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Rifampicin information from DrugsUpdate  

See Available Brands of Rifampicin in India

P - Caution when used during pregnancy
L - Caution when used during lactation
FI - Food *
LI - Lab *

Rifampicin or rifampin is a bactericidal antibiotic drug of the rifamycin group. It is a semisynthetic compound derived from Amycolatopsis rifamycinica (formerly known as Amycolatopsis mediterranei and Streptomyces mediterranei). Rifampicin may be abbreviated R, RMP, RD, RA, or RIF (US).

Pharmacodynamics

Rifampicin inhibits DNA-dependent RNA polymerase in bacterial cells by binding its beta-subunit, thus preventing transcription to RNA and subsequent translation to proteins. Its lipophilic nature makes it a good candidate to treat the meningitis form of tuberculosis, which requires distribution to the central nervous system and penetration through the blood-brain barrier.

Rifampicin acts directly on messenger RNA synthesis. It inhibits only prokaryotic DNA-primed RNA polymerase, especially those that are Gram-stain-positive and Mycobacterium tuberculosis. Evidence shows that in vitro DNA treated with concentrations 5000 times higher than normal dosage remained unaffected; in vivo eukaryotic specimens' RNA and DNA polymerases suffered few problems as well. Much of this acid-fast positive bacteria's membrane is mycolic acid complexed with peptidoglycan, which allows easy movement of the drug into the cell. Rifampicin interacts with the β subunit of RNA polymerase when it is in an α2β trimer. This halts mRNA transcription, therefore preventing translation of polypeptides. It should be made clear, however, that it cannot stop the elongation of mRNA once binding to the template-strand of DNA has been initiated. The Rifampin-RNA polymerase complex is extremely stable and yet experiments have shown that this is not due to any form of covalent linkage. It is hypothesized that hydrogen bonds and π-π bond interactions between naphthoquinone and the aromatic amino acids are the major stabilizers, though this requires the oxidation of naphthohydroquinone which is found most commonly in Rifampin. It is this last hypothesis that explains the explosion of multi-drug-resistant bacteria: mutations in the rpoB gene that replace phenylalanine, tryptophan, and tyrosine with non-aromatic amino acids result in poor bonding between Rifampin and the RNA polymerase.

Rifampin-resistant bacteria produce RNA Polymerases with subtly different β subunit structures which are not readily inhibited by the drug. In molecular biology research, plasmids containing rifampicin-resistant genes are often used for colony screening. Many plasmids containing these resistant genes are commercially available to researchers.

Pharmacokinetics

Orally-administered Rifampin results in peak plasma concentrations in about 2 to 4 hours. Aminosalicyclic acid significantly reduce absorption of Rifampin, and peak concentrations may not be reached. If these two drugs must be used concurrently, they must be given separately with an interval of 8 to 12 hours between administrations.

Rifampin is easily absorbed from the gastrointestinal tract; its ester functional group is quickly hydrolyzed in the bile; and it is catalyzed by a high pH and substrate-specific enzymes called esterases. After about 6 hours, almost all of the drug is deacetylated. Even in this deacetylated form, Rifampin is still a potent antibiotic; however, it can no longer be reabsorbed by the intestines and it is subsequently eliminated from the body. Only about 7% of the administered drug will be excreted unchanged through the urine, though urinary elimination accounts for only about 30% of the dose of the drug that is excreted. About 60% to 65% is excreted through the feces.

The half-life of Rifampin ranges from 1.5 to 5 hours, though hepatic impairment will significantly increase it. Food consumption, on the other hand, inhibits absorption from the GI tract, and the drug is more quickly eliminated.

Distribution of the drug is high throughout the body, and reaches effective concentrations in many organs and body fluids, including the CSF. This high distribution is the reason for the orange-red color of the saliva, tears, sweat, urine, and feces. About 60% to 90% of the drug is bound to plasma proteins.

Rifampicin Indications / Rifampicin Uses

Information Not Available

Rifampicin Adverse Reactions / Rifampicin Side Effects

GI disturbances, pseudomembranous colitis (rare), abnormalities of liver function, fatalities in those with liver disorders, influenza- like symptoms, skin reactions, eosinophilia, transient leucopenia, thrombocytopenia, purpura, shock, drowsiness, headache, ataxia, visual disturbances, menstural irregularities. Reddish coloured urine & tears. IV: thrombophloebitis; extravasation following local irritation & inflammation. Hepatitis or shock like syndrome with hepatic involvement.

Precautions

Information Not Available

Special Precautions

Impaired hepatic or renal function. Elderly, malnourished or very young patients. Alcoholic patients. Monitor blood counts & liver function regularly. Body fluids may colour red. Discontinue use if thrombocytopenia or use if thrombocytopenia or purpura occurs. Pregnancy & lactation. care should be taken during IV admin to prevent extravasation.

Other Drug Interactions

Increased metabolism of chloramphenicol, clofibrate, dapsone, digoxin, hexobarbitone, ketaconazole & quindine. Absorption may be decreased when taken with antacids, anticholingergics, opioids & ketaconazole. Increased metabolism of losartan & its active metabolite, diazepam & nitrazepam. Reduces serum levels of aprepitant, atovaquone, bisoprolol, carvedilol, metoprolol, proanolol, buspirone, bunazosin, diltiazem, nifedipine & verapamil. Increased risk of translant rejection when used with ciclosporin, Deceases effects of tolbutamide, clofibrate, coumarin anticoagulates, diazepam & oral contraceptives. May reduce efficacy or corticosteriods in Addison's disease & induce an addisonian crisis.

Other Interactions

Food Interaction

Dosage

Oral
Tuberculosis
Adult: 10mg/kg daily 0r 2-3 times weekly. Max; 600 mg/day.
Child: 10-20 mg/kg daily 2-3 times weekly. Max; 600 mg/day.

Prophylaxis against meningococcal meningitis:
Adult: 600 mg/bid for 2 days.
Child: 1-12 years: 10 mg/kg; < 12 months: 5 mg/kg, doses to be given bid for 2 days.

Food(before/after)

Information Not Available

List of Contraindications

Rifampicin and Pregnancy

Caution when used during pregnancy

Rifampicin and Lactation

Caution when used during lactation

Rifampicin and Children

Information Not Available

Rifampicin and Geriatic

Information Not Available

Rifampicin and Other Contraindications

Hypersensitivity, jaundice, severe hepatic disease. IM/SC admin. Porphyria. Not to be used for treatment of meningcoccal disease.

Storage

Information Not Available

Lab interference

Information Not Available

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