Table 2.
Characteristics of the investigated solid lipid microparticle (SLM) dispersions prepared “de novo” (FL—liquid formulations) and reconstituted (FS—spray-dried formulations). API: active pharmaceutical ingredient, d 0.5 and d 0.9: the particle size at which the cumulative particle size distribution curve reaches 50% and 90% of the volume, respectively.
| Formulation | Particle Size (µm) | pH | API Distribution (%) | API Release (%) 2 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| d 0.5 | d 0.9 | Aqueous Phase | Interphase | Lipid Matrix | 0.5 h 2 | 24 h 2 | ||||||||
| FL | FS | FL | FL | FL | FL | FS | FL | FS | FL | FS | FL | FS | FL | FS |
| F1L | F1S | 1.6 ± 0.01 | 5.7 ± 0.22 | 5.44 ± 0.14 | - | - | - | - | - | - | - | - | - | - |
| F2L | F2S | 1.6 ± 0.01 | 6.1 ± 0.40 | 5.71 ± 0.08 | 0.1 ± 0.04 | 0.1 ± 0.15 | 52.1 ± 7.8 | 69.3 ± 8.2 | 47.8 ± 7.9 | 30.6 ± 8.3 | 21 ± 0.8 | 65 ± 4.9 | 62 ± 0.6 | 80 ± 3.7 |
| F3L | F3S | 1.8 ± 0.09 | 6.4 ± 0.58 | 5.82 ± 0.15 | 0.1 ± 0.01 | 0.4 ± 0.14 | 70.9 ± 10.4 | 72.6 ± 6.7 | 29.0 ± 10.4 | 27.0 ± 6.8 | 50 ± 3.1 | 66 ± 3.6 | 67 ± 1.8 | 81 ± 2.4 |
| F4L | F4S | 2.3 ± 0.66 | 6.0 ± 0.74 | 5.29 ± 0.20 | 2.5 ± 3.43 | 4.2 ± 2.77 | 76.6 ± 1.8 | 67.5 ± 4.3 | 20.9 ± 3.1 | 28.3 ± 4.3 | 13 ± 6.2 | 81 ± 5.3 | 100 ± 2.6 | 89 ± 5.7 |
| F5L | F5S | 4.4 ± 1.67 | 10.5 ± 4.88 | 5.48 ± 0.09 | 0.3 ± 0.44 1 | 0.4 ± 0.56 1 | 24.9 ± 12.6 1 | 50.1 ± 5.0 1 | 74.8 ± 11.9 1 | 49.5 ± 5.4 1 | 25 1 – | 54 1 – | 89 1 – | 82 1 – |
| F6L | F6S | 2.2 ± 0.36 | 5.7 ± 0.30 | 5.30 ± 0.10 | - | - | - | - | - | - | - | - | - | - |
| F7L | F7S | 2.3 ± 0.05 | 5.8 ± 0.20 | 5.63 ± 0.11 | 1.3 ± 1.79 | 2.0 ± 2.79 | 76.3 ± 8.6 | 73.8 ± 6.2 | 22.4 ± 9.3 | 24.2 ± 5.3 | 53 ± 2.9 | 59 ± 1.5 | 63 ± 4.2 | 63 ± 5.7 |
| F8L | F8S | 6.4 ± 0.17 | 14.6 ± 0.51 | 5.93 ± 0.23 | 0.6 ± 0.77 | 0.1 ± 0.08 | 73.7 ± 3.3 | 73.5 ± 4.5 | 25.7 ± 3.5 | 26.4 ± 4.5 | 73 ± 2.8 | 88 ± 3.0 | 94 ± 1.9 | 90 ± 4.3 |
| F9L | F9S | 2.1 ± 0.54 | 7.2 ± 1.85 | 5.21 ± 0.11 | 3.6 ± 1.05 | 4.1 ± 1.42 | 39.6 ± 1.1 | 46.8 ± 2.1 | 56.8 ± 0.9 | 49.1 ± 2.2 | 53 ± 6.8 | 50 ± 3.9 | 50 ± 12.4 | 94 ± 0.2 |
| F10L | F10S | 6.4 ± 1.01 | 14.6 ± 1.43 | 5.24 ± 0.07 | 0.6 ± 0.03 1 | 0.5 ± 0.06 1 | 43.7 ± 33.7 1 | 70.4 ± 3.2 1 | 55.7 ± 32.8 1 | 29.1 ± 3.1 1 | 8 1 – | 73 1 – | 21 1 – | 73 1 – |
1 Incomplete incorporation of spironolactone (SPIR) during preparation (active substance crystals in dispersions were observed). Data are presented as mean ± SD (n = 3 and 2 n = 2).