Lidocaine and Liquid Paraffin

The combination of lidocaine and liquid paraffin is primarily used for urological procedures, such as urodynamic studies and catheterization in men, to reduce pain and facilitate ease of procedure. ## Composition and Mechanism **Lidocaine** is an amide local anesthetic. Its mechanism involves stabilizing the neuronal membrane by inhibiting the ionic fluxes required for the initiation and conduction of impulses, thereby producing a local anesthetic effect that blocks pain signals. **Liquid paraffin** (also known as mineral oil) acts as a lubricant. While commonly used as a laxative, in this combination, its primary function is to provide lubrication for urethral insertion, complementing lidocaine's anesthetic action. ## Clinical Evidence A randomized, single-blind comparison trial indicated that liquid paraffin alone was more efficient than 2% lidocaine gel in reducing urethral pain during urodynamic studies in men. Pain scores were significantly lower with liquid paraffin compared to lidocaine gel both during lubricant instillation and catheter delivery.