Effect of Bedaquiline and Delamanid Pharmacokinetics on Sputum Culture Conversion and Adverse Events in Drug-Resistant Tuberculosis

BACKGROUND

Pharmacokinetic studies of bedaquiline and delamanid in patients with pre-extensively drug-resistant tuberculosis (pre-XDR TB) will help in the optimization of these drugs for both culture conversion and adverse events.

METHODS

A prospective cohort of 165 adult patients (56% male with mean [SD] age 29 [9.7] years) with pre-XDR TB was treated with bedaquiline, delamanid, clofazimine, and linezolid for 24 weeks at 5 sites in India. Bedaquiline was administered at 400 mg daily for 2 weeks followed by 200 mg thrice weekly for 22 weeks, whereas delamanid was administered at 100 mg twice daily. In 23 consenting participants at 8 and 16 weeks of treatment, blood was collected at 0, 2, 4, 5, 6, 8, 12, and 24 hours postdosing for an intense pharmacokinetic study. Pharmacokinetic parameters were correlated with sputum culture conversion and adverse events.

RESULTS

The mean (SD) age and weight of patients were 30 (10) years and 54 kg, respectively. The median minimum concentration (C min ) and time-concentration curve (AUC) for bedaquiline, respectively, were 0.6 mcg/mL and 27 mcg/mL·h at week 8 and 0.8 mcg/mL and 36 mcg/mL·h at week 16, suggesting drug accumulation over time. The median C min and AUC of delamanid, respectively, were 0.17 mcg/mL and 5.1 mcg/mL·h at week 8 and 0.20 mcg/mL and 7.5 mcg/mL·h at week 16. Delay in sputum conversion was observed in patients with drug concentrations lower than the targeted concentration. At weeks 8 and 16, 13 adverse events were observed. Adverse events were resolved through symptomatic treatment. Body mass index was found to be significantly associated with drug-exposure parameters.

CONCLUSIONS

Bedaquiline and delamanid when co-administered exhibit plasma drug levels within the targeted concentrations, showing an exposure-response relationship.

Assessing potential drug-drug interactions between clofazimine and other frequently used agents to treat drug-resistant tuberculosis

Clofazimine is included in drug regimens to treat rifampicin/drug-resistant tuberculosis (DR-TB), but there is little information about its interaction with other drugs in DR-TB regimens. We evaluated the pharmacokinetic interaction between clofazimine and isoniazid, linezolid, levofloxacin, and cycloserine, dosed as terizidone. Newly diagnosed adults with DR-TB at Klerksdorp/Tshepong Hospital, South Africa, were started on the then-standard treatment with clofazimine temporarily excluded for the initial 2 weeks. Pharmacokinetic sampling was done immediately before and 3 weeks after starting clofazimine, and drug concentrations were determined using validated liquid chromatography-tandem mass spectrometry assays. The data were interpreted with population pharmacokinetics in NONMEM v7.5.1 to explore the impact of clofazimine co-administration and other relevant covariates on the pharmacokinetics of isoniazid, linezolid, levofloxacin, and cycloserine. Clofazimine, isoniazid, linezolid, levofloxacin, and cycloserine data were available for 16, 27, 21, 21, and 6 participants, respectively. The median age and weight for the full cohort were 39 years and 52 kg, respectively. Clofazimine exposures were in the expected range, and its addition to the regimen did not significantly affect the pharmacokinetics of the other drugs except levofloxacin, for which it caused a 15% reduction in clearance. A posteriori power size calculations predicted that our sample sizes had 97%, 90%, and 87% power at P < 0.05 to detect a 30% change in clearance of isoniazid, linezolid, and cycloserine, respectively. Although clofazimine increased the area under the curve of levofloxacin by 19%, this is unlikely to be of great clinical significance, and the lack of interaction with other drugs tested is reassuring.

Clofazimine pharmacokinetics in HIV-infected adults with diarrhea: Implications of diarrheal disease on absorption of orally administered therapeutics

Oral drug absorption kinetics are usually established in populations with a properly functioning gastrointestinal tract. However, many diseases and therapeutics can alter gastrointestinal physiology and cause diarrhea. The extent of diarrhea-associated impact on drug pharmacokinetics has not been quantitatively described. To address this knowledge gap, we used a population pharmacokinetic modeling approach with data collected in a phase IIa study of matched human immunodeficiency virus (HIV)-infected adults with/without cryptosporidiosis and diarrhea to examine diarrhea-associated impact on oral clofazimine pharmacokinetics. A population pharmacokinetic model was developed with 428 plasma samples from 23 HIV-infected adults with/without Cryptosporidium infection using nonlinear mixed-effects modeling. Covariates describing cryptosporidiosis-associated diarrhea severity (e.g., number of diarrhea episodes, diarrhea grade) or HIV infection (e.g., viral load, CD4+ T cell count) were evaluated. A two-compartment model with lag time and first-order absorption and elimination best fit the data. Maximum diarrhea grade over the study duration was found to be associated with a more than sixfold reduction in clofazimine bioavailability. Apparent clofazimine clearance, intercompartmental clearance, central volume of distribution, and peripheral volume of distribution were 3.71 L/h, 18.2 L/h (interindividual variability [IIV] 45.0%), 473 L (IIV 3.46%), and 3434 L, respectively. The absorption rate constant was 0.625 h-1 (IIV 149%) and absorption lag time was 1.83 h. In conclusion, the maximum diarrhea grade observed for the duration of oral clofazimine administration was associated with a significant reduction in clofazimine bioavailability. Our results highlight the importance of studying disease impacts on oral therapeutic pharmacokinetics to inform dose optimization and maximize the chance of treatment success.

