The Importance Of Filter Testing - Pharmaceutical Technology

Latest Issue
PharmTech

Latest Issue
PharmTech Europe

The Importance Of Filter Testing


Pharmaceutical Technology Europe
Volume 23, Issue 8

How important is filter testing in the pharma industry?


Graham Rideal
Filtration in the pharmaceutical industry covers a wide range of applications from powder processing to liquid purification, such as saline or dextrose solutions. In the case of the former, the advantage of good filtration processes mainly lies in recovering valuable drugs, which can cost in excess of $1 million per kilogram. The advantage here is purely commercial.

For intravenous products, however, good filtration is a matter of life and death; a simple internet search on recalled drugs reveals particulate contaminants from the clearly visible, such as glass fragments, wood fibres and mould, to the invisible, and potentially lethal, bacteriological contamination.

The primary test of a filter begins with the filter medium itself to ensure it is fit for purpose. Thereafter the filter system must be tested in situ. Failure can occur in the filter medium or in the sealing arrangement when assembled.

Porosity

One of the simplest methods of comparing filter media is to test porosity either by air or water flow under prescribed conditions. Lower flow rates or higher back pressures indicate better filter performance.

Bubble point

The flow rate method is refined in the so-called bubble point test. Here, the filter is saturated with a liquid and then a gas (usually air) is pressurised from below. As the pressure increases, the air finds the single largest pore, which is blown out, forming a bubble on the surface: the bubble point. The Washburn equation is then applied to convert the applied pressure into the diameter of the pore.

Porometry

Porometry takes the bubble point one step further by continuing the pressurisation of the filter beyond the bubble point. Successively smaller pores are blown clear by the air pressure until the smallest pore is finally evacuated. The applied pressure versus flow rate profile can then be interpolated to provide complete pore size distribution.


ADVERTISEMENT

blog comments powered by Disqus
LCGC E-mail Newsletters

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

Survey
What role should the US government play in the current Ebola outbreak?
Finance development of drugs to treat/prevent disease.
Oversee medical treatment of patients in the US.
Provide treatment for patients globally.
All of the above.
No government involvement in patient treatment or drug development.
Finance development of drugs to treat/prevent disease.
24%
Oversee medical treatment of patients in the US.
12%
Provide treatment for patients globally.
10%
All of the above.
44%
No government involvement in patient treatment or drug development.
10%
Jim Miller Outsourcing Outlook Jim MillerCMO Industry Thins Out
Cynthia Challener, PhD Ingredients Insider Cynthia ChallenerFluorination Remains Key Challenge in API Synthesis
Marilyn E. Morris Guest EditorialMarilyn E. MorrisBolstering Graduate Education and Research Programs
Jill Wechsler Regulatory Watch Jill Wechsler Biopharma Manufacturers Respond to Ebola Crisis
Sean Milmo European Regulatory WatchSean MilmoHarmonizing Marketing Approval of Generic Drugs in Europe
FDA Reorganization to Promote Drug Quality
FDA Readies Quality Metrics Measures
New FDA Team to Spur Modern Drug Manufacturing
From Generics to Supergenerics
CMOs and the Track-and-Trace Race: Are You Engaged Yet?
Source: Pharmaceutical Technology Europe,
Click here