Dose Equivalents for Antipsychotic Drugs: The DDD Method

Area of Science:

• Pharmacology
• Psychiatry
• Drug Utilization

Background:

• Establishing antipsychotic dose equivalents is crucial for clinical practice and research but presents significant challenges.
• Existing methods for determining dose equivalence have inherent limitations and varying strengths.

Purpose of the Study:

• To calculate and compare antipsychotic dose equivalents using the World Health Organization's Defined Daily Doses (DDDs).
• To evaluate the utility and limitations of the DDD method against other established approaches for dose equivalence.

Main Methods:

• Dose equivalents were calculated based on DDDs from the WHO Collaborating Centre for Drug Statistics Methodology.
• Calculated DDD-based equivalents were compared with results from the minimum effective dose, classical mean dose, and international consensus methods.
• Equivalents were determined for 57 antipsychotic drugs across oral, parenteral, and depot formulations.

Main Results:

• Dose equivalents were presented for 57 antipsychotic medications, encompassing both first-generation and second-generation agents.
• The DDD-derived equivalent doses generally aligned with other methods, though notable outliers were observed.

Conclusions:

• The DDD method offers a widely available and internationally recognized measure for antipsychotic dose equivalence.
• Limitations include potential variability in data sources for DDD estimation and the WHO's caution against using DDDs solely for dose equivalence.
• The study recommends prioritizing more scientifically robust methods when available and suggests the generated summary serves as a valuable resource for pharmacovigilance.