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19-Epi FK-506 (Tacrolimus Impurity) is one of the impurities of Tacrolimus, which is potent immunosuppressant and could restrain the activity of FK-506 binding protein.
Physicochemical Properties
| Molecular Formula | C44H69NO12 |
| Molecular Weight | 804.018174886703 |
| Exact Mass | 803.482 |
| CAS # | 144490-63-1 |
| Related CAS # | 1356841-89-8; 109581-93-3 |
| PubChem CID | 5372 |
| Appearance | Typically exists as solid at room temperature |
| LogP | 4.576 |
| Hydrogen Bond Donor Count | 3 |
| Hydrogen Bond Acceptor Count | 12 |
| Rotatable Bond Count | 7 |
| Heavy Atom Count | 57 |
| Complexity | 1480 |
| Defined Atom Stereocenter Count | 0 |
| SMILES | COC1CC(CCC1O)\C=C(/C)C1OC(=O)C2CCCCN2C(=O)C(=O)C2(O)OC(C(CC2C)OC)C(CC(C)C\C(C)=C\C(CC=C)C(=O)CC(O)C1C)OC |t:45| |
| InChi Key | QJJXYPPXXYFBGM-UHFFFAOYSA-N |
| InChi Code | InChI=1S/C44H69NO12/c1-10-13-31-19-25(2)18-26(3)20-37(54-8)40-38(55-9)22-28(5)44(52,57-40)41(49)42(50)45-17-12-11-14-32(45)43(51)56-39(29(6)34(47)24-35(31)48)27(4)21-30-15-16-33(46)36(23-30)53-7/h10,19,21,26,28-34,36-40,46-47,52H,1,11-18,20,22-24H2,2-9H3 |
| Chemical Name | 1,14-dihydroxy-12-[1-(4-hydroxy-3-methoxycyclohexyl)prop-1-en-2-yl]-23,25-dimethoxy-13,19,21,27-tetramethyl-17-prop-2-enyl-11,28-dioxa-4-azatricyclo[22.3.1.04,9]octacos-18-ene-2,3,10,16-tetrone |
| Synonyms | Tacrolimus 19-epimer; Tacrolimus anhydrous 19-epimer; UNII-CN64Z1Q9FN; CN64Z1Q9FN; Tacrolimus compound II [EP]; Tacrolimus monohydrate impurity G [EP]; 144490-63-1; CHEBI:94694; |
| HS Tariff Code | 2934.99.9001 |
| Storage |
Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month |
| Shipping Condition | Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs) |
Biological Activity
| Targets | Tacrolimus Impurity |
| ADME/Pharmacokinetics |
Absorption, Distribution and Excretion The aim of this study was to assess tacrolimus levels in breast milk and neonatal exposure during breastfeeding. An observational cohort study was performed in two tertiary referral high-risk obstetric medicine clinics. Fourteen women taking tacrolimus during pregnancy and lactation, and their 15 infants, 11 of whom were exclusively breast-fed, were assessed. Tacrolimus levels were analyzed by liquid chromatography-tandem mass spectrometry. Samples from mothers and cord blood were collected at delivery and from mothers, infants, and breast milk postnatally where possible. All infants with serial sampling had a decline in tacrolimus level, which was approximately 15% per day (ratio of geometric mean concentrations 0.85; 95% confidence interval, 0.82-0.88; P<0.001). Breast-fed infants did not have higher tacrolimus levels compared with bottle-fed infants (median 1.3 ug/L [range, 0.0-4.0] versus 1.0 ug/L (range, 0.0-2.3), respectively; P=0.91). Maximum estimated absorption from breast milk is 0.23% of maternal dose (weight-adjusted). Ingestion of tacrolimus by infants via breast milk is negligible. Breastfeeding does not appear to slow the decline of infant tacrolimus levels from higher levels present at birth. Maternal and umbilical cord (venous and arterial) samples were obtained at delivery from eight solid organ allograft recipients to measure tacrolimus and metabolite bound and unbound concentrations in blood and plasma. Tacrolimus pharmacokinetics in breast milk were assessed in one subject. Mean (+ or - SD) tacrolimus concentrations at the time of delivery in umbilical cord venous blood (6.6 + or - 1.8 ng ml(-1)) were 71 + or - 18% (range 45-99%) of maternal concentrations (9.0 + or - 3.4 ng ml(-1)). The mean umbilical cord venous plasma (0.09 + or - 0.04 ng ml(-1)) and unbound drug concentrations (0.003 + or - 0.001 ng ml(-1)) were approximately one fifth of the respective maternal concentrations. Arterial umbilical cord blood concentrations of tacrolimus were 100 + or - 12% of umbilical venous concentrations. In addition, infant exposure to tacrolimus through the breast milk was less than 0.3% of the mother's weight-adjusted dose. Differences between maternal and umbilical cord tacrolimus concentrations may be explained in part by placental P-gp function, greater red blood cell partitioning and higher haematocrit levels in venous cord blood. Ten colostrum samples were obtained from six women in the immediate postpartum period (0-3 days) with a mean drug concentration of 0.79 ng/mL (range 0.3-1.9 