The purpose of this study is to determine whether Tramadol Hcl is as effective as Voltaren a non-steroidal antiinflammatory drug, and Dipyrone in amelioration of the pain caused by acute renal colic.

Renal stones is a common condition affecting up to 1% of the american population. The main symptom is renal colic. Acute treatment is based on the administration of analgesics mainly those belonging to non-steroidal antiinflammatory drugs (NSAIDs). Tramadol is an analgesic of the opioid class of analgesics (i.e morphine) and it is considered to cause less side effects with more or less the same analgesic potency. In the present study the analgesic effect of intramuscular Tramadol will be compared with Voltaren (NSAID)in patients attending the Emergency Department (ED) for acute renal colic (Stage I). Most of these patients will not pass their stone during their visit to the ED and they are prone to develop another attack of renal colic.In the second phase of the study (Stage II)patients who improved, and are ready to go home, will be enrolled to get Dipyrone or Tramadol orally for the prevention of further pain.

Inclusion Criteria:

• Patients with clinical diagnosis of acute renal colic (Stage I)
• Patients with diagnosed renal colic who might need prevention of pain and are able to swallow medicines (Stage II)

Exclusion Criteria:

• Patients with known hypersensitivity to the study drugs
• Pregnancy or lactation
• Known renal failure or hepatic disease
• Concommitant drug use which could adversely affect patient's outcome (oral anticoagulant, MAO inhibitors)