An Exhausting Emulsion - Pharmaceutical Technology

Latest Issue

Latest Issue
PharmTech Europe

An Exhausting Emulsion

Equipment and Processing Report

Untitled Document

Q: We are making an emulsion using a high-shear in-line mixer. First we prepare the aqueous phase, which includes an emulsifying agent and the active ingredient. Then we add the discontinuous phase, which comprises organic solvents and a monomer, to the vessel, and the in-line mixer is used in a recirculation line to form the emulsion. It’s a 60-gal batch, and it’s taking nearly an hour to get the results we’re looking for. We have tried changing the in-line mixer’s workheads to a two-stage configuration, but it doesn’t affect the mixing time. Where are we going wrong?

A: If you’re adding the discontinuous phase to the aqueous phase in the vessel, the chances are that your in-tank agitation is the problem. The agitator blades are probably positioned near the base of the vessel, which is running fairly slow to avoid aeration because oxidation can damage the active ingredient. But as you add the discontinuous phase and the liquid level rises in the vessel, the agitator won’t be capable of premixing the two phases. Instead, the in-line mixer is drawing the aqueous phase from the bottom of the vessel and recirculating it back into the top, while the solvents remain on the surface. Switching to a two-stage in-line mixer will increase shear, but not solve the problem, as you experienced. The ideal way to prepare an emulsion of this sort is to add the discontinuous phase to the recirculation loop through a manifold just before the in-line mixer, so that both phases are mixed on contact in the mixer’s high-shear zone. However, if you have to add the two phases to each other in the vessel, make sure the in-tank agitator is premixing them properly. Speeding it up as the liquid level rises to maintain the required in-tank movement should allow it to form a rough premix. The in-line mixer will then be able to subject this premix to intense shear and reduce the droplet size to form a finely dispersed, stable emulsion more quickly.

—Peter Matthews, technical manager of Silverson Machines


If you have a problem with your equipment or process, an industry expert may have the solution. Please send your question to Erik Greb, editor of Equipment and Processing Report, and we may be able to provide an answer in a future issue. All questions will remain anonymous.


blog comments powered by Disqus
LCGC E-mail Newsletters

Subscribe: Click to learn more about the newsletter
| Weekly
| Monthly
| Weekly

FDASIA was signed into law two years ago. Where has the most progress been made in implementation?
Reducing drug shortages
Breakthrough designations
Protecting the supply chain
Expedited reviews of drug submissions
More stakeholder involvement
Reducing drug shortages
Breakthrough designations
Protecting the supply chain
Expedited reviews of drug submissions
More stakeholder involvement
View Results
Eric Langerr Outsourcing Outlook Eric LangerRelationship-building at Top of Mind for Clients
Cynthia Challener, PhD Ingredients Insider Cynthia ChallenerRisk Reduction Top Driver for Biopharmaceutical Raw Material Development
Jill Wechsler Regulatory Watch Jill Wechsler Changes and Challenges for Generic Drugs
Faiz Kermaini Industry Insider Faiz KermainiNo Signs of a Slowdown in Mergers
Ebola Outbreak Raises Ethical Issues
Better Comms Means a Fitter Future for Pharma, Part 2: Realizing the Benefits of Unified Communications
Better Comms Means a Fitter Future for Pharma, Part 1: Challenges and Changes
Sandoz Wins Biosimilar Filing Race
NIH Translational Research Partnership Yields Promising Therapy
Source: Equipment and Processing Report,
Click here