PYTEST^®

MIMS Revision Date: 01 November 2025

1 Name of Medicine

Urea [¹⁴C].

2 Qualitative and Quantitative Composition

Each clear gelatin capsule contains 1 microgram yellow beads equivalent to 37 kBq ¹⁴C.
Each PYtest Kit (C14-urea Breath Test) contains one capsule.
Excipients with known effect. Sucrose.
For the full list of excipients, see Section 6.1 List of Excipients.

3 Pharmaceutical Form

Clear, hard gelatin capsules containing light yellow sugar spheres.

4 Clinical Particulars

4.1 Therapeutic Indications

PYtest (C14-urea breath test) is indicated for use in the detection of gastric urease as an aid in the diagnosis of H. pylori infection in the human stomach.

4.2 Dose and Method of Administration

PYtest (C14-urea breath test) is a qualitative and non-invasive method for the diagnosis of Helicobacter pylori (H. pylori).
Dosage. Adults. One PYtest capsule.
Children. Clinical studies in children have not been conducted.
Method of administration. For oral administration.
Procedural notes. Inform the patient to fast for 4 hours prior to the test.
The patient should not have taken antibiotics and bismuth containing products for 1 month, proton pump inhibitors for 1 week and sucralfate for 2 weeks prior to the test.
Have patient sitting at rest while doing the test.
The capsule should not be handled directly as this may interfere with the test result.
To avoid contamination by bacteria in the mouth, the capsule should be swallowed intact. Do not chew capsule.
Also see Section 4.4 Special Warnings and Precautions for Use.
Step by step procedure for balloon. Materials needed but not provided. 1. Clock or suitable timepiece capable of measuring 10 minutes in minute intervals.
2. Water (40 mL).
Materials provided. As shown in Figure 1, the PYtest kit contains: PYtest capsule, paper cup (x2), straw, balloon, package seals, return carton.
The PYtest Kit (C14-urea breath test) is designed for use with the PYtest capsule, a gelatin capsule for oral administration containing 37 kBq of ¹⁴C labelled urea. The urea is absorbed on sugar spheres and coloured yellow with fluorescein.

Breath sample collection. 1. Label the balloon with the required details. (Recommend using a permanent marker.)
2. Check that all materials are present.
3. Sit the patient down.
4. Place the capsule into one of the paper cups provided.
5. Fill the second cup 2/3 full (20 mL) with water.
6. Instruct the patient to swallow the capsule whole and to drink the water to wash the capsule down.
7. Three minutes later, fill a paper cup 2/3 full (20 mL) with water and instruct the patient to drink it. This is to ensure the capsule has been 'washed' into the stomach.
8. With the patient still sitting, wait for a further seven minutes.
9. On the neck of the balloon, separate the larger flap from the smaller flap at the black line. This can be achieved by gently squeezing the sides of the flaps together whilst pushing the flaps apart until an opening appears.
10. Insert approximately one third of the straw into the opening.
11. Instruct the patient to take a deep breath, get them to hold it for 5-10 seconds then ask them to blow slowly through the straw into the balloon until it is firm. If the balloon is not filled with the first attempt, a second breath can be used.
12. Hold the neck of the balloon at the base and remove the straw. The balloon will seal.
13. Record the finish time on the balloon.
14. Discard waste (e.g. capsule packaging, used straws) according to your facility's regulations.
Sample preparation. The breath sample is transferred to collection fluid to trap the labelled CO₂. The liquid sample is then analysed in a liquid scintillation counter.
Quality control. A minimum of 1 mmol of CO₂ is required to perform analysis of a breath sample. The amount of breath required to provide 1 mmol of CO₂ varies depending on the amount of CO₂ the patient is producing. Since a full balloon typically contains at least 1 mmol of CO₂, the balloon should be completely filled.
Post treatment evaluation. A negative PYtest 28 days after completing antibiotic treatment is evidence that the infection has been eradicated.
Results. Interpretation of results (10 minute sample). < 50 DPM Negative for H. pylori.
50-199 DPM Borderline positive for H. pylori.
≥ 200 DPM Positive for H. pylori.
Borderline positive results should be evaluated by repeating the PYtest or using an alternative diagnostic method. If repeat breath testing is undertaken, careful history to exclude confounding factors should be obtained. If confounding factors are present, wait an appropriate time (see Table 1) before repeating the PYtest. The cut-off point of 50 DPM was determined to be the mean +3SD of results obtained in-patients who did not have H. pylori.
Expected values. As shown in Figure 2, approximately 30% of patients tested will be positive for H. pylori.

