99% Hot Sale Original Powder Abiraterone Acetate CAS154229-18-2 with Low Price

Basic Information

Description
Abiraterone acetate, sold under the brand name Zytiga among others, is a medication used to treat prostate cancer. Specifically it is used together with a corticosteroid for metastatic castration-resistant prostate cancer (mCRPC) and metastatic high-risk castration-sensitive prostate cancer (mCSPC). It should either be used following removal of the testicles or along with a gonadot ropin-releasing hormone (GnRH) analog. It is taken by mouth.

Common side effects include tiredness, vomiting, headache, joint pain, high blood pressure, swelling, low blood potassium, high blood sugar, hot flashes, diarrhea, and cough. Other severe side effects may include liver failure and adrenocortical insufficiency. In males whose partners can become pregnant, birth control is recommended. Supplied as abiraterone acetate it is converted in the body to abiraterone. Abiraterone acetate works by suppressing the production of androgens - specifically it inhibits CYP17A1 - and thereby decreases the production. In doing so, it prevents the effects of these hormones in prostate cancer.

Abiraterone acetate was described in 1995, and approved for medical use in the United States and Europe in 2011. It is on the World Health Organization's List of Essential Medicines, the safest and most effective medicines needed in a health system. The medication is marketed widely throughout the world.

Medical Uses

Prostate Cancer

Abiraterone acetate is used in combination with prednison, a corticosteroid, as a treatment for mCRPC (previously called hormone-resistant or hormone-refractory prostate cancer). This is a form of prostate cancer that is not responding to first-line androgen deprivation therapy or treatment with androgen receptor antagonists. Abiraterone acetate has received Food and Drug Administration (FDA) (28 April 2011), European Medicines Agency (EMA) (23 September 2011), Medicines and Healthcare products Regulatory Agency (MHRA) (5 September 2011) and Therapeutic Goods Administration (TGA) (1 March 2012) approval for this indication. In Australia it is covered by the Pharmaceutical Benefits Scheme when being used to treat castration-resistant prostate cancer and given in combination with prednison/prednisolon (subject to the conditions that the patient is not currently receiving chemotherapy, is either resistant or intolerant of docetaxel, has a WHO performance status of <2, and his disease has not since become progressive since treatment with PBS-subsidised abiraterone acetate has commenced).

Abiraterone acetate may be useful for prevention of the flare at the initiation of GnRH agonist therapy in men with prostate cancer.

In people previously treated with docetaxel survival is increased by 3.9 months (14.8 months versus 10.9 months for placebo).

In people with castration-refractory prostate cancer but who had not received chemotherapy those who received abiraterone acetate had a progression-free survival of 16.5 months rather than 8.3 months with placebo. After a median follow-up period of 22.2 months, overall survival was better with abiraterone acetate.

Contraindications

Contraindications include hypersensitivity to abiraterone acetate. Although documents state that it should not be taken by women who are or who may become pregnant, there is no medical reason that any woman should take it. Women who are pregnant should not even touch the pills unless they are wearing gloves. Other cautions include severe baseline hepatic impairment, mineralocorticoid excess, cardiovascular disease including heart failure and hypertension, uncorrected hypokalemia, and adrenocorticoid insufficiency.

 

Pharmacology

1.Pharmacodynamics

2.Antiandrogenic Activity

Abiraterone, the active metabolite of abiraterone acetate, inhibits CYP17A1, which manifests as two enzymes, 17α-hydroxylase (IC₅₀ = 2.5 nM) and 17,20-lyase (IC₅₀ = 15 nM) (approximately 6-fold more selective for inhibition of 17α-hydroxylase over 17,20-lyase) that are expressed in testicular, adrenal, and prostatic tumor tissues. CYP17A1 catalyzes two sequential reactions: (a) the conversion of pregnenolone and progesterone to their 17α-hydroxy derivatives by its 17α-hydroxylase activity, and (b) the subsequent formation and androstenedion, respectively, by its 17,20-lyase activity. DH EA and androstenedion are androgens and precursors. Inhibition of CYP17A1 activity by abiraterone acetate thus decreases circulating levels of androgens such as DH EA, and DHT. Abiraterone acetate, via abiraterone, has the capacity to lower circulating levels to less than 1 ng/dL (i.e., undetectable) when added to castration. These concentrations are considerably lower than those achieved by castration alone (~20 ng/dL). The addition of abiraterone acetate to castration was found to reduce levels of DHT by 85%, DH EA by 97 to 98%, and androstenedion by 77 to 78% relative to castration alone. In accordance with its antiandrogenic action, abiraterone acetate decreases the weights of the prostate gland, seminal vesicles, and testes.

Abiraterone also acts as a partial antagonist of the androgen receptor (AR), and as an inhibitor of the enzymes 3β-hydroxysteroid dehydrogenase (3β-HSD), CYP11B1 (steroid 11β-hydroxylase), CYP21A2 (Steroid 21-hydroxylase), and other CYP450s (e.g., CYP1A2, CYP2C9, and CYP3A4). In addition to abiraterone itself, part of the activity of the drug has been found to be due to a more potent active metabolite, δ⁴-abiraterone (D4A), which is formed from abiraterone by 3β-HSD. D4A is an inhibitor of CYP17A1, 3β-hydroxysteroid dehydrogenase/Δ^5-4 isomerase, and 5α-reductase, and has also been found to act as a competitive antagonist of the AR reportedly comparable to the potent antagonist enzalutamide. However, the initial 5α-reduced metabolite of D4A, 3-keto-5α-abiraterone, is an agonist of the AR, and promotes prostate cancer progression. Its formation can be blocked by the coadministration of dutasteride, a potent and selective 5α-reductase inhibitor.

3.Estrogenic Activity

There has been interest in the use of abiraterone acetate for the treatment of breast cancer due to its ability to lower estrogen levels. However, abiraterone has been found to act as a direct agonist of the estrogen receptor, and induces proliferation of human breast cancer cells in vitro. If abiraterone acetate is used in the treatment of breast cancer, it should be combined with an estrogen receptor antagonist like fulves trant. In spite of its antiandrogenic and estrogenic properties, abiraterone acetate does not appear to produce gynecomastia as a side effect.

4.Other Activities

Due to inhibition of glucocorticoid biosynthesis, abiraterone acetate can cause glucocorticoid deficiency, mineralocorticoid excess, and associated adverse effects. This is why the medication is combined with prednison, a corticosteroid, which serves as a means of glucocorticoid replacement and prevents mineralocorticoid excess.

Abiraterone acetate, along with galeterone, has been identified as an inhibitor of sulfotransferases (SULT2A1, SULT2B1b, SULT1E1), which are involved in the sulfation of DH EA and other endogenous steroids and compounds, with K_i values in the sub-micromolar range.

5.Pharmacokinetics

After oral administration, abiraterone acetate, the prodrug form in the commercial preparation, is converted into the active form, abiraterone. This conversion is likely to be esterase-mediated and not CYP-mediated. Administration with food increases absorption of the drug and thus has the potential to result in increased and highly variable exposures; the drug should be consumed on an empty stomach at least one hour before or two hours after food. The drug is highly protein bound (>99%), and is metabolised in the liver by CYP3A4 and SULT2A1 to inactive metabolites. The drug is excreted in feces (~88%) and urine (~5%), and has a terminal half-life of 12 ± 5 hours.

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