Heroin was co-prescribed in newly established treatment units. Each unit consisted of a lobby, a waiting-room, a dispensing-room, separate rooms for injecting and inhaling heroin, and rooms for the physician, nurses, social worker, administrative staff and researchers. In addition, in each unit a specially secured room contained a vault in which the medication was stored. The surface of the treatment units was approximately 300 m².
The dispensing-room was situated in between the two administration rooms and separated from these rooms by safety glass windows, which enabled personnel in the dispensing-room to closely observe the safety and behavior of the patients self-administering the prescribed heroin. In order to prevent passive inhalation of heroin vapors by the treatment staff, negative pressure was created in the heroin inhalation room, by means of ventilation equipment.
The staff of the treatment units consisted of a physician ( 0.6 fte), treatment co-ordinator ( 1.0 fte), nurses ( 7.0 fte), social worker ( 0.6 fte), administrator ( 0.5 fte), supervising pharmacist ( 0.1 fte) and security personnel ( 1.5 fte). Each treatment unit had to be open for patients at least two hours during the morning, afternoon and evening for seven days a week. Common hours for dispensing co-prescribed heroin were from 8.30-10.30/11.30 a.m., from 13.00-15.00/16.00 p.m. and from 18.00-20.00/20.30 p.m.

Each day the necessary amount of medication was taken out of the vault by two nurses. The inhalable heroin was originally available in capsules and later on in sachets, containing 75, 100, 150 or 200 mg of heroine base. The injectable heroin was available in multi-dose vials containing 3,000 mg of freeze-dried heroin HCl. The individual dosages of injectable heroin were prepared in a flow-chamber for each patient separately and checked by a second nurse.
In general, patients received their daily methadone dosage preceding the first heroin prescription. The number of patients allowed to be in the heroin administration rooms ranged from five to six patients simultaneously. Patients were requested by the nurse to enter the heroin administration room. Patients who received co-prescribed injectable heroin entered the injection room and were given a syringe containing the injectable heroin, plus additional attributes through a dispensing window. Patients were allowed sufficient time to self-administer the injectable heroin, following the injection instructions, which for instance precluded injecting in the neck or groin. After injecting the prescribed heroin, the patient had to clean the table and return the used syringe and all the other materials. During the whole process of self-administration the patient was closely observed by the nurse from the dispensing-room.
Patients who received co-prescribed inhalable heroin were requested by the nurse to enter the inhalable administration room and were given their heroin dosage, one sachet at a time, together with a piece of aluminum foil, marked with a CCBH logo, and a small pipe or straw (to inhale the heroine base vapors) through the dispensing window. In order to minimize the possibility that nurses could come into contact with heroin base (and might develop a contact dermatitis, see chapter 10), patients opened the sachets themselves. Since 'chasing the dragon' takes more time than injecting, inhaling patients were allowed approximately 30 minutes to self-administer the inhalable heroin. At the end of the self-administration, patients had to clean the table and return all the remaining materials, including the sachets and aluminum foil. As with injecting patients, inhaling patients were closely observed by the nurse from the dispensing-room.
Finally, a series of additional measures ('house rules') were taken to prevent disturbing effects of the trials and its participants on public order and safety within the treatment center as well as in the surroundings of the treatment center. Among others, these included:
- no lingering in the vicinity of the treatment center during and outside the opening hours;
- no use of other drugs than the prescribed heroin and/or methadone in the treatment center;
- no use of drugs in the vicinity of the treatment center;
- no attempts to take prescribed heroin out of the administration rooms or the treatment units.
Serious or repeated violations of the house rules were followed by temporary or sometimes definite exclusion from the heroin treatment program.