Amina M Bagher
Background: Minor phytocannabinoids engage CB1 and CB2 receptors, as well as broader receptors and ion-channel targets. However, fragmented evidence limits translation into central nervous system (CNS) therapeutics. This review introduces pharmacological switching, defined as a dose-, state-, or model-dependent shift in the dominant determinant of a compound's net effect that reverses the direction, rather than merely the magnitude, of that effect on a defined functional endpoint, as a framework for compound-indication matching. Unlike biased agonism, which redistributes downstream coupling without reversing direction, switching requires directional reversal between or within receptor systems. Methods: This narrative review integrates receptor pharmacology, preclinical CNS disease-model data, early-phase clinical evidence, and pharmacokinetics identified through a structured literature search. Results: Three mechanistic axes recurred: PPARγ/CB2/Nrf2-linked neuroinflammatory modulation; TRP/GABAA/5-HT1A-linked control of neuronal excitability; and low-efficacy CB1 antagonism with 5-HT1A potentiation. Their expression was context-dependent: tetrahydrocannabivarin is reported to shift from CB1 antagonism toward partial agonism as receptor occupancy rises, cannabidiolic acid shows stress-conditional anxiolytic and antiemetic activity, and cannabigerolic acid displays seizure-model-dependent bidirectionality. No instance yet meets all five defining criteria; each is graded provisional or proposed pending systematic testing. Human evidence remains limited: inconclusive cannabidivarin efficacy in epilepsy and neuropathic pain, proof-of-mechanism neuroimaging in autism, and early tetrahydrocannabivarin safety data. Conclusions: Minor phytocannabinoids are pharmacologically diverse but clinically underdeveloped. A tiered, biomarker-guided framework is proposed to match compound-indication pairs to the doses, formulations, and subgroups most likely to express their therapeutic pharmacology.