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Walter Holberg

Walter Holberg

Walter Holberg is a 30-year veteran of the pharmaceutical industry with experience in analytical and product development for both branded and generic products. Walter has been granted four patents and has collaborated on seven scientific publications and posters since 1989. He currently holds the position of Scientific Advisor – Laboratory Operations Support for Alcami. He has successfully managed several abuse-deterrent studies, including the execution of Category 1 in vitro abuse-deterrent studies. He manages MD/MV studies for API and Drug Products, generates technical test protocols and reports, and is the subject matter expert for the company.

Recent Posts by Walter Holberg:

Extractables and Leachables – Why?

Regulatory agencies have become increasingly rigorous with regards to the detection, identification and quantification of extractable and leachable compounds in pharmaceuticals, drug delivery systems and biomedical devices. This increased scrutiny is the result of several well-documented incidents of contaminants leaching from containers and packaging, resulting in a potential or real risk to humans. 

Topics: Thought Leadership Extractables & Leachables

Elemental Impurities – Highlights of the Coming Regulation

Replacement of the wet chemistry “heavy metals” limit tests with more modern analytical methodology and conformance to new and specific limits for individual elements was a dramatic, although anticipated, change in the regulation.

The ICH recognized that prior to the Q3D Guidance, regulation of elemental impurities fell under Guideline Q3A for inorganic impurities. Existing pharmacopoeial procedures included the Heavy Metals test, Residue on Ignition/Sulfated Ash test and other wet chemistry tests. The problem with these procedures was that they were non-specific and were never intended to detect the low-level residual metal catalysts and reagents used in some modern synthetic processes. In addition, the acceptance criteria were based upon historical precedent and, although risk factors for metal contamination had changed significantly throughout the 20th century, the existing limits had not changed accordingly and had little toxological basis.

Topics: Regulatory Compliance Elemental Impurities

Antibiotic Potency Testing: The Methods - Part 2

Using the Turbidimetric Method

In part one of this blog series, we discussed Antibiotic Potency Testing using the Diffusion (Cylinder-Plate) method.

Antibiotic potency assays using microbiological methods are required by both the European and United States Pharmacopoeia for some antibiotic products. Physicochemical methods, such as immunological assays and High-Performance Liquid Chromatography (HPLC) have become commonplace for determining the concentration of API and for the concomitant determination of Assay and impurities. However, microbiological assays provide a true measure of how effectively an antibiotic kills or inhibits a target microorganism at a specified concentration.

Topics: Thought Leadership

Antibiotic Potency Testing: The Methods – Part 1

Using the Diffusion (Cylinder-Plate) Method 

Both the European Pharmacopoeia and the US Pharmacopeial Convention (USP) require testing of antibiotic potency using microbiological assays for some products. When the potency of an antibiotic is measured chemically, its concentration in solution is all that is determined. Conversely, a microbiological assay verifies the ability of the antibiotic to kill the target organisms, as well as the concentration at which the antibiotic will kill effectively.

A microbiological potency assay measures the effectiveness of an antibiotic by the degree of growth inhibition on susceptible strains of microorganisms at differing concentrations. One of the two methods defined in the pharmacopoeia to make this determination is the Diffusion (Cylinder-Plate) method.

Topics: Thought Leadership