CD is short for controlled drug.
Substances subject to the full controlled drug requirements; e.g. Cannabis, diamorphine (heroin), pethidine, cocaine, methadone, methylphenidate, dextroamphetamine, fentanyl and oxycodone. Under the Act, a prescription for these drugs need to show full details including the form and strength of the preparation, with the total quantity written out in both words and figures. It is an offence for a doctor to issue an incomplete prescription or for a pharmacist to dispense a controlled drug unless all the required details are given.