*2.3. Formulation Yield*

The formulation yield was calculated by relating the total formulation weight (actual yield) to the mass of the component excipients used in the preparation of the formulation (theoretical yield). The constituting excipient plus the model drug and produced RDS formulation were weighed as separate entities using a laboratory scale balance (Kern EG 620-3NM, Kern and Sohn, GmbH, Balingen, Germany). The percentage yield was calculated using Equation (1) below:

$$\% \text{Yield} = \frac{\text{Actual yield (g)}}{\text{Theoretical yield (g)}} \times 100\tag{1}$$

#### *2.4. Physicochemical Characterization of the Reconstitutable Dry Suspension*

#### 2.4.1. Particle Size, Polydispersity Index, and Zeta Potential

Measurement of particle size (PS) and polydispersity index (PDI) was based on the principle of dynamic light scattering using the Nano series Zetasizer (Malvern Instruments Ltd, Malvern, UK). For each quantification, RDS samples were re-dispersed in deionized water, appropriately diluted, and sonicated (Table-type Supersonic Cleaner KQ118, Nanjing T-Bota Scietech Instruments and Equipment, Co, Ltd., Nanjing, China) for 15 min at 37 ± 0.5 ◦C. All measurements were performed as three independent replicates with 10 readings per sample at a measurement angle of 173◦ and temperature of 25 ◦C. Zeta potential (ZP) is an indicator of particle surface charge, which determines particle stability in dispersions [23,24]. It was computed based on the Smoluchowski equation [25] using the Nano series Zetasizer with RDS samples dispersed in deionized water and placed in disposable folded capillary zeta cells maintained at 25 ◦C. For statistical relevance, samples were measured in triplicate with 20 runs per measurement cycle.

### 2.4.2. Visualization of Surface Morphology

The surface microstructure of the RDS was observed under a JEOL Transmission Electron Microscope (TEM) (JEM-2100 LaB6 200 kV Transmission Electron Microscope, JEOL, MA, USA). About 1 mg of the test sample was dispersed in ethanol and spotted on a carbon coated copper grid. Ethanol

was allowed to evaporate under atmospheric conditions prior to sample loading into the TEM viewing stage (JEOL JEM-2100 LaB6 200 kV Massachusetts, USA). The Gatan Digital Micrograph Software was used to facilitate sample viewing.
