Breath tests using

A breath test, used to determine the presence of Helicobacter pylori, associated with stomach ulcers, is an example of a diagnostic product involving separate drug and device components. To perform the test, a patient swallows some isotopically (e.g. 

How HDI affects your health depends on how much is in the air you breathe. Tests using laboratory animals showed that breathing in high concentrations of HDI can irritate the nose, eyes, and throat. 

Recent drug assay development involved LC-MS methods (Caubet et al. 2004 Kanazawa et al. 2000). A less practical breath test, using 13C or 14C labeled caffeine, can also be used (Kalow and Tang 1991). 

Sucrase-isomaltase deficiency can be investigated by using 50 g sucrose instead of lactose. An increase in breath hydrogen of >20 ppm (20 pL/L) within 2 hours is diagnostic. It is rarely necessary to test for trehalase deficiency, although a breath test using 25 g trehalose has been described. ... 

The diagnostic gold standard requires intubation with aspiration of jejunal contents and the demonstration of a bacterial count of >10 organisms/mL and >10 anaer-obes/mL. In practice, hydrogen breath tests using eitiier lactulose or glucose as substrates are used more frequently. An alternative diagnostic approach is to use a therapeutic trial of antibiotics. 

Urea breath test Used to identify patients with HeScobaclerpylori rltec6on which is strongly associated with peptic ulcer disease... 

Office-based serologic testing provides a quick assessment (within 15 minutes) of an exposure to HP, but patients can remain seropositive for up to 1 year after eradication, making the clinical utility of this test limited. Stool antigen assays can be useful for the initial diagnosis or to confirm HP eradication, and unlike the urea breath test, are less affected by concomitant medication use.9... 

Rapid intestinal transit may result in a false-positive breath test, in particular when hyperosmolar nonabsorbable substrates are used. A false-negative outcome in patients with culture-proven Gram-negative bacilli in the upper gut further query the sensitivity and usefulness of breath tests for clinical practice [10-13]. Positive microbial culture from small intestine is thus advantageous when major alterations of clinical management are considered. 

Studies of small bowel transit time have demonstrated a great variability both within and between individuals. When the hydrogen breath test was performed under fasting conditions, using 10 ml of lactulose, the coefficient of variation amounted to 18%. Di Lorenzo et al. [129] showed that variations under fasting conditions are partly accounted for by the phase of the migrating motor complex at the intake of test solution. Moreover, when a lactose-containing meal was used, the coefficient of variation was reduced to 4% [130],... 

Breath tests are, therefore, less useful for testing of intestinal transit in the presence of bacterial overgrowth. 

Hepatic Effects. Hepatic changes were observed in one chronic human exposure to mirex, as well as in a number of workers exposed to chlordecone for intermediate or chronic durations. In the mirex study, human subjects (sex and number not specified) from a chronically exposed cohort from southeast Ohio (route of exposure not specified, assumed to be oral) were assessed for cytochrome P- 4501A2 induction using a breath test that measures caffeine metabolism. The subjects exposed to mirex had elevated caffeine metabolism as compared to negative control individuals (subjects with no known exposure to polyhalogenated biphenyls or other related chemicals) in which the metabolism did not increase (Lambert et al. 1992). In the chlordecone study, liver function and structure in 32 men exposed to high levels of chlordecone while employed for 1-22 months (5.6... 

Wolfe has presented an excellent description of the systematic application of stable and radioactive isotope tracers in determining the kinetics of substrate oxidation, carbon dioxide formation (including C02 breath tests), glucose oxidation, and fat oxidation in normal and diseased states. Quantification of the rate and extent of substrate oxidation can be achieved by using a specific or C-substrate which upon oxidation releases radioactive carbon dioxide. 

Tateishi, T., Graham, S. G., Krivoruk, Y., and Wood, A. J. J. (1995) Omeprazole does not affect measured CYP3A4 activity using the erythromycin breath test. Bn J. Clin. Pharmacol. 40, 411-412. 

Blood alcohol concentration (BAG) is often based not on an actual sample of blood but rather on the concentration of alcohol in a sample of breath (Figure 3.3). Alcohol is volatile, and, as described by Henry s law, there is a constant relationship between the amount of alcohol vapor found in a volume of air (breath sample) and the amount of alcohol found in a volume of liquid (blood). All breath-testing equipment uses the blood-breath ratio of 2,100 1 for alcohol. This means that the amount of alcohol found in 2,100 milliliters of breath is equivalent to the amount of alcohol found in 1 milliliters of blood. 

MattisonLK, EzzeldinH, Carpenter Met al. Rapid identification of dihydropyrimidine dehydrogenase deficiency by using a novel 2-13C-uracil breath test. Clin Cancer Pes 2004 10 2652-2658. 

Polybrominated Biphenyls. A recent study has used caffeine as a potential tool to characterize exposure and/or effect of PBBs (Lambert et al. 1990). In this test, caffeine is used as a metabolic probe of cytochrome P-450 isozymes activity from the CYPIA family, which in animals is significantly induced by PBBs (Safe 1984). Tire caffeine breath test (CBT) is primarily useful for detecting induction of CYP1A2 activity in human liver, and for that reason, it also has been used as a marker for exposure to PCBs, CDDs, and CDFs (Lambert et al. 1992). A volunteer population of 50 Michigan subjects with previously high serum PBB levels and 50 with undetectable or low serum levels was compared to a control population not exposed to PBBs (Lambert et al. 1992). Two tests were conducted, the CYP1A2-dependent caffeine... 

Sonnenberg A, Koelz HR, Herz R, Benes I, Blum AL. Limited usefulness of the breath test in evaluation of drug metabolism a study in human oral contraceptive users treated with dimethylaminoantipyrine and diazepam. Hepatogastroenterology 1980 27(2) 104-8. 

The O-deethylation of phenacetin is CYPlA2-mediated and results in the liberation of acetaldehyde that is subsequently metabolized to acetate and then CO2. Thus, a breath test based on the use of phenacetin labeled with 14C in the 1-position of the ethyl side chain could function to assess CYP1A2 activity. Early studies demonstrated the feasibility of this approach and its potential application to evaluating hepatic function (65,66). No extensive validation was attempted, so it is difficult to determine how well this test reflects the enzyme s intrinsic clearance, rather than perhaps some other determinant, such as liver blood flow. However, the situation appears to be moot since phenacetin is no longer an approved dmg worldwide because of its renal side effects following chronic dosing accordingly, further studies of this approach are unlikely. 

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