This study focuses on patients with acute rheumatological pain who are being treated with Nefopam, a pain-relief medication. The study compares two different forms of the same medication: a tablet form (30 mg) taken by mouth and an injectable solution (20 mg) given through intravenous administration. The purpose is to understand how the body processes these two different forms of the medication.

During the study, participants who are hospitalized for rheumatological conditions will receive both forms of the medication at different times. The study will measure how the medication moves through the body and how well it is absorbed when given as a tablet compared to when it is given as an injection. This information will help determine the most effective way to give the medication to future patients.

The research will analyze several aspects of how the medication works in the body, including how long it takes to reach its highest level in the blood, how long it stays in the body, and how much of the medication becomes available for use. This information will help doctors better understand the differences between the tablet and injectable forms of Nefopam and potentially improve pain treatment for patients with rheumatological conditions.