Tafsure — Tenofovir Alafenamide 25 mg Tablets, 30 Tabs

Tafsure 25 mg is formulated as film-coated tablets intended for oral administration. The tablets feature a uniform coating designed to mask taste, facilitate swallowing, and protect the core against environmental degradation.

Qualitative and Quantitative Formula per Tablet:

• • Active Pharmaceutical Ingredient: Tenofovir Alafenamide (TAF) — 25 mg (equivalent to tenofovir alafenamide fumarate or hydrochloride).
• • Core Excipients: Lactose monohydrate (diluent/filler), microcrystalline cellulose (MCC, binder), croscarmellose sodium (disintegrant ensuring rapid dissolution), magnesium stearate (lubricant), colloidal anhydrous silica (glidant).
• • Film-Coating System: Hypromellose (HPMC), titanium dioxide (E171), polyethylene glycol/macrogol, and iron oxide yellow dye, providing moisture containment and light-protective properties.

Packaging Configurations: Tafsure is packaged in high-density polyethylene (HDPE) plastic bottles containing 30 tablets with child-resistant closures and induction-sealed tamper-evident liners, or in high-barrier PVC/Aluminum blister strips. Each HDPE bottle contains an internal silica gel desiccant packet to prevent moisture uptake. Bottles or blister cards are enclosed in a branded cardboard box alongside complete prescribing information.

Pharmacodynamics and Molecular Action:
Tenofovir Alafenamide (TAF) is an L-alaninyl isopropyl ester prodrug of tenofovir (an acyclic nucleoside phosphonate analog of adenosine 5'-monophosphate). TAF itself is pharmacologically inactive until internalized by target host cells.

Following oral absorption, TAF enters hepatocytes (via active uptake transporters OATP1B1 and OATP1B3) and lymphocytes. Inside hepatocytes, TAF is intracellularly hydrolyzed by carboxylesterase-1 (CES1), whereas in peripheral blood mononuclear cells (PBMCs), it is cleaved by cathepsin A (CatA). This intracellular cleavage yields tenofovir, which is subsequently phosphorylated by cellular kinases to form the pharmacologically active intracellular metabolite, tenofovir diphosphate (TFV-DP).

Tenofovir diphosphate inhibits viral replication through two distinct mechanisms:

• 1. Competitive Inhibition: TFV-DP competes directly with the natural endogenous substrate, deoxyadenosine triphosphate (dATP), for binding to the active site of HBV reverse transcriptase (polymerase) or HIV-1 reverse transcriptase.
• 2. DNA Chain Termination: Once incorporated into the growing viral DNA strand, TFV-DP causes premature termination of DNA synthesis due to the absence of a 3'-hydroxyl group required for further nucleotide elongation. TAF demonstrates negligible inhibitory affinity toward human host nuclear α-, β-, and mitochondrial γ-DNA polymerases, eliminating mitochondrial toxicity.

Pharmacokinetics:

• • Absorption: TAF is rapidly absorbed across the gastrointestinal tract with peak plasma concentrations ($C_{max}$) reached within 0.5 to 1.0 hour post-dose. Co-administration with a high-fat meal increases TAF systemic exposure (AUC) by approximately 65%; therefore, administration with food is clinically recommended.
• • Distribution: Human plasma protein binding of TAF is approximately 80%. Intracellular concentrations of active TFV-DP in target cells are 5- to 7-fold higher compared to legacy TDF administration.
• • Metabolism: Intracellular metabolism is the predominant clearance pathway (>80%). TAF undergoes minimal systemic metabolism by CYP3A4 enzymes in the liver.
• • Elimination: TAF is eliminated primarily via fecal excretion (31.7%) and renal clearance (1%) as tenofovir. Plasma terminal half-life ($T_{1/2}$) of TAF is brief (~0.47 hours), but the intracellular half-life of active TFV-DP inside target cells is exceptionally long (>150 hours), supporting sustained 24-hour antiviral efficacy with once-daily dosing.

Tafsure 25 mg is clinically indicated for:

• • Chronic Hepatitis B Virus (HBV): Treatment of chronic HBV infection in adults and pediatric patients (aged 12 years and older weighing at least 35 kg) with compensated liver disease (including both HBeAg-positive and HBeAg-negative status, with or without compensated cirrhosis).
• • HIV-1 Infection (Combination Therapy): Treatment of HIV-1 infection in adults and adolescents (aged ≥12 years, ≥35 kg) exclusively as part of multi-drug combination antiretroviral regimens alongside other complementary ARV agents (e.g., integrase inhibitors, NNRTIs, or boosted protease inhibitors).
• • Renal and Bone Optimization: Regimen optimization in patients with history of TDF-associated nephrotoxicity, declining eGFR, or bone mineral density loss.

