Myeloperoxidase [1]
Phospholipase A2 (activation in neutrophils) [1]
Bacterial DNA (postulated intercalation with guanine residues) [1]

In vitro activity: Clofazimine stimulates oxygen consumption and superoxide generation by neutrophils, Clofazimine also causes phospholipase A2 activation in neutrophils, resulting in increased release of lysophosphatidylcholine and arachidonic acid from neutrophil membranes. Clofazimine inhibits mitogen-induced stimulation of peripheral blood mononuclear cells. Clofazimine stabilizes lysosomal membranes in macrophages and inhibits Mycobacterium leprae metabolism in mouse peritoneal macrophages. Clofazimine (5 mg/mL) causes dose-related enhancement of the activity of phospholipase A2 in S. aureus, according to an increase in the release of 3H-radiolabeled arachidonate and lysophosphatidylethanolamine ([3H]LPE) from bacterial-membrane phospholipids. Clofazimine inhibits 90% of twenty M. tuberculosis strains with MICs<1.0 μg/mL, to be noted, clofazimine inhibits M. tuberculosis strain 2227 with MICs of 0.06 μg/mL. Clofazimine (1 μg/mL) dose-dependently inhibits activity of J774A.1 macrophages.
Cell Assay: Clofazimine is a fat-soluble iminophenazine dye, has a marked anti-inflammatory effect, has been used in combination with other antimycobacterial drugs to treat AIDS and Crohns disease.

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Clofazimine scavenges hypochlorous acid, reducing chlorination of proteins by neutrophils. [1]
Clofazimine stimulates oxygen consumption and superoxide generation by neutrophils. [1]
Clofazimine causes phospholipase A2 activation in neutrophils, resulting in increased release of lysophosphatidylcholine and arachidonic acid from neutrophil membranes. [1]
Purified phospholipase was not stimulated by Clofazimine in vitro. [1]
Clofazimine augments prostaglandin E2 production in normal neutrophils as well as those from chronic myelocytic leukemia and chronic granulomatous disease. [1]
Clofazimine partially reverses inhibition of monocyte function by a Mycobacterium tuberculosis glycolipid. [1]
Clofazimine inhibits mitogen-induced stimulation of peripheral blood mononuclear cells. [1]
Clofazimine stabilizes lysosomal membranes in macrophages and inhibits Mycobacterium leprae metabolism in mouse peritoneal macrophages. [1]
Clofazimine exerts antiproliferative effects on a variety of malignant cell lines; this effect was antagonized by α-tocopherol. [1]
Clofazimine has broad-spectrum activity against gram-positive, but not gram-negative, bacteria. Anaerobic conditions increased susceptibility of gram-positive organisms to Clofazimine. The activity was antagonized by α-tocopherol. [1]
Clofazimine increases activity of bacterial phospholipase A2 and release of lysophospholipids, which are toxic to gram-positive organisms and Mycobacterium. [1]
Clofazimine binds to guanine residues of bacterial DNA (postulated). [1]

Clofazimine (20 mg/kg) prevents mortality and causes a significant reduction in the numbers of CFU in the lungs and spleens of C57BL/6 mice infected M.tuberculosis H37Rv. Liposomal Clofazimine (L-CLF) (50 mg/kg) dose-dependently reduces CFU 2 to 3 log units in the spleen, liver, and lungs of acutely infected mice with Mycobacterium tuberculosis Erdman. Clofazimine (500 μg, bid) results in highest Clofazimine concentrations in spleens and livers of mice whereas Clofazimine concentrations in the lungs are significantly lower. Clofazimine (20 mg/kg) is effective in reducing bacterial loads in the liver, spleen and lungs of C57BL/6 mice experimentally infected with M. avium strain TMC 724.

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In guinea pigs infected by intracardiac injection of Mycobacterium tuberculosis, Clofazimine did not increase survival. [1]
In beige mice with Mycobacterium avium intracellulare (MAI) infection, Clofazimine was found to be more efficacious than ethionamide and rifabutin. [1]
Clofazimine enhances the effectiveness of amikacin and clarithromycin against MAI in beige mice. [1]
In patients with AIDS and disseminated MAI infection, Clofazimine in conjunction with rifampin, ethambutol, and ciprofloxacin reduced bacterial counts and alleviated symptoms. [1]
In a trial of low-dose Clofazimine alone in patients with advanced AIDS, no benefit was shown for prophylaxis against MAI. [1]
Clofazimine was effective in treating extensive Mycobacterium marinum infection in an infant and Mycobacterium hemophilum/Mycobacterium kansasii in AIDS patients. [1]
For Buruli ulcer (Mycobacterium ulcerans), Clofazimine monotherapy was found to be ineffective in a controlled trial. [1]
In multibacillary leprosy, WHO regimen: Clofazimine 50 mg daily and 300 mg once monthly along with dapsone and rifampin for at least 2 years. [1]
Clofazimine alone was insufficient for lepromatous leprosy. [1]
In malakoplakia, Clofazimine with trimethoprim-sulfamethoxazole induced remission in a kidney transplant patient. [1]
In rhinoscleroma, Clofazimine led to complete resolution in 38 of 76 patients. [1]
In cutaneous Leishmania major infection in mice, Clofazimine was highly effective. [1]
In pyoderma gangrenosum, Clofazimine 300-400 mg daily induced remission in several patients resistant to steroids, antibiotics, etc. [1]
In pustular psoriasis, Clofazimine 200 mg daily for 1-2 months led to rapid improvement in two patients. [1]
In acne fulminans, Clofazimine 200 mg three times weekly was successful. [1]
In discoid lupus erythematosus, Clofazimine 100 mg daily was effective in two thirds of patients. [1]
In Melkersson-Rosenthal syndrome, Clofazimine induced complete remissions in 5 of 11 patients (45%). [1]
In necrobiosis lipoidica and disseminated granuloma annulare, Clofazimine gave 60% response and 30% complete remission. [1]