Pharmacokinetics and cardiac safety of clofazimine in children with rifampicin-resistant tuberculosis

Clofazimine is recommended for the treatment of rifampicin-resistant tuberculosis (RR-TB), but there is currently no verified dosing guideline for its use in children. There is only limited safety and no pharmacokinetic (PK) data available for children. We aimed to characterize clofazimine PK and its relationship with QT-interval prolongation in children. An observational cohort study of South African children <18 years old routinely treated for RR-TB with a clofazimine-containing regimen was analyzed. Clofazimine 100 mg gelatin capsules were given orally once daily (≥20 kg body weight), every second day (10 to <20 kg), or thrice weekly (<10 kg). PK sampling and electrocardiograms were completed pre-dose and at 1, 4, and 10 hours post-dose, and the population PK and Fridericia-corrected QT (QTcF) interval prolongation were characterized. Fifty-four children contributed both PK and QTcF data, with a median age (2.5th-97.5th centiles) of 3.3 (0.5-15.6) years; five children were living with HIV. Weekly area under the time-concentration curve at steady state was 79.1 (15.0-271) mg.h/L compared to an adult target of 60.9 (56.0-66.6) mg.h/L. Children living with HIV had four times higher clearance compared to those without. No child had a QTcF ≥500 ms. A linear concentration-QTcF relationship was found, with a drug effect of 0.05 (0.027, 0.075) ms/µg/L. In some of the first PK data in children, we found clofazimine exposure using an off-label dosing strategy was higher in children versus adults. Clofazimine concentrations were associated with an increase in QTcF, but severe prolongation was not observed. More data are required to inform dosing strategies in children.

An Expandable Mechanopharmaceutical Device (1): Measuring the Cargo Capacity of Macrophages in a Living Organism

PURPOSE

Clofazimine (CFZ) is an FDA-approved, poorly soluble small molecule drug that precipitates as crystal-like drug inclusions (CLDIs) which accumulate in acidic cytoplasmic organelles of macrophages. In this study, we considered CLDIs as an expandable mechanopharmaceutical device, to study how macrophages respond to an increasingly massive load of endophagolysosomal cargo.

METHODS

First, we experimentally tested how the accumulation of CFZ in CLDIs impacted different immune cell subpopulations of different organs. Second, to further investigate the mechanism of CLDI formation, we asked whether specific accumulation of CFZ hydrochloride crystals in lysosomes could be explained as a passive, thermodynamic equilibrium phenomenon. A cellular pharmacokinetic model was constructed, simulating CFZ accumulation driven by pH-dependent ion trapping of the protonated drug in the acidic lysosomes, followed by the precipitation of CFZ hydrochloride salt via a common ion effect caused by high chloride concentrations.

RESULTS

While lower loads of CFZ were mostly accommodated in lung macrophages, increased CFZ loading was accompanied by organ-specific changes in macrophage numbers, size and intracellular membrane architecture, maximizing the cargo storage capabilities. With increasing loads, the total cargo mass and concentrations of CFZ in different organs diverged, while that of individual macrophages converged. The simulation results support the notion that the proton and chloride ion concentrations of macrophage lysosomes are sufficient to drive the massive, cell type-selective accumulation and growth of CFZ hydrochloride biocrystals.

CONCLUSION

CLDIs effectively function as an expandable mechanopharmaceutical device, revealing the coordinated response of the macrophage population to an increasingly massive, whole-organism endophagolysosomal cargo load.

An Expandable Mechanopharmaceutical Device (2): Drug Induced Granulomas Maximize the Cargo Sequestering Capacity of Macrophages in the Liver

PURPOSE

Drug-induced liver injuries (DILI) comprise a significant proportion of adverse drug reactions leading to hospitalizations and death. One frequent DILI is granulomatous inflammation from exposure to harmful metabolites that activate inflammatory pathways of immune cells of the liver, which may act as a barrier to isolate the irritating stimulus and limit tissue damage.

