International Journal of Biological Macromolecules 59 (2013) 72–83 Contents lists available at SciVerse ScienceDirect International Journal of Biological Macromolecules jo ur nal home p age: www. elsevier.com/locate/ijbiomac Optimization of brain targeted chitosan nanoparticles of Rivastigmine for improved efficacy and safety Kalpana Nagpal ∗ , S.K. Singh, D.N. Mishra Department of Pharmaceutical Sciences, Guru Jambeshwar University of Science & Technology, Hisar, Haryana 125001, India a r t i c l e i n f o Article history: Received 27 February 2013 Received in revised form 17 March 2013 Accepted 9 April 2013 Available online 15 April 2013 Keywords: Chitosan Elevated plus maze Maximum tolerated dose Morris water maze Optimization Rivastigmine tartrate a b s t r a c t The study aims at formulation and optimization brain targeted nanoparticles (NP) of Rivastigmine (RT) to improve its therapeutic potential and to verify its safety profile. The NP were optimized using a two factor three level (3 2 ) central composite design aiming to minimize particle size; maximize zeta potential and drug entrapment efficiency of NP. The optimized formulation (cRTNP) was evaluated using in vitro drug release study; in vivo behavioral, and biochemical and maximum tolerated dose (MTD) study. The optimized formulation evidenced a significant reversal of scopolamine-induced amnesia by Tween 80 ® coated nanoparticles as compared to both pure RT as well as uncoated nanoparticles. The MTD of RT was increased by 10% by formulating them as cRTNP. Thus, formulation of RT as cRTNP improved the therapeutic and safety profile of RT. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Drug delivery to brain is a challenge for formulation scien- tists. Two physiological barriers, i.e., blood–brain barrier (BBB) and blood–cerebrospinal fluid barrier, restrict the transport of bioactive compounds to brain [1] and render them therapeutically ineffec- tive. The efficacy of a central nervous system (CNS) acting drug depends on the ability of the drug to cross such physiological bar- riers so as to show its therapeutic effect [2]. Many CNS drugs are administered at high doses for their therapeutic efficacy, causing peripheral side effects [3]. Approximately 98% of small molecules and nearly all large molecules with molecular weight > 1000 Da do not cross BBB in pharmacologically active concentration [1]. Rivastigmine (RT), a reversible cholinesterase inhibitor, is used in management of Alzheimer’s disease. Absolute bioavailability of RT after a 3-mg dose is approximately 36% [4]. It has limited entry to brain owing to its hydrophilic nature. This restricted entry into brain necessitates frequent dosing and cholinergic side effects such as severe bradycardia, nausea, dyspepsia, vomiting and anorexia [6,7]. The targeted delivery of RT to brain may improve its thera- peutic efficacy. Nanoparticulate drug delivery is a promising strategy to improve the entry of drugs across physiological barriers such as BBB. The nanoparticles have the ability to interact cellular ∗ Corresponding author. Tel.: +91 9416729190; fax: +91 1662276240. E-mail address: kalpananagpal@gmail.com (K. Nagpal). functions in new way owing to their tiny size, tailored surface, better solubility, multi-functionality, ability to persist in the circulatory system and accumulate at the target site [1,2]. Chitosan is a promising polymer for preparation of biodegrad- able and biocompatible nanoparticles [8]. Some workers have formulated RT loaded chitosan nanoparticles. Wilson et al. for- mulated chitosan NP containing RT by spontaneous emulsification method [5] using toluene and glutaraldehyde. According to the Occupational and Health Safety Administration (OSHA), exposure to toluene may adversely affect the health specially, CNS. The exposure to glutaraldehyde has been reported to cause respiratory irritation, corneal opacity, corneal injury, conjunctivitis, irritation and necrosis in eye irritation test. Necropsy findings depicted adverse effects of glutaraldehyde on stomach, intestine, lungs, liver, spleen, kidney and adrenal glands when tested on mice and rats [9]. In human, glutaraldehyde may irritate skin, eye, and respi- ratory tract. Glutaraldehyde is reported as mutagenic in several short-term genotoxicity assays [9]. Fazil et al. formulated RT encapsulated chitosan NP for intranasal delivery [6]. Using intranasal brain drug delivery, the concentration achievable in different regions of the brain and spinal cord, may vary with each agent. Moreover, some therapeutic agents may be susceptible to partial degradation in the nasal mucosa or may cause irritation to the mucosa. Nasal congestion may hamper this method of delivery and its frequent use results in mucosal damage. Keeping in view of the above factors, the present investigation was designed to develop biodegradable and biocompatible chitosan NP avoiding use of hazardous organic solvents. The selected route 0141-8130/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ijbiomac.2013.04.024