AR/androgen receptor

Bicalutamide has an IC50 of 160 nM and competes with androgens for binding to AR in a whole-cell binding experiment (LNCaP/AR (cs) cells) [1]. Bicalutamide partially counteracts the effects of R1881, a synthetic androgen, while inducing VCaP cell proliferation in a dose-dependent manner [1].

In a mouse model of prostate cancer, belicutamide (10 mg/kg; ig; daily; for 28 days) shows anticancer efficacy [1].

Ligand-binding studies were performed either in a whole-cell assay (LNCaP/AR(cs)), using whole-cell extracts (MDA-MB-453), or in vitro with purified receptor. Proliferation assays (VCaP) were performed in either agonist- or antagonist-mode (without/with R1881). RNA was isolated from LNCaP/AR cells for RT-PCR analysis with primers (Suppl. Table 1) specific for AR target-genes. Fluorescence microscopy was performed in LNCaP cells transfected with AR-EYFP as previously described. AR antibody PG-21 was used for chromatin immunoprecipitation (ChIP) experiments (LNCaP/AR(cs)) together with primers for PSA and TMPRSS2 enhancers. Luciferase reporter-gene assays were performed in LNCaP/AR-luc or Hep-G2 cells expressing VP16-AR[1].

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Ligand binding studies [1]
Whole cell LNCaP/AR: Whole-cell competitive binding assays were performed in LNCaP/AR(codon-switch) (LNCaP/AR(cs)) (harbors a mixture of exogenous wild-type AR and endogenous mutant AR (T877A)) and cells propagated in Iscove’s or RPMI media supplemented with 10% fetal bovine serum (FBS), or during the assay with 10% charcoal-stripped, dextran-treated fetal bovine serum (CSS). Cells were pre-incubated with 18F-FDHT, increasing concentrations (1pM to 1μM) of cold competitor were added, and the assay was performed according to published procedures to measure specific uptake of 18F-FDHT.

Proliferation assays[1]
Trypsinized VCaP cells were adjusted to a concentration of 100,000 cells per mL in phenol-red-free RPMI 1640 (with 5% CSS), and dispensed in 16 µL aliquots into CellBIND 384 well plates. Cells were incubated for 48 hours, after which ligand was added in a 16 µL volume to the RPMI culture medium.

Animal/Disease Models: Castrate male mice, bearing LNCaP/AR(cs) xenograft tumors[1]
Doses: 10 mg/kg
Route of Administration: po (oral gavage), daily, for 28 days
Experimental Results: Inhibited tumor growth.

Absorption, Distribution and Excretion
Bicalutamide is well-absorbed following oral administration, although the absolute bioavailability is unknown.
Apparent oral cl=0.32 L/h [Normal Males]
Bicalutamide is well-absorbed following oral administration, although the absolute bioavailability is unknown. Co-administration of bicalutamide with food has no clinically significant effect on rate or extent of absorption.
Bicalutamide is highly protein-bound (96%).
... Bicalutamide metabolites are excreted almost equally in urine and feces with little or no unchanged drug excreted in urine; conversely, unchanged drug predominates in plasma. Bicalutamide in feces is thought to arise from hydrolysis of bicalutamide glucuronide and from unabsorbed drug. ...
... Healthy male volunteers (n = 15) were administered single oral doses of bicalutamide (50 mg) after food and after fasting as part of a three-treatment, three-period, randomized cross-over study, with a 9 week washout. After fasting, plasma concentrations of (R)-bicalutamide were much higher than those of (S)-bicalutamide; the mean (R)-enantiomer Cmax (734 ng mL-1) was about nine times higher than the (S)-enantiomer value (84 ng mL-1). The corresponding tmax values were 19 and 3 hr for (R)- and (S)-bicalutamide, respectively. Elimination of (R)-bicalutamide from plasma was monoexponential and slow (t1/2 = 5.8 d). Elimination of (S)-bicalutamide was biphasic in some volunteers but monophasic in others (terminal t1/2 =1.2 d; n = 11). There was no significant effect of food on AUC, tmax, or t1/2 data for either enantiomer. The observed slightly higher values of Cmax for (R)-bicalutamide (14%) and (S)-bicalutamide (19%), when dosing with food, achieved statistical significance. ...
For more Absorption, Distribution and Excretion (Complete) data for BICALUTAMIDE (9 total), please visit the HSDB record page.

