Pharmacology and Substance Use Disorders: Clinical Foundations, Neurobiology, and Treatment Considerations is a self-paced professional training designed for clinicians who want to better understand how psychoactive substances affect the brain and body, and how pharmacological knowledge informs substance use assessment, diagnosis, risk evaluation, treatment planning, and ongoing clinical care. Pharmacology provides an important foundation for substance use treatment because it helps clinicians understand how substances are absorbed, distributed, metabolized, and eliminated, as well as how they influence mood, cognition, behavior, reward, tolerance, dependence, and withdrawal. This course offers a clinically relevant overview of how psychoactive substances interact with the central nervous system and contribute to the development and maintenance of substance use disorders. Participants will explore key concepts related to neurotransmitter activity, brain reward pathways, neuroadaptation, tolerance, dependence, withdrawal, DSM-5 diagnostic criteria, routes of administration, blood-brain barrier dynamics, metabolism, half-life, elimination, and polysubstance use. The training also considers how biological, psychological, and environmental risk factors interact in the progression of substance use disorders. Clinical implications for assessment, psychoeducation, relapse prevention, level of care decisions, withdrawal management, documentation, and treatment planning are emphasized throughout the course. Applied case examples support clinical decision-making around tolerance, dependence, trauma-related use, workplace impairment, polysubstance patterns, and the use of substances to manage emotional or physiological distress.