Microspheres and tablet in capsule system: A novel chronotherapeutic system of ketorolac tromethamine for site and time specific delivery

The objective of the present work was to develop a novel delivery system of ketorolac tromethamine (KT) for dual pulse release based on microspheres and tablet in capsule system (MATICS) as a treatment modality for rheumatoid arthritis. The design consisted of an impermeable hard gelatin capsule body, in which a core tablet was (second pulse) placed in the bottom and sealed with a hydrogel plug (HP2). The body was locked with enteric coated cap filled with KT microspheres (first pulse). The microspheres for first pulse were selected by screening the formulations (M1–M6), and M1 with least particle size of 96.38 ± 0.05 μm, highest drug loading of 25.10% ± 0.28% and maximum CDR of 89.32% ± 0.21% was adjudged as the best formulation. The HP2 tablet was selected based on its capability for maintaining a lag period of 6 h. The selection criterion of the second pulse (core tablet: T3) was its disintegration time of 4.02 ± 0.53 min and CDR of 99.10% ± 0.32% in 30 min. All the optimized formulations were assembled in accordance with the proposed design to form pulsatile MATICS and evaluated for in vitro release. MATICS displayed delayed sustained CDR of 80.15% in 8 h from the first pulse (microspheres) after a lag time of 2 h, followed by 97.05% KT release from second pulse (core tablet) in simulated colonic fluid within 10 h. Conclusively, in vitro pulsatile release was a rational combination of delayed sustained and immediate release of KT that has the potential to combat the pain at night and morning stiffness. Incorporation of two pulses in one system offers a reduction in dose frequency and better pain management.