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Metabolism / Metabolites
Bicalutamide undergoes stereo specific metabolism. The S (inactive) isomer is metabolized primarily by glucuronidation. The R (active) isomer also undergoes glucuronidation but is predominantly oxidized to an inactive metabolite followed by glucuronidation.
Bicalutamide undergoes stereospecific metabolism. The S (inactive) isomer is metabolized primarily by glucuronidation. The R (active) isomer also undergoes glucuronidation but is predominantly oxidized to an inactive metabolite followed by glucuronidation. Both the parent and metabolite glucuronides are eliminated in the urine and feces. The S-enantiomer is rapidly cleared relative to the R-enantiomer, with the R-enantiomer accounting for about 99% of total steady-state plasma levels.
Bicalutamide undergoes stereo specific metabolism. The S (inactive) isomer is metabolized primarily by glucuronidation. The R (active) isomer also undergoes glucuronidation but is predominantly oxidized to an inactive metabolite followed by glucuronidation.
Half Life: 5.9 days

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Biological Half-Life
5.9 days
... Elimination of (S)-bicalutamide was biphasic in some volunteers but monophasic in others (terminal t1/2 =1.2 d; n = 11). ...
/The/ apparent plasma elimination half-life observed following repeated administration was 8.4 +/- 1.1 days.

Toxicity Summary
Bicalutamide competes with androgen for the binding of androgen receptors, consequently blocking the action of androgens of adrenal and testicular origin which stimulate the growth of normal and malignant prostatic tissue. Organic nitriles decompose into cyanide ions both in vivo and in vitro. Consequently the primary mechanism of toxicity for organic nitriles is their production of toxic cyanide ions or hydrogen cyanide. Cyanide is an inhibitor of cytochrome c oxidase in the fourth complex of the electron transport chain (found in the membrane of the mitochondria of eukaryotic cells). It complexes with the ferric iron atom in this enzyme. The binding of cyanide to this cytochrome prevents transport of electrons from cytochrome c oxidase to oxygen. As a result, the electron transport chain is disrupted and the cell can no longer aerobically produce ATP for energy. Tissues that mainly depend on aerobic respiration, such as the central nervous system and the heart, are particularly affected. Cyanide is also known produce some of its toxic effects by binding to catalase, glutathione peroxidase, methemoglobin, hydroxocobalamin, phosphatase, tyrosinase, ascorbic acid oxidase, xanthine oxidase, succinic dehydrogenase, and Cu/Zn superoxide dismutase. Cyanide binds to the ferric ion of methemoglobin to form inactive cyanmethemoglobin. (L97)

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Hepatotoxicity
Bicalutamide therapy is associated with mild, asymptomatic and transient elevations in serum aminotransferase levels in approximately 6% of patients. The frequency and height of the ALT elevations appears to be less with bicalutamide than flutamide. Similarly, there have been rare case reports of clinically apparent liver injury due to bicalutamide, but less frequently than with flutamide. In the Spanish pharmacovigilance study, there were 11 reports of hepatotoxicity from bicalutamide, none of which were fatal. On the other hand, the product label for bicalutamide mentions that a few cases of fatal hepatic failure have been reported. The clinical pattern of liver injury with bicalutamide appears to resemble that of flutamide. The latency to onset is usually 2 to 3 months, but can be shorter with reexposure and occasionally arises 4 to 6 months after starting. The typical pattern of serum enzyme elevations is hepatocellular and severe, fulminant cases have been described. Rash, fever and eosinophilia are not common and autoantibody formation is not described.
Likelihood score: B (likely cause of clinically apparent liver injury).

