Determination of Saturated Solubility of Mirtazapine Using UV Visible Spectrophotometer

Solubility is an important parameter for designing new drug formulations. Many drugs possess poor aqueous solubility hence, poor bioavailability. Many pharmaceutical industries face these issues while designing new drug entities. A new assessment revealed that about 70–90% of drug candidates are in the development stage, while up to 40% of the marketed products are water-insoluble which leads to low bioavailability, reduced therapeutic effects, and increased dose. Poor solubility is one of the major driving forces behind the development of numerous new drugs. There are various techniques to enhance the drug solubility such as particle size reduction, Nano-suspension, use of surfactants, salt formation, solid dispersion, etc. Mirtazapine (BCS Class II) has poor water solubility; to test an optimum pH for its solubility, a saturated solubility method was applied. Saturated solubility is a method in which drugs with poor solubility are dissolved in different acidic, basic media, and in distilled water. This study suggests proper dissolution media improves the solubility of water-insoluble drugs. UV-spectroscopy is a method to determine the solubility of drugs in various media and through this method, maximum absorption at a particular wavelength is determined for drug solution. Afterward, this solution of the drug, in various media, is studied to decipher the unknown concentration of the drug in a given solution by the Beer-Lambert law. With the aid of UV-spectroscopy, it was determined that the solubility of mirtazapine increases with increasing pH of mediums.