Double-blind controlled clinical trial of clofazimine in reactive phases of lepromatous leprosy

Why do we use 100 mg of clofazimine in TB and NTM treatment?

Current tuberculosis and non-tuberculous mycobacterial disease guidelines recommend the use of clofazimine in a 100 mg once-daily dose. The rationale behind this exact dose is not provided. I performed a literature review to determine the reasoning behind the current dosing regimen. The current 100 mg once-daily dose of clofazimine stems from a deliberate attempt to find the minimum effective daily dose in leprosy treatment, driven by efficacy, economical and toxicity considerations. While this dose is safe, economical and practical, a higher dose with a loading phase may add relevant efficacy and treatment-shortening potential to both tuberculosis and non-tuberculous mycobacterial disease treatment. We need to revisit dose-response and maximum tolerated dose studies to get the best out of this drug, while continuing efforts to generate more active r-iminophenazine molecules that accumulate less in skin and intestinal tissues and have pharmacokinetic properties that do not require loading doses.

Clofazimine as a substitute for rifampicin improves efficacy of Mycobacterium avium pulmonary disease treatment in the hollow-fiber model

Mycobacterium avium complex pulmonary disease is treated with an azithromycin, ethambutol, and rifampicin regimen, with limited efficacy. The role of rifampicin is controversial due to inactivity, adverse effects, and drug interactions. Here, we evaluated the efficacy of clofazimine as a substitute for rifampicin in an intracellular hollow-fiber infection model. THP-1 cells, which are monocytes isolated from peripheral blood from an acute monocytic leukemia patient, were infected with M. avium ATCC 700898 and exposed to a regimen of azithromycin and ethambutol with either rifampicin or clofazimine. Intrapulmonary pharmacokinetic profiles of azithromycin, ethambutol, and rifampicin were simulated. For clofazimine, a steady-state average concentration was targeted. Drug concentrations and bacterial densities were monitored over 21 days. Exposures to azithromycin and ethambutol were 20%-40% lower than targeted but within clinically observed ranges. Clofazimine exposures were 1.7 times higher than targeted. Until day 7, both regimens were able to maintain stasis. Thereafter, regrowth was observed for the rifampicin-containing regimen, while the clofazimine-containing regimen yielded a 2 Log10 colony forming unit (CFU) per mL decrease in bacterial load. The clofazimine regimen also successfully suppressed the emergence of macrolide tolerance. In summary, substitution of rifampicin with clofazimine in the hollow-fiber model improved the antimycobacterial activity of the regimen. Clofazimine-containing regimens merit investigation in clinical trials.

Seventy years of evidence on the efficacy and safety of drugs for treating leprosy: a network meta-analysis

OBJECTIVE

The World Health Organization (WHO) recommends multidrug therapy (MDT) with rifampicin, dapsone, and clofazimine for treating leprosy, which is based on very low-quality evidence. Here, we performed a network meta-analysis (NMA) to produce quantitative evidence to strengthen current WHO recommendations.

METHOD

All studies were obtained from Embase and PubMed from the date of establishment to October 9, 2021. Data were synthesized with frequentist random-effects network meta-analyses. Outcomes were assessed using odds ratios (ORs), 95% confidence intervals (95% CIs), and P score.

RESULTS

Sixty controlled clinical trials and 9256 patients were included. MDT was effective (range of OR: 1.06-1255584.25) for treating leprosy and multibacillary leprosy. Six treatments (Range of OR: 1.199-4.50) were more effective than MDT. Clofazimine (P score=0.9141) and dapsone+rifampicin (P score=0.8785) were effective for treating type 2 leprosy reaction. There were no significant differences in the safety of any of the tested drug regimens.

CONCLUSIONS

The WHO MDT is effective for treating leprosy and multibacillary leprosy, but it may not be effective enough. Pefloxacin and ofloxacin may be good adjunct drugs for increasing MDT efficacy. Clofazimine and dapsone+rifampicin can be used in the treatment of a type 2 leprosy reaction. Single-drug regimens are not efficient enough to treat leprosy, multibacillary leprosy, or a type 2 leprosy reaction.

AVAILABILITY OF DATA AND MATERIALS

All data generated or analyzed during this study are included in this published article [and its supplementary information files].

Tuberculosis--advances in development of new drugs, treatment regimens, host-directed therapies, and biomarkers

Tuberculosis is the leading infectious cause of death worldwide, with 9·6 million cases and 1·5 million deaths reported in 2014. WHO estimates 480,000 cases of these were multidrug resistant (MDR). Less than half of patients who entered into treatment for MDR tuberculosis successfully completed that treatment, mainly due to high mortality and loss to follow-up. These in turn illustrate weaknesses in current treatment regimens and national tuberculosis programmes, coupled with operational treatment challenges. In this Review we provide an update on recent developments in the tuberculosis drug-development pipeline (including new and repurposed antimicrobials and host-directed drugs) as they are applied to new regimens to shorten and improve outcomes of tuberculosis treatment. Several new or repurposed antimicrobial drugs are in advanced trial stages for MDR tuberculosis, and two new antimicrobial drug candidates are in early-stage trials. Several trials to reduce the duration of therapy in MDR and drug-susceptible tuberculosis are ongoing. A wide range of candidate host-directed therapies are being developed to accelerate eradication of infection, prevent new drug resistance, and prevent permanent lung injury. As these drugs have been approved for other clinical indications, they are now ready for repurposing for tuberculosis in phase 2 clinical trials. We assess risks associated with evaluation of new treatment regimens, and highlight opportunities to advance tuberculosis research generally through regulatory innovation in MDR tuberculosis. Progress in tuberculosis-specific biomarkers (including culture conversion, PET and CT imaging, and gene expression profiles) can support this innovation. Several global initiatives now provide unique opportunities to tackle the tuberculosis epidemic through collaborative partnerships between high-income countries and middle-income and low-income countries for clinical trials training and research, allowing funders to coordinate several national and regional programmes for greatest overall effect.

