Codeine.HCl is classified as an opioid agonist with analgesic, antidiarrheal, and antitussive properties. Sometimes referred to as a narcotic, codeine.HCL is used to treat moderate to severe pain and reduce coughing when used in combination with other medicines. Similar to other opioids, codeine. hcl is commonly abused.Codeine.HCl is available as reference material (bulk powder and/or solution) and as calibrated, Ready-to-Use, certified reference material (CRM). This product is designed for qualitative and quantitative protocols and can be used for forensic, toxicology, research, and other chemical/biochemical analytical applications.