Anaflex SR 500 mg Tablet (Naproxen Sodium Sustained-Release) – ACI Limited

1. About Anaflex SR 500 mg

Anaflex SR 500 mg is a sustained-release (SR) formulation of Naproxen Sodium 500 mg manufactured by ACI Limited, Bangladesh. The SR matrix technology controls drug release over an extended period — providing a smoother plasma concentration profile than immediate-release naproxen, reducing peak concentration-related GI irritation while maintaining therapeutic levels throughout the dosing interval. Particularly beneficial for RA patients with early-morning joint stiffness when taken as a single evening dose.

2. Mechanism of Action

Non-selective COX-1/COX-2 inhibitor reducing prostaglandin synthesis. The SR matrix achieves lower Cmax (~70% of IR) with delayed Tmax (~4–6 hours) while preserving total bioavailability — reducing direct GI mucosal irritation while maintaining 12–17 hour anti-inflammatory coverage enabling once-daily dosing.

3. Indications

• Rheumatoid Arthritis: Especially once-nightly dosing for early-morning stiffness control
• Osteoarthritis
• Ankylosing Spondylitis
• Chronic musculoskeletal pain requiring regular NSAID therapy
• Patients with GI intolerance to immediate-release NSAIDs

4. Dosage and Administration

500–1000 mg once daily (evening preferred for RA). Alternatively 500 mg twice daily. Max 1,000 mg/day. Swallow whole — do not crush, cut, or chew. Take with food or milk.

5. Contraindications

• Active peptic ulcer or NSAID-related GI bleeding history
• Hypersensitivity to naproxen, aspirin, or any NSAID
• NSAID-sensitive asthma; Severe renal/hepatic impairment; Severe heart failure
• Third trimester of pregnancy

6. Warnings and Precautions

Critical: Do not crush or split — destroys SR mechanism causing dose-dumping. GI, CV, and renal risks of NSAIDs apply as with all naproxen. In diabetic patients: monitor eGFR and BP; consider topical Anaflex Gel for localised joint pain as safer alternative.

7. Side Effects

Lower GI symptom incidence vs. IR naproxen. Common: nausea, dyspepsia, headache, oedema. Uncommon: peptic ulcer, elevated BP, renal impairment, rash. Rare: GI perforation, anaphylaxis, severe skin reactions.

8. Drug Interactions

• Warfarin — increased bleeding risk (monitor INR)
• ACE inhibitors/ARBs/diuretics — reduced efficacy; AKI risk
• Sulphonylureas — enhanced hypoglycaemia (monitor glucose)
• Methotrexate — increased toxicity
• Corticosteroids — markedly increased GI ulceration risk

9. Pharmacokinetics

Tmax ~4–6 hours (vs 1–2h IR). Cmax ~70% of IR. Equivalent total bioavailability. t½ 12–17 hours. Hepatic CYP2C9 metabolism. Renal elimination ~95%.

10. SR vs. IR Naproxen

SR provides: (1) Lower GI peak exposure — reduced dyspepsia vs. IR. (2) Evening/nocturnal dosing flexibility — therapeutic levels overnight control early-morning RA stiffness without midnight dose. (3) Once-daily option — improved adherence for chronic arthritis patients.

11. Use in Diabetic Arthritis Patients

SR formulation offers modest GI tolerability advantage but does not reduce renal, CV, or fluid-retention risks. In diabetic CKD patients, topical Anaflex Gel remains preferred for localised pain. Where systemic NSAID is unavoidable, SR at lowest effective dose with PPI cover and close monitoring of BP and eGFR is recommended.

12. ACI Limited Anaflex Range

Anaflex SR sits alongside Anaflex 250/500 mg IR, Anaflex Max 375/500 mg (with esomeprazole gastroprotection), and Anaflex Gel 15/30 g (topical). Clinicians select based on chronicity, GI risk, renal function, and need for nocturnal coverage.

13. Storage

• Store below 30°C, cool and dry, protected from light
• Do not crush or split tablets. Keep in original blister pack.
• Keep out of reach of children. Do not use after expiry date.

Frequently Asked Questions (FAQ)

Q1: What does SR mean in Anaflex SR?

SR = Sustained-Release. The matrix tablet slowly releases naproxen over hours — lower GI peak exposure, consistent drug levels, and once-daily evening dosing option to control overnight and early-morning arthritis symptoms.

Q2: Can I crush or split Anaflex SR tablets?

Never — crushing destroys the SR matrix, releasing the full 500 mg immediately (dose-dumping), greatly increasing GI side effect risk. Always swallow whole with a full glass of water.

Q3: When is Anaflex SR preferred over regular Anaflex?

SR is preferred for: GI intolerance with IR naproxen; once-daily simplified dosing; early-morning stiffness needing overnight coverage. For acute pain requiring rapid onset, immediate-release Anaflex 500 mg acts faster.

Q4: Is Anaflex SR safe for long-term arthritis use?

Yes, under physician supervision at the lowest effective dose. Monitor renal function, BP, haemoglobin, and liver function periodically. Add PPI cover or switch to Anaflex Max for high-GI-risk patients.