Therapy with Tafsure 25 mg must be initiated and managed under the supervision of a physician experienced in the clinical management of viral hepatitis B or HIV infection.

Method of Administration:
Tablets are administered orally. Swallow the tablet whole with a full glass of water (100–200 mL). Do not crush, chew, split, or dissolve the tablet in liquids prior to ingestion, as this may disrupt controlled drug release and alter bioavailability.

Food Effect:
Tafsure must be taken with food (a meal or snack). Food significantly enhances gastrointestinal absorption and maximizes systemic exposure of tenofovir alafenamide.

Dosing Schedule:

• • Adults and Adolescents (≥12 years, weighing ≥35 kg): The recommended dose is one tablet (25 mg) taken orally once daily. Patients should establish a consistent routine by taking their dose at the same time every day (e.g., during breakfast or dinner).
• • Duration of Treatment: Treatment of chronic HBV is long-term and often indefinite depending on HBsAg loss, HBeAg seroconversion, and clinical guidelines (EASL/AASLD). Unsupervised treatment cessation must be strictly avoided.

Missed Dose Management:

• • If a dose is missed by less than 18 hours from the scheduled time: Take the missed tablet with food as soon as possible, then resume the normal daily dosing schedule.
• • If a dose is missed by more than 18 hours: Skip the missed dose entirely and take the next scheduled tablet at the regular time. Do not double the dose to compensate for a missed tablet.

Special Patient Populations:

• • Geriatric Patients (≥65 years): No dose adjustment is required.
• • Renal Impairment: No dose adjustment is required in patients with estimated creatinine clearance (CrCl) ≥15 mL/min, or in patients with CrCl <15 mL/min undergoing chronic hemodialysis (on hemodialysis days, administer dose post-dialysis).
• • Hepatic Impairment: No dose adjustment is required in patients with mild (Child-Pugh Class A) or moderate (Child-Pugh Class B) hepatic impairment.

The clinical administration of Tafsure 25 mg is strictly contraindicated under the following conditions:

• • Hypersensitivity: Known severe hypersensitivity or allergic reaction to tenofovir alafenamide, tenofovir, or any non-medicinal excipients in the tablet formulation.
• • Pediatric Limitations: Children under 12 years of age or weighing under 35 kg (safety and efficacy profiles have not been established in this cohort).
• • End-Stage Renal Disease (ESRD) without Dialysis: Patients with CrCl <15 mL/min who are not receiving ongoing chronic hemodialysis.
• • Severe Decompensated Hepatic Impairment: Patients with Child-Pugh Class C cirrhosis due to a lack of safety data.
• • HIV-1 Monotherapy: Tafsure 25 mg must never be administered as a standalone agent for HIV-1 (risk of rapid emergence of K65R nucleoside resistance mutations).
• • Hereditary Galactose Intolerance: Patients with rare hereditary problems of galactose intolerance, total lactase deficiency, or glucose-galactose malabsorption (due to lactose monohydrate content).

Tenofovir Alafenamide (TAF) is a substrate of efflux transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). Metabolism via hepatic cytochrome P450 enzymes is minimal.

Key Drug Interaction Profiles:

• • Strong P-gp and CYP3A Inducers: Co-administration with potent inducers such as rifampin, rifabutin, carbamazepine, phenobarbital, phenytoin, or St. John's Wort (Hypericum perforatum) significantly decreases TAF plasma concentrations, leading to therapeutic failure and resistance. Concurrent use is not recommended.
• • P-gp and BCRP Inhibitors: Co-administration with strong inhibitors (e.g., ketoconazole, itraconazole, cobicistat, ritonavir) increases TAF systemic absorption and plasma exposure. Dose adjustments are generally not required, but monitoring is advised.
• • Nephrotoxic Medications: Concurrent use of Tafsure with agents that impair renal function (e.g., high-dose NSAIDs such as ibuprofen/naproxen, aminoglycosides, amphotericin B, ganciclovir, vancomycin) may elevate the risk of renal toxicities. Renal parameters (serum creatinine and serum phosphate) should be routinely monitored.
• • Other Tenofovir Prodrugs: Tafsure must not be co-administered with other medicinal products containing tenofovir disoproxil or tenofovir alafenamide (e.g., Truvada, Descovy, Biktarvy, Viread) to avoid drug duplication and additive toxicity.
• • Antacids and Acid-Reducing Agents: Gastric pH-altering medications (proton pump inhibitors, H2-blockers, antacids) do not exert clinically relevant effects on TAF oral absorption.