METHODS

Paralleling the accumulation of CFZ precipitates in the liver, granulomatous inflammation was studied to gain insight into its effect on liver structure and function. A structural analog that does not precipitate within macrophages was also studied using micro-analytical approaches. Depleting macrophages was used to inhibit granuloma formation and assess its effect on drug bioaccumulation and toxicity.

RESULTS

Granuloma-associated macrophages showed a distinct phenotype, differentiating them from non-granuloma macrophages. Granulomas were induced by insoluble CFZ cargo, but not by the more soluble analog, pointing to precipitation being a factor driving granulomatous inflammation. Granuloma-associated macrophages showed increased activation of lysosomal master-regulator transcription factor EB (TFEB). Inhibiting granuloma formation increased hepatic necrosis and systemic toxicity in CFZ-treated animals.

CONCLUSIONS

Granuloma-associated macrophages are a specialized cell population equipped to actively sequester and stabilize cytotoxic chemotherapeutic agents. Thus, drug-induced granulomas may function as drug sequestering "organoids" -an induced, specialized sub-compartment- to limit tissue damage.

Efficacy of Rifampin Plus Clofazimine in a Murine Model of Mycobacterium ulcerans Disease

Treatment of Buruli ulcer, or Mycobacterium ulcerans disease, has shifted from surgical excision and skin grafting to antibiotic therapy usually with 8 weeks of daily rifampin (RIF) and streptomycin (STR). Although the results have been highly favorable, administration of STR requires intramuscular injection and carries the risk of side effects, such as hearing loss. Therefore, an all-oral, potentially less toxic, treatment regimen has been sought and encouraged by the World Health Organization. A combination of RIF plus clarithromycin (CLR) has been successful in patients first administered RIF+STR for 2 or 4 weeks. Based on evidence of efficacy of clofazimine (CFZ) in humans and mice with tuberculosis, we hypothesized that the combination of RIF+CFZ would be effective against M. ulcerans in the mouse footpad model of M. ulcerans disease because CFZ has similar MIC against M. tuberculosis and M. ulcerans. For comparison, mice were also treated with the gold standard of RIF+STR, the proposed RIF+CLR alternative regimen, or CFZ alone. Treatment was initiated after development of footpad swelling, when the bacterial burden was 4.64±0.14log₁₀ CFU. At week 2 of treatment, the CFU counts had increased in untreated mice, remained essentially unchanged in mice treated with CFZ alone, decreased modestly with either RIF+CLR or RIF+CFZ, and decreased substantially with RIF+STR. At week 4, on the basis of footpad CFU counts, the combination regimens were ranked as follows: RIF+STR>RIF+CLR>RIF+CFZ. At weeks 6 and 8, none of the mice treated with these regimens had detectable CFU. Footpad swelling declined comparably with all of the combination regimens, as did the levels of detectable mycolactone A/B. In mice treated for only 6 weeks and followed up for 24 weeks, there were no relapses in RIF+STR treated mice, one (5%) relapse in RIF+CFZ-treated mice, but >50% in RIF+CLR treated mice. On the basis of these results, RIF+CFZ has potential as a continuation phase regimen for treatment of M. ulcerans disease.

Buruli ulcer (BU) is caused by Mycobacterium ulcerans and its toxin, mycolactone. Since 2004, BU has been treated primarily with antibiotics rather than surgery and skin grafting. The current first-line regimen is an oral drug, rifampin (RIF), and an injectable drug, streptomycin (STR), daily for 8 weeks. Because STR injections are painful and have potential side effects, such as hearing loss, a replacement drug is sought. Emerging evidence of the efficacy of the anti-leprosy drug clofazimine (CFZ) against tuberculosis prompted an evaluation of CFZ + RIF as well as another all-oral regimen, RIF + clarithromycin (CLR) in a mouse model of BU. The results showed that RIF+CFZ initially acts more slowly against M. ulcerans than RIF+STR or RIF+CLR but it stops mycolactone production and is as good as RIF+STR and better than RIF+CLR at preventing relapse of infection. A drug regimen with a combination of three drugs, RIF+STR+CFZ, for one or two weeks followed by RIF+CFZ has the potential to limit the duration of STR treatment and achieve comparable cure.

