Tacrolimus

Absorption

Absorption of tacrolimus from the gastrointestinal tract after oral administration is incomplete and variable. The absolute bioavailability in adult kidney transplant patients is 17±10%; in adults liver transplant patients is 22±6%; in healthy subjects is 18±5%. The absolute bioavailability in pediatric liver transplant patients was 31±24%. Tacrolimus maximum blood concentrations (Cmax) and area under the curve (AUC) appeared to increase in a dose-proportional fashion in 18 fasted healthy volunteers receiving a single oral dose of 3, 7, and 10 mg. When given without food, the rate and extent of absorption were the greatest. The time of the meal also affected bioavailability. When given immediately after a meal, mean Cmax was reduced 71%, and mean AUC was reduced 39%, relative to the fasted condition. When administered 1.5 hours following the meal, mean Cmax was reduced 63%, and mean AUC was reduced 39%, relative to the fasted condition.

Toxicity

Side effects can be severe and include blurred vision, liver and kidney problems (it is nephrotoxic), seizures, tremors, hypertension, hypomagnesemia, diabetes mellitus, hyperkalemia, itching, insomnia, confusion. LD50=134-194 mg/kg (rat).

Description

Tacrolimus, isolated from the microorganism Streptomyces tsukubaensis, is a macrolide immunosuppressant developed by Fujisawa for organ transplantation. It displays similar but more potent immunosuppressive activity than cyclosporin. It inhibits both cell mediated and humoral immune responses. In animal models of organ transplantation, tacrolimus has been shown to prolong survival of hepatic, renal, cardiac, small intestine, pancreatic and skin allografts and to reverse cardiac and renal allograft rejection. It has been used effectively in humans as rescue or primary immunosuppressant therapy in liver or kidney transplantation. Compared to cyclosporin, tacrolimus causes reduced incidence of infectious complications and of hypertension and hypercholesterolemia for the allograft recipients. In common with cyclosporin, tacrolimus binds with high affinity to a family of cytoplasmic immunosuppressant binding proteins, the immunophilins. This tight complex is proposed as the biologically active moiety that interacts with intracellular molecules involved in signal transduction.It inhibits phosphatase activity of calcineurin, an action that may impair the generation and/or activation of nuclear transcription factors required for lymphokine (particularly interleukin-2) gene expression. Tacrolimus has also been reported to have potential in multiple sclerosis, psoriasis, rheumatoid arthritis and uveitis associated with Behcet‘s disease.

Description

FK-506 is a potent immunosuppressant in the same molecular class as cyclosporin A and rapamycin . Its mechanism of action involves the formation of a high affinity complex (K_i = 0.2 nM) with FK-506 binding protein 12 (FKBP12). This complex then inhibits the activity of the calcium/calmodulin-dependent protein phosphatase, calcineurin, leading to disruption of T cell activation. The physiological effects of FK-506 also include regulation of nitric oxide neurotoxicity, neurotransmitter release, and regulation of Ca²⁺ release via the ryanodine and inositol-(1,4,5)-trisphosphate (IP₃) receptors. In the latter case, FKBP12 forms a tight complex with both ryanodine and IP₃ receptors which can be disrupted by FK-506, thereby rendering the receptors leaky to Ca²⁺.

Chemical properties

White Crystalline Solid

Originator

Fujisawa (Japan)

The Uses of Tacrolimus

FK-506 (Tacrolimus) is a macrolide immunosuppressive drug that is mainly used after allogeneic organ transplant to reduce the activity of the patient's immune system

The Uses of Tacrolimus

An immunosuppressant that blocks T cell proliferation in vitro by inhibiting the generation of several lymphokines, especially IL-2. Shown to inhibit the activity of FK-506 binding protein, thereby reversing its effects on sarcoplasmic reticulum Ca+2 release.

The Uses of Tacrolimus

Tacrolimus (fujimycin) was discovered as a potent inhibitor of IL2 production in a targeted search for novel immunosuppressants. Tacrolimus acts by blocking T cell proliferation in vitro by inhibiting the generation of several lymphokines, notably the original target IL-2. Tacrolimus inhibits the activity of FK-506 binding protein, Ca2+-dependent phosphatase and calcineurin, and activates NF-κB through phosphorylation and degradation of IκBα.

The Uses of Tacrolimus

treatment of Cushing's syndrome

The Uses of Tacrolimus

For use after allogenic organ transplant to reduce the activity of the patient's immune system and so the risk of organ rejection. It was first approved by the FDA in 1994 for use in liver transplantation, this has been extended to include kidney, heart,

Background

Tacrolimus (also FK-506 or Fujimycin) is an immunosuppressive drug whose main use is after organ transplant to reduce the activity of the patient's immune system and so the risk of organ rejection. It is also used in a topical preparation in the treatment of severe atopic dermatitis, severe refractory uveitis after bone marrow transplants, and the skin condition vitiligo. It was discovered in 1984 from the fermentation broth of a Japanese soil sample that contained the bacteria Streptomyces tsukubaensis. Tacrolimus is chemically known as a macrolide. It reduces peptidyl-prolyl isomerase activity by binding to the immunophilin FKBP-12 (FK506 binding protein) creating a new complex. This FKBP12-FK506 complex inhibits calcineurin which inhibits T-lymphocyte signal transduction and IL-2 transcription.

