Medicine > All about Abiracine (Abiraterone acetate) tablet

All about Abiracine (Abiraterone acetate) tablet

Name of Medicine:- Abiracine

Chemical Formula:- C26H33NO2

Active Ingredient:- Abiraterone Acetate

Inactive Ingredients:- Colloidal Silicon Dioxide, Lactose Monohydrate, Magnesium Stearate, Croscarmellose Sodium, Microcrystalline Cellulose, Povidone, and Sodium Lauryl Sulfate.

Description:- Abiracine is an innovative composition of Abiraterone Acetate that offers clinical benefits to patients suffering from metastatic castration-resistant Prostate Cancer. 

What is Abiracine?

Abiracine is an anti-cancer prescription medicine, comprising Abiraterone Acetate. The compound works as a partial antagonist of the Androgen Receptor (AR). It works to prevent the production of androgen (male hormone) in men. It inhibits the CYP17 enzyme that is responsible for producing androgen. 

Clinical Relevance

The clinical relevance of a drug tells about its significance in the medical field and its relevance in the treatment of diseases. It is important to know the indications/relevance of the medicine before administering it. Abiracine tablets are used in the treatment of  Metastatic Castration-Resistant Prostate Cancer (mCRPC) and metastatic high-risk Castration Sensitive Prostate Cancer (mCSPC). It is prescribed for use in men with a glucocorticoid medication like Prednisone. 

Clinical Pharmacology 

Pharmacodynamics 

Abiraterone Acetate (Abiracine) is associated with the decreased levels of PSA, shrunk tumor (as calculated by RECIST criteria), radiographic regression of bone metastases, and a notable improvement in pain. Levels of adrenocorticotropic hormones get increased up to six-fold but this may be suppressed by Dexamethasone.

Mechanism of Action 

Abiraterone Acetate, an orally active inhibitor of the steroidal enzyme, works to inhibit CYP17A1 selectively and irreversibly with the help of a covalent binding mechanism. CYP17A1 is an enzyme that tends to catalyze the biosynthesis of the androgen. It is majorly expressed in adrenal, testicular, and prostatic tumor tissue. More precisely, the compound works to inhibit the conversion of 17-hydroxypregnenolone to dehydroepiandrosterone (DHEA) by the enzyme (CYP17A1) in order to decrease serum levels of testosterone and other androgens.

Absorption

After the administration of Abiraterone Acetate, Abiraterone’s peak plasma concentrations reached in about 1.5–4 hours (mean 2). Its administration with food increases systemic exposure to Abiraterone. The maximum concentration (Cmax) was seven-fold greater after administering it with a low-fat meal and seventeen-fold greater after administering it with a high-fat meal when compared to a fasted state. Likewise, the AUC was affected too and was five-fold greater after the low-fat meal and ten-fold greater after the high-fat meal.

Distribution 

Abiraterone’s plasma protein binding is more than 99% in human plasma. The average distribution volume is about 19,669 L, which suggests that the compound extensively distributes to peripheral tissues.

Biotransformation

In man, Abiraterone acetate (AA) is rapidly hydrolyzed to Abiraterone(ABT). The major human circulating metabolites are sulfated ABT (ABT14 S) and the N-oxide of ABT-S. In vitro, the evaluation of the metabolic stability of C-AA and -ABT was done in the human stomach mucosa, human hepatocytes, human and dog intestinal subcellular fractions, and human blood. The combination of in vitro phenotyping data shows that esterase-mediated hydrolysis took place in gastrointestinal tissue. Hence, ABT (instead of AA) is the main entity being absorbed from the intestine, which is further sulfated and oxidized mainly in the liver to ABT-S and N-oxide ABT-S.  

Elimination

Based on data from healthy subjects, the mean half-life of Abiraterone Acetate in plasma is about 10.3 hours. After orally administering C-abiraterone acetate 1,000 mg, about 88% of the radioactive dose was excreted via feces and nearly 5% via urine. The major compounds present in feces were unaffected Abiraterone Acetate and Abiraterone. 

Clinical Trials

From a phase I trial in 21 men with Hormone Refractory Prostate Cancer, it is evident that Abiraterone Acetate may be an effective hormonal therapy for Prostate Cancer. In this clinical study, treatment with this compound was associated with tumor shrinkage and a notable decrease in the levels of prostate-specific antigen in approximately 70% of patients. These variations were accompanied by several symptomatic improvements, like reduced pain.

