Around the year 200, the medical teachings of Galen began to fundamentally reshape the practice of pharmacy, establishing a framework that would dominate medical thought for over a millennium. By emphasising the importance of compound preparations and specific dosage forms, Galenic pharmacy moved beyond simple herbalism to create a more structured approach to drug formulation. Central to this system was the theory of balancing the body's four humours—blood, yellow bile, black bile, and phlegm—which dictated how medicines were prepared and prescribed to restore health.

The influence of these methods was profound, as Galen’s systematic approach provided a universal language for practitioners across diverse cultures. His work helped to standardise the preparation of medicines, ensuring that therapeutic practices remained consistent across the Byzantine, Islamic, and European medical traditions. This standardisation was crucial for the development of early pharmaceutical science, as it allowed for the systematic recording and replication of complex remedies.

Key aspects of the Galenic approach included:

• The development of complex compound preparations to treat specific ailments.
• A focus on precise dosage forms to ensure consistent patient outcomes.
• The application of humoral theory to guide the selection of ingredients.
• The creation of a standardised methodology for drug formulation.
• The integration of these practices across multiple global medical traditions.

By codifying the preparation of drugs, Galenic pharmacy laid the groundwork for the professionalisation of the apothecary. The emphasis on balancing bodily qualities through carefully measured ingredients remained the cornerstone of Western and Middle Eastern medicine until the rise of modern pharmacology. This period marked a significant transition in medical history, where the focus shifted from purely empirical observation to a more rigorous, theoretical, and standardised system of pharmaceutical care.