This review explores the challenges posed by biological variability in drug development, particularly in terms of drug solubility and bioavailability. It highlights how nanotechnology, especially magnetic nanoparticles (MNPs), offers innovative solutions to enhance drug solubility and improve therapeutic outcomes. The review discusses the impact of biological variability on drug response, emphasizing the need for personalized medicine. It reviews recent advancements in nanotechnology, focusing on MNPs, which can be engineered to improve drug solubility, targeted delivery, and controlled release. MNPs are shown to enhance drug solubility by increasing surface area and facilitating drug dispersion. They also enable targeted drug delivery through magnetic responsiveness and functionalization with targeting ligands, improving therapeutic efficacy and reducing side effects. The review includes case studies demonstrating the effectiveness of MNPs in improving drug solubility and bioavailability, such as in the treatment of colorectal cancer and breast cancer. It also discusses the engineering considerations for MNPs, including surface modification, functionalization, and optimization for biocompatibility and controlled release. Overall, the review underscores the potential of MNPs in revolutionizing drug delivery and personalized medicine, offering a promising approach to address the challenges of biological variability in drug development.This review explores the challenges posed by biological variability in drug development, particularly in terms of drug solubility and bioavailability. It highlights how nanotechnology, especially magnetic nanoparticles (MNPs), offers innovative solutions to enhance drug solubility and improve therapeutic outcomes. The review discusses the impact of biological variability on drug response, emphasizing the need for personalized medicine. It reviews recent advancements in nanotechnology, focusing on MNPs, which can be engineered to improve drug solubility, targeted delivery, and controlled release. MNPs are shown to enhance drug solubility by increasing surface area and facilitating drug dispersion. They also enable targeted drug delivery through magnetic responsiveness and functionalization with targeting ligands, improving therapeutic efficacy and reducing side effects. The review includes case studies demonstrating the effectiveness of MNPs in improving drug solubility and bioavailability, such as in the treatment of colorectal cancer and breast cancer. It also discusses the engineering considerations for MNPs, including surface modification, functionalization, and optimization for biocompatibility and controlled release. Overall, the review underscores the potential of MNPs in revolutionizing drug delivery and personalized medicine, offering a promising approach to address the challenges of biological variability in drug development.