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. 2022 Dec 8;10:rbac099. doi: 10.1093/rb/rbac099

Table 4.

Applications, manufacturing method and properties of MPs based on synthetic polymers used in pulmonary drug delivery

Polymer API Manufacturing method MPs properties Aerodynamic properties References
PLGA Rifampicin
(tuberculosis)		 Emulsification

  • Methanol in the O-phase—decreased roundness,

  • Size: 4.47 ± 2.51 µm

  • EE: 99.62 ± 0.12%

  • LE: 19.92 ± 0.02%

 FPF: 40.99 ± 4.58% (DCM: methanol = 70:30) Nii et al. (2018) [85]
PLGA Cinaciguat (pulmonary hypertension) Single emulsification

  • Size: 12.39–18.85 µm

  • Morphology: porous

  • EE: 68–86%

  • MMAD: 4.82–6.17 µm

  • FPF: 19.8–36.0%

 Ni et al. (2017) [84]
PLGA BAY 41-2272 (pulmonary arterial hypertension) Premix membrane emulsification/single emulsification

  • Porosity up to 43.2%, smaller diameters thanks to premix membrane: (5.5–6.6) µm,

  • EE: 70–89%

  • MMAD: 2.6–4.4 µm

  • FPF: 25–30%

 Zhang et al. (2020) [83]
PLGA Budesonide/coumarin (tuberculosis) Premix membrane emulsification/single emulsification

  • Lipid surface-modified,

  • Size: 2.6–3.5 µm,

  • EE: 81–89%

 MMAD: 2.8–3.8 µm Li et al. (2019) [86]
PLGA Budesonide (asthma) Premix membrane emulsification/single emulsification

  • PEG surface-modified,

  • Size: 3.46 ± 0.05 µm

  • EE: 89.11 ± 3.87%

  • (chosen formulation)

 D ae: 3.82 ± 0.06 µm (chosen formulation) Li et al. (2021) [87]
PLGA Rifampicin (tuberculosis) Spray-drying

  • Leucine-modified for non-spherical shape,

  • Size: 10.65 ± 5.95 µm

  • EE: 88.89 ± 1.40%

  • LE: 15.46 ± 0.01%

 FPF: 43.4 ± 5.7% Takeuchi et al. (2018) [88]
PLGA IDR-1018 (tuberculosis) Double-emulsification

  • N-acetyl cysteine surface-modified for better mucus penetration,

  • Size: 6.24 ± 1.04 µm

  • EE: 59.34 ± 3.79%

  • LE: 12.93 ± 1.44%

  • MMAD: 3.79 ± 1.04 µm

  • FPF: 52.87 ± 5.11 %

 Sharma et al. (2020) [89]
PLGA Moxifloxacin (tuberculosis) Vortex-induced single emulsification

  • Size: 3.16 ± 0.38 µm

  • Morphology: round (chosen formulation)

  • MMAD: 2.85 ± 1.04 µm

  • FPF: 72.77 ± 1.73%

  • GSD: 3.10 ± 1.23

 Vishwa et al. (2021) [94]
PLGA Gatifloxacin (tuberculosis) Single emulsification Size: 4.5 ± 0.8 µm for the formulation with the highest EE and LE (89.6 ± 1.2% and 8.0 ± 0.5%, respectively) FPF: 15.9% of the formulation with the highest EE Marcianes et al. (2020) [95]
PLGA Levofloxacin (cystic fibrosis) Double emulsification + premix membrane homogenization

  • Size: 5.0 ± 1.7 µm

  • Morphology: internal slightly porous, agglomeration

  • EE: 23.1%

  • LE: 10.5 ± 1.4%

  • MMAD: 7.1 ± 0.2 µm

  • FPF: 30.2 ± 2.3%

 Gaspar et al. (2019) [98]
PEG-PLGA Tobramycin (lung bacterial infections) Double emulsification

  • Size (hydrodynamic diameter): 0.896 ± 0.172 µm

  • PdI: 0.18 ± 0.10

  • EE: 3.05 ± 0.40%

  • LE: 0.15 ± 0.2%

 – Ernst et al. (2018) [99]
PCL Azithromycin (pneumonia) Double emulsification

  • Morphology: hollow MPs

  • Size (median diameter): 5.76 ± 0.26 µm

  • EE: 61.51 ± 0.83%,

  • LE: 23.07 ± 0.31%

  • (for formulation with the highest EE and LE values)

 D ae: 3.63 ± 0.22 µm Kasten et al. (2016) [97]
PLGA Bacteriophages (bacterial lung infections) Double emulsification

  • Size: 8.0 ± 4.5 µm, 2.6 × 106 p.f.u. (plaque forming units)/mg MPs, endotoxin units (EU): 0.078 ± 0.003 EU/mg

  • Morphology: highly porous

 D ae: 2–5 µm Agarwal et al. (2018) [100]
PLGA Curcumin (idiopathic pulmonary fibrosis) Double emulsification

  • Size: 11.58 µm,

  • Morphology: porous

  • Span: 4.197

  • EE: 95.8%

  • LE: 16.9%

  • MMAD: 3.12 µm

  • FPF: 13.41%

 Hu et al. (2018) [101]
PSA Curcumin (COPD) Single emulsification

  • Size: 1.43 µm

  • Morphology: non-porous,

  • EE: 42.8 ± 0.7%

  • LE: 11.0 ± 0.2%

 – Kwiecień et al. (2021) [102]
PEG-PMA Alkaloids from Alstonia scholaris (anti-inflammatory, cough relief) Double emulsification