What are the applications of Application

FK-506 is an agent that binds to the immunophilin FKBP2 and inhibits calcineurin

Indications

Immediate-release formulations of tacrolimus are indicated for the prophylaxis of organ rejection in adult and pediatric patients receiving allogeneic liver, kidney, heart, or lung transplants, in combination with other immunosuppressants. Extended-release formulations of tacrolimus are indicated for the prophylaxis of organ rejection in adult and pediatric patients receiving kidney transplants, in combination with other immunosuppressants, and may be used in patients converted from immediate-release formulations.
Topical tacrolimus ointment is indicated as second-line therapy for short-term and non-continuous treatment of moderate-to-severe atopic dermatitis in non-immunocompromised adults and children who have failed to respond adequately to other topical treatments or for whom alternative treatments are not advisable. Both available strengths are indicated in adult patients, while only the lower strength (0.03%) formulation is indicated in pediatric patients between 2 and 15 years of age.

Definition

ChEBI: Tacrolimus is a macrolide containing a 23-membered lactone ring, originally isolated from the fermentation broth of a Japanese soil sample that contained the bacteria Streptomyces tsukubaensis.

Indications

Tacrolimus is a macrolide lactone originally derived from Streptomyces tsukubaensis. Although structurally unrelated to cyclosporine, tacrolimus has a very similar mechanism of action; that is, it blocks the production of proinflammatory cytokines by T lymphocytes by inhibiting calcineurin.Tacrolimus, however, appears to be 10 to 100 times as potent as an immunosuppressive. Oral tacrolimus (FK506) is used for prevention of organ rejection in recipients of renal and hepatic transplants.

Indications

Tacrolimus (Prograf) is a second-generation immunosuppressive agent that has been approved for use in liver transplantation. Its efficacy for other transplantations is being evaluated. It has properties similar to those of cyclosporine except that weight for weight it is 10 to 100 times more potent. It is a macrolide antibiotic that selectively inhibits transcription of a specific set of lymphokine genes in T lymphocytes (e.g., IL-2, IL-4, and interferon-) and binds to cytoplasmic proteins in lymphocytes. Although the binding proteins (cytophilins) for cyclosporine and tacrolimus are different, they share similar functions in that the cytophilins are important for the intracellular folding of proteins. It is speculated that these proteins are important in regulating gene expression in T lymphocytes and that both drugs somehow interfere in this process.
Absorption of tacrolimus from the gastrointestinal (GI) tract is variable. It is extensively metabolized in the liver and excreted in the urine.As with cyclosporine, nephrotoxicity is its principal side effect.