Synthesis and biological evaluation of novel 2-methoxypyridylamino-substituted riminophenazine derivatives as antituberculosis agents

Clofazimine, a member of the riminophenazine class, is one of the few antibiotics that are still active against multidrug-resistant Mycobacterium tuberculosis (M. tuberculosis). However, the clinical utility of this agent is limited by its undesirable physicochemical properties and skin pigmentation potential. With the goal of maintaining potent antituberculosis activity while improving physicochemical properties and lowering skin pigmentation potential, a series of novel riminophenazine derivatives containing a 2-methoxypyridylamino substituent at the C-2 position of the phenazine nucleus were designed and synthesized. These compounds were evaluated for antituberculosis activity against M. tuberculosis H37Rv and screened for cytotoxicity. Riminophenazines bearing a 3-halogen- or 3,4-dihalogen-substituted phenyl group at the N-5 position exhibited potent antituberculosis activity, with MICs ranging from 0.25~0.01 μg/mL. The 3,4-dihalogen- substituted compounds displayed low cytotoxicity, with IC50 values greater than 64 μg/mL. Among these riminophenazines, compound 15 exhibited equivalent in vivo efficacy against M. tuberculosis infection and reduced skin discoloration potential in an experimental mouse infection model as compared to clofazimine. Compound 15, as compared to clofazimine, also demonstrated improved physicochemical properties and pharmacokinetic profiles with a short half-life and less drug tissue accumulation. This compound is being evaluated as a potential drug candidate for the treatment of multidrug resistant tuberculosis.

Tissue Distribution and Deposition of Clofazimine in Mice Following Oral Administration with or without Isoniazid

Tissue distribution and deposition of clofazimine (CAS 2030-63-9) in mice were investigated following administration of clofazimine with or without isoniazid (CAS 54-85-3). Balb/c mice were administered clofazimine suspension in mustard oil orally at a daily dose of 20 mg/kg body weight either alone or along with isoniazid (10 mg/kg body weight) for 15 or 30 days. Various tissues (liver, lung, spleen, small intestine, heart, kidneys, mesentric fat, foot pad and nerve) and pooled plasma were analysed for clofazimine in all the treated groups. High levels of clofazimine were observed in tissues having reticulo-endothelial components (53-263 microg/g wet tissue). In other tissues the levels of the drug were relatively lower (8.1-42.8 microg/g of wet tissue). There was a significant amount of the drug in foot pads and pooled nerve tissue showed detectable amount of the drug. The plasma concentrations in all treated groups were in the range of 0.5-0.8 microg/ml. Tissue levels were found to be increased in selective tissues with the length of drug administration. Concomitant administration of isoniazid reduced clofazimine levels significantly in tissues like small intestine, spleen, and foot pad and resulted in an increase in plasma levels.

[Tissue distribution and deposition of clofazimine in mice following oral administration of isoniazid]

OBJECTIVE

Tissue distribution and deposition of clofazimine in mice were investigated following administration of clofazimine with or without isoniazid.

METHODS

Kunming mice were given clofazimine suspension orally at a daily dose of 13 mg/kg body weight either alone or with isoniazid (25 mg/kg body weight) for a single dose or for 1 or 2 months. Tissues (liver, lung, spleen, small intestine, kidneys, fat) and pooled plasma were analyzed for clofazimine in all the treated groups by high-performance liquid chromatography.

RESULTS

The levels of clofazimine in fat tissues, kidneys, spleens, livers, lungs and small intestine were the highest in mice receiving the drug continuously for 2 months, and were also higher in mice receiving the drug for 1 month as compared to mice receiving a single dose administration. After continuous administration for 1 or 2 months, the clofazimine level was the highest in fat tissues as compared to other tissue samples. The clofazimine level in the lungs was higher in mice receiving concomitant administration of isoniazid [1 month (57 +/- 11) microg/g, 2 months (73 +/- 49) microg/g]than in those receiving clofazimine alone [1 month (32 +/- 8) microg/g, 2 months (47 +/- 12) microg/g], but the clofazimine level in the fat tissue was significantly lower in mice receiving concomitant isoniazid [1 month (289 +/- 30) microg/g, 2 months (275 +/- 119) microg/g], than in those receiving clofazimine alone [1 month (433 +/- 53) microg/g, 2 months (527 +/- 158) microg/g].

CONCLUSION

Concomitant administration of isoniazid reduced clofazimine levels significantly in fat tissues while resulted in an increase of its level in lung tissues.

Pharmacokinetics and relative bioavailability of clofazimine in relation to food, orange juice and antacid

BACKGROUND

Clofazimine is potentially useful for the treatment of disease due to multidrug resistant Mycobacterium tuberculosis, as well as leprosy and certain chronic skin diseases. Its pharmacokinetics have been incompletely characterized. This study was conducted to explore issues relating to bioavailability in the presence of food, orange juice, and antacid.

METHODS

A 5 drug regimen consisting of clofazimine, cycloserine, ethionamide, para-aminosalicyclic acid, and pyridoxime was administered to healthy subjects four times using a four period cross-over design with two weeks washout between treatments. Subjects also received orange juice, a high fat meal, aluminum/magnesium antacid, or only water in random order with the drug regimen. The pharmacokinetics of clofazimine were assessed using individual- and population-based methods and relative bioavailability compared to fasting administration was determined.

