Dual-Release Gastroretentive System of Tizanidine Hydrochloride: Formulation and Evaluation of Floating Bilayer Tablets

Background

To formulate and assess floating bilayer tablets of Tizanidine Hydrochloride (TZN) intended to extend gastric retention and for sustained release of the drug.

Materials and Methods

Six bilayered floating tablets(F7-F12) were prepared using one of the best immediate release formulations out of the six immediate release formulations (F1-F6) prepared and the other is sustained release layer. The Immediate-Release (IR) layer contained super-disintegrants Lycoat and Ludiflash, while the Sustained-Release (SR) layer included Sodium Alginate and Carbopol 934P. Formulation additives comprised Magnesium stearate, Sodium bicarbonate, Citric acid, Talc, PVP K30, Microcrystalline Cellulose (MCC), Lactose, and Isopropyl alcohol. The compressed bilayered tablets were evaluated for post compression parameters like drug release studies, lag time, floating time etc.

Results and Discussion

Formulations F3 (IR) and F12 (SR) were identified as optimal. The F12 tablets exhibited excellent buoyancy, with a lag time of 123 sec and remained floating beyond 12 hr; they delivered approximately 99.12% of the drug over this period. The release of drug from the SR layer was zero-order kinetics and Super Case II transport, reflecting a stable, controlled release pattern. FTIR spectra showed no interactions between TZN and formulation components.

Conclusion

The developed tizanidine hydrochloride floating bilayer tablets especially F12 successfully combined prolonged gastric residence with sustained drug release, highlighting a promising gastro-retentive delivery system to improve TZN’s therapeutic efficiency and bioavailability.