Spray-dried Curcumin–Piperine Dry Powder Inhaler Incorporating Suvarnasindoor: Characterization and Acute Pulmonary Tolerability

The objective of this research was to formulate a respirable dry powder inhaler formulation of Suvarnasindoor, a classical herbomineral formulation, co-formulated with curcumin and piperine. The formulation was optimized using a spray-drying method (F10) and a ball milling method (F6), wherein mannitol and lactose were used as excipients. The formulation was characterized using scanning electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma-atomic emission spectrometry to ascertain that it had a spherical morphology (2–5 µm), was in a stable crystalline phase of α-HgS without any organic mercury complexes. The aerodynamic performance of the formulation was tested using an Andersen Cascade Impactor to evaluate its FPF (31.85% for Suvarnasindoor, 38.56% for Curcumin, 38.86% for Piperine) and mass median aerodynamic diameter (3.971 µm for Suvarnasindoor; 5.593 µm for Curcumin and 5.556 µm for Piperine), which may be suitable for dry powder inhaler delivery to the lungs. The chemical integrity of all phytoconstituents of the formulation was also tested using liquid chromatography–mass spectrometry and differential scanning calorimetry. Acute intratracheal toxicity studies in rats were conducted to further evaluate its safety profile. The results showed no mortality or signs of toxicity in rats at a dose equivalent to humans, thus demonstrating acceptable tolerability under acute exposure conditions. Physicochemical stability was evaluated per ICH Q1A (R2) guidelines over 6 months under real-time and accelerated conditions. These findings collectively suggest that the spray-dried Suvarnasindoor DPI may serve as a feasible formulation approach for pulmonary delivery, warranting further investigation in inflammatory respiratory conditions.