Antiinfectives targeting enzymes and the proton motive force

There is a growing need for new antibiotics. Compounds that target the proton motive force (PMF), uncouplers, represent one possible class of compounds that might be developed because they are already used to treat parasitic infections, and there is interest in their use for the treatment of other diseases, such as diabetes. Here, we tested a series of compounds, most with known antiinfective activity, for uncoupler activity. Many cationic amphiphiles tested positive, and some targeted isoprenoid biosynthesis or affected lipid bilayer structure. As an example, we found that clomiphene, a recently discovered undecaprenyl diphosphate synthase inhibitor active against Staphylococcus aureus, is an uncoupler. Using in silico screening, we then found that the anti-glioblastoma multiforme drug lead vacquinol is an inhibitor of Mycobacterium tuberculosis tuberculosinyl adenosine synthase, as well as being an uncoupler. Because vacquinol is also an inhibitor of M. tuberculosis cell growth, we used similarity searches based on the vacquinol structure, finding analogs with potent (∼0.5-2 μg/mL) activity against M. tuberculosis and S. aureus. Our results give a logical explanation of the observation that most new tuberculosis drug leads discovered by phenotypic screens and genome sequencing are highly lipophilic (logP ∼5.7) bases with membrane targets because such species are expected to partition into hydrophobic membranes, inhibiting membrane proteins, in addition to collapsing the PMF. This multiple targeting is expected to be of importance in overcoming the development of drug resistance because targeting membrane physical properties is expected to be less susceptible to the development of resistance.

Interventions for erythema nodosum leprosum

BACKGROUND

Erythema nodosum leprosum (ENL) is a serious immunological complication of leprosy, causing inflammation of skin, nerves, other organs, and general malaise. Many different therapies exist for ENL, but it is unclear if they work or which therapy is optimal.

OBJECTIVES

To assess the effects of interventions for erythema nodosum leprosum.

SEARCH STRATEGY

We searched the Cochrane Skin Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (Issue 1, 2009), MEDLINE (from 2003), EMBASE (from 2005), LILACS and AMED (from inception), CINAHL (from 1981), and databases of ongoing trials, all in March 2009. We checked reference lists of articles and contacted the American Leprosy Missions in Brazil to locate studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of interventions for ENL in people with leprosy.

DATA COLLECTION AND ANALYSIS

Two authors performed study selection, assessed trial quality, and extracted data.

MAIN RESULTS

We included 13 studies with a total of 445 participants. The quality of the trials was generally poor and no results could be pooled due to the treatments being so heterogeneous. Treatment with thalidomide showed a significant remission of skin lesions compared to acetylsalicylic acid (aspirin) (RR 2.43; 95% CI 1.28 to 4.59) (1 trial, 92 participants). Clofazimine treatment was superior to prednisolone (more treatment successes; RR 3.67; 95% CI 1.36 to 9.91) (1 trial, 24 participants), and thalidomide (fewer recurrences; RR 0.08; 95% CI 0.01 to 0.56) (1 trial, 72 participants). We did not find any significant benefit for intravenous betamethasone compared to dextrose (1 trial, 10 participants), pentoxifylline compared to thalidomide (1 trial, 44 participants), indomethacin compared to prednisolone, aspirin or chloroquine treatments (2 trials, 80 participants), or levamisole compared to placebo (1 trial, 12 participants). Mild to moderate adverse events were significantly lower in participants taking 100 mg thalidomide compared to 300 mg thalidomide daily (RR 0.46; 95% CI 0.23 to 0.93). Significantly more minor adverse events were reported in participants taking clofazimine compared with prednisolone (RR 1.92; 95% CI 1.10 to 3.35). None of the studies assessed quality of life or economic outcomes.

AUTHORS' CONCLUSIONS

There is some evidence of benefit for thalidomide and clofazimine, but generally we did not find clear evidence of benefit for interventions in the management of ENL. However, this does not mean they do not work, because the studies were small and poorly reported. Larger studies using clearly defined participants, outcome measures, and internationally recognised scales are urgently required.

Autofluorescence of clofazimine in discoid lupus erythematosus

A 70-year-old woman developed dark reddish blue pigmentation in scarred areas of discoid lupus erythematosus after taking clofazimine intermittently over a period of 10 years. Although light microscopy of routinely processed tissue failed to define the cause of the pigment, fluorescent microscopy showed vivid red deposits concentrated around larger vessels within the dermis. These deposits were shown to correspond to birefringent red clofazimine crystals on fresh frozen sections. Although the hyperpigmentation may clinically resemble melanin, biopsy specimens from our patient revealed a loss of melanin pigment in lesional skin, suggesting a primary role for clofazimine in producing the color changes observed.

In vitro activity of clofazimine against rapidly growing nonchromogenic mycobacteria

The in vitro activity of clofazimine against 80 isolates of rapidly growing nonchromogenic mycobacteria was studied by an agar dilution method. The drug inhibited 96% of strains tested at concentrations less than or equal to 1 microgram/ml, and it appears to be an agent of potential efficacy against Mycobacterium fortuitum and M. chelonae.

Controlled clinical trial of clofazimine in untreated lepromatous leprosy

A comparison of clofazimine and dapsone in the management of untreated lepromatous leprosy showed no significant differences between the two drugs in terms of morphological and bacterial indices. The incidence of erythema nodosum leprosum was similar in the two groups. Since dapsone is cheaper than clofazimine it remains the drug of choice for the routine management of untreated lepromatous leprosy.