The story of evolution of human civilization would feel unfinished if the devastating role of diseases is left untold. Since, the dawn of the civilization in the known history, human race has been afflicted by several infectious and autoimmune diseases. Epidemics such as plague factually demonstrated a potential to cause mass extinction of human population. The beginning of 20th century introduced a new era where significant development in medical sciences promised greater life expectancy as either cure or acute preventive therapies were invented to triumph over large number of medical conditions. The dispersal of a majority of life threatening diseases has been put to leash as the development in medical sciences since the early 20th century introduced a large number of lifesaving drugs. In spite of these achievements, to the date, a therapy is still far from curing the life-threatening diseases such as AIDS, hepatitis, cancer, Alzheimer etc. These are few notorious names to mention with where a successful vaccine is yet to be developed, which renders, implementation of precautionary measures to prevent from infection to be the best strategy for survival. These diseases affect people not only physically, but also emotionally, as contracting and living with a disease can alter one's personality as well as perspective on life.

The beginning of current century marked the engagement of scientific community in intense research to invent measures, if not cure, to prevent the infection from these diseases and cease the further spread of the disease in human body after being diagnosed. A research to invent and develop not only an effective drug against these diseases but also an efficient drug delivery system to administer the drug in infected human body is incessantly underway. Hats off! to their perseverance as now we are aware of few drugs which have proven ability against these diseases. It is rather interesting to know that majority of these drugs contain phosphorous, one of the most frequently characterized heteroatoms alongside sulfur & fluorine in pharmaceutical-medicinal field.

Delivery & Detection of Drugs

In recent years interest in nanoparticle drug delivery systems has also grown dramatically as they have shown improvement in the pharmacological and therapeutic properties of conventional drugs. The extensive research in the field of nanotechnology has provided scientific community with a plausible solution to overcome the problems faced while developing suitable drug delivery system. Problems such as limited effectiveness, poor bio-distribution, and lack of selectivity encountered during conventional ways of application of drug can be overcome by controlling drug delivery. Nanoparticles (structures smaller than 100 nm) due to their small size, exhibit unique physicochemical and biological properties such as enhanced reactive area and ability to cross cell & tissue barriers. Nanoparticles are favorable material for biomedical applications and have a great potential as drug carriers, as drug molecule encapsulated in nano-formulation can be delivered directly to the site of action. Nano-formulations are now being synthesized using numerous types of materials which are designed to release the encased drug exclusively when triggered by change in the pH of the surrounding media.

It is quintessential to understand the encapsulation capacity of these nano-formulations in their solid form. In any drug development process, to be able to accurately quantify the amount of drug being delivered in human body is a crucial requirement. Various in vitro drug release testing methods were developed and implemented to predict the in vivo pharmacokinetics and performance specifications. The most prevalently used methods such as ultrafiltration, ultracentrifugation and dynamic & reverse dialysis, rotating dialysis & Franz diffusion cell incorporated significant errors in the experimental data obtained and proved to be inefficient due to their poor sensitivity & specificity. Even though, the chromatographic techniques such as HPLC & LCMS utilized for the quantification of drug proved to be highly accurate, practical limitations incorporated within the dialysis method rendered it to be far from being tagged flawless. Thus, the demand for an ideal solution to search for the direct, accurate, real time method for detection and quantification of drug molecule was very compelling.

Nuclear magnetic resonance (NMR) spectroscopy is perhaps the most important, powerful, and prevalent form of spectroscopy in both academic and industrial research since its discovery in early 1950s. It is an effective spectroscopic tool for quantitative analysis, as the intensity of a resonance line is directly proportional to the number of resonant nuclei or spins. In contrast to chromatography, quantitative NMR (qNMR) employs a universal reference standard as an internal standard for majority of chemical products assayed, as NMR response can be made the same for all chemical components including an internal standard by optimizing certain instrumental parameters. As qNMR does not need a reference standard for each analyte, it competes effectively with chromatographic methods while maintaining higher standards of sensitivity, speed, precision, and accuracy.

Advances in Detection Technique

A researcher from Department of Chemistry, University of Missouri Kansas City (UMKC), USA ingeniously came up with a plan where quantitative nuclear magnetic resonance (qNMR) spectroscopy was employed to analyze the drug under study by taking advantage of the phosphorous atom in the drug molecule.  Dr. Sudhaunshu S. Purohit, a native of Mumbai, focused primarily on the development and implementation of a general 31P-qNMR method to achieve direct, real time quantification of in vitro drug release. He utilized both solution state & solid state NMR spectroscopic techniques to establish the pharmacokinetics of drug release and to determine the encapsulation efficiency of nano-formulation for a particular drug. The respective findings have been published in excellent scientific journals (Journal of Pharmaceutical Sciences, Molecular Pharmaceutics, The AAPS Journal) in 2017.

Dr. S.S. Purohit teamed up with Dr. V. Agrahari & Dr. J. Meng from School of Pharmacy, UMKC in a collaborative research aimed to provide medical field with a better understanding of the drug loading and drug releasing profiles of the large number of phosphorus containing drugs. Tenofovir, an antiretroviral topical microbicide with proven mettle against HIV/AIDS was chosen as model phosphorous containing drug. The proven effectiveness of a specific type of mucoadhesive, pH sensitive nano-formulations composed of alginate & thiolated chitosan, intended to serve as an encasing for Tenofovir was selected. The research primarily focused on the development and validation of a 31P-qNMR method that can be implemented to determine the amount of drug released from its placebo-encasing in the simulated human body fluids such as simulated plasma, vaginal & seminal fluids. Considering the drawbacks of 1H-NMR & 13C-NMR assays, 31P-qNMR is an excellent technique for studying phosphorus containing compounds. It typically gives rise to a single sharp peak that corresponds to single phosphorous atom being a part of the drug molecule with natural isotopic abundance of 100% allowed high signal-to-noise (S/N) ratio and is directly proportional to the amount of Tenofovir. Thus, the integrated peak area of the phosphorous in Tenofovir was used to estimate the amount of drug.

Taking into account the principles of 31P-qNMR, this method signifies a huge scope as it can be extensively applied to all of the phosphorous containing drug molecules which can in turn provide great deal of information about the actual performance of the drug before being tested on animals or humans. This research contribution would potentially aid scientific community; build improved versions of drug delivery systems that will further decrease the probability of infection or spreading of the disease in human body, saving greater number of human lives. In 21st century, developing nations like India, should invest in research & development of such innovative technologies which would positively impact the health of millions. For centuries we have been affected by these dire diseases. It is time we take the battle to their doorsteps. 


Blog by:

Padmakar Tillu,

Effec Tech Gases Pvt. Ltd, Thane