Biol. Pharm. Bull. 30(6) 1171—1176 (2007)

powder with a melting point of about 50 °C is a lipid soluble vitamin like substance that inhabits inside of the inner mitochondrial membrane where it functions as an integral part of electron transport of oxidative phosphorylation. It is used as a nutritional supplement, antioxidant and in the treatment of cardiovascular disorders such as angina pectoris, hypertension, and congestive heart failure. It is practically insoluble in water and poorly absorbed (Tmax 5—10 h) from the gastrointestinal tract due to its high molecular weight and poor water solubility thereby presenting a challenge in the development of a formulation for oral administration. Many approaches for formulating CoQ10 have been reported. Oil based or powder filled capsules and tablet formulations are currently available on the market as nutritional supplements. However, dissolution and oral bioavailability of these formulations differ widely. Other reported formulation strategies include a solubilized system with soy lecithin, a micellar solution of CoQ10 with polyoxyethylene (60) hydrogenated castor oil, lipid microspheres prepared as a soybean oil emulsified with yolk phospholipids, a redispersible dry emulsion, the complexation of CoQ10 with cyclodextrins, self-emulsifying drug delivery systems, and a solubilized form of CoQ10 in a blend of polysorbate 80 and medium chain triglycerides. However, dissolution profiles are not reported for most of these formulations either due to their oily nature and poor aqueous solubility or due to the absence of a suitable dissolution medium. Further, these approaches were tedious, time consuming and costly. Thus, there is a great need for an efficient, easy, quick, and costeffective method to improve the solubility and dissolution of CoQ10. Dispersion of poorly water soluble drug in an inert hydrophilic carrier matrix at solid state either by melting or solvent or solvent-melting method leads to products known as solid dispersions (SD) that have tremendous potential for improving drug solubility because of the drug solubilizing or co-solvent effect of hydrophilic carrier, better wettability and dispersibility of drug by the carrier material, and the formation of amorphous forms of drug and carriers. However, the SDs prepared by high temperature melting, solvent or solvent-melting method etc. are problematic because 1. The high melting temperatures could chemically decompose drugs and carriers, 2. The hardening of melts could lead to difficulties in pulverization for subsequent formulation into an appropriate dosage form, 3. It is difficult to identify a common solvent to dissolve hydrophobic drug and hydrophilic carrier, 4. The large volumes of solvents and heating are necessary to enable complete dissolution of both components. 5. Vacuum drying, spray drying, spraying on sugar beads using a fluidized bed-coating system, lyophilization etc. used for the removal of organic solvents from SDs further make it tedious, costly and most reports did not address how much residual solvents were present in SDs when different solvents, carriers, or drying techniques were used. Hence, the objective of this work was to provide a process, the low temperature melting method, which does not have the disadvantages of prior art and makes it possible to prepare a Poloxamer 188 (P188)/CoQ10 binary solid dispersion (BSD) in a rapid, cost effective and uncomplicated manner to improve the water solubility and dissolution of CoQ10.