Improved Bioavailability with Dry Powder Cannabidiol Inhalation: A Phase 1 Clinical Study

J Pharm Sci. 2021 Dec;110(12):3946-3952. doi: 10.1016/j.xphs.2021.08.012. Epub 2021 Aug 13.


Oral cannabidiol (CBD) is approved by the Food and Drug Administration (FDA) to treat patients with Dravet and Lennox-Gastaut syndromes and tuberous sclerosis complex. The therapeutic potential of oral CBD formulations is limited by extensive first-pass hepatic metabolism. Following oral administration, the inactive metabolite blood concentration is ∼40-fold higher than CBD. Inhalation bypasses the pharmacokinetic (PK) variability attributed to irregular gastrointestinal absorption and first-pass hepatic metabolism and may efficiently deliver CBD into systemic circulation. This phase 1 study compared the PK of a dry-powder inhaler (DPI) CBD formulation (10 mg powder containing 2.1 mg CBD) with an oral CBD solution (Epidiolex®, 50 mg) in healthy participants. Following a single dose of Epidiolex or DPI CBD (n=10 PK evaluable participants each), the maximum CBD concentration for the inhaled powder was 71-fold higher than that of Epidiolex while administering 24-fold less CBD. The mean time to reach maximum concentration was 3.8 min for the DPI CBD formulation compared with 122 min for Epidiolex. Both Epidiolex and DPI CBD were generally safe and well-tolerated. These data indicate that DPI CBD provided more rapid onset and increased bioavailability than oral CBD and support further investigations on the use of DPI CBD for acute indications.

Keywords: Bioavailability; Clinical pharmacokinetics; First-pass metabolism; Inhalation; Pulmonary drug delivery.

Publication types

  • Clinical Trial, Phase I
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Inhalation
  • Administration, Oral
  • Biological Availability
  • Cannabidiol*
  • Gastrointestinal Absorption
  • Humans
  • Powders


  • Powders
  • Cannabidiol