RESULTS

Clofazimine exhibited a sometimes prolonged and variable lag-time and considerable variability in plasma concentrations. From the population analysis (one-compartment model), the mean oral clearance was 76.7 l/h (CV=74.2%) and mean apparent volume of distribution was 1470 l (CV=36.3%). The first-order absorption rate constant ranged from 0.716 to 1.33 h(-1) (pooled CV=61.7%). Residual (proportional) error was 49.1%. Estimates of bioavailability compared to fasting administration were 145% (90% CI, 107-183%) for administration with high fat food, 82.0% (63.2-101%) for administration with orange juice, and 78.5% (55.1-102%) for administration with antacid.

CONCLUSION

Administration of clofazimine with a high fat meal provides the greatest bioavailability, however, bioavailability is associated with high inter- and intra-subject variability. Both orange juice and aluminum-magnesium antacid produced a reduction in mean bioavailability of clofazimine.

Tissue concentration, systemic distribution and toxicity of clofazimine--an autopsy study

There are very few autopsy studies available on systemic distribution of clofazimine, a drug with anti-mycobacterial activity, used in multidrug therapy (MDT) regimen of leprosy and in erythema nodosum leprosum (ENL). An autopsy study was done on a 45 year old female of lepromatous leprosy (LL) on MDT and long term high dosage of clofazimine. Patient succumbed to intractable abdominal pain, diarrhoea, hypokalemia following clofazimine treatment. Autopsy study revealed yellowish brown discoloration of skin, viscera and body fluids. Chemical extraction of the drug revealed the highest concentration of the drug in jejunum (1.5mg/gm),followed by spleen (1.2mg/gm), pancreas (0.4mg/gm), adrenal (0.25mg/gm), liver (0.21mg/gm), and less than 0.2mg/gm in lung, fat, large intestine and stomach. It can be inferred from the present study that the drug is absorbed from the jejunum and gets deposited in fat, reticulo-endothelial cells (R-E cells) and hepatocytes. The drug is best demonstrated in cryostat sections and is lost partly during tissue processing and staining. The drug toxicity can be fatal as seen in the present case.

Determination of Clofazimine in Leprosy Patients by High-Performance Liquid Chromatography

An original, simple, specific, and rapid high-performance liquid chromatography assay for the determination of clofazimine in human plasma is presented. The procedure consists of extracting the drug and the internal standard (medazepam) from 0.5 mL plasma with dichloromethane/diisopropyl ether (1:1, v/v) at pH 3.0, after precipitating the proteins with methanol. The drugs were then quantitated on a reversed-phase C8 using a mobile phase consisting of a mixture of methanol/0.25 N sodium acetate buffer at pH 3.0 (74:26, v/v). The flow-rate and wavelength were set at 1 mL/min and 286 nm, respectively. The precision, linearity, and limit of quantitation of the method were within acceptable limits. The method was considered adequate and could be applied in studies involving blood level monitoring and pharmacokinetics in leprosy patients.

Preparation of a clofazimine nanosuspension for intravenous use and evaluation of its therapeutic efficacy in murine Mycobacterium avium infection

Clofazimine nanosuspensions were produced by high pressure homogenization and the formulation was optimized for lyophilization. Characterization of the product by photon correlation spectroscopy, laser diffraction and Coulter counter analysis showed that the clofazimine nanosuspensions were suitable for iv injection with a particle size permitting passive targeting to the reticuloendothelial system. Following iv administration to mice of either the nanocrystalline or a control liposomal formulation at a dose of 20 mg clofazimine/kg bodyweight, drug concentrations in livers, spleens and lungs reached comparably high concentrations, well in excess of the MIC for most Mycobacterium avium strains. When C57BL/6 mice were experimentally infected with M. avium strain TMC 724, nanocrystalline clofazimine was as effective as liposomal clofazimine in reducing bacterial loads in the liver, spleen and lungs of infected mice. Nanocrystalline suspensions of poorly soluble drugs such as riminophenazines are easy to prepare and to lyophilize for extended storage and represent a promising new drug formulation for intravenous therapy of mycobacterial infections.

The effect of hemodialysis on cycloserine, ethionamide, para-aminosalicylate, and clofazimine

STUDY OBJECTIVES

Determine hemodialysis clearances of the second-line antitubercular drugs cycloserine (CS), ethionamide (ETA), para-aminosalicylate (PAS), and clofazimine (CFZ).

DESIGN

Open-label, pharmacokinetic study

SETTING

Outpatient long-term hemodialysis unit

PARTICIPANTS

Eight long-term hemodialysis patients Interventions: Single oral doses of CS, 500 mg, ETA, 500 mg, PAS, 4,000 mg, and CFZ, 200 mg, were given 2 h (4 h for PAS) prior to hemodialysis (median blood flow rate, 400 mL/min; median dialysate flow rate, 600 mL/min; median hemodialysis time, 3.5 h).

