Research Article Unstructured Formulation Data Analysis for the Optimization of Lipid Nanoparticle Drug Delivery Vehicles Jessica Silva, 1,2 Maria Mendes, 1,2 Tânia Cova, 3 João Sousa, 1,4 Alberto Pais, 3 and Carla Vitorino 1,2,4,5 Received 22 February 2018; accepted 17 May 2018 Abstract. Designing nanoparticle formulations with features tailored to their therapeutic targets in demanding timelines assumes increased importance. In this context, nanostructured lipid carriers (NLCs) offer an excellent example of a drug delivery nanosystem that has been broadly explored in the treatment of glioblastoma multiforme (GBM). Distinct fundamental NLC quality attributes can be harnessed to fit this purpose, namely particle size, size distribution, and zeta potential. These critical aspects intrinsically depend on the formulation components, influencing drug loading capacity, drug release, and stability of the NLCs. Wide variations in their composition, including the type of lipids and other surface modifier excipients, lead to differences on these parameters. NLC target product profile involves small mean particle sizes, narrow size distributions, and absolute values of zeta potential higher than 30 mV. In this work, a wealth of data previously obtained in experiments on NLC preparation, encompassing, e.g., results of preliminary studies and those of intermediate formulations, is analyzed in order to extract information useful in further optimization studies. Principal component analysis (PCA) and partial least squares (PLS) are performed to evaluate the influence of NLC composition on the respective characteristics. These methods provide a rapid and discriminatory analysis for establishing a preformulation framework, by selecting the most suitable types of lipids, surfactants, surface modifiers, and drugs, within the set of investigated variables. The results have direct implications in the optimization of formulation and processes. KEY WORDS: glioblastoma multiforme (GBM); nanostructured lipid carriers (NLCs); critical quality attributes (CQAs); multivariate analysis. INTRODUCTION Lipid nanoparticles (LNs) have sparked great attention, since they gather interesting advantages over the conven- tional colloidal systems. These include (i) high physicochem- ical stability, avoiding problems associated with sterilization procedures; (ii) easy scale-up production; (iii) use of low-cost raw materials; and (iv) absence or reduction of acute or chronic toxicity, because they are composed by excipients with accepted status by the regulatory authorities (e.g., GRAS status – generally regarded as safe) (1,2). LNs have a solid matrix at both room and body temperatures, allowing a controlled release and chemical protection of the drug. Therefore, the therapeutic efficiency is improved, as a result of the modulation in release, combined with a better tolerability and targeting of the encapsulated drug. Among the different types of LNs, nanostructured lipid carriers (NLCs) composed of blends of lipids in solid and liquid states, lead to a less organized matrix with more imperfec- tions (1,3–5). This enables a higher loading capacity in comparison to the other types of LNs and avoids the occurrence of polymorphic transitions, resulting in an in- creased stability during the storage period (6,7). In order to overcome chemoresistance and to improve the capacity to cross the blood-brain barrier (BBB), LNs have been reported as promising brain tumor-targeted delivery systems, including the NLCs (3,8–11). The NLC formulations addressed in the present work have a common purpose, i.e., being used in the treatment of Electronic supplementary material The online version of this article (https://doi.org/10.1208/s12249-018-1078-0) contains supplementary material, which is available to authorized users. 1 Faculty of Pharmacy, University of Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548, Coimbra, Portugal. 2 Centre for Neurosciences and Cell Biology (CNC), Faculty of Medicine, University of Coimbra, Rua Larga, Pólo I, 1st floor, 3004- 504, Coimbra, Portugal. 3 Coimbra Chemistry Center, Department of Chemistry, University of Coimbra, Rua Larga, 3004-535, Coimbra, Portugal. 4 LAQV. REQUIMTE, Group of Pharmaceutical Technology, R. D. Manuel II, Apartado 55142, 4051-401, Porto, Portugal. 5 To whom correspondence should be addressed. (e–mail: csvitorino@ff.uc.pt) AAPS PharmSciTech ( # 2018) DOI: 10.1208/s12249-018-1078-0 1530-9932/18/0000-0001/0 # 2018 American Association of Pharmaceutical Scientists