Abdominal pain resulting from chronic pancreatitis (CP) is often recurrent, intense and long-lasting, and is extremely difficult to treat. Medical analgesic therapy is considered as first choice in pain management of CP, resulting in regularly prescription of opioids. The adverse consequences of prolonged opioid use, including addiction, tolerance and opioid induced hyperalgesia, call for an alternative medical treatment. Cannabis has been used to treat pain for many centuries. Delta-9-tetrahydrocannabinol (Δ9-THC), the psychoactive substance of the cannabis plant, has been shown in previous studies to be a promising analgesic. The development of Namisol®, a tablet containing purified Δ9-THC showing an improved pharmacokinetic profile, provides the opportunity to test the analgesic potential of Δ9-THC in favourable conditions. The current study aims to investigate the analgesic efficacy of Namisol® as add-on analgesic during a long-term treatment (52 days) of abdominal pain resulting from CP.
BACKGROUND & AIMS: Delta-9-tetrahydrocannabinol (THC) is the most abundant cannabinoid from the plant Cannabis sativa. There is only equivocal evidence that THC has analgesic effects. We performed a phase 2 controlled trial to evaluate the analgesic efficacy, pharmacokinetics, safety, and tolerability of an oral tablet containing purified THC in patients with chronic abdominal pain.
METHODS: Sixty-five patients with chronic abdominal pain for 3 months or more (numeric rating scale scores of 3 or more) after surgery or because of chronic pancreatitis were randomly assigned to groups given the THC tablet or identical matching placebos for 50-52 days. Subjects in the THC group were given the tablet first in a step-up phase (3 mg 3 times daily for 5 days and then 5 mg 3 times daily for 5 days), followed by a stable dose phase (8 mg 3 times daily until days 50-52). Preceding and during the entire study period, patients were asked to continue taking their medications (including analgesics) according to prescription. Patients reported any additional pain medications in a diary. Efficacy and safety assessments were conducted preceding medication intake (day 1), after 15 days, and at 50-52 days. Plasma samples were collected on study days 1, 15, and 50-52; mean plasma concentration curves of THC and 11-OH-THC were plotted. The primary end point was pain relief, which was measured by a visual analogue scale (VAS) of the mean pain (VAS mean scores) on the basis of information from patient diaries. Secondary end points included pain and quality of life (determined from patient questionnaires), pharmacokinetics, and safety.
RESULTS: At days 50-52, VAS mean scores did not differ significantly between the THC and placebo groups (F1,46 = 0.016; P = .901). Between the start and end of the study, VAS mean scores decreased by 1.6 points (40%) in the THC group compared with 1.9 points (37%) in the placebo group. No differences were observed in secondary outcomes. Oral THC was generally well-absorbed. Seven patients in the THC group stopped taking the tablets because of adverse events, compared with 2 patients in the placebo group. All (possibly) related adverse events were mild or moderate.
CONCLUSIONS: In a phase 2 study, we found no difference between a THC tablet and a placebo tablet in reducing pain measures in patients with chronic abdominal pain. THC, administered 3 times daily, was safe and well-tolerated during a 50-day to 52-day treatment period. ClinicalTrials.gov number: NCT01562483 and NCT01551511.
Abdominal pain resulting from chronic pancreatitis (CP) is often recurrent, intense and long-lasting, and is extremely difficult to treat. Medical analgesic therapy is considered as first choice in pain management of CP, resulting in regularly prescription of opioids. The adverse consequences of prolonged opioid use, including addiction, tolerance and opioid induced hyperalgesia, call for an alternative medical treatment. Cannabis has been used to treat pain for many centuries. Delta-9-tetrahydrocannabinol (Δ9-THC), the psychoactive substance of the cannabis plant, has been shown in previous studies to be a promising analgesic. The development of Namisol®, a tablet containing purified Δ9-THC showing an improved pharmacokinetic profile, provides the opportunity to test the analgesic potential of Δ9-THC in favourable conditions. The current study aims to investigate the analgesic efficacy of Namisol® as add-on analgesic during a long-term treatment (52 days) of abdominal pain resulting from CP.