Pregnancy Considerations:
There are limited clinical data regarding the use of tenofovir alafenamide in pregnant women (fewer than 300 pregnancy outcomes). Animal reproduction studies have demonstrated no direct or indirect harmful effects on embryonic development, fetal viability, or parturition.

Tafsure 25 mg should be used during pregnancy only if the potential maternal clinical benefit clearly outweighs the potential risks to the fetus. If a woman receiving TAF treatment becomes pregnant, therapy for chronic HBV should not be abruptly discontinued, as sudden withdrawal can trigger severe acute exacerbations ("flares") of hepatitis B. Clinical decisions must be made in consultation with a specialist.

Lactation & Breastfeeding:
It is unknown whether tenofovir alafenamide is excreted in human breast milk. Animal studies demonstrate that tenofovir is present in animal milk. Because of the potential for viral transmission (HBV/HIV) and adverse drug reactions in nursing infants, mothers taking Tafsure 25 mg should be advised not to breastfeed during treatment.

Tafsure 25 mg is generally well-tolerated in clinical practice. The majority of adverse reactions reported in clinical trials were mild to moderate (Grade 1–2) in severity, rarely requiring treatment discontinuation.

Adverse Reaction Frequency Profile:

• • Nervous System Disorders: Very common (≥1/10) — headache; common (≥1/100 to <1/10) — dizziness, abnormal dreams, insomnia.
• • Gastrointestinal Disorders: Common (≥1/100 to <1/10) — nausea, diarrhea, abdominal pain, flatulence, abdominal distension, vomiting, dyspepsia.
• • Hepatobiliary Disorders: Common — elevated serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Uncommon — severe acute hepatitis flare following therapy withdrawal.
• • Skin and Subcutaneous Tissue: Common — pruritus, maculopapular rash. Uncommon — angioedema, urticaria.
• • Musculoskeletal Disorders: Common — arthralgia, back pain, muscle spasms.
• • General Disorders: Common — fatigue, asthenia, malaise.
• • Metabolic Parameters: Minor increases in LDL cholesterol, fasting triglycerides, and blood glucose. Rarely reported with NRTIs — lactic acidosis and severe hepatomegaly with steatosis.

Symptoms of Overdose:
Data regarding acute TAF overdose in humans are limited. Ingestion of supratherapeutic doses may exacerbate known clinical side effects, resulting in severe nausea, persistent headache, gastrointestinal distress, and dizziness.

Management & Treatment:
There is no specific pharmacological antidote for TAF overdose. In the event of acute overdose, immediately discontinue Tafsure. Gastric lavage or administration of activated charcoal may be considered if performed shortly after ingestion (within 1–2 hours).

Management consists of supportive clinical care, including continuous monitoring of vital signs, cardiac monitoring, renal function, and serum electrolytes. Tenofovir is efficiently removed by hemodialysis with an extraction coefficient of approximately 54%. A 4-hour hemodialysis session removes approximately 10% of the administered tenofovir dose. Peritoneal dialysis efficiency is unknown.

Storage Guidelines and Requirements for Tafsure 25 mg:

• 🌡️ Temperature Controls: Store in the original manufacturer packaging at controlled room temperature below 30 °C (86 °F). Protect from freezing or excessive heat exposure.
• ☀️ Environmental Safeguards: Keep the bottle or blister pack inside the outer cardboard carton to protect tablets from direct sunlight, UV exposure, and excessive humidity. Do not remove the internal silica gel desiccant from the HDPE bottle.
• 👶 Safety Precautions: Store in a dry, secure location out of the reach and sight of children and pets.
• ⏳ Shelf Life: 24 months (2 years) from the manufacturing date printed on the package. Do not use past the expiration date (EXP) debossed on the carton. Prescription status: Rx-only.

To safeguard patients against counterfeit pharmaceutical products, Aprazer Healthcare Pvt. Ltd. incorporates multi-tiered physical and digital security features on every package of Tafsure 25 mg:

• ✅ Corporate Identity: Official two-tone blue and red Aprazer health care logo printed with crisp typography on front, back, and side panels.
• ✅ Scannable 2D QR Code: A scannable 2D QR code located on the side panel provides digital product verification and authentication via smartphone scanner.
• ✅ Factory Debossing: Essential manufacturing data including Batch Number (Batch No.), Manufacturing Date (Mfg Date), and Expiration Date (Expiry Date) are deeply debossed/imprinted into the side flap of the outer carton.
• ✅ Product Labeling Specifications: Clean packaging text featuring "TAFSURE®", "25 mg", and official regulatory notices ("For India Only" or designated export markings).
• ✅ Tamper-Evident Seals: High-tack clear or holographic security seal sticker over outer carton end flaps to ensure tamper-proof distribution.