Safety, Pharmacokinetics and Pharmacodynamics of Spectrum Red Softgels in Healthy Participants

J Anal Toxicol. 2022 May 20;46(5):528-539. doi: 10.1093/jat/bkab035.


Due to a lack of published pharmacokinetic (PK) and/or pharmacodynamic (PD) data, informed physician and patient decision-making surrounding appropriate dosing of cannabis for medical purposes is limited. This Phase 1, multiple-dose study evaluated the safety, tolerability, PK and PD of Spectrum Red softgels (2.5 mg Δ9-tetrahydrocannabinol (THC) and <0.25 mg cannabidiol (CBD)). Participants (n = 41) were randomized to one of five groups: 5 mg THC and 0.06 mg CBD daily (Treatment A), 10 mg THC and 0.12 mg CBD daily (Treatment B), 15 mg THC and 0.18 mg CBD daily (Treatment C), 20 mg THC and 0.24 mg CBD daily (Treatment D) or placebo. Study medication was administered in divided doses, every 12 h, ∼60 min after a standardized meal, for 7 consecutive days. All treatment-emergent adverse events (TEAEs) (65/65) were of mild-to-moderate severity; none was serious. The highest number of TEAEs (30/65) occurred on the first day of treatment. The most common TEAEs included somnolence, lethargy and headache (reported by eight, seven and five participants, respectively). On Day 7, maximum observed plasma concentration of 11-carboxy-THC increased by 2.0- and 2.5-fold as the dose doubled between Treatments A and B and between Treatments B and D, respectively. Mean peak post-treatment ratings of self-reported subjective effects of 'feel any effect' and 'dazed' differed between Treatment D and placebo on Days 1, 3 and 7. Over a week of twice-daily dosing of Spectrum Red softgels, daily doses of THC up to 20 mg and of CBD up to 0.24 mg were generally safe and became better tolerated after the first day of treatment. A prudent approach to improve tolerability with Spectrum Red softgels might involve initial daily doses no higher than 10 mg THC and 0.12 mg CBD in divided doses, with titration upward over time as needed based on tolerability.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Analgesics
  • Cannabidiol* / pharmacokinetics
  • Cannabis*
  • Dronabinol
  • Healthy Volunteers
  • Humans


  • Analgesics
  • Cannabidiol
  • Dronabinol