Rifabutin is an exogenous compound that exists as a solid at room temperature. Rifabutin belongs to the macrolactams, a class of phenylpropanoids and polyketides within the organic compounds. With an average molecular weight of 847.00 g/mol, Rifabutin is a heavy molecule. It has the chemical formula C46H62N4O11.
Used as an antitubercular agent, Rifabutin is found in pharmaceuticals and veterinary products, specifically antibiotics and drugs for the treatment of tuberculosis. Exposure to the compound occurs through oral or inhalation routes. Its protein targets include Heat shock protein HSP 90-alpha (HSP90AA1), Endoplasmin (HSP90B1), and the alpha (rpoA), beta (rpoB), and beta' (rpoC) subunits of DNA-directed RNA polymerase. Rifabutin acts via the inhibition of DNA-dependent RNA polymerase, leading to a suppression of RNA synthesis and cell death.
belongs to the class of organic compounds known as macrolactams. These are cyclic amides of amino carboxylic acids, having a 1-azacycloalkan-2-one structure, or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring. They are nitrogen analogues (the a nitrogen atom replacing the o atom of the cyclic carboxylic acid group ) of the naturally occurring macrolides.
Rifabutin is readily absorbed from the gastrointestinal tract, with an absolute bioavailability averaging 20%.
Mechanism of Toxicity
Rifabutin acts via the inhibition of DNA-dependent RNA polymerase in gram-positive and some gram-negative bacteria, leading to a suppression of RNA synthesis and cell death.
Metabolism
Hepatic. Of the five metabolites that have been identified, 25-O-desacetyl and 31-hydroxy are the most predominant. The former metabolite has an activity equal to the parent drug and contributes up to 10% to the total antimicrobial activity.
Route of Elimination: A mass-balance study in three healthy adult volunteers with 14C-labeled rifabutin showed that 53% of the oral dose was excreted in the urine, primarily as metabolites. About 30% of the dose is excreted in the feces.
Half Life: 45 (± 17) hours
No indication of carcinogenicity to humans (not listed by IARC).
Uses/Sources
For the prevention of disseminated Mycobacterium avium complex (MAC) disease in patients with advanced HIV infection. Used in the treatment of tuberculosis. It has also found to be useful in the treatment of (Chlamydia) Chlamydophila pneumoniae (Cpn) Infection.[Wikipedia]
Minimum Risk Level
Not Available
Health Effects
Not Available
Symptoms
Symptoms include diarrhea, eructation, abdominal pain, vomitting, nausea, and insomnia.
Treatment
Clinical experience with rifamycins suggests that gastric lavage to evacuate gastric contents (within a few hours of overdose), followed by instillation of an activated charcoal slurry into the stomach, may help absorb any remaining drug from the gastrointestinal tract. (2)