Van Zyl et al. (1991) studied the mechanism by which Clofazimine inhibits the myeloperoxidase system. They demonstrated that Clofazimine scavenges hypochlorous acid, thereby reducing the chlorination of proteins by neutrophils. The experimental details likely involved measuring hypochlorous acid scavenging activity or protein chlorination inhibition. [1]
Anderson et al. (1988) investigated phospholipase A2 involvement. They found that Clofazimine stimulates phospholipase A2 activity in neutrophils, but when purified phospholipase A2 was used in a cell-free system, Clofazimine did not directly stimulate the enzyme. This suggests an indirect mechanism. The assay for phospholipase A2 activity likely involved measuring release of arachidonic acid or lysophosphatidylcholine from substrate. [1]
Van Rensberg et al. (1992) studied bacterial phospholipase A2. They found that Clofazimine increases the activity of bacterial phospholipase A2, leading to release of lysophospholipids, which are toxic to gram-positive organisms. The assay probably measured enzymatic hydrolysis products. [1]

Krajewska et al. (1993) examined the effects of Clofazimine on human polymorphonuclear leukocyte functions. They measured oxygen consumption (using an oxygen electrode) and superoxide generation (likely via cytochrome c reduction assay). [1]
Anderson et al. (1988) studied neutrophil phospholipase A2 activation by Clofazimine. They measured release of lysophosphatidylcholine and arachidonic acid from neutrophil membranes, possibly using radiolabeled precursors and thin-layer chromatography. [1]
Clofazimine was tested for its effect on mitogen-induced stimulation of peripheral blood mononuclear cells. Lymphocyte proliferation was measured by [3H]thymidine incorporation. [1]
In mouse peritoneal macrophages, Clofazimine was shown to stabilize lysosomal membranes (assessed by enzyme release) and inhibit M. leprae metabolism (measured by incorporation of radiolabeled precursors or bacterial viability). [1]
Van Rensburg et al. (1993) evaluated the antiproliferative effect of Clofazimine on various malignant cell lines. Cells were cultured with increasing concentrations of Clofazimine in the presence or absence of α-tocopherol, and cell proliferation was measured by cell counting or thymidine incorporation. [1]
Antibacterial activity of Clofazimine was tested against gram-positive and gram-negative bacteria under aerobic and anaerobic conditions. Minimum inhibitory concentrations were determined. [1]

20 mg/kg Mice

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In the guinea pig model of tuberculosis, animals were infected by intracardiac injection of Mycobacterium tuberculosis. Clofazimine was administered (dose and route not specified), and survival was monitored. No increase in survival was observed. [1]
The beige mouse model was used for Mycobacterium avium intracellulare (MAI) infection. Mice were infected (likely intravenously) with MAI. Clofazimine was administered alone or in combination with other drugs (e.g., ethionamide, rifabutin, amikacin, clarithromycin). Efficacy was assessed by bacterial counts in organs (spleen, liver, lungs). [1]
For cutaneous Leishmania major infection in mice, Clofazimine was administered (route and dose not specified), and lesion size or parasite burden was measured. [1]

Clofazimine is administered orally; absorption is increased when taken with food. [1]
Once absorbed, it concentrates in lipid-rich tissues, primarily the reticuloendothelial system, with high concentrations also found in breast, liver, and intestines. [1]
The elimination half-life of Clofazimine is 70 days. [1]
Clofazimine does not affect the bioavailability of dapsone. [1]
Isoniazid increases the serum levels and urinary excretion of Clofazimine. [1]
Clofazimine may have a minor interaction affecting rifampin levels, but this interaction is not expected to alter its therapeutic effect. [1]
Clofazimine is excreted in various body fluids, such as tears, milk, and sputum. [1]