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Protein Binding
96%

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Interactions
In vitro protein-binding studies have shown that bicalutamide can displace coumarin anticoagulants from binding sites. Prothrombin times should be closely monitored in patients already receiving coumarin anticoagulants who are started on /bicalutamide/.
In vitro studies have shown that R-bicalutamide is an inhibitor of CYP 3A4 with lesser inhibitory effects on CYP 2C9, 2C19 and 2D6 activity. Clinical studies have shown that with co-administration of bicalutamide, mean midazolam (a CYP 3A4 substrate) levels may be increased 1.5 fold (for Cmax) and 1.9 fold (for AUC). Hence, caution should be exercised when bicalutamide is co-administered with CYP 3A4 substrates.

[1]. Nicola J. Clegg,1 John Wongvipat,1,2 Jim Joseph, ARN-509: a novel anti-androgen for prostate cancer treatment. Cancer Res. 2012 March 15; 72(6): 1494-1503.

Therapeutic Uses
Androgen Antagonists; Antineoplastic Agents
/Bicalutamide/ 50 mg daily is indicated for use in combination therapy with a luteinizing hormone-releasing hormone (LHRH) analogue for the treatment of Stage D2 metastatic carcinoma of the prostate. /Included in US product label/
/Bicalutamide/ 150 mg daily is not approved for use alone or with other treatments. /Included in US product label/

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Drug Warnings
/Bicalutamide/ is contraindicated in any patient who has shown a hypersensitivity reaction to the drug or any of the tablet's components.
/Bicalutamide/ has no indication for women, and should not be used in this population, particularly for non-serious or non-life threatening conditions.
FDA Pregnancy Risk Category: X /CONTRAINDICATED IN PREGNANCY. Studies in animals and or humans, or investigational or post-marketing reports, have demonstrated positive evidence of fetal abnormalities or risk which clearly outweighs any possible benefit to the patient./
It is not known whether /bicalutamide/ drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when /bicalutamide/ is administered to a nursing woman.
For more Drug Warnings (Complete) data for BICALUTAMIDE (10 total), please visit the HSDB record page.

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Pharmacodynamics
Bicalutamide is an antineoplastic hormonal agent primarily used in the treatment of prostate cancer. Bicalutamide is a pure, nonsteroidal anti-androgen with affinity for androgen receptors (but not for progestogen, estrogen, or glucocorticoid receptors). Consequently, Bicalutamide blocks the action of androgens of adrenal and testicular origin which stimulate the growth of normal and malignant prostatic tissue. Prostate cancer is mostly androgen-dependent and can be treated with surgical or chemical castration. To date, antiandrogen monotherapy has not consistently been shown to be equivalent to castration.

C18H14F4N2O4S

430.37

430.061

C, 50.23; H, 3.28; F, 17.66; N, 6.51; O, 14.87; S, 7.45

90357-06-5

(R)-Bicalutamide;113299-40-4;Bicalutamide-d4;1185035-71-5

2375

White to off-white solid powder

1.5±0.1 g/cm3

650.3±55.0 °C at 760 mmHg

191-193°C

347.1±31.5 °C

0.0±2.0 mmHg at 25°C

1.578

4.94

2

9

5

29

750

0

LKJPYSCBVHEWIU-UHFFFAOYSA-N

InChI=1S/C18H14F4N2O4S/c1-17(26,10-29(27,28)14-6-3-12(19)4-7-14)16(25)24-13-5-2-11(9-23)15(8-13)18(20,21)22/h2-8,26H,10H2,1H3,(H,24,25)

N-(4-cyano-3-(trifluoromethyl)phenyl)-3-((4-fluorophenyl)sulfonyl)-2-hydroxy-2-methylpropanamide

ICI-176334; ICI 176334; ICI176334; CDX. US trade name: Casodex; Cosudex. Calutide;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

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: ≥ 2.5 mg/mL (5.81 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 25.0 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: ≥ 2.5 mg/mL (5.81 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in 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 25.0 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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Solubility in Formulation 3: ≥ 2.5 mg/mL (5.81 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (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 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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