Formulation and evaluation of a novel oral osmotic pump tablet for citalopram hydrobromide

Depression affects over 280 million people globally, with significant prevalence among women and elderly populations. Citalopram hydrobromide, a widely prescribed SSRI antidepressant, often causes side effects like tachycardia and drowsiness due to fluctuations in plasma concentration from traditional dosage forms. This study developed an Elementary Osmotic Pump (EOP) tablet to achieve controlled citalopram release, reducing these adverse effects. The formulation used potassium chloride (25-100 mg) as an osmogent and a semi-permeable membrane of cellulose acetate (3% w/v) plasticized with PEG-400. Core tablets (120 mg) were prepared via non-aqueous granulation with PVP-K30 as the binder and coated with 2.5% or 5% polymer solutions. The optimized formulation (50 mg KCl, 5% coating) showed zero-order kinetics (R²>0.98) with 90-97% release over 12 hours in pH 7.4 buffer (Table 5), outperforming higher osmogent concentrations that caused burst release (Table 4). Tablets met pharmacopeial standards for hardness (3.5-5.5 kg/cm²), friability (<0.73%), and content uniformity (92-101%). FTIR confirmed drug-excipient compatibility, while SEM verified precise orifice drilling (0.8-1.0 mm) necessary for controlled release. Dissolution studies in 0.1N HCl and pH 7.4 buffer confirmed pH-independent release, important for consistent GI absorption. The 5% coating provided more stable release than 2.5%, with PEG-400 improving membrane flexibility. Kinetic analysis showed formulations with ≤50 mg KCl best fit zero-order models, while higher concentrations followed first-order or Higuchi kinetics due to rapid osmotic diffusion. This EOP system effectively addresses the limitations of immediate-release citalopram by maintaining therapeutic levels and reducing dosing frequency. Future studies should evaluate in vivo pharmacokinetics and long-term stability to confirm clinical potential for depression treatment.