A formulation of delta-9-tetrahydrocannabinol in a semi-aqueous solvent, such as 35:10:55 alcohol:water:propylene glycol (v/v), produces a stable clear solution near the solubility point of the drug. Because delta-9-tetrahydrocannabinol has poor affinity for the formulation, it is able to partition out and transport across cell membranes to reach the bloodstream quickly. This has been demonstrated by the comparative t.sub.max values achieved in single dose intravenous and 14 day multiple dose inhalation studies conducted in dogs and rats.
