Formulation development of hard capsules containing orthosiphon stamineus anddesmodium styracifolium extracts

Tóm tắt

Objective: To develop a hard gelatin capsule formulation containing dry extracts of Orthosiphon stamineus and Desmodium styracifolium and to evaluate selected preformulation characteristics, manufacturing conditions, and quality attributes of the finished capsules according to the Vietnamese Pharmacopoeia V. 
Methods: Preformulation studies of the dry extracts were conducted, including evaluation of moisture content, hygroscopicity, flowability, and drug–excipient compatibility. Hard capsules were prepared using the wet granulation method, with investigations into appropriate binders, diluents, and lubricants. The quality attributes of intermediate products and finished capsules were evaluated according to the Vietnamese Pharmacopoeia V.
Results: The dry extract of Orthosiphon stamineus had a moisture content below 5%, showed hygroscopic characteristics, and exhibited very poor flowability (Carr’s index approximately 35%). Wet granulation using 5% PVP in 96% ethanol as a binder, dicalcium phosphate as a diluent, and 1% talc as a lubricant significantly improved the flowability of granules (Carr’s index approximately 15–18). Size 0 hard capsules had an average weight of approximately 500 mg and met the requirements for appearance, uniformity of mass, disintegration, and contents of rosmarinic acid and sinensetin.
Conclusion: The developed formulation and wet granulation process improved the physicochemical properties and flowability of the herbal extracts and produced hard gelatin capsules meeting selected pharmacopoeial quality requirements at laboratory scale. The findings provide preliminary evidence supporting further studies on dissolution, stability, and scale-up feasibility.