The increasing prevalence of irrational fixed-dose combinations (FDCs) poses persistent challenges for pharmaceutical education, formulation design, and regulatory oversight, particularly in the absence of transparent tools for early-stage conceptual appraisal. Existing approaches to identifying such combinations are largely retrospective, resource-intensive, or dependent on post-marketing regulatory action, limiting their utility during preliminary formulation planning. This work presents an author-developed, conceptual framework designed to support structured reasoning around fixed-dose combinations at an early, exploratory stage. The framework employs a deterministic, rule-based and explainable logic architecture that organizes established pharmacological considerations—including mechanistic compatibility, pharmacokinetic alignment, and safety overlap—into a step-wise qualitative screening process. Inputs are knowledge-driven and literature-informed, enabling transparent, human-readable interpretation of conceptual outcomes. The proposed framework is intended solely for awareness-building, educational use, and preliminary conceptual screening. It does not involve machine learning, statistical inference, outcome prediction, or empirical validation, and it does not generate clinically or regulatorily actionable outputs. Accordingly, the framework is explicitly non-validated, non-predictive, and non-clinical, and is not intended to replace expert judgment, experimental investigation, or formal regulatory review. Its contribution lies in promoting transparent pharmacological reasoning and methodological discussion in the context of fixed-dose combination assessment