Rifabutin

證據等級: L5

預測適應症: 10 個

Rifabutin: From Mycobacterial Infection to HIV Infectious Disease (TB/MAC Co-Infection Management)

One-Sentence Summary

Rifabutin is an antimycobacterial antibiotic (rifamycin class) used in the treatment and prevention of tuberculosis (TB) and Mycobacterium avium complex (MAC) infection. The TxGNN model predicts a link to HIV infectious disease, with 39 clinical trials and 20 publications identified — however, the underlying evidence shows this reflects rifabutin’s established role in managing TB/MAC co-infection in HIV-positive patients, not a direct antiretroviral effect. Formal regulatory and safety documentation for Denmark is currently a data gap, limiting readiness for clinical decision-making.

Quick Overview

Item	Content
Original Indication	Antimycobacterial antibiotic (tuberculosis / M. avium complex prophylaxis and treatment) — inferred from drug class and trial context; approved indication text not available in Danish registration data
Predicted New Indication	HIV infectious disease (see caveat below — actual evidence supports TB/MAC co-infection management, not direct anti-HIV activity)
TxGNN Prediction Score	99.88%
Evidence Level	L2
Denmark Market Status	Not marketed
Number of Marketing Authorisations	0
Recommended Decision	Proceed with Guardrails

Why is This Prediction Reasonable?

Detailed mechanism-of-action data for rifabutin is not available in this evidence pack. Based on the evidence collected, rifabutin inhibits bacterial DNA-dependent RNA polymerase and has no direct antiretroviral activity — it does not act on HIV itself.

The link to “HIV infectious disease” arises indirectly: HIV-positive patients, especially those with low CD4 counts, are highly susceptible to concurrent tuberculosis and disseminated MAC infection, and rifabutin is a standard antimycobacterial agent for treating and preventing these co-infections. Its favorable pharmacokinetic profile (longer half-life, comparatively less enzyme induction than rifampicin) makes it preferable to rifampicin in patients on protease-inhibitor- or integrase-inhibitor-based antiretroviral therapy (ART), which explains why a large share of the trial evidence focuses on pharmacokinetics and drug-drug interaction (DDI) management rather than direct efficacy against HIV.

Important caveat: the TxGNN label “HIV infectious disease” should not be read as an antiviral indication. The clinically accurate framing is “treatment/prevention of TB or MAC co-infection in HIV-positive patients,” which is already a well-established, decades-old use rather than a novel repurposing hypothesis.

Clinical Trial Evidence

Trial Number	Phase	Status	Enrollment	Key Findings
NCT00002122	Phase 3	Completed	720	Randomized study of daily/intermittent azithromycin and rifabutin (alone/combined) for prevention of disseminated MAC in HIV-infected patients
NCT00001047	Phase 3	Completed	400	Open-label randomized trial of four regimens (clarithromycin + ethambutol + rifabutin or clofazimine) for treatment of disseminated MAC in AIDS patients
NCT00002101	Phase 3	Completed	450	Three-arm trial comparing clarithromycin/ethambutol with rifabutin (two doses) or placebo for MAC bacteremia treatment
NCT00001030	Phase 3	Completed	1100	Prospective randomized comparison of clarithromycin vs. rifabutin vs. combination for prevention of MAC bacteremia in advanced HIV
NCT00002080	N/A (Treatment IND)	Completed	N/A	Rifabutin provided to HIV-positive patients to prevent/delay MAC infection; characterizes monotherapy safety
NCT00002267	N/A	Completed	750	Double-blind, placebo-controlled trial of rifabutin monotherapy for prevention of MAC bacteremia in AIDS patients with CD4 ≤200
NCT00023361	N/A (TBTC Study 23)	Completed	215	Rifabutin-based intermittent regimen for treatment of HIV-related, rifamycin-susceptible tuberculosis; measured treatment failure/relapse rate
NCT00023348	Phase 2/3	Completed	150	Pharmacokinetics of intermittent isoniazid and rifabutin in HIV-related TB treatment; correlated PK abnormalities with toxicity
NCT00651066	Phase 2	Completed	47	Evaluates rifabutin as a rifampicin substitute for combined TB/HIV treatment in Vietnam; PK with concurrent ART
NCT01059422	Phase 4	Completed	10	Raltegravir + 3TC/ABC efficacy and safety in ART-naïve HIV/TB co-infected adults on rifabutin-based first-line anti-TB therapy

Note: 39 trials were identified in total; the majority not listed here are single-purpose pharmacokinetic/DDI studies (e.g., interactions with maraviroc, cabotegravir, dolutegravir, indinavir) rather than efficacy trials, and were deprioritized in this table.

