Anant Patel is a Ph.D. candidate at Arnold and Marie Schwartz College of Pharmacy and Health Sciences at Long Island University. He is skilled in formulation and characterization of small molecules and equally interested in other branches of pharmaceutical sciences. Rutesh H. Dave, Ph.D., is currently Division Director of Pharmaceutical Sciences at Arnold and Marie Schwartz College of Pharmacy and Health Sciences at Long Island University. His current interests are in the field of preformulation, formulation and drug delivery.
According to leading market research, the global oral drug delivery market share in 2010 was valued at $49 billion and expected to grow to $97 billion by 2017. Success of the oral drug formulations relies on the aqueous solubility and intestinal permeability of drug molecules, which govern oral absorption. Despite increased demand for oral formulations, nowadays, most new drug molecules discovered are poorly soluble and/or have low permeability, which are major obstacles in oral formulations development. As a result of tremendous efforts in past few decades, various techniques have been developed in order to resolve solubility issues. But most of these techniques offer benefits associated with certain drawbacks. Widely accepted solid dispersions by the spray drying technique involves the excessive use of environmentally challenging volatile organic solvents.
Volatile organic solvents, which cause increasing air pollution, are commonly used in the pharmaceutical and chemical industry. As environmental awareness has grown, efforts have been made to develop alternative environmentally friendly solvent systems to replace traditional volatile solvents. In the interest of “green”, liquid salts (aka ionic liquids) have been identified as ecofriendly alternatives to conventional solvents. Liquid salts are salts in a liquid state at normal room conditions. In broad contexts, salts with the melting point lower than 100°C are considered as liquid salts. Their negligible vapor pressure and high thermal stability offers advantages such as minimum air pollution and ease of product recovery and recycling. Their properties such as solvation ability, density, viscosity, melting point, water/cosolvent miscibility, polarity and acid/base character can be tailored by the appropriate selection of cations and anions. Because of these tunable properties, these materials are often referred to as “designer solvents”.
As a part of research conducted at Long Island University’s Brooklyn campus, an effort was made to imply liquid salt as a green solvent alternative in the formulation development of poorly soluble model drugs ibuprofen, indomethacin, and gemfibrozil. The formulations were developed using the green, nontoxic solvent 1-Ethyl-3-methylimidazolium ethyl sulfate (EMIM ES). Concentrated solutions containing drugs in liquid salt were adsorbed onto a porous carrier to form a free-flowing powder to be compressed into tablets. These liquid salt formulations demonstrated greater drug-release rate and extent compared to pure crystalline drug and controls. When samples were exposed to severe conditions of 40°C/80% Relative Humidity (RH) for 8 weeks, they exhibited excellent physical stability. Overall, liquid salt served as a compelling alternative to the volatile organic solvents.
After over 100 years of existence, the pharmaceutical industry has the opportunity to innovate its processes to minimize their environmental impacts. Hence, our objective was to introduce pharmaceutical scientists to these novel environmentally friendly solvents and motivate their application in the development for the betterment of the Earth.