The erythromycin breath test (ERMBT) is a method used to measure

metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...

(oxidation and elimination from the system) by a part of the

cytochrome P450 Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compo ...

system. Erythromycin produces ¹⁴CO_2, and this ¹⁴CO₂ can be measured to study drugs that interact with the

system.

Erythromycin Erythromycin is an antibiotic used for the treatment of a number of bacterial infections. This includes respiratory tract infections, skin infections, chlamydia infections, pelvic inflammatory disease, and syphilis. It may also be used du ...

is tagged with carbon-14 and given as an intravenous injection; after 20 minutes the subject blows up a balloon and the

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

exhaled that is tagged with carbon-14 shows the activity of the

CYP3A4 Cytochrome P450 3A4 (abbreviated CYP3A4) () is an important enzyme in the body, mainly found in the liver and in the intestine. It oxidizes small foreign organic molecules ( xenobiotics), such as toxins or drugs, so that they can be removed from t ...

isoenzyme In biochemistry, isozymes (also known as isoenzymes or more generally as multiple forms of enzymes) are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. Isozymes usually have different kinetic parameters (e.g. dif ...

on the erythromycin. ERMBT can be used to determine how drugs that the CYP3A4 isoenzyme metabolizes will function in a given individual. Erythromycin is a drug that treats bacterial infections like

bronchitis Bronchitis is inflammation of the bronchi (large and medium-sized airways) in the lungs that causes coughing. Bronchitis usually begins as an infection in the nose, ears, throat, or sinuses. The infection then makes its way down to the bronchi ...

sexually transmitted diseases Sexually transmitted infections (STIs), also referred to as sexually transmitted diseases (STDs) and the older term venereal diseases, are infections that are Transmission (medicine), spread by Human sexual activity, sexual activity, especi ...

, and

pneumonia Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severi ...

. The medication is in a capsule form and takes on a "delayed-release," to ensure it is only broken down once it reaches the intestine and not by stomach acids. The test allows doctors to determine or predict an individual’s drug treatment outcome. Will a patient develop serious or fatal side effects from a certain drug? Which foods and drugs should not be taken together? With this and other tests a physician may determine treatment outcomes in advance or study the effects of new drugs. Some patients have a

congenital A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities c ...

inability to synthesize certain enzymes, so drugs may build up to toxic levels in their system or other drugs and foods a patient is taking may consume all of their ability to metabolize certain foods and drugs. An example is: when a person taking a cholesterol-lowering

statin Statins, also known as HMG-CoA reductase inhibitors, are a class of lipid-lowering medications that reduce illness and mortality in those who are at high risk of cardiovascular disease. They are the most common cholesterol-lowering drugs. L ...

drug then drinking

grapefruit juice Grapefruit juice is the juice from grapefruits. It is rich in vitamin C and ranges from sweet-tart to very sour. Variations include white grapefruit, pink grapefruit and ruby red grapefruit juice.The World's Healthiest Foods; Grapefruit. ''The G ...

, they may have a poor treatment outcome (

adverse drug reaction An adverse drug reaction (ADR) is a harmful, unintended result caused by taking medication. ADRs may occur following a single dose or prolonged administration of a drug or result from the combination of two or more drugs. The meaning of this term ...

) and sustain liver damage or kidney failure due to drug induced

rhabdomyolysis Rhabdomyolysis (also called rhabdo) is a condition in which damaged skeletal muscle breaks down rapidly. Symptoms may include muscle pains, weakness, vomiting, and confusion. There may be tea-colored urine or an irregular heartbeat. Some of t ...

(the breaking up of muscle tissue).

References

Enzymes Breath tests {{Metabolism-stub