A Randomized, Controlled Study of Repeat Dose Sustained Release Lidocaine for Treatment of Chronic Scrotal Pain

Inclusion Criteria: 1. Adult (≥ 19 years) male 2. Unilateral or bilateral scrotal pain lasting \> 3 months 3. Have nociceptive scrotal pain 4. Average daily maximum scrotal pain score over 7 days ≥ 4 on the 0-10 NRS (Appendix 2). Participants with bilateral scrotal pain must be able to distinguish one side with pain score ≥ 4 and the opposite side must have a maximum scrotal pain score of ≤ 3.0 at baseline. 5. Positive response to test spermatic cord block with 1% lidocaine (Lidocaine Hydrochloride Injection, USP, 1%, 10 mg/mL), defined as a decrease in pain score of at least 2 within 1 hour of injection 6. Baseline blood levels without clinically significant abnormalities including liver function tests (alanine aminotransferase \[ALT\], aspartate aminotransferase \[AST\], gamma-glutamyl transferase \[GGT\], and alkaline phosphatase \[ALP\]) no greater than 50% above the upper limit of normal 7. If sexually active, is willing to use adequate birth control methods to prevent pregnancy over the course of the study Exclusion Criteria: 1. Negative response to test spermatic cord block, defined as absence of a decrease in pain score of at least 2 within an hour of injection 2. Other pain generator site with NRS pain score ≥ 4 that interferes with evaluation of scrotal pain 3. History of allergic reaction to lidocaine or any component of ST-01 4. Any contraindication to local anesthesia with lidocaine (e.g., known hypersensitivity to anesthetics of the amide type; hypokalemia, complete heart block, anticoagulants (aspirin permitted), antiarrhythmic medication.) 5. Active infection involving the urinary tract or scrotum 6. Inability to give consent 7. Inability to follow up according to the protocol 8. Negative response to previous spermatic cord block 9. Any other condition that the investigator believes may interfere with the safety of the participant, study conduct, or interpretation of the data.