Case studies formulation choice

Case Study-The Choice of Capsule or Tablet Formulation for Early Clinical Trials... 

The ability of a flexible vinyl film to withstand the rigors of environmental exposure has been the subject of many studies, both reported and unreported. The extreme complexity of a vinyl system stems not only from the number of individual components necessary from a processing and performance point of view, but it is factorially compounded by the number of choices between components and their relative resistance to the environment. In many cases, the ability to formulate is not totally compatible with the performance requirement, and a compromise must be struck that will provide the optimum conformity to the most critical specifications. The development of unique products or additives to existing commercial materials to broaden formulating latitude has been and is a major stimulus to the growth of the vinyl industry. 

The choice of chemical is usually based on trial-and-error procedures hence, demulsifier technology is more of an art than a science. In most cases a combination of chemicals is used in the demulsifier formulation to achieve both efficient flocculation and coalescence. The type of demulsifiers and their effect on interfacial area are among the important factors that influence the coalescence process. Time-dependent interfacial tensions have been shown to be sensitive to these factors, and the relation between time-dependent interfacial tensions and the adsorption of surfactants at the oil-aqueous interface was considered by a number of researchers (27, 31-36). From studies of the time-dependent tensions at the interface between organic solvents and aqueous solutions of different surfactants, Joos and coworkers (33—36) concluded that the adsorption process of the surfactants at the liquid-liquid interface was not only diffusion controlled but that adsorption barriers and surfactant molecule reorientation were important mecha-... 

In almost all studies, a reference formulation is needed, either as a comparator for assessment of relative performance compared to the test formulation, or as a simple vehicle, to characterise the drug substance pharmacokinetics. If the aim is to investigate the influence of certain formulations on the rate and extent of absorption, which is the case in early development or IVIVC studies, an oral solution of the drug is the first choice as a reference formulation. Stability of the solution, regarding drug compound degradation and precipitation, is an important factor to verify before study start. Inclusion of a parenteral reference formulation, if feasible, provides additional information, as will be further discussed below. 

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