ng/mL). The median milk:maternal plasma ratio was 0.5. The plasma protein binding of tacrolimus is approximately 99% and is independent of concentration over a range of 5-50 ng/mL. Tacrolimus is bound mainly to albumin and alpha-1-acid glycoprotein, and has a high level of association with erythrocytes. The distribution of tacrolimus between whole blood and plasma depends on several factors, such as hematocrit, temperature at the time of plasma separation, drug concentration, and plasma protein concentration. In a US study, the ratio of whole blood concentration to plasma concentration averaged 35 (range 12 to 67). There was no evidence based on blood concentrations that tacrolimus accumulates systemically upon intermittent topical application for periods of up to 1 year. As with other topical calcineurin inhibitors, it is not known whether tacrolimus is distributed into the lymphatic system. For more Absorption, Distribution and Excretion (Complete) data for Tacrolimus (9 total), please visit the HSDB record page. Metabolism / Metabolites Tacrolimus is extensively metabolized by the mixed-function oxidase system, primarily the cytochrome P-450 system (CYP3A). A metabolic pathway leading to the formation of 8 possible metabolites has been proposed. Demethylation and hydroxylation were identified as the primary mechanisms of biotransformation in vitro. The major metabolite identified in incubations with human liver microsomes is 13-demethyl tacrolimus. In in vitro studies, a 31-demethyl metabolite has been reported to have the same activity as tacrolimus. Biological Half-Life In a mass balance study of IV administered radiolabeled tacrolimus to 6 healthy volunteers, ... the elimination half-life based on radioactivity was 48.1+ or - 15.9 hours whereas it was 43.5 + or- 11.6 hours based on tacrolimus concentrations. ... When administered PO, the elimination half-life based on radioactivity was 31.9 + or- 10.5 hours whereas it was 48.4 + or - 12.3 hours based on tacrolimus concentrations ... . ... A case of tacrolimus toxicity in a non-transplant patient /is presented/. ... /The/ patient's tacrolimus dose was 2.1 mg/kg/day for 4 days (therapeutic 0.03 to 0.05 mg/kg/day). Her tacrolimus elimination half-life was 16.5 hours, compared to a mean half-life in healthy volunteers of 34.2 +/- 7.7 hours. ... |
| Toxicity/Toxicokinetics |
Effects During Pregnancy and Lactation ◉ Summary of Use during Lactation Limited data indicate that amounts of systemically administered tacrolimus are low in breastmilk and probably do not adversely affect the breastfed infant. United States and European experts and guidelines consider tacrolimus to be probably safe to use during breastfeeding. Exclusively breastfed infants should be monitored if this drug is used during lactation, possibly including measurement of serum levels to rule out toxicity if there is a concern. Topical tacrolimus presents a low risk to the nursing infant because it is poorly absorbed after topical application and peak blood concentrations are less than 2 mcg/L in most patients. Ensure that the infant's skin does not come into direct contact with the areas of skin that have been treated. Current guidelines allow topical tacrolimus to be applied to the nipples just after nursing, with the nipples cleaned gently before nursing. Only water-miscible cream or gel products should be applied to the breast or nipple because ointments may expose the infant to high levels of mineral paraffins via licking, so pimecrolimus cream may be preferable to tacrolimus ointment for nipple application. ◉ Effects in Breastfed Infants One infant was exclusively breastfed during maternal tacrolimus therapy throughout gestation to at least 2.5 months of age at which time the infant was developing normally physically and neurologically. An ultrasound examination of the infant's thymus was normal. The National Transplantation Pregnancy Registry reported data gathered from 1991 to 2011 on mothers who breastfed their infants following organ transplantation. A total of 68 mothers with transplants (mostly kidney or liver) used tacrolimus while breastfeeding a total of 83 infants. Duration of nursing ranged from 1 week to 1.5 years and follow-up of the children ranged from weeks to 16 years. There were no reports of problems in any of the infants or children. As of December 2013, a total of 92 mothers had breastfed 