Any substrate employed in the drug delivery process that improves the selectivity, efficacy, and/or safety of drug administration is referred to as a drug carrier. Drug carriers are generally employed to regulate a drug's release into the bloodstream. Therapeutic drug carrier systems are designed technologies that allow medicinal drugs to be delivered with precision and/or controlled release. Many chronic diseases, including cancer, have a substantial impact on the treatment and potential cure of a range of drug carrier systems. Nasal and pulmonary routes of medication administration are becoming increasingly important in the treatment of human diseases. These methods, especially for peptide and protein therapies, offer intriguing alternatives to parenteral drug administration. This can be performed either by slow drug release over time (usually diffusion) or by triggering drug release at the drug's target by a stimulus, such as changes in pH, application of heat, or light activation.