Manufacturing Process

The novel 17-allyl-1,14-dihydroxy-12-[2-(4-hydroxy-3-methoxycyclohexyl)-1- methylvinyl]-23,25-dimethoxy-13,19,21,27-tetramethyl-11,28-dioxa-4- azatrcyclo[22.3.1.04,9]octacos-18-ene-2,3,10,16-tetraone (FR-900506), substance can be produced by culturing a FR-900506 substance(s)-producing strain belonging to the genus Streptomyces (e.g. Streptomyces tsukubaensis No. 9993, FERM BP-927) in a nutrient medium.
Fermentation
A culture medium (160 ml) containing glycerin (1%), corn starch (1%), glucose (0.5%), cottonseed meal (1%), dried yeast (0.5%), corn steep liquor (0.5%) and calcium carbonate (0.2%) (adjusted to pH 6.5) was poured into each of ten 500 ml-Erlenmeyer flasks and sterilized at 120°C for 30 min. A loopful of slant culture of Streptomyces tsukubaensis No. 9993 was inoculated to each of the medium and cultured at 30°C for 4 days on a rotary shaker. The resultant culture was inoculated to a medium containing soluble starch (5%), peanut powder (0.5%), dried yeast (0.5%), gluten meal (0.5%), calcium carbonate (0.1%) and Adekanol (deforming agent, Trade Mark, maker Asasi Denka Co.) (0.1%) (150 liters) in a 200-liter jar-fermentor, which had been sterilized at 120°C for 20 min in advance, and cultured at 30C for 4 days under aeration of 150 liters/minutes and agitation of 250 rpm.
Isolation and Purification
The cultured broth thus obtained was filtered with an aid of diatomaseous earth (5 kg). The mycelial cake was extracted with acetone (50 liters), yielding 50 liters of the extract. The acetone extract from mycelium and the filtrate (135 L) were combined and passed through a column of a non-ionic adsorption resin "Diaion HP-20" (Trade Mark, maker Mitsubishi Chemical Industries Ltd.) (10 L). After washing with water (30 L) and 50 % aqueous acetone (30 L), elution was carried out with 75 aqueous acetone. The eluate (30 liters) was evaporated under reduced pressure to give residual water (2 L). This residue was extracted with ethyl acetate (2 L) three times. The ethyl acetate extract was concentrated under reduced pressure to give an oily residue. The oily residue was mixed with twice weight of acidic silica gel (special silica gel grade 12, maker Fuji Devison Co.), and this mixture was slurried in ethyl acetate. After evaporating the solvent, the resultant dry powder was subjected to column chromatography of the same acidic silica gel (800 ml) which was packed with n-hexane. The column was developed with nhexane (3 L), a mixture of n-hexane and ethyl acetate (4:1 v/v, 3 L) and ethyl acetate (3 L). The fractions containing the object compound were collected and concentrated under reduced pressure to give an oily residue. The oily residue was dissolved in a mixture of n-hexane and ethyl acetate (1:1 v/v, 30 ml) and subjected to column chromatography of silica gel (maker Merck Co., Ltd. 230-400 mesh) (500 ml) packed with the same solvents system. Elution was carried out with a mixture of n-hexane and ethyl acetate (1:1 v/v, 2 liters and 1:2 v/v, 1.5 L) and ethyl acetate (1.5 L). Fractions containing the first object compound were collected and concentrated under reduced pressure to give crude FR-900506 substance (3 g) in the form of yellowish powder.
This powder of the FR-900506 substance could be transformed into a form of white crystals by recrystallization thereof from acetonitrile. Melting point: 127°-129°C.

brand name

Prograf (Astellas); Protopic (Astellas).

Therapeutic Function

Immunosuppressive

General Description

Immunosuppressant that blocks T-cell proliferation in vitro by inhibiting the generation of several lymphokines, especially IL-2. Shown to inhibit the activity of FK-506 Binding Protein, thereby reversing its effects on sarcoplamic reticulum Ca²⁺ release. Shown to inhibit the Ca²⁺-dependent phosphatase, Calcineurin (Cat. No. 539565), as well as Na⁺-K⁺-ATPase in nephron segments. Also shown to inhibit aldosterone-induced synthesis of Giα-3 protein.

Biochem/physiol Actions

Product does not compete with ATP.

Pharmacokinetics

Tacrolimus acts by reducing peptidyl-prolyl isomerase activity by binding to the immunophilin FKBP-12 (FK506 binding protein) creating a new complex. This inhibits both T-lymphocyte signal transduction and IL-2 transcription. Tacrolimus has similar activity to cyclosporine but rates of rejection are lower with tacrolimus. Tacrolimus has also been shown to be effective in the topical treatment of eczema, particularly atopic eczema. It suppresses inflammation in a similar way to steroids, but is not as powerful. An important dermatological advantage of tacrolimus is that it can be used directly on the face; topical steroids cannot be used on the face, as they thin the skin dramatically there. On other parts of the body, topical steroid are generally a better treatment.

Clinical Use

A topical formulation (Protopic) has recently been approved for treatment of moderate to severe atopic dermatitis in children and adults who have not responded to other therapies. Levels of systemic absorption are low even when applied to a relatively large body surface area.

Side Effects

Local irritant reactions (burning, stinging, erythema) are a common side effect, but these usually resolve within the first few days of treatment. The major benefit of topical tacrolimus over topical corticosteroids is that tacrolimus does not cause atrophy, striae, or telangiectasia, even with chronic use.

Veterinary Drugs and Treatments

Tacrolimus has recently been studied at the University of Tennessee College of Veterinary Medicine where investigators found it equally effective as cyclosporine and effective for cyclosporine-resistant cases of KCS. It exerts its effects through a mechanism similar to that of cyclosporine, however exact mechanisms of action in causing tear production are still being determined.

Veterinary Drugs and Treatments

Tacrolimus ointment may be of benefit in veterinary patients in the adjunctive treatment of atopic dermatitis, discoid lupus erythematosus, pemphigus erythematosus or foliaceous, pinnal vascular disease, alopecia areata, vitiligo and for perianal fistulas (terminal phase or maintenance treatment after cyclosporine therapy). Unlike topical corticosteroids, tacrolimus or pimecrolimus do not have atrophogenic or metabolic effects associated with long-term or large area treatment.
Tacrolimus acts similarly as cyclosporine, namely inhibiting T-lymphocyte activation primarily by inhibiting the phosphatase activity of calcineurin. It also inhibits the release of inflammatory cytokines and mediators from mast cells and basophils.

in vitro

tacrolimus (fk506) has been reported to inhibit the interleukin 2(il-2) production and the response of mixed lymphocyte culture. in addition, tacrolimus (fk506) added to the cell cultures has been revealed to inhibit murine or human mixed lymphocyte reactivity and the generation of cytotoxic t cells. furermor, tacrolimus (fk506) has also been reported to dose-dependently suppress the production of various cytokines including il-2, il-3, il-4, and γ-interferon, in response to different stimulis. besides, tacrolimus has shown its efficacy in the prevention of allograft rejection in animal transplant models. tacrolimus has been found to be significantly efficient in experimental hepatic allografts, and has hepatotrophic properties [1].

