Virodip 10 mg

Indication:

Virodip 10 mg is indicated for the treatment of-

• Chronic Hepatitis B (HBV): Treatment of chronic hepatitis B infection in adult patients with evidence of active viral replication, persistently elevated serum aminotransferases (ALT or AST), or histologically active liver disease.
• Compensated and Decompensated Liver Disease: Indicated for both HBeAg-positive and HBeAg-negative chronic HBV status, as well as patients showing resistance to lamivudine.

”রেজিস্ট্রার চিকিৎসকের পরামর্শ অনুযায়ী ঔষধ সেবন করুন”

Dogase & Adminstration:

Adult Dosing Protocols (Ages 18 and Above):

• Standard Dosing Schedule: 10 mg orally once daily, taken with or without food.
• Therapeutic Duration: The optimal duration of treatment is not established. Therapy must be sustained continuously unless clinical or serological non-response, or adverse renal markers appear.

Pediatric Dosing Protocols:

• Children and Adolescents under 18 years: Safety and efficacy parameters have not been comprehensively established. It is strictly not recommended for pediatric populations.

Administration Guidelines:

• Tablets must be swallowed whole with water at approximately the same time every day.
• Baseline renal function monitoring (Serum Creatinine and Calculated Creatinine Clearance) is mandatory prior to starting therapy.

Renal Impairment Dosing Adjustments: Because adefovir is eliminated via renal filtration, the dosing interval must be modified based on Creatinine Clearance (CrCl):

• CrCl 30 to 49 mL/min: Administer 10 mg every 48 hours.
• CrCl 10 to 29 mL/min: Administer 10 mg every 72 hours.
• Hemodialysis Patients: Administer 10 mg every 7 days (following the dialysis session).

”রেজিস্ট্রার চিকিৎসকের পরামর্শ অনুযায়ী ঔষধ সেবন করুন”

Pharmacology:

• Mechanism of Action (MOA): Adefovir dipivoxil is an acyclic nucleotide analogue of adenosine monophosphate. It enters the cell as an inactive prodrug, where cellular esterases cleave the dipivoxil moieties to release the parent compound, adefovir.
  • Phosphorylation: Intracellular kinases then convert adefovir into its active metabolite, adefovir diphosphate.
  • Inhibition of HBV DNA Polymerase: Active adefovir diphosphate competes directly with the natural substrate, deoxyadenosine triphosphate, for incorporation into viral DNA by the HBV DNA polymerase (reverse transcriptase).
  • Chain Termination: Once incorporated into the growing viral DNA chain, adefovir acts as a terminal chain terminator due to the lack of a necessary 3′-hydroxyl group, permanently halting further elongation of the viral DNA and stopping replication.
• Pharmacodynamics: It exhibits highly selective and potent activity against Hepatitis B Virus (HBV) genotypes A through G. It successfully suppresses viral load (HBV DNA levels), promotes HBeAg seroconversion, and normalizes serum alanine aminotransferase (ALT) levels.
• Pharmacokinetics:
  • Absorption: Following oral administration, the dipivoxil prodrug is rapidly absorbed and converted to active adefovir. The absolute oral bioavailability is approximately 59%. Peak plasma concentrations (Cmax​) are achieved within 0.6 to 2.1 hours. Absorption is unaffected by food.
  • Distribution: Minimally bound to plasma or serum proteins (≤4%). It distributes widely throughout systemic tissues, particularly into the kidneys and liver.
  • Metabolism & Elimination: It does not undergo hepatic CYP450 metabolism. It is cleared entirely unchanged via the kidneys through a combination of glomerular filtration and active tubular secretion. The terminal elimination half-life is approximately 7.5 hours in patients with normal renal function, but prolongs significantly in renal impairment.

Side Effects:

• Common: Asthenia (weakness), headache, abdominal pain, nausea, flatulence, and diarrhea.
• Severe: Nephrotoxicity (dose-dependent increases in serum creatinine and decreases in serum phosphorus), lactic acidosis, severe hepatomegaly with steatosis, and severe acute exacerbations of hepatitis B upon abrupt discontinuation of therapy.

Drug Interaction:

• Nephrotoxic Drugs: Co-administration with drugs that impair renal function or compete for active tubular secretion (e.g., Cyclosporine, Aminoglycosides, high-dose NSAIDs, Vancomycin) elevates systemic adefovir levels, multiplying the risk of nephrotoxicity.
• Tenofovir Disoproxil Fumarate: Concurrent use with Tenofovir is not recommended due to overlapping metabolic toxicity profiles and increased risk of renal impairment.

Pregnancy & Lactation:

• Pregnancy: Category C. There are no adequate and well-controlled studies in pregnant women. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
• Lactation: It is unknown whether adefovir is excreted in human milk. Mothers should be instructed not to breastfeed if they are taking Adefovir Dipivoxil to prevent secondary toxicities in the infant.

Over Dosage:

Massive acute overdose can result in severe gastrointestinal toxicity and accelerated nephrotoxicity. In case of significant overdose, monitor the patient closely for signs of toxicity (especially renal function and electrolyte panels). Adefovir can be partially removed via hemodialysis (a 4-hour dialysis session clears approximately 35% of the dose).

Therapeutic Class:

Antiviral Agent / Reverse Transcriptase Inhibitor / Nucleotide Analogue

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.