Available online on www.ijddt.com International Journal of Drug Delivery Technology 2018; 8(1); 19-32 doi: 10.25258/ijddt.v8i01.11903 ISSN: 0975 4415 Research Article *Author for Correspondence: garnpimol.r@chula.a.cth Optimization of Redispersible Spray Dried Powder of Chitosan Coated Solid Lipid-Based Nanosystems Munawiroh S Z 1, 2 , Lipipun V 2 , Ritthidej G C 2* 1 Faculty of Mathematics and Sciences, Universitas Islam Indonesia, Yogyakarta, Indonesia 2 Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand Received: 6 th Oct, 17; Revised: 27 th Jan, 18, Accepted: 4 th Mar, 18; Available Online: 25 th Mar, 2018 ABSTRACT The present work describes the optimization of spray dried powder of solid lipid-based nanosystems to improve drug stability, surface modification and to obtain nanosystems after redispersion. Chitosan coated solid lipid nanoparticles containing bromocriptine mesylate (cBMSLN) were prepared by high pressure homogenization technique following by chitosan addition. For spray drying, response surface methodology with central composite rotatable design was to optimize 3 parameters: inlet temperature, pump rate and feed concentration. From regression analysis, powder yield, moisture content and size of redispersed nanoaggregates as responses were fitted well with linear, quadratic and quadratic equation models, respectively. Spherical powders with size of 4-5 μm and 70% yield were obtained at optimum parameters which were also used to prepare powder of chitosan coated nanostructured lipid carriers containing BM (cBMNLC). Amorphous characteristics were confirmed from powder XRD patterns and DSC chromatograms in all prepared powders. Redispersion of powders yielded nanosystems of some original nanosize and a greater portion of larger size. Smoother surface of NLC systems was observed, so was with chitosan coating. Drug entrapment was >85% but significantly decreased in chitosan coated formulations while drug retention after spray drying showed opposite results. After storage, spray dried powder could retain higher drug content than the original nanosystems. Obviously, NLC systems had better drug stability results than SLN systems. It could be concluded that redispersible spray dried powders of chitosan coated lipid-based nanosystems especially NLC systems were successfully obtained with surface modification, nanoaggregate size range and improved drug stability. Keywords: Solid lipid nanoparticles, nanostructure lipid carriers, chitosan, spray drying, optimization, redispersion, bromocriptine mesylate. INTRODUCTION Recently, redispersion of dried nanosystems for oral administration has gained much attention 1 . Transformation of liquid nanosystems into powders was to overcome aging and long term stability problems including to improve handling. Moreover, the powders can be further manufactured as conventional solid dosage forms such as tablets and capsules for better patient compliance. These solid nanosystems can be achieved by several techniques with the addition of carriers such as maltodextrin and lactose 2 , trehalose 3 , charge surfactant 4 and porous carrier 5 . Redispersion efficiency can partially or totally recover the size of original nanostructure depending on drying conditions and original nanosystems 6 . Spray drying, the most widely used drying process with advantages of low cost and less time consuming is able to produce spherical powder with narrow distribution, uniformed drug content and amorphous state 6, 7 . However, due to limitations and high number of critical process parameters 8 , formulation and process control require particular attention that a prudential optimization design is practical to minimize total number of experiments. Meanwhile, lipid-based nanosystems are able to enhance oral absorption 9 . Their gastrointestinal absorption includes lymphatic transport bypassing hepatic metabolism 5 and consequent transport across blood brain barrier 10 . Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) are two kinds of lipid-based nanosystems that have potential advantages of low toxicity, high loading capacity of water insoluble drug, sterilization ability, best production scalability 11 . Improved drug loading and stabilized drug incorporation during storage are additional advantages of NLC 12 . Adversely, lipid-based nanosystems could be easily opsonized by plasma opsonins and uptaken by the mononuclear phagocyte system (MPS) 13 . Surface modification by hydrophilic compounds could prolong SLN blood circulation such as Pluronic F68 14 , poloxamer 188 15 , polyethylene glycol 16 and polysorbate 80 17 . Recently, chitosan, a biopolymer, not only improves blood circulation upon SLN surface modification 18 but can increase oral absorption by opening tight junction of intestinal epithelial and be specific to brain targeting 19-21 . Therefore, spray dried powder of chitosan coated solid lipid-based nanosystems has been attempted to develop in