Patients with certain polymorphism in the MOR and COMT genes will display differences in their response to analgesics.

After tissue injury, there is great interindividual variability among patients in the amount of pain experienced (pain intensity and duration of pain) and in the degree of pain relief from analgesics. In experimental settings, Single Nucleotide Polymorphisms (SNP) at the MOR and COMT genes have been found to alter the response to opioids in in vitro models and in human.We will collect clinical data on one hundred patients undergoing surgery. We will obtain DNA extracted via PCR techniques from the patients' blood and we will identify SNPs at the mu opioid receptor and catechol-O-methyltransferase genes. We will analyze the data to search for correlation between clinical patterns of postoperative pain and opioid effects and SNPs.

Inclusion Criteria:

• 18 years of age and older
• Give informed consent to participate in this study

Exclusion Criteria:

• Neurologic or psychiatric disease sufficient, in the clinical judgment of the investigator, to compromise informed consent or data collection
• ASA classification score 3 or above
• Patients with past or present history of substance abuse.
• Patients with a history of chronic pain requiring daily analgesic use for more then one month.
• Patients with a current diagnosis of anxiety or depression requiring medical treatment
• Patients allergic to morphine

patients with prostate cancer