4.3 Contraindications

Hypersensitivity to the active substance, or any of the excipients.

4.4 Special Warnings and Precautions for Use

After the patient ingests the urea [¹⁴C] capsule, the sample collected for test purposes is for in vitro diagnostic use only.
A false positive test could occur in patients who have achlorhydria.
Very rarely, a false positive test may occur due to urease associated with Helicobacters other than H. pylori (e.g. Helicobacter heilmannii).
Information for patients. It is necessary for the patient to fast for 4 hours before the test. The patient should not have taken antibiotics or bismuth containing products for 4 weeks, sucralfate for 2 weeks and proton pump inhibitors for 1 week prior to the test.
Do not handle the capsule directly as this may interfere with the test result. The capsule should be swallowed intact. The capsule should not be chewed.
Limitations of the test. The test has been evaluated in outpatients before elective endoscopy.
Test results should be considered together with clinical signs and patient history when diagnosing H. pylori infection.
A negative result does not completely rule out the possibility of H. pylori infection. If clinical signs and patient history suggest H. pylori infection, repeat the PYtest or use an alternative diagnostic method.
Use in renal and hepatic impairment. No data available.
Use in the elderly. No data available.
Paediatric use. Clinical studies in children have not been conducted. No data available.
Effects on laboratory tests. No data available.

4.5 Interactions with Other Medicines and Other Forms of Interactions

Antibiotics, proton pump inhibitors, sucralfate, and bismuth containing drug preparations are known to suppress H. pylori. Ingestion of antibiotics or bismuth within 4 weeks, sucralfate within 2 weeks or proton pump inhibitors within 1 week prior to performing the test may give false negative results.

4.6 Fertility, Pregnancy and Lactation

Effects on fertility. Animal reproduction studies have not been conducted with PYtest (urea [¹⁴C]). It is also not known whether PYtest can affect reproduction capacity.
Use in pregnancy. Animal reproduction studies have not been conducted with PYtest (urea [¹⁴C]). It is also not known whether PYtest can cause fetal harm when administered to a pregnant woman.
When administration of PYtest to a woman of child-bearing potential is considered, information should always be sought about pregnancy.
Use in lactation. It is not known whether this drug is excreted in human milk.

4.7 Effects on Ability to Drive and Use Machines

The effects of this medicine on a person's ability to drive and use machines were not assessed as part of this registration.

4.8 Adverse Effects (Undesirable Effects)

There were no adverse reactions reported in clinical trials at a rate > 1%. All adverse reactions reported were felt by the investigators to be unrelated to the PYtest.
Reporting suspected adverse effects. Reporting suspected adverse reactions after registration of the medicinal product is important. It allows continued monitoring of the benefit-risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions at www.tga.gov.au/reporting-problems.

4.9 Overdose

In the event of overdose, the patient should drink one glass of water (150 mL) every hour to hasten excretion of the radioisotope. Maximum excretion of urea is achieved at a urine output of > 2.0 mL/min.
For information on the management of overdose, contact the Poisons Information Centre on 13 11 26 (Australia).

5 Pharmacological Properties

5.1 Pharmacodynamic Properties

Mechanism of action. The urease enzyme is not present in mammalian cells, so the presence of urease in the stomach is evidence that bacteria are present. The presence of urease is not specific for H. pylori, but other bacteria are not usually found in the stomach. The principle of the breath test is shown in Figure 3.

Clinical trials. Two studies were performed. In both studies, patients with gastrointestinal symptoms underwent the breath test and an endoscopy. During the endoscopy, biopsy samples were taken from the antral gastric mucosa for histological analysis (2 samples, Giemsa stain) and rapid urease test (1 sample, CLOtest). Breath samples were mailed to a laboratory where they were read in a liquid scintillation counter. Results were reported as disintegrations per minute (DPM). Analysis for accuracy used the ten minute breath sample. A breath sample DPM < 50 was defined as a negative result. DPM ≥ 200 was defined as a positive result. DPM in the range of 50-199 was classified as indeterminate.
Study 1. Of 186 patients who had histopathology and Campylobacter Like Organism [(CLO)test] (80 men, 106 women), 53 were infected with H. pylori as determined by agreement between histology and CLOtest. The study results are summarized in Table 2.
Study 2. Breath tests were performed on seventy-six patients (40 men, 36 women) who had histology and CLOtest performed also. The results are summarized in Table 3.
Summary of accuracy. See Table 4.