Drug interactions

Potentially hazardous interactions with other drugs
Ciclosporin: may increase the half-life of ciclosporin and exacerbate any toxic effects. The two should not be prescribed concomitantly. Care should be taken when converting from ciclosporin to tacrolimus.
Tacrolimus levels increased by: amlodipine, atazanavir, basiliximab, boceprevir, bromocriptine, chloramphenicol, cimetidine, cortisone, danazol, dapsone, diltiazem, ergotamine, ethinyloestradiol, felodipine, fosamprenavir, gestodene, grapefruit juice, imidazole and triazole antifungals, lidocaine, lansoprazole, possibly levofloxacin, macrolides, midazolam, nicardipine, nifedipine, norethisterone, omeprazole, pantoprazole, posaconazole, ranolazine; ritonavir, saquinavir, Chinese herbal remedies containing extracts of Schisandra sphenanthera, tamoxifen, theophylline, verapamil and voriconazole.
Tacrolimus levels decreased by: carbamazepine, caspofungin, fosphenytoin, isoniazid, phenobarbital, phenytoin (fosphenytoin and phenytoin levels possibly increased), primidone, rifampicin, possibly rifabutin and St John’s wort.
Increased nephrotoxicity with: aminoglycosides, amphotericin, NSAIDs, sulfamethoxazole, trimethoprim and vancomycin.
Increased risk of hyperkalaemia with: potassiumsparing-diuretics and potassium salts.
Anticoagulants: possibly increases concentration of dabigatran - avoid.
Antipsychotics: avoid with droperidol, increased risk of ventricular arrhythmias.
Antivirals: increased risk of nephrotoxicity with acyclovir, ganciclovir, valaciclovir and valganciclovir; concentration affected by efavirenz; concentration of both drugs increased with telaprevir; concomitant use with dasabuvir and ombitasvir/paritaprevir/ ritonavir is not recommended unless the benefits outweigh the risks, if used concomitantly, tacrolimus should not be administered on the day dasabuvir and ombitasvir/paritaprevir/ritonavir are initiated. Beginning the day after dasabuvir and ombitasvir/ paritaprevir/ritonavir are initiated; reinitiate tacrolimus at a reduced dose based on tacrolimus levels. The recommended tacrolimus dosing is 0.5 mg every 7 days, monitor levels at initiation and throughout treatment.
Clotrimazole: more than doubles the bioavailability of tacrolimus (US-based researchers report that concomitant clotrimazole substantially increases the relative oral bioavailability of tacrolimus in renal transplant recipients. Inpharma. 2005 Dec 10; 1517: 15).
Cytotoxics: concentration of afatinib possibly increased - separate dose by 6-12 hours; use crizotinib with caution; concentration increased by imatinib.

Metabolism

The metabolism of tacrolimus is predominantly mediated by CYP3A4 and secondarily by CYP3A5. Tacrolimus is metabolized into 8 metabolites: 13-demethyl tacrolimus, 31-demethyl tacrolimus, 15-demethyl tacrolimus, 12-hydroxy tacrolimus, 15,31-didemethyl tacrolimus, 13,31-didemethyl tacrolimus, 13,15-didemethyl tacrolimus, and a final metabolite involving O-demethylation and the formation of a fused ring. 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.

Metabolism

Tacrolimus is extensively bound to erythrocytes in the blood, and variations in red cell binding account for much of the variability in pharmacokinetics. It is extensively metabolised in the liver, mainly by cytochrome P450 isoenzyme CYP3A4, and excreted, primarily in bile, almost entirely as metabolites. Considerable metabolism also occurs in the intestinal wall.
There are several metabolites identified. Only one of these has been shown in vitro to have immunosuppressive activity similar to that of tacrolimus. The other metabolites have only weak or no immunosuppressive activity. In systemic circulation only one of the inactive metabolites is present at low concentrations. Therefore, metabolites do not contribute to pharmacological activity of tacrolimus.

storage

-20°C

References

1) Yu et al. (2006), Effects of cyclosporine A, FK506 and rapamycin on calcineurin phosphatase activity in mouse brain; IUBMB Life, 58 429