95%-CI: 94.05%-99.72%], and a specificity range from 96.7% to 100%. [95%-CI: 94.17%-103.63%], whereas in clinical trials on 93 adolescents from the age 12–17, a sensitivity of 97.7% [90%-CI: 91.3%], and a specificity of 96.0% [90%-CI: 89.7%] were achieved.

In the absence of bacterial urease, the whole amount of the administered urea after absorption from the gastrointestinal tract will be metabolised like the endogenous urea. Ammonia which is produced as described above by the bacterial hydrolysis is included into the metabolism as NH₄+.