2.2.5. Formulation Optimization

Numerical optimization was undertaken using version 11 Design Expert® software (Stat-Ease Inc.) with the aim of identifying an optimum formulation composition and associated formulation parameters that would ensure the production of nanosuspension formulations of optimum stability with the potential to target reservoirs of HIV in the body. Although di fferent methods are used to achieve optimization of process and formulation parameters, the use of a numerical optimization is a comprehensive and effective approach for any continuous optimization process [40]. Numerical optimization locates a point in space that maximises the desirability function while modifying the characteristics of a target by adjusting the importance of that target [41]. The summary of formulation parameters used for the optimization of nano co-crystals are listed in Table 2.

**Table 2.** Summary of optimized formulation conditions for the manufacture of optimized nano co-crystal (OPT-NCC).


### *2.3. Characterization of Optimized Nano Co-Crystal (OPT-NCC)*
