Screening of Formulation Components and Their Compatibility Study for Development of A Combinatorial Lipid Based Nanoformulation for Psoriasis

Background: The global prevalence of psoriasis; which is affecting skin cells and immune cells in upto 11.43% of the
global population; as well as due to its complex and dynamic pathophysiology; still possess a serious health concern.
Conventionally, many therapies are available for the management of psoriasis. However, they have limited efficacy
due to higher side effects and also no single topical agent is perfect in itself in the management of psoriasis. Therefore,
combination therapy using lipid-based nanoformulation may be regarded as one of the most powerful strategies to
obviate the compensatory mechanisms and dose-related undesired off-target effects. Further synergistic
combinations of two or more therapeutically relevant molecules, acting through different mechanisms, maximize the
therapeutic effect by providing a multi-target treatment approach.

Aim: The present work aims to screen liquid lipid, solid lipid and surfactants for development of dual drug-loaded
lipidic nanoformulation of thymoquinone (TQ) and tacrolimus (TC) and to evaluate the compatibility between
screened lipids, surfactants and drugs.

Methods: The solubility of both drugs TQ and TC in liquid lipids and solid lipids was done by adding an excess of drugs
in lipids. The lipid showing maximum solubility for drugs are selected for formulation development. Further, the ratio
of solid lipid to liquid lipidis was selected based on the miscibility study. The selection of surfactant and co-surfactant
was done based on emulsification capacity determined by %transmittance. After that, compatibility between drugs
and drug-excipients was done by UV, DSC and FTIR analysis.

Results: Based on maximum solubility Capryol 90 and Monostearin was selected as liquid lipid and solid lipid for
formulation development. Based on miscibility study and maximum oil content, 6:4 ratio of Monostearin and Capryol
90 was selected. Further based on emulsification capacity Tween 80 and Span 20 was selected as surfactant and cosurfactant.
After that, UV, DSC and FTIR analysis confirmed compatibility between drugs and excipients.

Conclusions: Screening of formulation components and compatibility study helps in better selection of excipients
which leads to improved formulation stability, drug loading, particle size etc. which ultimately leads to improved
psoriasis treatment.