Getting up close and personal with the problem at hand is the best way to solve it. This is similarly true with medical illnesses. One would need to get to the roots of the problem to cure them or to provide the maximum relief to the person suffering from it. However, most of medical diseases have their roots berried in the fundamental building blocks human itself; the cells. Most of the human cells are quite small, typically in the range of one fifth of the width of a human hair and not visible to naked eyes. This presents the first problem in fixing the bad ones. Also, there are so many of them. No technique can physically work on each and every one of them.
This is reason why we use drugs; substances which has a physiological effect when ingested or otherwise introduced in to the body. If we are like “Madam M”, drugs are like “James Bond”. We do all the thinking and planning. Since we can’t physically get in to the field and do the job, we send our “James Bond” (or Bonds to that matter) to pull the trigger. Now like Mr. Bond usually makes a quite a mess of thing in the movie, drugs also have unintended side effects. Major part of our biomedical research in the last two decades has been focused on getting, Mr. Bond to get the job done fast without interfering with other important thing and equipping him with new tools to deal with problems that we couldn’t address previously. Nanotechnology, has helped lot of scientists and doctors to reach this goal and shows a great potential in future applications.
Nano pharmaceuticals today
Nano drugs are specially engineered class of medicine using nanotechnology related techniques. Major body of Nano drugs in the market today are focused on nano drug delivery. These novel types of drugs has emerged as one of the fastest growing sectors in the field of medicine. The annual global R&D investment form drug companies just on nanopharmaceuticals is close to 40 billion dollars today. According to the BBC research LLC, the global market on nano medicine was estimated to be US$50.1 billion in 2011 and estimated to expand to US$96.9 billion in 2016. This presents a 5% sector in the total pharmaceutical market size. U.S. remains as the top player in market as well as nano medicine research and product development. The major companies who have invested on nano drugs include, GlaxoSmithKline (GSK), Merck, Johnson & Johnson, Novartis and Pfizer. Following are the top seven types of nanopharmaceuticals available in the market today.
Liposomes based nanopharmaceuticals
Liposomes are a form of self-assembled nanomaterials made by organization of phospholipids and cholesterol in aqueous medium. They are like very small spheres with a hollow core. The hollow core can encapsulate an aqueous phase drug or several of them. The shell is made by one or more phospholipid bilayers. The size of the liposomes used in nanopharmaceuticals have sizes ranging from 50 to 200 nm. These materials are excessively used as drug carriers and nano drug delivery systems due their ability to encapsulate water soluble drug molecules in their aqueous inner space. They are quite useful because, their hydrophobic bilayer membranes can be modified with hydrophobic molecules to target specific places or to improve effectively of the drug.
The most known types of liposome based on nanopharmaceuticals include, AmBisome® , DaunoXome®, DepoCyt®, DepoDur®, Doxil®, Marqibo®, Mepact™, Myocet® and Visudyne®.
Solid lipid nanoparticles
Solid lipid nanoparticles are typically spherical in shape and have diameters that average between 10 to 200 nm. Like liposomes contain hydrophilic core that can encapsulate water soluble drugs, solid lipid nanoparticles possess a solid lipid core that can solubilize lipophilic molecules. This type of nano drugs may also contains surfactants and emulsifiers to stabilize the particles. The lipids used in these nanoparticles contain, triglycerides ,monoglycerides, fatty acids steroids, and waxes. This type of nanoparticles has seen a tremendous growth in the nano medicine field over the years.
Solid lipid nanoparticle are advantageous primarily because they allow drug manufactures to avoid organic solvent that otherwise require to dissolve the lipophilic drug types. They are also well tolerated in the body and have wide application spectrum. Solid lipid nanoparticles in the market include, Amphotec®, Abelcet®.
PEGylated proteins and polypeptides
Proteins, enzymes and polypeptides are common in conventional drug formulations and the fundamental particle sizes of these material are already in the nanoscale. However, specialized nanotechnology modifications can further increase additional functions and provide new characteristics to the already established drug. PEGylation is one such nanotechnology based process that would increase the drug effectively through one or more pathways among prolonging the circulation, decreasing proteolysis, decreasing renal excretion and decrease the immune detection.
Drugs containing PEGylated proteins and polypeptides currently in the market include, Adagen®, Neulasta®, Neulasta®, Oncaspar®, PegIntron®,Somavert®.
Protein–drug conjugates as nanopharmaceuticals
Albumins are a form of globular proteins that are very common in the body. The serum alubumin is the main protein in the human blood plasma and can be used to bind with different cations, fatty acids and hormones. Over the last decade, albumin has attracted great interest as a potential drug carrier in nano pharmaceuticals due to advantages they can deliver to the pharmacokinetic profile of the drug. This means that these proteins can improve the aspects of the drug as circulation of the drug in the body, absorption, bioavailability, distribution and metabolism. The most popular, protein drug conjugate based medicine is Abraxane®, which is used for the treatment of breast cancer, lung cancer and pancreatic cancer and celebrated as one of the greatest achievements in nanotechnology in cancer treatments.
Nanocrystals are simply crystals of water insoluble drugs in the size typically ranging from 20 to 150 nm without adding any other excipient or any other carrier system. This technique is used commonly as a formulation method for sparingly soluble drug compounds. Due to the high surface area of the drug increases dissolution of these otherwise very low soluble drug types. This is also used as a method to increase the saturation limit of a drug. Typically, saturation limit of a bulk substance depend on the dissolution medium and the temperature. However, at the nanoscale, materials have shown much higher saturation limits compared to their bulk counterparts. Due to this unique phenomenon, nanocrystal based nano drugs can be used to increase the absorption of drug molecules through passive diffusion. Top drugs with nanocrystal based drug formulations include, Emend®, Rapamune®, Tricor®, and Triglide®.