Zytix 500 mg

Indication:

Zytix 500 mg is indicated for the treatment of-

• mHSPC (Metastatic Hormone-Sensitive Prostate Cancer): Indicated in combination with Androgen Deprivation Therapy (ADT) and low-dose oral corticosteroids for newly diagnosed, high-risk metastatic prostate cancer.
• mCRPC (Metastatic Castration-Resistant Prostate Cancer):
  • For adult men who are asymptomatic or mildly symptomatic after the failure of primary ADT, before chemotherapy is clinically indicated.
  • For adult men whose disease has progressed during or after a Docetaxel-based chemotherapy regimen.

Dogase & Adminstration:

Adult Dosage (Standard Protocol):

• Recommended Dose: 1,000 mg (1 g) administered orally as a single daily dose. This is taken as either four 250 mg tablets or two 500 mg tablets together.
• Corticosteroid Co-therapy: Must be taken with Prednisone or Prednisolone 5 mg orally twice daily (for mCRPC) or 5 mg once daily (for mHSPC).

Pediatric Dosage:

• Child: Safety and efficacy have not been established. There is no relevant indication for pediatric use; do not administer to children.

Administration Guidelines:

• Strict Empty Stomach Rule: Must be taken at least 1 hour before a meal or 2 hours after eating.
• Ingestion: Tablets must be swallowed whole with a glass of water. Do not crush, break, split, or chew.

Hepatic Impairment Adjustments:

• Mild Impairment (Child-Pugh Class A): No dosage adjustment needed.
• Moderate Impairment (Child-Pugh Class B): Reduce the starting dose to 250 mg once daily. Monitor liver function closely.
• Severe Impairment (Child-Pugh Class C): Contraindicated; do not administer.

”রেজিস্ট্রার চিকিৎসকের পরামর্শ অনুযায়ী ঔষধ সেবন করুন”

Pharmacology:

• Mechanism of Action (MOA): Abiraterone Acetate is an oral inhibitor of the enzyme CYP17 (17α-hydroxylase/C17,20-lyase). This enzyme is highly expressed in testicular, adrenal, and prostatic tumor tissues and is mandatory for androgen biosynthesis. Inhibition of CYP17 prevents the conversion of pregnenolone and progesterone into testosterone precursors (DHEA and androstenedione), thereby reducing serum testosterone to castrate levels.
• Pharmacodynamics: Because CYP17 inhibition selectively stops androgen production but also suppresses cortisol synthesis, it results in a compensatory increase in Adrenocorticotropic Hormone (ACTH) secretion. This elevation can lead to mineralocorticoid excess (causing hypertension, hypokalemia, and fluid retention). To mitigate this systemic effect, Abiraterone must always be co-administered with a low-dose corticosteroid (Prednisone or Prednisolone).
• Pharmacokinetics:
  • Absorption: Following oral ingestion, it is rapidly converted to its active form, Abiraterone. Food profoundly alters absorption. Taking the drug with a meal increases the area under the curve (AUC) up to 10-fold, creating unpredictable and dangerously high systemic exposure.
  • Distribution & Metabolism: It is highly bound to plasma proteins (>99%) and metabolized primarily in the liver via CYP3A4 and SULT2A1 into inactive metabolites.
  • Elimination: The terminal half-life is approximately 15 hours, excreted predominantly via feces (~88%) and minimally via urine (~5%).

Side Effects:

• Very Common (>10%): Peripheral edema (fluid retention), hypokalemia (low potassium), hypertension, urinary tract infections (UTI), diarrhea, and elevated alanine aminotransferase (ALT/AST) levels.
• Serious: Hepatotoxicity (severe liver injury), adrenocortical insufficiency (when steroid therapy is abruptly stopped), and cardiac arrhythmias.

Drug Interaction:

• CYP3A4 Inducers: Strong inducers (e.g., Rifampicin, Phenytoin, Carbamazepine) decrease Abiraterone plasma concentrations and reduce efficacy. Avoid co-administration.
• CYP2D6 Substrates: Abiraterone is a strong inhibitor of CYP2D6. It increases the systemic exposure of drugs metabolized by this enzyme (e.g., Dextromethorphan, Metoprolol, Haloperidol).
• Radium Ra 223 Dichloride: Concomitant use is strictly not recommended due to a documented increase in fractures and skeletal mortality risk.

Pregnancy & Lactation:

• Pregnancy: Strictly contraindicated. Abiraterone causes severe fetal harm. Handling Warning: Pregnant women or those of childbearing age must not handle or touch the tablets without gloves, as active ingredients can be absorbed through the skin.
• Lactation: Not applicable (indicated only for male patients); however, it must not be used by nursing mothers.
• Contraception: Men with female partners of childbearing potential must use highly effective contraception during treatment and for 3 months after the final dose.

Over Dosage:

There is no specific antidote for Abiraterone Acetate overdose. In case of accidental excess ingestion, hold the medication immediately and provide general supportive care, prioritizing the monitoring of cardiac rhythm, serum potassium levels, and blood pressure due to risks of mineralocorticoid excess.

Therapeutic Class:

Anti-androgen / Antineoplastic (Endocrine Therapy)

Storage Conditions:

Store below at 30°C  temperature in a dry place. Away from light and out of reach of children. Do not use the medication after its expiration date.