Formulation and Evaluation of Gastro-Retentive Effervescent Floating Tablets of Ranitidine Hydrochloride Using HPMC K100M as a Rate-Controlling Polymer

Abstract

Background: Ranitidine hydrochloride (HCl), a Histamine H₂-receptor antagonist, exhibits pharmacokinetic limitations including a short biological half-life (2–3 h), narrow absorption window confined to the upper gastrointestinal tract, and low oral bioavailability (~50%), necessitating twice- daily conventional dosing. A gastro-retentive floating drug delivery system (GFDDS) offers a rational approach to prolong gastric residence, sustain drug release, and improve bioavailability.

Objective: To develop and evaluate effervescent floating matrix tablets of Ranitidine HCl using HPMC K100M as a hydrophilic rate-controlling polymer and sodium bicarbonate as a gas-generating agent, with the goal of achieving once-daily therapeutic delivery.

Methods: Six formulation batches (F1–F6) were prepared by direct compression with systematically varied HPMC K100M (30–50% w/w) and NaHCO₃ (10–17.5% w/w) concentrations at a fixed Ranitidine HCl dose of 150 mg. Tabletswere evaluated for preformulation characterisation (FTIR, DSC, UV spectrophotometry), pre-compression flow properties, post-compression pharmacopoeial parameters, in vitro buoyancy, in vitro drug release (USP Type II, 0.1N HCl, 24 h), drug release kinetic modelling, and accelerated stability (40°C/75% RH, 3 months, ICH Q1A(R2)).

Results: FTIR and DSC confirmed absence of drug–excipient interactions. Batch F3 (HPMC K100M 40%, NaHCO₃15%) was identified as the optimised formulation with floating lag time (FLT) of 1.9 ±

0.2 min, total floating time (TFT) of 19.4 ± 0.7 h, drug release of 19.8% at 1 h and 96.8% at 24 h, and anomalous (non-Fickian) drug transport (Korsmeyer–Peppas n = 0.543, R² = 0.9968). Stability testing confirmed drug content ≥ 97.9% with unchanged release profiles (f₂ > 50) over 3 months.

Conclusion: A once-daily effervescent floating tablet of Ranitidine HCl was successfully developed using directly compressible excipients. Batch F3 fulfilled all buoyancy, release, and stability criteria, demonstrating the feasibility of GFDDS for bioavailability enhancement of narrow-absorption-window drugs.

Keywords: Gastro-retentive drug delivery; floating tablets; Ranitidine hydrochloride; HPMC K100M; sodium bicarbonate; effervescent; controlled release; floating lag time.