It is a single blind randomized symptom triggered study to assess efficacy and safety of pregablin combined with the symptom triggered treatment for opiate withdrawal syndrome vs. clonidne with the same with the symptom triggered treatment for opiate withdrawal syndrome.

Study design: Single-blind randomized symptom-regulated protocol with an active control. Eighty patients admitted to an inpatient addiction treatment program will be randomly assigned to two groups. The first group (N=40) receives up to 600 mg a day of Pregabalin for six days along with symptomatic therapy that is divided into basic treatment that is given to all patients (Doxylamin 30 mg/day) and additional medications based on patients' needs as determined by a psychiatrist using the Opioid Withdrawal Scale and included Ketorolac, Loperamide, Metoclopramide, Nefazolin and Phenazepam (benzodiazepine). The second group (N= 40) receives up to 600 micrograms of Clonidine a day as the main treatment along with the same basic and symptomatic regimen. Opiate withdrawal severity, craving, sleep disturbance, anxiety and depression, as well as general clinical impressions and side effects are assessed daily by psychiatrists who are blind to patients' group assignment using internationally validated quantitative psychometric instruments.

Inclusion Criteria:

• Opioid Use Disorders; Opioid Withdrawal Syndrome

Exclusion Criteria:

• Severe psychiatric and somatic disorders, other Substance Use Disorders (except tobacco)