MEASUREMENTS AND RESULTS

Arterial and venous serum samples were collected at the beginning and end of hemodialysis, and hourly during hemodialysis. Dialysate fluid was collected for the duration of hemodialysis. All samples were assayed for drug concentrations using validated high-performance liquid chromatography (for ETA and PAS), capillary electrophoresis (for CS), and colorimetry (for CFZ). Dialysate samples were analyzed for acetyl-PAS. Median recoveries of drug in dialysate were 56% (CS), 2.1% (ETA), 6.3% (PAS parent compound), and 0% (CFZ) of the doses administered. Acetyl-PAS was dialyzed to a greater extent than its parent compound. Median hemodialysis clearances calculated by dividing the amount recovered in dialysate by the serum area under the curve during dialysis were 189 (CS), 58 (ETA), 206 (PAS), and 0 (CFZ) mL/min.

CONCLUSIONS

ETA, CFZ, and PAS were not significantly dialyzed. CS is significantly removed by hemodialysis and should be dosed after hemodialysis.

A topical dosage form of liposomal clofazimine: research and clinical implications

A novel topical clofazimine (CLO) gel formulation containing liposomally encapsulated CLO, was prepared and investigated in vitro followed by a clinical evaluation. CLO liposomes were prepared by the lipid film hydration technique. Comparative in vitro diffusion studies were conducted with plain and liposomal CLO in HPMC K4M gel base (2% and 5%) using human cadaver skin (HCS). A double blind clinical study was conducted on eight leprosy patients. The results of these studies show that the new liposomal topical gel formulation not only prolongs the drug release but also promotes drug retention by the skin. Studies further support formation of a reservoir of drug on the skin modifying therapeutic efficacy of the formulation. The new liposomal gel formulation of CLO considerably reduces the healing time of external lesions due to a significantly prolonged skin residence time compared to plain CLO gel and hence is expected to reduce the time needed for leprosy treatment.

Excretion of clofazimine in human milk in leprosy patients

Clofazimine is an important and effective constituent of multi drug therapy for leprosy. A study has been conducted to determine the distribution of clofazimine in maternal milk so that the safety of breast-feeding during maternal ingestion of the drug can be ascertained. Eight female leprosy patients (LL/BL) on clofazimine, 50 mg daily or 100 mg on alternate days for 1-18 months, (mean 5.0 +/- 1.81 months; median 3.25 months) and in the early lactating phase were studied. Blood samples and milk specimens were collected 4-6 hr after the last daily dose. Clofazimine was assayed in the milk and plasma samples by HPTLC. Mean plasma and milk clofazimine levels were 0.9 +/- 0.03 micrograms/ml and 1.33 +/- 0.09 micrograms/ml respectively. The ratio of milk to plasma drug concentration ranged from 1.0 to 1.7 with a mean of 1.48 +/- 0.08. The amount of drug ingested by the infants was 0.199 +/- 0.013 mg/kg/day which represented 22.1 +/- 1.9% of the maternal dose.

Characterization of clofazimine metabolites in humans by HPLC-electrospray mass spectrometry

Clofazimine (CAS 2030-63-9) is an important drug used in the treatment of leprosy. Its important metabolites are investigated by thin layer chromatography (TLC), HPLC (diode array) and HPLC-electrospray mass spectrometry. The resulting analytical data, extraction, isolation and characterization methods are presented. Their applicability is described for human urine analysis.

Determination of serum and tissue levels of phenazines including clofazimine

A rapid and sensitive HPLC method is described for the analysis of synthetic phenazines, including clofazimine, from a variety of biological samples. Phenazines were extracted from serum, tissue and fat using a mixture of dichloromethane and sodium hydroxide. The drugs were then quantified on a reversed-phase C18 column using a mobile phase consisting of 594 ml of water, 400 ml of tetrahydrofuran, 6 ml of concentrated acetic acid and 0.471 g of hexanesulfonic acid. In this mobile phase, each phenazine tested had its own retention time. This allowed one phenazine to be used as an internal standard for the analysis of other phenazines. The method was validated for clofazimine [3-(4-chloroanilino)-10-(4-chlorophenyl)-2,10-dihydro-2-(isopro pylimino) phenazine] and B4090 [7-chloro-3-(4-chloranilino)-10-(4-chlorophenyl)-2, 10-dihydro-2-(2,2,6,6-tetramethylpiperid-4-ylimino)phenazine ] (VI) and shown to be accurate and precise across a broad concentration range from 0.01 to 50 micrograms/g (microgram/ml). Extraction was 100% for each agent across this range. This system was used to measure clofazimine and VI levels following their administration to rats. The pharmacokinetic profile of VI was different to that of clofazimine, with high tissue concentrations but lower fat levels.

