Effect of milling and compression on the solid-state Maillard reaction

Area of Science:

• Pharmaceutical Sciences
• Solid-State Chemistry
• Physical Pharmacy

Background:

• The Maillard reaction is a significant degradation pathway for pharmaceutical compounds.
• Understanding solid-state reactions is crucial for drug formulation and stability.
• Metoclopramide hydrochloride is a widely used antiemetic drug.

Purpose of the Study:

• To investigate the impact of mechanical processing (milling and compression) on the solid-state Maillard reaction.
• To elucidate the role of surface area, amorphous content, and defects in reaction kinetics.
• To compare the reactivity of metoclopramide hydrochloride with different forms of lactose under various processing conditions.

Main Methods:

• Anhydrous metoclopramide hydrochloride was subjected to milling for varying durations.
• Mixtures of metoclopramide hydrochloride and amorphous lactose were prepared and stored at 105°C and 0% relative humidity.
• Powder mixtures were compressed into tablets at pressures ranging from 70 to 350 MPa.
• Tablets and powder mixtures were stored under controlled conditions to assess Maillard reaction rates.

Main Results:

• Milling time positively correlated with the reactivity of metoclopramide hydrochloride in the Maillard reaction.
• Tablet formation significantly increased the Maillard reaction rate compared to powder mixtures, irrespective of lactose form.
• Higher compression pressures for tablet preparation led to accelerated reaction rates, attributed to enhanced reactant contact and retained moisture.

Conclusions:

• Mechanical processing, including milling and compression, plays a critical role in accelerating the solid-state Maillard reaction.
• Tablet compression is a more influential factor than lactose type in promoting this degradation pathway.
• Optimizing processing parameters can mitigate unwanted solid-state reactions in pharmaceutical formulations.