SOLID LIPID NANOPARTICLES: A REVIEW ON DIFFERENT TECHNIQUES AND APPROACHES TO TREAT BREAST CANCER Review Article SHILPA A. GAJBHIYE * , MORESHWAR P. PATIL Department of Pharmaceutics, MET’s Institute of Pharmacy, Bhujbal Knowledge City, Adgaon, Nasik 422003, Maharashtra, India Email: gajbhiye.shilpa81@gmail.com Received: 30 Nov 2022, Revised and Accepted: 14 Jan 2023 ABSTRACT Breast cancer, the most common malignancy among women, is also the second-leading cause of cancer deaths all over the world. As commonly used chemotherapy drugs, which are given systematically, causes toxicity not only to cancerous cells but also to proliferating normal cells. Similarly, drug resistance leads to drastic side effects and treatment failure. Thus arises the need for improving the therapeutic index of anticancer drugs. Owing to these failures, nanotechnology holds significant promises. Using keywords like multi-drug resistance, effective targeting, therapeutics, intracellular pathways, efficacy, and breast cancer, references were looked up from specialised databases including Elsevier, Pubmed, and Cambridge from the year 1994 to 2023. This review was supplemented by a few references from Springer Nature and pertinent data from an online source. Along with online articles from Medscape, StatPearls, and The Lancet Respiratory Medicine, it was excellent. Supported literature was used to overcome these challenges; therapeutic drugs are encapsulated in nanoparticles. Concurrently, solid lipid nanoparticles (SLN), with their few merits, like enhancing the therapeutic profile, overcoming multidrug resistance, providing a targeted approach, and serving as a controlled release, have gained the attention of researchers. SLNs confine significant promises, overcome these challenges, and help to possibly deliver the drug to a specific part of the body, particular organ, or tissue by an actively or passively targeted delivery system, which will be beneficial in the diagnosis and treatment of breast cancer. The objective of this article is to highlight the factors that influence the targeted drug delivery system and resultant bioavailability and also provide updates on recent research and various approaches used for breast drug delivery systems. Keywords: Breast cancer, Efficacy, Multi-drug resistance, Effective Targeting, Therapeutics, Intracellular pathways © 2023 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (https://creativecommons.org/licenses/by/4.0/) DOI: https://dx.doi.org/10.22159/ijap.2023v15i2.46970. Journal homepage: https://innovareacademics.in/journals/index.php/ijap INTRODUCTION Drug delivery systems have started a new parade to enhance the therapeutic benefits of active compounds. Solid lipid nanoparticles (SLNs), in particular, have emerged as an advantageous nanocarrier system in the treatment of cancer [1]. With a few significant advantages such as increased bioavailability, low toxicity, the ability to incorporate both lipophilic and hydrophilic drugs, and the feasibility of large-scale production. Moreover, it has the ability to sidestep the problems that are faced during conventional cancer therapy [2]. Non-specificity and burst release, in general, cause toxicity, side effects, and the destruction of normal cells [3]. The composition and preparation process of SLN will determine its performance. The ability of SLN to go past several physiological obstacles that prevent drug delivery to tumour sites and also get beyond the primary drug resistance mechanism of cancer cells [4]. In 1999, Yang S. C. et al. prepared SLNs of camptothecin (CA), a specific drug targeting the brain. Among the investigated organs, the brain had the greatest CA-SLN to CA-Sol AUC ratio. These findings suggest that SLNs are a viable sustained release and drug targeting strategy for lipophilic antitumor medications that are possible, with a potential for dosage reduction and less systemic toxicity [5]. Drug delivery to the target site can be achieved by different mechanisms, like passive targeting while considering the tumour microenvironment and similarly active targeting by performing surface modification of solid lipid nanoparticles as well as co-delivery mechanisms [6]. Different drugs can be easily incorporated irrespective of their solubility criteria and are effective in different types of tumours like breast, colon, lung, brain, and liver, validating their potential [7]. Still, many challenges need consideration while formulating SLN’s for cancer therapy, but their possibilities appear to be quite high [8]. Many therapeutic nanoparticles are used to treat cancer, which results in toxicity due to high drug accumulation or enhanced permeation and retention (EPR) effects. These significant drawbacks are due to leaky vasculature and inefficient drainage at tumour sites [9]. As we found, the response rate of these drugs is very poor, and drug resistance developed by the patient is very high [10]. Early menarche, late menopause, null parity, advanced age at first birth, reduced nursing, and postmenopausal hormone therapy are risk factors for breast cancer, according to GLOBOCAN 2020, as well as oral contraceptives. Alcohol consumption, obesity, and a lack of exercise are additional breast cancer risk factors [11]. Anticancer medications are used to treat cancer, extend life, or lessen cancer-related symptoms [12]. The majority of anticancer medications work by interfering with cell division [13]. Breast abscesses are one of the main causes of morbidity for women in developing nations, but they are less frequent in affluent nations due to improvements in maternal hygiene, nutrition, the standard of living, and early antibiotic administration. It has been demonstrated that ultrasound is effective for diagnosing breast abscesses, directing needle placement during aspiration, and enabling visibility of multiple abscess locations, all of which are necessary for needle aspiration and re-aspiration of breast abscesses [14]. Proteins belonging to the family ATP-binding cassette (ABC) have a vital role in drug resistance in multiple malignancies and high resistance to chemotherapy [15]. The major obstacle in breast cancer treatment and the prognosis is multidrug resistance (MDR) [16], which is usually due to high expression of certain proteins, namely P-glycoprotein (P-gp/ABCB1), ABCG2, and BCRP [17]. The most common malignancy and the second leading cause of cancer death among women is breast cancer [18]. The reason behind this is the potential for metastasis to obscure organs. The modulation of breast cancer and its progression to metastasis are mainly mediated by several pathways [19]. The various biological receptors responsible for breast cancer are oestrogen receptors (ERs), progesterone receptors (PRs), and human epidermal growth factor receptor 2 (HER-2) for multiple subtypes of breast cancer [20]. Breast receptors: targeted drug delivery system Over few decades, while comparing free drugs, nanocarriers have played a vital role in various cancer therapies [21]. As nanocarrier- encapsulated drugs are target oriented and accumulate at tumor International Journal of Applied Pharmaceutics ISSN- 0975-7058 Vol 15, Issue 2, 2023