Tissue distribution and deposition of clofazimine in rat following subchronic treatment with or without rifampicin

Tissue distribution and deposition characteristics of clofazimine (CAS 2030-63-9), an antileprotic drug in rats have been investigated following controlled sub-chronic administration (p.o.) for a period of 1-2 months. The drug was administered alone at a dose of 20 mg/kg body weight and in combination with rifampicin (CAS 13292-46-1) (20 mg/kg p.o.). Various tissues (liver, lung, spleen, small intestine, brain, heart, kidney, skin, stomach and subcutaneous fat) were analyzed for clofazimine in all the treated groups. High levels (range 0.9-3.6 mg/g of wet tissue) were observed in tissues having reticuloendothelial components. In other tissues the levels were relatively lower (range 3-114 micrograms/g of wet tissue). Histopathological studies revealed that clofazimine is deposited in many tissues in the form of reddish-orange crystals. Concomitant treatment with rifampicin did not significantly alter tissue distribution or deposition profile of clofazimine nor did it influence the histopathology.

Comparative bioavailability of clofazimine coevaporate in the pig

The systemic availability of a solid dispersion (coevaporate) of clofazimine (CLF) in poly(vinyl methyl ether maleic anhydride) copolymer (PVM/MA) was tested in the pig. Single 100 mg oral doses of the coevaporate and the commercial product, Lamprene (Ciba-Geigy) were administered on separate occasions (separated by a two-week washout period) to four pigs (two males, two females) in a random cross-over study. Multiple plasma samples, obtained from an indwelling jugular-vein cannula, following drug administration, were analysed by an HPLC method for CLF. Pharmacokinetic analyses of the plasma CLF concentration-time data were performed. A paired t-test indicated significant differences (p < 0.05) between the coevaporate and Lamprene in the Cpmax, tmax, and AUC. The calculated relative systemic bioavailability (Frel) of CLF from the coevaporate, relative to that from Lamprene, was three. It is concluded that formulation of CLF, as a solid dispersion, may provide enhanced aqueous dissolution and systemic absorption and may also provide high therapeutic blood levels. These could lead to reduction in the current therapeutic doses and, consequently, minimization of drug-related side effects.

Bioavailability and chemotherapeutic activity of clofazimine against Mycobacterium avium complex infections in beige mice following a single implant of a biodegradable polymer

We have studied the bioavailability of clofazimine following administration of a single dose of the drug in the biodegradable polymer polylactic-co-glycolic acid (PLGA). We compared the levels of clofazimine achieved in the liver with single implants with those obtained with daily oral treatment. Even though the levels achieved with implants were much lower than those obtained after daily oral treatment, they were higher than the MIC of clofazimine for Mycobacterium leprae, Mycobacterium tuberculosis and Mycobacterium avium complex (MAC). Experimental studies in beige mice after infection with MAC strain 101 showed similar reductions in cfu counts, after both single dose polymer and daily oral treatment. Macroscopically, hyperpigmentation giving an orange-yellow colour to all visceral organs, was seen in animals after daily oral treatment but not in those animals that received polymer implants.

Bioavailability of dapsone on oral administration of Dapsomine--a comparative evaluation

This study describes a comparative evaluation of dapsone kinetics in humans on administration of Dapsomine, a capsule containing dapsone 100 mg dispersed in oily-base suspension of clofazimine 50 mg. Seven untreated lepromatous leprosy patients were given one capsule of Dapsomine a day for seven days and the pharmacokinetics parameters in this group were compared with those from another group of seven patients who received dapsone 100 mg and clofazimine 50 mg separately. There were no statistically significant differences in parameters such as peak dapsone plasma concentration (Cmax), basal plasma level (C24h), time to peak level (tmax), absorption half-life (t1/2 alpha), elimination half-life t1/2 beta) and areas under plasma concentration-time curves (AUC0-8h) and AUC0-24h) between the two groups.

Study of intracellular deposition of the anti-leprosy drug clofazimine in mouse spleen using laser microprobe mass analysis

Laser microprobe mass analysis (LAMMA) was used to study the composition of the brick-red crystalline material which had accumulated in the spleen of mice that had received the anti-leprosy drug Clofazimine in their diet for several months. The crystalline deposits light-microscopically resembled pure Clofazimine crystals. The presence of the drug in the crystals was indicated by LAMMA by the appearance of the chloride mass peaks in the negative mass spectra. More specific information was obtained from the positive mass spectra. A mass signal for the protonated molecule was present.

