Verilopam is a potent analgesic.

Conorphone (TR5109) is an opioid of mixed agonist-antagonist analgesic class. In animal models, conorphone demonstrated an analgesic activity in the same range as morphine, and lack of addiction liability. Conoprphone was evaluated in a clinical trial for postoperative pain in the oral surgery model and in patients with postepisiotomy pain. The 40 mg dose of conorphone resulted in a significant incidence of side effects such as drowsiness, dizziness, nausea, and vomiting.

Faxeladol (GRT9906) is a μ-opioid receptor agonist and inhibitor of noradrenalin/serotonin re-uptake. Faxeladol was being studied in the treatment of fibromyalgia and neuropathic pain, however its development has been discontinued.

Varespladib (LY315920; A-001) is a potent and selective inhibitor of IIa, V, and X isoforms of human non-pancreatic secretory phospholipase A2 with nM IC50. The molecule acts as an anti-inflammatory agent by disrupting the first step of the arachidonic acid pathway of inflammation. Varespladib methyl is being developed by Anthera Pharmaceuticals Inc for the potential treatment of coronary artery disease, acute coronary syndrome and inflammation. Varespladib methyl is a prodrug that is rapidly metabolized to varespladib, and both compounds are able to potently inhibit the enzymes of the human secretory phospholipase groups. Phase II clinical trials of varespladib methyl in patients with coronary artery disease, rheumatoid arthritis, asthma and ulcerative colitis revealed that the drug was well tolerated. Varespladib methyl did not demonstrate a good efficacy profile in patients with rheumatoid arthritis, asthma and ulcerative colitis; whereas in patients with coronary artery disease, varespladib methyl consistently reduced LDL-cholesterol levels, (elevated LDL-cholesterol levels are a marker of increased cardiovascular risk). Varespladib methyl could represent a novel therapy for the treatment of cardiovascular disease, although the efficacy, safety profile and advantages of this drug compared with existing therapeutic options would need to be established in upcoming phase III trials.

Trefentanil is a short-acting synthetic opioid of the piperidine class. The drug caused potent analgesia with the peak effect occurring 3 min after injection. There was no significant difference in analgesic potency of trefentanil and alfentanil as measured by tolerance to tibial pressure at 3 min. Trefentanil had a pharmacokinetic and pharmacodynamic profile similar to alfentanil, with a small extent of tissue distribution and a rapid blood/brain equilibration. Trefentanil caused significant respiratory depression at doses of 32 ug/kg and 64 ug/kg. It is a mu-opioid receptor agonist. Trefentanil produced naloxone reversible anti-nociception equi-efficacious to that of fentanyl.

Enolicam (CGS 5391B) is a non-steroidal anti-inflammatory drug with combined cyclooxygenase and lipoxygenase inhibitory activity. It is able to trap oxygen radicals. Enolicam was effective in animal models of traumatic shock and osteoarthritis.

Pyrroliphene is a dialkylaminodiphenylbutanol ester with antitussive and analgesic activities. In clinical trials the major side effect of Pyrroliphene was sedation, and the other side effect liabilities were similar to those of morphine.

Fluradoline (also known as HP-494), a centrally acting antinociceptive agent with antidepressant properties. Experiments on rodents have shown that fluradoline blocked the reuptake of NE, 5-HT, and DA in the brain. Besides, fluradoline was studied for the prevention of acute and chronic postsurgical pain.

Levoxadrol is an active enantiomer of dexoxadrol.