Research Article Treatment of Brucellosis in Guinea Pigs via a Combination of Engineered Novel pH-Responsive Curcumin Niosome Hydrogel and Doxycycline-Loaded Chitosan–Sodium Alginate Nanoparticles: an In Vitro and In Vivo Study Fatma I. Abo El-Ela, 1,8 Khaled H. Hussein, 2 Hossny A. El-Banna, 3 Amr Gamal, 4 Sherin Rouby, 2 Ahmed M. S. Menshawy, 2 EL-Shimaa EL-Nahass, 5 Shehata Anwar, 5 Mohamed M. A. Zeinhom, 6 Heba F. Salem, 4 Marawa Ahmed Yahia Al-Sayed, 7 Hala A. El-Newery, 7 Khaled A. M. Shokier, 7 Khalid A. EL-Nesr, 5 and H. I. Hosein 2 Received 21 July 2020; accepted 25 September 2020 Abstract. Brucellosis is a common zoonotic infection, particularly in the developing world. The recommended treatment regimens for brucellosis involve the use of two medications such as doxycycline and curcumin in order to avoid relapses and prolonged use of these drugs. Doxycycline has excellent activity in the acidic phagolysosomal environment, while curcumin modulates the immune system function and macrophage activity. Due to the intracellular existence of Brucellae and the different anti- immune mechanisms of Brucella, the treatment of Brucella infection faces many limitations. The design of nanosystems is a promising treatment approach for brucellosis. The objective of this study was to design and evaluate the ef ficacy of in situ pH-responsive curcumin-loaded niosome hydrogel and doxycycline-loaded chitosan–sodium alginate nanoparticles as chemotherapeutic agents against brucellosis. The prepared formulae showed a spherical nano shape with a slow drug release pattern and small particle size. The prepared formulae were evaluated in vivo using Guinea pigs experimentally infected with Brucella melitensis biovar3. The prepared formula combination gave a signi ficant high reduction rate of Brucella spleen viable count compared with that of untreated controls at p < 0.05. The results showed that the treatment schemes were not fully successful in eliminating Brucella infection in Guinea pigs; however, they signi ficantly (p < 0.05) reduced the viable Brucella count in a shorter time and sub-therapeutic doses. Collectively the novel prepared formulae could be a successful therapy for the effective treatment of brucellosis infection at the recommended therapeutic doses. KEY WORDS: brucellosis; curcumin; doxycycline; pH-responsive; niosomes; chitosan. INTRODUCTION Brucellosis is an important zoonosis caused by members of the genus Brucella that affects a broad range of animal species including cattle, sheep, and goats causing genital infection, abortion, and fetal death [1]. Worldwide, over 500,000 cases of brucellosis occur each year [2]. Brucella can be transmitted to humans from infected animals which coexist closely, complicating the control of brucellosis in enzootic areas [3, 4]. The World Health Organization recommended the use of doxycycline (DOX) as a successful antibiotic for the treatment of brucellosis [5]. Doxycycline is a broad- spectrum tetracycline-class antibiotic which exhibits excellent activity in the acidic phagolysosomal environment where the compound interfaces with Brucellae [6, 7]. The recommended treatment regimens for brucellosis involve the use of two or more antibiotics in order to avoid relapses occurring and to prevent prolonged use of these drugs [6, 8]. Curcumin is a natural polyphenolic flavonoid which has anti-inflammatory 1 Department of Pharmacology, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, 62511, Egypt. 2 Department of Veterinary Medicine, Faculty of Veterinary Medi- cine, Beni-Suef University, Beni-Suef, 62511, Egypt. 3 Pharmacology Department, Faculty of Veterinary Medicine, Cairo University, Cairo, Egypt. 4 Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt. 5 Pathology Department, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, Egypt. 6 Food Hygiene and Control Department, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, 62511, Egypt. 7 Animal Health Research Institute, Beni-11Suef branch, Beni-Suef, Egypt. 8 To whom correspondence should be addressed. (e–mail: fa.pharma@yahoo.com; fatma.aboel3la@vet.bsu.edu.eg) Abbreviations: DOX, Doxycycline; LD 50 , Median lethal dose; GMO, Glyceryl monooleate; b.wt, Body weight; h, Hour; IPB, Isotonic phosphate buffer; EE, Entrapment efficiency; PDI, Polydispersity index; TEM, Transmission electron microscopy; BPAT, Buffered plate antigen test; RBT, Rose Bengal test; BAPA, Buffered acidified plate antigen; CFU, Colony-forming unit. AAPS PharmSciTech (2020) 21:326 DOI: 10.1208/s12249-020-01833-7 1530-9932/20/0000-0001/0 # 2020 American Association of Pharmaceutical Scientists