Rifabutin


Generic Medicine Info
Indications and Dosage
Oral
Nontuberculous mycobacterial infections
Adult: As part of a multidrug regimen: 450-600 mg once daily for up to 6 months after negative cultures are obtained. Treatment recommendations may vary among individual products or between countries (refer to specific product or local guidelines).

Oral
Pulmonary tuberculosis
Adult: As part of a multidrug regimen: 150-450 mg once daily for at least 6 months. Treatment recommendations may vary among individual products or between countries (refer to specific product or local guidelines).

Oral
Prophylaxis of Mycobacterium avium complex infections in immunocompromised patients
Adult: In patients with low CD4 counts: 300 mg once daily. Treatment recommendations may vary between countries (refer to specific local guidelines).
Special Patient Group
Patients taking amprenavir, fosamprenavir, or indinavir: Reduce the dose of rifabutin by 50%.

Patients taking ritonavir in combination with either atazanavir, fosamprenavir, or lopinavir: Reduce the dose of rifabutin by 75%.
Renal Impairment
CrCl (mL/min) Dosage
<30 Reduce dose by 50%.
Contraindications
Hypersensitivity to rifabutin and other rifamycins (e.g. rifampicin).
Special Precautions
Severe renal and hepatic impairment. Pregnancy and lactation.
Adverse Reactions
Significant: Hypersensitivity reactions (e.g. anaphylaxis, angioedema, acute bronchospasm, hypotension, flu-like syndrome); superinfection including Clostridioides difficile or pseudomembranous colitis (prolonged use); haematologic toxicity (e.g. neutropenia and/or thrombocytopenia; uveitis (in combination with macrolides or azole antifungals); discolouration (red, orange or brown) of tears, saliva, sputum, sweat, urine, faeces, and skin.
Blood and lymphatic system disorders: Leucopenia, anaemia, pancytopenia, agranulocytosis.
Eye disorders: Corneal deposits.
Gastrointestinal disorders: Nausea, vomiting, dysgeusia, abdominal pain, dyspepsia, flatulence, eructation.
General disorders and administration site conditions: Pyrexia.
Hepatobiliary disorders: Jaundice.
Investigations: Increased hepatic enzymes.
Musculoskeletal and connective tissue disorders: Myalgia, arthralgia.
Skin and subcutaneous tissue disorders: Rash.
Potentially Fatal: Severe cutaneous adverse reactions (SCAR) including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), acute generalized exanthematous pustulosis (AGEP), and drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome; Clostridioides difficile-associated diarrhoea (long-term use).
Patient Counseling Information
This drug may cause permanent staining of soft contact lenses. Remove soft contact lenses during therapy.
Monitoring Parameters
Perform culture and susceptibility tests; consult local institutional recommendations before treatment initiation due to antibiotic resistance risks. Monitor LFTs, CBC with differential, and platelet count periodically. Assess for signs and symptoms of hypersensitivity, severe cutaneous adverse reactions, uveitis, vision changes, and severe bloody diarrhoea.
Drug Interactions
May reduce the plasma concentrations and efficacy of antiretroviral (e.g. bictegravir, elvitegravir, doravirine, oral rilpivirine) and anti-HCV agents (e.g. sofosbuvir). Increased plasma concentrations with HIV protease inhibitors (e.g. amprenavir, indinavir, ritonavir,  atazanavir, fosamprenavir, lopinavir), delavirdine, clarithromycin, azole antifungals (e.g. voriconazole, itraconazole, ketoconazole, posaconazole). May reduce the serum concentration of tacrolimus, clarithromycin, azole antifungals (e.g. voriconazole, itraconazole, ketoconazole, posaconazole), hormonal contraceptives. May decrease the activity of anticoagulants, analgesics, corticosteroids, ciclosporin, narcotics, oral hypoglycaemics, phenytoin, quinidine.
Food Interaction
Food may delay absorption.
Action
Description:
Mechanism of Action: Rifabutin is a rifamycin antimycobacterial which inhibits DNA-dependent RNA polymerase at the β-subunit in susceptible strains of prokaryotic organisms thereby preventing chain initiation. It also inhibits thymidine incorporation into the DNA of rifampicin-resistant Mycobacterium tuberculosis which may indicate DNA synthesis inhibition.
Pharmacokinetics:
Absorption: Readily but incompletely absorbed from the gastrointestinal tract. Food may delay absorption. Time to peak plasma concentration: 2-4 hours.
Distribution: Widely distributed in body tissues and fluids (except the brain). Plasma protein binding: Approx 85%.
Metabolism: Rapidly metabolised in the liver by CYP3A4 isoenzyme mainly to active 25-O-deacetyl and 31-hydroxy metabolites.
Excretion: Via urine (approx 53%, mainly as metabolites); faeces (approx 30%). Terminal elimination half-life): 45 hours (range: 16-69 hours).
Storage
Store between 15-30°C.
MIMS Class
Anti-TB Agents / Other Antibiotics
ATC Classification
J04AB04 - rifabutin ; Belongs to the class of antibiotics. Used in the systemic treatment of tuberculosis.
References
Anon. Rifabutin. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 12/12/2023.

Anon. Rifabutin. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 12/12/2023.

Buckingham R (ed). Rifabutin. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 12/12/2023.

Joint Formulary Committee. Rifabutin. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 12/12/2023.

Mycobutin 150 mg Capsules (Pfizer Ltd). MHRA. https://products.mhra.gov.uk. Accessed 12/12/2023.

Pfizer New Zealand Limited. Mycobutin 150 mg Capsule data sheet 10 October 2023. Medsafe. http://www.medsafe.govt.nz. Accessed 12/12/2023.

Rifabutin Capsule (Lupin Pharmaceuticals, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 12/12/2023.

Disclaimer: This information is independently developed by MIMS based on Rifabutin from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2024 MIMS. All rights reserved. Powered by MIMS.com
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