5.2 Pharmacokinetic Properties

Metabolism. To detect H. pylori, urea labelled with ¹⁴C is swallowed by the patient. If gastric urease from H. pylori is present, urea is split to form CO₂ and NH₃ at the interface between the gastric epithelium and lumen.
Excretion. ¹⁴CO₂ is absorbed into the blood and exhaled in the breath.
Following ingestion of the capsule by a patient with H. pylori, ¹⁴CO₂ excretion in the breath peaks between 10 and 15 minutes and declines thereafter with a biological half-life of about 15 minutes. ¹⁴C-urea that is not hydrolysed by H. pylori is excreted in the urine with a half-life of approximately 12 hours. About 10% of the ¹⁴C remains in the body at 72 hours and is gradually excreted with a biological half-life of 40 days.

5.3 Preclinical Safety Data

Radiation safety. To allow radiation sources to be effectively compared emissions of various origins are expressed in terms of "effective dose" (ED). The ED of ¹⁴C takes into account the fraction of isotope sequestered in each organ tissue (as recommended by the International Commission for Radiological Protection 60 [ICRP-60] which is adopted in Australia), the biological half life of the isotope in that tissue, the effective energy of the beta particles compared with standard ionising radiation (200kV x-ray source) and the administered dose. ED is expressed in Sieverts (1 Sievert [Sv]; 10^-6 Sv = 1 microSv). The maximum estimated ED received from a single administration of PYtest capsule (37 kBq of [¹⁴C]-urea) is 3 microSv; Figure 4 summarizes radiation exposure from the PYtest in comparison with other common sources of radiation exposure.
The Australian population is subjected to an annual radiation dose of about 1800 microSv to 2400 microSv per caput as a result of natural environmental radiation and the in vivo presence of radionuclides such as natural ¹⁴C and ⁴⁰K in the body. 2400 microSv is equivalent to the radiation dose afforded by the ingestion of 800 PYtest capsules. A single PYtest procedure is the equivalent of about 11 hours of normal and essentially inevitable radiation exposure from the environment.

Genotoxicity. No data available.
Carcinogenicity. No data available.
Radiation dosimetry. Maximum effective dose (ED) (H. pylori positive): 3 microSv/37 kBq.

6 Pharmaceutical Particulars

6.1 List of Excipients

Sugar spheres containing sucrose and starch, fluorescein sodium, capsule shell: empty gelatin capsule size 3 Natural TR-Natural TR.

6.2 Incompatibilities

Incompatibilities were either not assessed or not identified as part of the registration of this medicine.

6.3 Shelf Life

PYtest capsules and kit have a shelf life of three years.

6.4 Special Precautions for Storage

Store below 30°C in an area designated by each individual institution's regulations.

6.5 Nature and Contents of Container

PYtest capsules are supplied in unit dose packages of 1, 10* and 100*.
*Presentations are not marketed.
PYtest kit (C14-urea breath test) is supplied as a kit containing a PYtest capsule and breath collection accessories.

6.6 Special Precautions for Disposal

Because of the very low radioactivity of individual PYtest capsules, no special precautions are needed for the disposal of small numbers of capsules. Where it is necessary to dispose of large quantities of capsules, the disposal of waste should be carried out in accordance with the NHMRC Code of Practice for Disposal of Radioactive Waste by Users, (1985).

6.7 Physicochemical Properties

Chemical structure. Molecular formula: NH₂¹⁴CONH₂.

CAS number. 594-05-8.
Physical characteristics of ¹⁴C. Radiation emission: Beta-emission, 49 keV mean, 156 keV max, no other emissions.
External emission: No external radiation hazard. Low-energy beta emissions only. Maximum range of 0.3 mm in water.
Physical half-life: 5730 years.

7 Medicine Schedule (Poisons Standard)

Not scheduled.

Date of First Approval

16 December 1998

Date of Revision

30 September 2025

Summary Table of Changes