Pharmacotherapeutic group: Drugs for constipation, peripheral opioid receptor antagonists, ATC code: A06AH05.
Mechanism of action
Naldemedine is an antagonist of opioid binding at the mu-, delta-, and kappa-opioid receptors. Naldemedine functions as a peripherally-acting mu-opioid receptor antagonist in tissues such as the gastrointestinal tract, thereby decreasing the constipating effects of opioids without reversing the central nervous system (CNS)-mediated opioid effects.
Naldemedine is a derivative of naltrexone to which a side chain has been added that increases the molecular weight and the polar surface area, thereby reducing its ability to cross the blood-brain barrier (BBB); the CNS penetration of naldemedine is expected to be negligible at the recommended dose. Additionally, naldemedine is a substrate of the P-glycoprotein (P-gp) efflux transporter, which may also be involved in reducing naldemedine penetration into the CNS. Based on this, naldemedine is expected to exert its anti-constipating effects on opioids without reversing their CNS-mediated analgesic effects.
Clinical efficacy and safety
The efficacy and safety of naldemedine has been established in patients with chronic non-cancer pain and OIC and in patients with cancer and OIC.
Clinical studies in patients with chronic non-cancer pain and OIC
The safety and efficacy of naldemedine was evaluated in two identical, 12-week randomised, double-blind placebo-controlled trials (Studies V9231 and V9232) in which naldemedine was used without laxatives and in a third long-term 52-week randomised, double-blind placebo-controlled trial (study V9235) in which naldemedine was used with or without stable laxatives in patients with chronic non-cancer pain and OIC.
Patients receiving a stable opioid morphine equivalent daily dose of ≥ 30 mg for at least 4 weeks before enrollment and self-reported OIC were eligible to participate.
In studies V9231 and V9232, OIC was confirmed through a 2-week run-in period and was defined as no more than 4 spontaneous bowel movements (SBMs) total over 14 consecutive days and <3 SBMs in a given week with at least 25% of the SBMs associated with one or more of the following conditions: (1) straining, (2) hard or lumpy stools; (3) having a sensation of incomplete evacuation; and (4) having a sensation of anorectal obstruction/blockage. In study V9235, OIC was confirmed through a 2-week run-in period and was defined as no more than 4 SBMs total over 14 consecutive days and <3 SBMs in a given week.
A SBM was defined as a bowel movement (BM) without rescue laxative taken within the past 24 hours.
In studies V9231 and V9232, patients had to either not be using laxatives or be willing to discontinue laxative use at the time of Screening and be willing to use only the provided rescue laxatives during the Screening and Treatment Periods. All study participants took laxatives previously for the treatment of OIC. In study V9235, patients on a stable laxative regimen at screening (52.4%) were allowed to continue using that same regimen without change throughout the study duration. In the run-in and treatment periods for all three studies, bisacodyl was used as rescue laxative if patients had not had a BM for 72 hours and were allowed one-time use of an enema if after 24 hours of taking bisacodyl, they still had not had a BM.
Patients with evidence of significant structural abnormalities of the gastrointestinal tract were not enrolled in these studies.
A total of 547 patients in study V9231, 551 patients in study V9232 and 1246 patients in study V9235 were randomised in a 1:1 ratio to receive 200 micrograms of naldemedine or placebo once daily for 12 weeks for studies V9231 and V9232, for 52 weeks for study V9235.
In studies V9231, V9232 and V9235, the mean age of the subjects in these three studies was 53.2 years; 14.8% were 65 years of age or older; 62.0% were women; 80.2% were white.
In study V9231, the three most common types of pain were back pain (62.0%); neck pain (8.3%) and osteoarthritis (5.3%). In study V9232, they were back pain (53.6%); pain (10.2%) and arthralgia (7.8%). In study V9235, the three most common types of pain were back pain (58.0%); osteoarthritis (9.5%) and neck pain (8.1%).
Prior to enrollment, patients had been using their current opioid for an average of 5 years. The patients who participated in studies V9231, V9232 and V9235 were taking a wide range of opioids.
The mean baseline opioid morphine equivalent daily dose was 132.42 mg, 120.93 mg, and 122.06 mg per day for studies V9231, V9232 and V9235 respectively. The mean baseline SBMs was 1.31, 1.17, and 1.60, for studies V9231, V9232 and V9235 respectively.
The primary endpoint for studies V9231 and V9232 was the proportion of SBM responders, defined as: ≥3 SBMs per week and a change from baseline of ≥1 SBM per week for at least 9 out of the 12 study weeks and 3 out of the last 4 weeks. The primary efficacy endpoint for study V9235 was the change in the frequency of BMs per week from baseline to weeks 12, 24, 36 and 52.
There was a statistically significant difference for naldemedine treatment group versus placebo for the primary endpoint in studies V9231 and V9232 (see Table 3).
There were 4 secondary endpoints in studies V9231 and V9232 (see Table 3).
