In short
Methyl parahydroxybenzoate, also called methylparaben, is a widely used preservative and antimicrobial ingredient. It is not an authorised medicine itself but appears in medicinal products and cosmetics. One Phase 3 clinical trial (2026-526288-40-00) is listed in the EU Clinical Trials Information System (CTIS) for a gel used during placement or exchange of a double-J ureteral stent, with 182 participants planned.
Methyl parahydroxybenzoate, also known as methylparaben, is a chemical substance used mainly as a preservative and antimicrobial agent. It is the methyl ester of 4-hydroxybenzoic acid. The sodium salt form, sodium methyl parahydroxybenzoate, is also used. This page describes what is known about methyl parahydroxybenzoate and the clinical research that involves it.
Key points
- Methyl parahydroxybenzoate is a preservative and antimicrobial ingredient, also known as methylparaben.
- One Phase 3 trial is authorised in the EU for a gel used during double-J ureteral stent placement or exchange.
- The trial plans to enrol 182 participants.
- The study compares a test gel containing methyl parahydroxybenzoate with standard lidocaine gel.
- The main outcome is intraoperative pain intensity measured on a 100 mm visual analogue scale.
- The trial is currently authorised, meaning it has received regulatory approval to proceed.
What is methyl parahydroxybenzoate?
Methyl parahydroxybenzoate is a chemical substance classified as a preservative and antimicrobial. It is also known as methylparaben, methyl 4-hydroxybenzoate, and 4-hydroxybenzoic acid methyl ester. The sodium salt, sodium methyl parahydroxybenzoate, is a related form. In Canada, methylparaben is listed as an approved chemical substance for non-medicinal purposes, including as a fragrance ingredient and preservative antimicrobial, with an acceptable daily intake of up to 10 mg per kilogram of body weight per day as the sum of ethyl, methyl and propyl esters of p-hydroxybenzoic acid. It is not authorised as a medicine in its own right in the records reviewed here.
Other names for this substance include maseptol, p-carbomethoxyphenol, p-hydroxybenzoic acid methyl ester, and p-methoxycarbonylphenol. The CAS registry number is 99-76-3.
How does methyl parahydroxybenzoate work?
Methyl parahydroxybenzoate acts as an antimicrobial preservative. It is used to prevent the growth of microorganisms in products. One source notes that it is used as a preservative in cosmetics, but also mentions that it potentiates UV-induced damage of skin in laboratory studies. The sources reviewed do not describe a specific molecular target for this substance.
Which conditions is it used or studied for?
- Placement or exchange of double-J (DJ) ureteral stent — a transurethral procedure in which a thin tube is placed or replaced in the ureter to help urine drain from the kidney to the bladder. The Phase 3 trial investigates a gel containing methyl parahydroxybenzoate for pain reduction during this procedure.
How is methyl parahydroxybenzoate given?
In the clinical trial, methyl parahydroxybenzoate is part of a gel formulation called Instillagel, given as 11 ml by urethral use. The trial compares this product with a standard lidocaine gel, also given as 11 ml by urethral use. The sources reviewed do not describe other pharmaceutical forms for this substance.
What do the clinical trials show?
One Phase 3 clinical trial is authorised in the EU Clinical Trials Information System (CTIS) involving methyl parahydroxybenzoate as part of a gel product. The trial is a multicentre, randomised, controlled, double-blind study comparing the efficacy and safety of the test product versus standard local anaesthesia in transurethral procedures. It plans to enrol 182 participants.
The primary outcome is intraoperative pain intensity, defined as the participant's strongest procedure-related pain experienced during placement or exchange of the DJ ureteral stent, assessed retrospectively within 5 minutes after completion of the transurethral procedure using a 100 mm visual analogue scale (VAS). The study aims to demonstrate the superiority of the test product over the comparator in reducing intraoperative pain intensity.
The trial status is authorised, meaning it has received regulatory approval to proceed but may not yet be recruiting participants.
What side effects are known?
The sources reviewed do not provide information on side effects of methyl parahydroxybenzoate. The clinical trial record does not list known adverse events for this substance.