. 2022 May 18;14(2):423–436. doi: 10.3390/neurolint14020035

Table 1.

Studies on chronic pain and cannabinoids.

Author (y)	Groups Studied and Interventions	Results and Findings	Conclusions
Almog et al. (2020) [23]	Adults with chronic pain (VAS ≥ 6) and a medical cannabis license. Exclusion criteria included severe comorbidities, substance abuse, pregnancy, breastfeeding, insufficient contraception.	Dose-dependent pharmacokinetics. Significant VAS pain reduction with 1.0 mg THC (39%, p = 0.0015) and 0.5 mg THC (25%, p = 0.0058). Two point reduction in 70% of 1.0 mg THC, 63% 0.5 mg THC, and 26% of placebo.	Low, precise doses of inhaled THC in chronic pain patients provided significant analgesia.
Ware et al. (2015) [24]	Adults with chronic non-cancer pain for ≥ 6 months. Exclusion criteria included psychosis history, pregnancy, breastfeeding, unstable cardiac or respiratory disease.	Higher risk of non-serious adverse events with medical cannabis (IRR = 1.64, 95% CI = 1.35–1.99), but no increased risk of serious events.	Mild adverse events occurred with cannabis, but 2.5 g/d may be safe for experienced users with chronic pain.
de Vries et al. (2017) [25]	Adults with abdominal pain (≥3 months, NRS ≥ 3) from chronic pancreatitis or surgery. Exclusion criteria: daily cannabis, previous cannabis sensitivity, severe comorbidity, positive urine drug or alcohol screen, BMI > 36 kg/m², pregnancy, breastfeeding.	No significant difference in VAS pain score reduction between groups (placebo = 37% reduction, THC = 40% reduction, p = 0.901).	THC tablets did not provide pain relief for patients with chronic abdominal pain.
Lichtman et al. (2018) [26]	Adults with advanced cancer pain refractory to opioids. Exclusion criteria included history of schizophrenia, substance abuse, using > 1 opioid, >500 mg morphine equivalents/day.	There are no significant differences between groups on NRS score pain improvement (10.7% improvement vs. 4.5% improvement, p = 0.085).	Nabiximols were not superior to placebo as adjunctive therapy for advanced cancer patients.
Narang et al. (2008) [27]	Adults with chronic non-cancer pain (≥4 NRS) refractory to opioids (≥6 months). Exclusion criteria: <8 h between opioids, transdermal/intrathecal opioids, psychiatric disorder, substance abuse, cancer.	Phase I: significant total pain relief with dronabinol (20 mg = 41.7, p < 0.01; 10 mg = 39.7, p < 0.05). Phase II: significant decrease from baseline average pain scores with dronabinol (p < 0.001).	Dronabinol provided adequate analgesia when used as adjunctive therapy for chronic pain.
Notcutt et al. (2004) [28]	Adults with chronic pain. Exclusion criteria included severe comorbidity, psychiatric disorder, substance abuse, history of recreational cannabis use.	Improved S1 VAS scores for THC (p < 0.01) and THC: CBD (p < 0.05). Improved S2 VAS scores for THC (p < 0.001). Improved sleep quality with THC: CBD (p < 0.001), THC (p < 0.001), and CBD (p < 0.05).	THC and THC: CBD extracts greatly improved pain and sleep quality.