Meptazinol is a unique opioid analgesic. Binding studies suggest a relative selectivity for mu-1 opioid receptor sites. Meptid is indicated for the treatment of moderate to severe pain, including post-operative pain, obstetric pain and the pain of renal colic. The most commonly reported adverse reactions after treatment with meptazinol are nausea, vomiting, dizziness, diarrhoea and increased sweating, constipation, abdominal pain, rash, vertigo, headache, drowsiness, somnolence and dyspepsia.

Lappaconitine is an alkaloid isolated from the root of Aconltitum sinomantanum Nakai. It has a strong analgesic activity that does not involve the opioid receptor. It was shown to have class-I antiarrhythmic action and irreversibly blocks cloned human heart (hH1) channels by binding to the site 2 receptor.