By Calvin A. Omolo Bpharm (St John’s University of Tanzania, MPharm (University of Kwazulu-Natal), PhD candidate (University of Kwazulu-Natal).
Over 100 years ago, Paul Ehrlich hypothesized the creation of ‘magic bullets’ for use in the fight against human diseases.
Ehrlich envisioned a drug that could kill specific disease causing organism without harming the body.
He imagined that just like a bullet fired from a gun to hit a specific target, medicine could target specific disease causing organisms, as the biological effect of a chemical compound depends on its chemical composition and the cell on which it acts.
For centuries, man has searched for this miracle. The healthcare industry is striving to achieve increased cost effective, efficient and accessible high quality methods of treatment at lower costs.
Treatment of chronic, neurological disorders, cancers, diabetes, HIV/AIDS and heart diseases have been a challenge for health care professionals for a long time.
In infectious diseases, this is compounded by multiple drug resistance and poor patients’ compliance.
Many researchers believe the applications of nanotechnology in medicine may be mankind’s first ‘giant step’ toward this goal and achieving the illusive Ehrlich ‘magic bullets’.
Nanotechnology is the manipulation of material on an atomic, molecular, and supramolecular scale involving the design, production, characterization, and application of different nanoscale materials.
The use of nanotechnology in medicine is revolutionizing diagnosis and treatment, drawing parallels to concepts only imagined in sci-fi movies.
Nanomedicine enhances pharmacokinetic properties, bioavailability and drug targeting in various disorders. Besides prevention and treatment of diseases, nanomedicine possesses potential applications in diagnosis, monitoring therapy, drug discovery, surgery, and gene delivery using molecular knowledge of human system.
In past two decades, several nano-therapeutics have been approved by FDA for treatment of hepatitis, cancer, cardiovascular diseases, neurological diseases, autoimmune diseases, diabetes, high cholesterol, Parkinson’s disease, and other infectious diseases.
Moreover, hundreds of nanocarrier based products are currently available at various stages of the preclinical and clinical development.
Recently an MIT-led research team developed a drug capsule that could be used to deliver oral doses of insulin, potentially replacing injections.
The capsule contains a small needle made of compressed insulin. The tip of the needle is made of nearly 100 percent compressed, freeze-dried insulin, using the same process used to form tablets of medicine.
The shaft of the needle, which does not enter the stomach wall, is made from another biodegradable material. Within the capsule, the needle is attached to a compressed spring that is held in place by a disk made of sugar.
When the capsule is swallowed, water in the stomach dissolves the sugar disk, releasing the spring and injecting the needle into the stomach wall. Once the tip of the needle is injected into the stomach wall, the insulin dissolves at a rate that can be controlled by the researchers as the capsule is prepared.
The researchers found no adverse effects from the capsule, as it is made from biodegradable polymer and stainless-steel components. This device is believed will reduce the frequency of administration of insulin, relief from pain of injecting insulin experienced by patients using the conventional system.
Norvodisk has taken the mantle to work with team to put the product in market. It has also been found that nanoparticles of chitosan (a derivative of chitin, a natural structural polymer found in crustaceans and fungi), can be used as a carrier for oral insulin. It shown to protect the insulin from digestive juices and allows the insulin to be absorbed into the bloodstream much more effectively.
Conventional chemotherapeutic agents, used for cancer chemotherapy, have major limitations including non-specificity, ubiquitous biodistribution, low concentration in tumor tissue, and systemic toxicity.
This toxicity has led to side effects such as nausea, vomiting, immune suppression, hepatotoxicity, nephrotoxicity, memory loss, anemia, and death.
To overcome these limitations, nanotechnology has been extensively studied for potential applications in cancer diagnosis and treatment. Nanomedicine has been designed to respond to special biomarkers, specifically releasing drugs to these cancer cells. They are considered intelligent, smart, or environmentally-responsive and often exploit differences between normal cells and cancer cells.
Doxil was the first cancer nanomedicine to be approved by FDA in 1995. It showed to be superior to the conventional anticancer, with few side effects. Another example of nanomedicine in the market is Onivyde® which is an irinotecan liposome injection known to treat resistant and pancreatic cancer that has spread to other parts of the body.
Currently, there are several nanotechnology-enabled therapeutic agents undergoing clinical trials apart from those already approved by the FDA.
The growth in nanotechnology is driving cheap, precise and quick means of diagnosing disease. Detecting diseases sometimes takes so much time that treatment is often administered too late.
Researchers at Chinese University of Hong Kong (CUHK) have developed fluorescent microrobots that can spot Clostridium difficile in a stool sample within a matter of minutes without relying on expensive laboratory equipment.
The technology relies on fungi spore-inspired microrobots that feature fluorescent functionalized carbon nanodots. When the microrobots encounter toxins produced by C. diff, the brightness of the fluorescence changes, something that can be detected with digital photo equipment.
Because the microrobots have iron-based nanoparticles in their structure, they can be manipulated by an external magnetic field and gathered together for best visualization. Researchers at Osaka University in Japan have also developed a nanopore sensor to detect single influenza viral particles in a biological sample.
The researchers used artificial intelligence to work out the “hallmarks” of the virus, which allowed them to identify it using the sensor. The technique has potential as a point-of-care diagnostic tool for influenza patients, which could be very helpful in case of a dangerous outbreak.
Nanotechnology has become increasingly important in advancing the frontiers of many key areas of healthcare, such as, drug delivery, tissue engineering and neuro-regeneration. Recent studies published in Nature Neuroscience showed that three patients with chronic paraplegia were able to walk thanks to precise electrical stimulation of their spinal cords via a wireless implant.
Swiss scientists Grégoire Courtine and Jocelyne Bloch showed that after a few months of training, the patients were able to control previously paralyzed leg muscles, even in the absence of electrical stimulation from the wireless implant.
The Need for tissue engineering and regenerative medicine to create living biological tissue that can repair and replace damaged tissues in the body is currently are of interest using nanotechnology. Many researches are being conducted and FDA has already approved two tissue engineering therapies.
In recent decades, nanomedicine has shown significant promise as a treatment modality for many diseases. Responsive nanomaterials represent a promising class of nanoparticles that can trigger delivery of medicines through the exploitation of a specific stimuli from diseases.
This is promising to bring to life the elusive Ehrlich’s magic bullet. Nano based therapies offer important advantages, and the field is rapidly progressing as evidenced by the extensive studies in the preclinical and clinical stages.
Despite significant progress, obstacles in overcoming the complexities of diseases still exist, preventing the full realization of nanomedicine. There is need for more collaborations between academia, pharmaceutical industry and regulatory authorities to fully mature the field.