When PSA levels subsequently started to rise, the addition of Dexamethasone to the ongoing administration of Abiraterone led to a decrease in the levels of PSA with approximately one-third of patients going through a decrease of about 50%. A second phase II trial evaluated the reactions of Abiraterone in men with Hormone Refractory Prostate Cancer who had failed the standard chemotherapeutic drugs with Docetaxel provided whose levels of PSA had started to increase. Treatment with Abiraterone again led to a decrease in the levels of PSA and no proof of tumor progression over a treatment period of 12-week.

COU-AA-301 Phase III trial in around 147 hospitals in Australia, Europe, and North America enrolled 1,195 patients. The result of the COU-AA-301 Phase III study showed that Abiraterone helps in improving the survival rate of patients. 

Interactions

Drug Interactions

  • Rifampin:- As Abiracine is a substrate of CYP3A4, its co-administration with Rifampin (a strong CYP3A4 inducer) may decrease the exposure of Abiraterone by approximately 55%. Therefore, during the treatment with Abiracine, make sure to avoid the consumption of any CYP3A4 inducer. However, if its consumption can not be avoided, dose adjustments may be needed. 

  • Ketoconazole:-  Coadministration of Ketoconazole with Abiracine showed no clinically relevant effects on Abiraterone’s pharmacokinetics in a dedicated drug interactions trial. However, consult your physician about the same before coadministering a strong inhibitor of CYP3A4 with Abiracine.

  • Dextromethorphan:- In a dedicated drug-drug interactions trial, when Dextromethorphan was administered with Abiracine, a notable increase in Cmax (about 2.8-fold) and AUC (about 2.9-fold) of Dextromethorphan were observed. Hence, avoid the administration of substrates of CYP2D6 with Abiracine. 

  • Pioglitazone:- In a dedicated drug-drug interactions trial, when Pioglitazone (CYP2C8 substrate) was coadministered with Abiracine, an increase of about 46% in the AUC of Pioglitazone was noted in the healthy subjects. Proper monitoring and dose adjustments need to be done while coadministering Pioglitazone with Abiracine.

Drug-Food Interactions

  • Grapefruit or grapefruit juice:- Concomitant consumption of grapefruit or grapefruit juice with Abiracine may increase the risk of adverse reactions and effects. Therefore, to avoid such severe effects, its consumption should be avoided during the course of Abiracine. 

Drug-Disease Interactions

  • Hepatic Impairment:- In a dedicated drug-disease interactions trial, the pharmacokinetics of Abiraterone in three cases were examined. The three cases included patients with normal hepatic function, mild hepatic impairment, and moderate hepatic impairment. In patients with normal hepatic function, no change was observed in the pharmacokinetics of Abiraterone. However, in the cases of patients with mild and moderate hepatic impairment, the AUC of Abiraterone was increased by 1.1-fold and 3.6-fold respectively. This is why dose adjustments are needed in the case of patients suffering from hepatic impairment. 

Drug Category

  • Androstanes:- It is a C19 steroid. Androstanes are as effective as androgens. They exist either as 5α-androstane or 5β-androstane. They are used in the treatment of a number of androgen-dependent and androgen-independent cancers.

  • Antineoplastic Agents:- These drugs are used in the treatment of certain types of cancers. Antineoplastic Agents are also known as cytotoxic or chemo drugs. Some of these drugs are liquids that are given as injections and others are taken as pills.

  • Steroids:- These drugs are used to treat various types of cancers. They are prescribed to reduce inflammation in the body and help in preventing related pains. In the treatment of cancer, steroids are given to achieve multiple goals.

  • Hormone Antagonists:- Receptor antagonists that act upon hormone receptors are known as Hormone Antagonists. These drugs are used in the treatment of a number of cancers. Hormone Antagonists are used in antihormone therapy. 

Dosage and Administration

Recommended Dose:- Abiracine is administered in the dose strength of 1,000mg (four tablets of 250mg each) on an empty stomach once daily while coadministering Prednisone 5mg twice daily. No food item should be consumed at least 2 hours before the administration of this medicine and at least one hour after the administration. The tablets should be swallowed with water as a whole. Do not cut or chew the tablets. 