Literature Evidence

PMID	Year	Type	Journal	Key Findings
23828580	2013	Cochrane Systematic Review	Cochrane Database Syst Rev	Compares rifamycins (including rifabutin) to isoniazid for TB prevention in people at risk of active TB
40310456	2025	Review	PNAS	Reviews next-generation rifamycins for mycobacterial infections; notes rifamycins induce CYP3A4, complicating co-administration
28233512	2017	Review	Microbiology Spectrum	Describes bidirectional impact of TB and HIV co-infection, underpinning the clinical rationale for rifabutin-based co-treatment
21406051	2011	Review	Infect Disord Drug Targets	Reviews management of adult active TB in the HIV era, including rifamycin–ART drug interactions
33294914	2021	Cohort/PK Study	J Antimicrob Chemother	Rifabutin PK and safety in TB/HIV-coinfected children on lopinavir/ritonavir-based second-line ART
31139825	2019	Cohort	J Antimicrob Chemother	Safety and efficacy of rifabutin in HIV/TB-coinfected children on lopinavir/ritonavir; notes prior study stopped early for neutropenia
25281400	2015	PK Study	J Antimicrob Chemother	Short-term safety and pharmacokinetics of rifabutin with lopinavir/ritonavir in young HIV-infected children
26832753	2016	Population PK Analysis	J Antimicrob Chemother	Pooled population PK/DDI analysis of rifabutin and HIV protease inhibitors to guide dosing in HIV-TB co-treatment
21726477	2009	Review	BMJ Clinical Evidence	Reviews treatment approaches for tuberculosis in people with HIV
7736687	1995	PK Review	Clinical Pharmacokinetics	Early review establishing rifabutin’s clinical effectiveness for MAC prophylaxis in HIV-positive patients with low CD4 counts

Note: 20 publications were identified in total; several additional PK/DDI studies (with tenofovir alafenamide, dolutegravir, saquinavir, methadone, etc.) were not included above to keep the table to the 10 most clinically relevant entries.

Denmark Market Information

No marketing authorisation is currently registered for rifabutin in Denmark (0 licenses on file; market status: not marketed). No national (Laegemiddelstyrelsen) or centralised (EMA) authorisation records are available in this evidence pack.

Safety Considerations

Regulatory Safety Data Gap: No structured warnings, contraindications, or DDI database records are currently available for rifabutin. Please refer to the approved Summary of Product Characteristics (SmPC) for authoritative safety information once available.
Known Drug-Drug Interaction Burden (from evidence review): Rifabutin is a CYP3A4 inducer/substrate with extensively documented pharmacokinetic interactions with protease inhibitors, NNRTIs, and integrase inhibitors (e.g., dolutegravir, cabotegravir, indinavir, darunavir/ritonavir), generally requiring dose adjustment when co-administered with ART. This DDI pattern is a dominant theme across the identified trial evidence, even though the formal DDI query in this evidence pack returned no records.
Adverse Drug Reaction Signal — Ocular Inflammation: Literature review (PMID 17353948) identifies rifabutin as a drug associated with drug-induced ocular inflammation, including uveitis and conjunctival involvement, particularly at higher doses or when combined with clarithromycin or fluconazole. A related case report (rifabutin-associated uveitis in a pediatric HIV patient) reinforces this signal.
Adverse Drug Reaction Signal — Neutropenia in Pediatric Co-Treatment: Cohort studies (PMID 33294914, PMID 31139825) report treatment-limiting neutropenia in children receiving rifabutin with protease-inhibitor-based ART, warranting hematological monitoring in this population.

Conclusion and Next Steps

Decision: Proceed with Guardrails

Rationale: Multiple completed Phase 3 randomized trials and a Cochrane systematic review support rifabutin’s established role in preventing and treating TB/MAC co-infection in HIV-positive patients, but this evidence is indirect with respect to the TxGNN label “HIV infectious disease” — rifabutin has no direct antiviral mechanism, and the label should be clinically reframed as “management of TB/MAC co-infection in HIV.” Combined with the current absence of Danish regulatory and safety documentation (market status: not marketed, 0 authorisations), this supports a guarded pathway rather than an unqualified “Go.”

To proceed, the following is needed:

SmPC/label warnings and contraindications from a reference regulatory source (currently a Blocking data gap; required before any S1 safety pre-assessment)
Formal mechanism-of-action documentation from DrugBank or equivalent (currently a High-severity data gap)
A structured DDI review focused on ART co-administration (protease inhibitors, NNRTIs, integrase inhibitors), given the strong CYP3A4-mediated interaction signal already evident in the literature
A monitoring plan addressing the identified ocular inflammation and pediatric neutropenia ADR signals
Reframing of the target indication from “HIV infectious disease” to “TB/MAC co-infection in HIV-positive patients” to avoid clinical misinterpretation as an antiretroviral therapy
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.