  • Size: 1.6–3.3 µm

  • EE: 64.3–72.9%

  • LE: 3.0–4.4%

  • – All increasing with longer PEG-chains

 – Jiang et al. (2021) [103]
PCADK/PLGA Doxorubicin (DOX) (lung cancer) Double emulsification

  • Size: 15.57 ± 8.86 µm

  • Morphology: Porous and round (less PCAKD) or irregular (more PCAKD)

  • EE: 77.22 ± 4.32%,

  • LE: 2.49 ± 0.14%

  • (chosen formulation)

 D ae: 2.48 ± 0.18 µm
(chosen formulation)		 Li et al. (2020) [104]
PLGA Doxorubicin (DOX) (lung cancer) Double emulsification

  • Size: 5.21 ± 0.95 µm

  • Morphology: internally porous

  • EE: 60.95 ± 0.88%

  • LE: 5.54 ± 0.08%

 MMAD: 2.58 ± 0.47 µm Feng et al. (2015) [105]
PLGA Doxorubicin (DOX), paclitaxel (PXT) (lung cancer) Double emulsification

  • Size: 11.47 ± 2.71 µm

  • Morphology: porous

  • EE: 62.42 ± 0.88% (DOX)

  • and 80.97 ± 0.99% (PXT)

  • Total LE: 6.02 ± 0.08%

  • (chosen formulation)

 MMAD: 3.51 ± 0.83 µm Feng et al. (2014) [106]
PLGA Doxorubicin (DOX), miR-519c (lung cancer) Double emulsification

  • Size: 47.4 ± 19.2 µm

  • Morphology: porous

  • Zeta potential:

  • –3.0 ± 1.6 mV

  • EE: 79.63 ± 3.21% (DOX) and 29.04 ± 1.33% (miR)

  • LE: 0.796 ± 0.032% (DOX) and 0.023 ± 0.001% (miR)

 D ae: 8.97 ± 1.49 µm Wu et al. (2016) [107]
PLGA Doxorubicin (DOX), TRAIL (metastatic lung cancer) Double emulsification

  • Size: 11.5 ± 0.4 µm

  • Morphology: porous

  • EE: 86.5 ± 6.5% (DOX) and 91.8 ± 2.4% (TRAIL)

 – Kim et al. (2013) [91]
PLGA Doxorubicin (DOX), p53
(lung cancer)		 Double emulsification

  • Size: 22.9 ± 11.8 µm

  • Morphology: porous

  • Zeta potential: 5.9 ± 5.8 mV

  • EE: 88.2 ± 1.7% (DOX) and 36.5 ± 7.5% (p53),

  • LE: 0.71 ± 0.03% (DOX) and 0.036 ± 0.008% (p53)

 – Shi et al. (2014) [90]
PLGA Artesunate (non-small cell lung cancer) Double emulsification

  • Size: 26.39 ± 2.12 µm,

  • Morphology: porous

  • EE: 30.27 ± 0.62%

  • LE: 86.85 ± 2.55%

 D ae: 5.28 ± 0.42 µm Xiong et al. (2021) [92]
PLGA Metformin (Met), docosahexaenoic acid (DHA) (anti-tumor lung metastasis) Double emulsification

  • Size: 20.38 ± 1.02 µm

  • Morphology: porous

  • EE: 53.68 ± 1.93% (Met) and 89.20 ± 2.07% (DHA)

  • LE: 1.79 ± 0.04% (Met) and 2.97 ± 0.07% (DHA)

 D ae: 3.59 ± 0.09 µm Chen et al. (2021) [108]
PLGA Oridonin (non-small cell lung cancer) Double emulsification

  • Size (D50): 11.6 ± 2.3 µm

  • Morphology: smooth spheres with small pores

  • EE: 81.5 ± 1.0%,

  • LE: 9.3 ± 0.1%

 D ae: 2.7 ± 0.3 µm Zhu et al. (2017) [109]
PLGA Disulfiram (lung cancer) Single emulsification

  • Size: 47.83 ± 13.21 µm

  • Morphology: porous

  • Zeta potential: –14.9 ± 4.7 mV

  • EE: 81.84 ± 2.35%,

  • LE: 4.09 ± 0.11%

 D ae: 8.31 ± 1.33 µm Wang et al. (2017) [110]
Poly(ester-thioether) Erlotinib, α-tocopheryl succinate (non-small cell lung cancer) Single emulsification

  • Size: 12.9 µm—non-porous; 13.6 µm—porous,

  • LE (non-porous): 7.1% (erlotinib), 6.2% (α-tocopheryl)

  • LE (porous): 6.3% (erlotinib), 5.0% (α-tocopheryl)

 – Cheng et al. (2020) [111]
PLGA Sildenafil (pulmonary hypertension) Spray-drying

  • Size: 3.7–7.9 µm

  • Morphology: non-porous, spherical

  • LE: 5.1–37.3%

  • (depending on formulation)

 – Beck-Broichsitter et al. (2017) [112], (2016) [113]
PLGA Sildenafil citrate (pulmonary hypertension) Double emulsification/spray freeze-drying

  • Size: 8.27 ± 1.70 µm

  • EE: 94.20 ± 0.06% (chosen formulation)

  • MMAD: 4.52 ± 0.37 µm

  • FPF: 25.33 ± 3.32% (chosen formulation)

 Shahin et al. (2021) [114]

MPs, microparticles; EE, encapsulation efficiency; LE, loading efficiency; MMAD, mass median aerodynamic diameter; Dae, aerodynamic diameter; GSD, geometric standard deviation; FPF, fine particle fraction.