The most common side effect is orange-pink discoloration of the skin, which disappears within a few months after cessation of therapy. [1]
Ichthyosis is the second most common cutaneous side effect. [1]
The most serious side effect is crystal deposition in the small bowel mucosa, which may cause severe and rarely fatal enteropathy. This occurs after several months of therapy with high-dose Clofazimine (>100 mg daily). One case of severe abdominal pain after long-term use of low-dose Clofazimine (approximately 100 mg daily for 10 years) has been described. [1]
More commonly, nausea and diarrhea occur. [1]
Other rare side effects include splenic infarction and eosinophilic enteritis. [1]
Clofazimine can stain the cornea, conjunctiva, and sputum. Ocular staining is temporary and does not affect vision. [1]
A few cases of bull's-eye retinopathy in patients with AIDS taking Clofazimine have been described, but this appears rare. [1]
In pregnant women with leprosy, a 20% neonatal mortality rate was noted in a review of 15 patients; it is not known whether these deaths were caused by drug toxicity or leprosy itself. Clofazimine should be used with caution in pregnant women. [1]

J Am Acad Dermatol.1995 Feb;32(2 Pt 1):241-7;Antimicrob Agents Chemother.1996 Mar;40(3):633-36.

Clofazimine is 3-isopropylimino-3,5-dihydrophenazine, where the hydrogen at position 5 is replaced by a 4-chlorophenyl group and the hydrogen at position 2 is replaced by a (4-chlorophenyl)amino group. Clofazimine is a deep red crystalline solid with antimycobacterial activity and is one of the main drugs for treating multibacillary leprosy. However, it causes reddish-brown discoloration of the skin, so other treatments are usually preferred for patients with lighter skin tones. It also has uses in treating leprosy, as a nonsteroidal anti-inflammatory drug, and for staining. It belongs to the phenazine and monochlorobenzene classes of compounds. Clofazimine is an antimycobacterial drug. Clofazimine has been reported to exist in Streptomyces hygroscopicus, and relevant data are available. It is a lipid-soluble iminophenazine dye used to treat leprosy. Clofazimine has been used in combination with other antimycobacterial drugs to treat Mycobacterium avium infection in AIDS patients, and this is currently under investigation. Clofazimine also has significant anti-inflammatory effects and can be used to control leprosy reactions, namely erythema nodosum. (From JAMA Drug Evaluation Yearbook, 1993, p. 1619)
See also: Clofazimine (note moved to).

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Clofazimine has been in clinical use for almost 40 years (as of 1995). Primary indication is multibacillary leprosy. Also useful in atypical mycobacterial infections, rhinoscleroma, pyoderma gangrenosum, necrobiosis lipoidica, severe acne, pustular psoriasis, discoid lupus erythematosus, Sweet's syndrome, malakoplakia, leishmaniasis, Melkersson-Rosenthal syndrome. [1]
Postulated mechanisms of action include intercalation with bacterial DNA and increasing levels of cellular phospholipase A2. [1]
Clofazimine has both proinflammatory and antiinflammatory effects. Proinflammatory: stimulates myeloperoxidase-mediated iodination, phagocytosis, release of lysosomal enzymes, superoxide generation. Antiinflammatory: scavenges hypochlorous acid. [1]
Clofazimine is lipophilic; pigmentation is associated with lipophilicity. Analogues with high lipophilicity are active against M. leprae but also cause hyperpigmentation. [1]
Resistance to Clofazimine has been reported in M. leprae, but difficult to assess in vitro because M. leprae cannot be cultured. [1]
For multibacillary leprosy, WHO recommends Clofazimine 50 mg daily and 300 mg once monthly, along with dapsone (100 mg daily) and rifampin (600 mg once monthly) for at least 2 years. [1]
Clofazimine decreases the incidence of erythema nodosum leprosum (type 2 lepra reaction) and is used to treat this reaction. [1]
In multiple drug-resistant tuberculosis, Clofazimine has been used as part of a multiple-drug regimen [1]

C27H22CL2N4

473.4

472.122

2030-63-9

Clofazimine-d7

2794

Pink to red solid powder

1.3±0.1 g/cm3

566.9±50.0 °C at 760 mmHg

210-212°

296.7±30.1 °C

0.0±1.6 mmHg at 25°C

1.667

7.26

1

4

4

33

829

0

WDQPAMHFFCXSNU-BGABXYSRSA-N

InChI=1S/C27H22Cl2N4/c1-17(2)30-24-16-27-25(15-23(24)31-20-11-7-18(28)8-12-20)32-22-5-3-4-6-26(22)33(27)21-13-9-19(29)10-14-21/h3-17,31H,1-2H3/b30-24+

N,5-bis(4-chlorophenyl)-3-propan-2-yliminophenazin-2-amine

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: This product requires protection from light (avoid light exposure) during transportation and storage.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 0.62 mg/mL (1.31 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 6.2 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: 0.62 mg/mL (1.31 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 6.2 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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 (Please use freshly prepared in vivo formulations for optimal results.)