Table 3. Clinical outcomes for studies V9231 and V9232
| | V9231 | V9232 |
| Naldemedine (N=273) | Placebo (N=272) | Naldemedine (N=276) | Placebo (N=274) |
| Proportion of SBM Responders | 47.6% | 34.6% | 52.5% | 33.6% |
| Treatment difference | 13.0% (95% CI: 4.8%, 21.3%, p=0.0020*) | 18.9% (95% CI: 10.8%, 27.0%, p<0.0001*) |
| Change in frequency of SBMs per week (LS Mean) |
| From baseline to the last 2 weeks of treatment** | 3.42 | 2.12 | 3.56 | 2.16 |
| From baseline to week 1** | 3.48 | 1.36 | 3.86 | 1.69 |
| Change in frequency of CSBMs per week (LS Mean) |
| From baseline to the last 2 weeks of treatment** | 2.58 | 1.57 | 2.77 | 1.62 |
| Change in frequency of SBMs without straining per week (LS Mean) |
| From baseline to the last 2 weeks of treatment*** | 1.46 | 0.73 | 1.85 | 1.10 |
CI=Confidence Interval
*Statistically significant: p-values based on the Cochran-Mantel-Haenszel test.
** p<0.0001
*** p=0.0003 for study V9231 and p=0.0011 for study V9232
For study V9235, the efficacy of naldemedine vs. placebo was assessed as secondary endpoints by the frequency of BMs as presented in Table 4.
Table 4. Change in the frequency of BMs per week from baseline to each visit (LS Mean) ITT population in study V9235
| | Naldemedine (N=621) | Placebo (N=620) |
| Mean frequency of BMs at baseline | 2.02 | 2.02 |
| Change in the Frequency of BMs per week |
| Week 12* | 3.70 | 2.42 |
| Week 24* | 3.77 | 2.77 |
| Week 36* | 3.88 | 2.88 |
| Week 52* | 3.92 | 2.92 |
*nominal p≤0.0001
The efficacy and safety were also assessed in the laxative inadequate responders (LIR) and non-LIR subgroups.
In studies V9231 and V9232, patients who, based on concomitant medication records, were on laxative therapy prior to entering the study and who stopped its use within 30 days prior to Screening, and had self-reported OIC, were considered to be a LIR.
Additionally, patients who were not on laxatives within 30 days prior to screening and only received rescue laxative at or after screening were considered non-LIR. The number of patients in the LIR and non-LIR subgroups were 629 (naldemedine: 317 and placebo: 312) and 451 (naldemedine: 223 and placebo: 228) for pooled Studies V9231 and V9232. All study participants took previous laxatives at some time for the treatment of OIC prior to entering the trials V9231 or V9232.
In the LIR subgroup, a greater proportion of responders was observed with naldemedine (46.4%) compared with placebo (30.2%) and the difference between groups (16.2%) was statistically significant (p<0.0001).
In the non-LIR subgroup, consistent with the results in the LIR subgroup, a greater proportion of responders was observed with naldemedine (54.3%) compared with placebo (38.9%) and the difference between groups (15.6%) was statistically significant (p=0.0009).
For study V9235, long term efficacy data defined as the change in frequency of BMs at week 52 from baseline, assessed as a secondary endpoint, showed that subjects in the naldemedine group had improvements in the frequency of BMs compared with subjects in the placebo group in both LIR (3.10 vs 1.90, p=0.0210) and non-LIR (4.26 vs 3.39, p=0.1349) subgroups.
Clinical studies in patients with cancer and OIC
The safety and efficacy of naldemedine was also evaluated in 2 randomised, double-blind and placebo-controlled studies (V9222 and V9236) in patients with cancer and OIC.
Subjects were required to be treated with opioids for ≥14 days prior to screening and had to be receiving a stable dose. The studies included a 2-week screening period, 2-week treatment period and 4-week follow-up period. For patients receiving laxative therapy at the screening visit, it had to be continued at a stable dose until the end of the treatment period. Patients were allowed to receive rescue laxative(s) as needed regardless of being on a stable laxative regimen at baseline (apart from within 24 hours of the start of the treatment period).
In studies V9222 and V9236, OIC was confirmed through a 2-week run-in period and was defined as ≤5 SBMs during the 14 consecutive days prior to the randomisation and ≥1 of the following bowel symptoms in ≥25% of all BMs regardless of the use of rescue laxatives: presence of straining during bowel movement, feeling of incomplete evacuation, passage of hard stools or small pellets.
In studies V9222 and V9236, the mean age of the subjects was 64.3 years; 51.8% were 65 years of age or older; 39.4% were women and 97.1% were Japanese.
Naldemedine 200 micrograms or placebo was administered for 2 weeks to cancer patients with OIC. The primary endpoint for study V9236 and the secondary endpoint, without multiplicity adjustment, for study V9222 were the proportion of SBM responders during the 2-week treatment period. A responder was defined as a patient with ≥3 frequency of SBMs per week and an increase from baseline ≥1 SBM per week during the 2-week treatment period.
Table 5. Proportion of SBM responders in patients with cancer and OIC during the 2-week treatment period (Studies V9222 and V9236)
| | V9222 | V9236 |
| Naldemedine (N=58) | Placebo (N=56) | Treatment Difference [95% Cl] | Naldemedine (N=97) | Placebo (N=96) | Treatment Difference [95% Cl] |
| Patients responding, n (%) | 45 (77.6%) | 21 (37.5%) | 40.1% [23.5%, 56.7%] | 69 (71.1%) | 33 (34.4%) | 36.8% [23.7%, 49.9%] |
| p value* | | | <0.0001 | | | <0.0001 |
*Statistically significant: p-values based on the Chi-square test.
Paediatric population
The European Medicines Agency has deferred the obligation to submit the results of studies with Rizmoic in one or more subsets of the paediatric population in the treatment of opioid-induced constipation (see section 4.2 for information on paediatric use).