125 infants for as long as 26 months with no apparent adverse effects in infants. The breastfed infants of six women who took tacrolimus during pregnancy for organ transplantation were breastfed (4 exclusive, 2 partial) for 45 to 180 days and followed for periods of 2 to 30 months. The mothers' mean daily tacrolimus dosage during breastfeeding was 9.6 mg daily (range 4.5 to 15 mg daily). Four mothers were also taking azathioprine 100 to 150 mg daily, one was taking diltiazem, and one was taking prednisolone 15 mg and aspirin 75 mg daily. None of the infants had any clear tacrolimus-related side effects, although one had transient thrombocytosis that resolved despite continued breastfeeding. Developmental milestones were normal and no pattern of infections was noted. Two mothers with systemic lupus erythematosus were reported who took tacrolimus 3 mg daily during pregnancy and lactation as well as prednisolone 30 or 40 mg daily. Three years after birth, both children were healthy. The durations of lactation were not stated. In a case series of women who had liver transplants over a 25-year period, one woman breastfed (extent not stated) her infant while taking tacrolimus. No neonatal complications were noted. A mother with a liver transplant was maintained on belatacept 10 mg/kg monthly, slow-release tacrolimus (Envarsus and Veloxis) 2 mg daily, azathioprine 25 mg daily, and prednisone 2.5 mg daily. She breastfed her infant for a year (extent not stated). The infant’s growth and cognitive milestones were normal. An Australian case series reported 3 women with heart transplants who had a total of 5 infants, all of whom were breastfed (extent not stated) during maternal tacrolimus therapy. Daily dosages ranged from 3 to 13 mg daily. No adverse infant effects were reported up to the times of discharge. A woman with rheumatoid arthritis refractory to etanercept took sarilumab 200 mg every two weeks during pregnancy until 37 weeks of gestation. She was also taking prednisolone 10 mg and tacrolimus 3 mg daily. She delivered a healthy infant at 38 weeks of gestation and breastfed her infant. Prednisolone was continued postpartum, tacrolimus was restarted at 7 days postpartum, and sarilumab was restarted at 28 days postpartum. The mother continued to breastfeed until 6 months postpartum. The infant was vaccinated with multiple live vaccines after reaching six months old, including the Bacille-Calmette-Guerin vaccine, with no adverse effects. A woman with a heart transplant took tacrolimus alone throughout pregnancy and postpartum while breastfeeding her infant (extent not stated) for one year. The child had normal weight gain, normal motor development, and no signs of metabolic disorders or significant infections. The age of the infant at evaluation was not stated. ◉ Effects on Lactation and Breastmilk A study in renal transplant patients who were on a tacrolimus-based immunosuppression regimen found that women’s median serum prolactin levels were 14.4 mcg/L compared with women who were not taking tacrolimus (17.6 mcg/L). The difference was statistically significant. Median serum testosterone levels (0.121 vs 0.137 mcg/L) and serum cortisol levels (82.5 vs 105 mg/L) were also significantly lower in the tacrolimus group. The reduced prolactin may be caused by inhibition of the transcription of the human prolactin gene. Not all studies have found a reduction in serum prolactin with tacrolimus. The prolactin level in a mother with established lactation may not affect her ability to breastfeed. |
| Additional Infomation |
Tacrolimus-13C,D2 has been reported in Streptomyces clavuligerus with data available. Mechanism of Action Tacrolimus is a macrolide immunosuppressant produced by Streptomyces tsukubaensis. Tacrolimus is commercially available for topical use as a 0.03 or 0.1% ointment. The exact mechanism(s) of action of tacrolimus in the treatment of atopic dermatitis has not been elucidated but appears to involve inhibition of the activation of T cells. Tacrolimus also has been shown to inhibit release of mediators from skin mast cells and basophils and to downregulate the expression of high-affinity receptors for immunoglobulin E (IgE) on Langerhans cells. Although tacrolimus is not genotoxic and does not interact directly with DNA, the drug may impair local immunosurveillance. Tacrolimus inhibits T-lymphocyte activation, although the