Studies on the tissue distribution of liposome-associated clofazimine, an antileprosy drug

Clofazimine, a potent antimycobacterial drug, being highly lipophilic accumulates in fatty tissue and in the reticuloendothelial system causing dose-dependent side effects. In this study, the distribution of the free drug and liposome-associated drug was compared after intravenous administration in mice. Differences in the distribution of the drug were observed in the liver, spleen, kidney and lung tissues when injected as free drug and as liposome-associated drug. Following intravenous challenge with the free drug, the drug accumulated quickly and high concentrations of the drug were seen in the spleen, liver, kidney and lung even after 24 h, indicating poor clearance. However, with liposome-associated drug, increased levels were seen in liver, spleen and lung at 1 h with levels falling considerably at 24 h, with no accumulation in the kidney either at 1 h or 24 h after challenge. Clofazimine associated with neutral liposomes was preferentially targetted to spleen and lung, positively charged liposome-associated drug accumulated more in the lungs than in other tissues, while negatively charged liposome-associated drug was directed to liver and spleen. The results suggest that inclusion of clofazimine into liposome not only targets the drug to the organs concerned but also facilitates clearance of the drug, resulting in little accumulation. Also, renal accumulation is much lower as compared to the free drug. This suggests the potential usefulness of liposome as a carrier for clofazimine, thereby reducing the harmful side effects due to excessive accumulation of the drug.

A rapid and sensitive high performance liquid chromatographic analysis of clofazimine in plasma

The high performance liquid chromatographic (HPLC) method of Gidoh, et al. has been modified substantially to provide a simple, rapid, and relatively inexpensive procedure for measuring clofazimine in plasma. The modification involves the use of commonly available laboratory reagents instead of custom-made ones. It also employs a solid phase system for efficient extraction instead of the conventional, less efficient and more labor intensive, liquid-liquid extraction. The inclusion of an internal standard (salicylic acid) improves the precision and reproducibility. It is demonstrated that the method can be used to monitor in vivo clofazimine levels as may be required in formal pharmacokinetic studies or therapeutic drug monitoring.

Clofazimine crystals in alveolar macrophages from a patient with the acquired immunodeficiency syndrome

An induced sputum specimen from a 35-year-old patient with the acquired immunodeficiency syndrome (AIDS) contained numerous bright orange-red needle-shaped crystal inclusions in his alveolar macrophages. Careful questioning revealed that he recently had been treated for 7 months with clofazimine (200 mg/d) for persistent Mycobacterium avium complex bacteremia. The striking cytologic finding observed is diagnosed easily if the characteristic morphologic appearance of the crystals and their location within the cytoplasm of macrophages and cells of the reticuloendothelial system is appreciated. Although this is the first observation at San Francisco (Calif) General Hospital of clofazimine crystals in a respiratory specimen from a patient with AIDS, the potential of more widespread therapy with clofazimine in patients with AIDS who are infected with M avium complex makes it imperative that the microscopic appearance of these crystals be recognized.

Clofazimine: a review of its use in leprosy and Mycobacterium avium complex infection

This article reviews the chemistry, pharmacology, spectrum of activity, pharmacokinetics, clinical efficacy in leprosy and Mycobacterium avium complex (MAC) infection, adverse effects, drug interactions, and special considerations of clofazimine. The drug is active in vivo against M. leprae and in vitro against MAC. In addition, it possesses antiinflammatory and immunosuppressive properties. Clinical studies support the efficacy of clofazimine as a part of multidrug therapy in treating leprosy. It also appears to reduce the incidence and severity of erythema nodosum leprosum reactions that often occur during the treatment of leprosy. Efficacy in treating MAC infection in patients with AIDS is not well documented, despite the use of clofazimine in combination with other agents. A few patients have responded symptomatically and by clearing their mycobacteremia, although there is no evidence that mortality is reduced. Clofazimine is well tolerated, at least when doses less than or equal to 100 mg/d are used. Adverse reactions include discoloration of the skin, self-limiting gastrointestinal intolerance, severe and life-threatening abdominal pain and organ damage due to clofazimine crystal deposition, and asymptomatic discoloration of the eye. Clofazimine should be considered for formulary inclusion.

Clinical pharmacokinetics of clofazimine. A review

Clofazimine is useful in the treatment of Hansen's disease (leprosy) and some dermatological disorders, and is currently being used in drug regimens for patients with human immunodeficiency viral infections who are also infected with Mycobacterium avium complex. After an oral dose, absorption is variable, but when given in an oil-wax suspension is approximately 70%. Administration with food appears to increase the peak plasma drug concentration and reduce the time to peak level. Data on the volume of distribution and percentage or type of protein binding are not available; however, the drug undergoes extensive tissue distribution. Clofazimine does not cross the blood-brain barrier, but does cross the placenta, and is found in human breast milk. To date 3 urinary metabolites have been identified in man, but their biological activity is unknown. A substantial portion of the unchanged drug is excreted in faeces. The elimination half-life is variable, with values as long as 70 days being quoted in the literature. Frequently reported side effects of clofazimine are hyperpigmentation of the skin and conjunctiva, and abdominal pain. These resolve upon cessation of therapy. Biochemical and haematological adverse effects have been reported, but are generally not clinically relevant. Pharmacokinetic drug interactions of potential clinical significance have been observed with dapsone, oestrogen, rifampicin and vitamin A.