Dose Modification:- In a clinical trial dedicated to studying the interaction of Hepatic Impairment, the pharmacokinetics of Abiraterone in three cases were examined. The three cases included patients with normal hepatic function, mild hepatic impairment, and moderate hepatic impairment. In patients with normal hepatic function, no change was observed in the pharmacokinetics of Abiraterone. However, in the cases of patients with mild and moderate hepatic impairment, the AUC of Abiraterone was increased by 1.1-fold and 3.6-fold respectively. This is why dose adjustments are needed in the case of patients suffering from hepatic impairment.

Overdosage:- No specific antidote for overdose of Abiracine is established by now. However, if you experience any symptoms of overdose, it is important to seek the emergency medical attention of a qualified medical practitioner. In such a case, a doctor will undertake general supportive measures such as monitoring for arrhythmias, cardiac failure, and assess liver function

Adverse Reactions

The most common adverse reactions noted in clinical trials include fatigue, joint pain, swelling in the joints, discomfort, edema (swelling or inflammation), hot flush, diarrhea, cough, vomiting, hypertension, dyspnea (shortness of breath), UTI (urinary tract infection), upper respiratory tract infection, nocturia (frequent urination at night), low blood potassium, arrhythmia (irregular heartbeat), and bruising. 

Certain gastrointestinal disorders like constipation, diarrhea (pain or discomfort in the upper abdomen), dyspepsia, and stomach ache are also common in patients administering Abiracine tablets. 

Allergic reactions such as skin rash, swelling, pain, itching, and irritation may occur in some patients who are allergic to Abiraterone Acetate or any other ingredient of this medicine. Therefore, it is important to know the ingredients of the medicine beforehand to avoid such adverse effects. 

Some patients also suffer from problems like insomnia and depression during the course of this medicine. A healthcare provider should be contacted immediately to know the appropriate ways of managing such effects. 

Other common side effects such as elevated alkaline phosphatase, anemia, elevated ALT and hypokalemia, hypertriglyceridemia (high level of fats in the blood), lymphopenia (reduced levels of certain types of blood cells), and hypercholesterolemia (high levels of cholesterol in the blood) may occur. 

DRUG DISCONTINUATION REACTIONS:- Sudden discontinuation of Abiracine may lead to an increase in aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT). It may also cause the symptoms of cardiac failure and urosepsis (a urinary tract infection). 

Warnings and Precautions

During the administration 

  • Abiracine and food:- Abiracine tablet should be taken on an empty stomach. No food item should be consumed at least 2 hours before the administration of this medicine and at least one hour after the administration. This is because Abiraterone  Cmax and AUC increase by approximately 17-fold and 10-fold respectively when administered with food. 

  • Handling:- Women who are pregnant should not handle Abiracine tablets without protection (gloves).

Special population

  • Pregnant Women:- Abiracine tablets can cause severe harm when administered to a woman during pregnancy or otherwise. This medication is not recommended for use in women in any case. 

  • Nursing Mothers:- Abiracine tablets can cause severe harm when administered to a woman during breastfeeding or otherwise. This medication is not recommended for use in women in any case. 

  • Pediatric Use:- Abiraterone Acetate is not safe for use in children. 

  • Geriatric Use:- During the clinical trials, Abiracine tablets did not show any difference in safety or effectiveness between elder and younger individuals.

  • Hepatic Impairment:- In patients with normal hepatic function, no change was observed in the pharmacokinetics of Abiraterone. However, in the cases of patients with mild and moderate hepatic impairment, the AUC of Abiraterone was increased by 1.1-fold and 3.6-fold respectively. This is why dose adjustments are needed in the case of patients suffering from hepatic impairment.

Reactions that may occur

  • Hypertension and Fluid Retention:- Some patients may suffer from increased levels of mineralocorticoid, which may lead to hypertension, hypokalemia, and fluid retention. Patients should be monitored for hypertension, hypokalemia, and fluid retention periodically. 

  • Adrenocortical Insufficiency:- Patients receiving Abiracine with Prednisone may experience Adrenal insufficiency with symptoms like fatigue, nausea, dizziness, and darkening of the skin. Signs and symptoms of adrenal insufficiency should be monitored periodically specifically in patients who had administered Prednisone previously. 

Packaging and Storage

Abiracine (Abiraterone Acetate) is available in the form of tablets for oral use in a high-density polyethylene bottle containing 120 tablets. Store the tablets at 59°F to 86°F (15°C to 30°C). Keep Abiracine tablets away from the reach of pets and children. Do not place it under direct light and heat. Protect from moisture. Know the ways to dispose of the used and expired packs of medicines from a pharmacist. Women who are pregnant should not handle Abiracine tablets without protection (gloves).