exact mechanism of action is not known. Experimental evidence suggests that tacrolimus binds to an intracellular protein, FKBP-12. A complex of tacrolimus-FKBP-12, calcium, calmodulin, and calcineurin is then formed and the phosphatase activity of calcineurin inhibited. This effect may prevent the dephosphorylation and translocation of nuclear factor of activated T-cells (NF-AT), a nuclear component thought to initiate gene transcription for the formation of lymphokines (such as interleukin-2, gamma interferon). The net result is the inhibition of T-lymphocyte activation (i.e., immunosuppression). The mechanism of action of tacrolimus in atopic dermatitis is not known. While the following have been observed, the clinical significance of these observations in atopic dermatitis is not known. It has been demonstrated that tacrolimus inhibits T-lymphocyte activation by first binding to an intracellular protein, FKBP-12. A complex of tacrolimus-FKBP-12, calcium, calmodulin, and calcineurin is then formed and the phosphatase activity of calcineurin is inhibited. This effect has been shown to prevent the dephosphorylation and translocation of nuclear factor of activated T-cells (NF-AT), a nuclear component thought to initiate gene transcription for the formation of lymphokines (such as interleukin-2, gamma interferon). Tacrolimus also inhibits the transcription for genes which encode IL-3, IL-4, IL-5, GM-CSF, and TNF-a, all of which are involved in the early stages of T-cell activation. Additionally, tacrolimus has been shown to inhibit the release of pre-formed mediators from skin mast cells and basophils, and to down regulate the expression of FceRI on Langerhans cells. Tacrolimus, formerly known as FK506, is a macrolide antibiotic with immunosuppressive properties. Although structurally unrelated to cyclosporin A (CsA), its mode of action is similar. It exerts its effects principally through impairment of gene expression in target cells. Tacrolimus bonds to an immunophilin, FK506 binding protein (FKBP). This complex inhibits calcineurin phosphatase. The drug inhibits calcium-dependent events, such as interleukin-2 gene transcription, nitric oxide synthase activation, cell degranulation, and apoptosis. Tacrolimus also potentiates the actions of glucocorticoids and progesterone by binding to FKBPs contained within the hormone receptor complex, preventing degradation. The agent may enhance expression of the transforming growth factor beta-1 gene in a fashion analogous to that demonstrated for CsA. T cell proliferation in response to ligation of the T cell receptor is inhibited by tacrolimus. Type 1 T helper cells appear to be preferentially suppressed compared with type 2 T helper cells. T cell-mediated cytotoxicity is impaired. B cell growth and antibody production are affected indirectly by the suppression of T cell-derived growth factors necessary for these functions. Antigen presentation appears to be spared. ... |
Solubility Data
| Solubility (In Vitro) | May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples |
| Solubility (In Vivo) |
Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples. Injection Formulations (e.g. IP/IV/IM/SC) Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline) *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution. Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil) Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals). Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)] *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. Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline) Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline) Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline) Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil) Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Oral Formulations Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium) Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals). Oral Formulation 3: Dissolved in PEG400 Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose Oral Formulation 6: Mixing with food powders Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently. (Please use freshly prepared in vivo formulations for optimal results.) |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 1.2438 mL | 6.2188 mL | 12.4375 mL | |
| 5 mM | 0.2488 mL | 1.2438 mL | 2.4875 mL | |
| 10 mM | 0.1244 mL | 0.6219 mL | 1.2438 mL |