Laboratory Testing Blog

One of the most important considerations in the drug manufacturing process is safety, not only of the drug itself, but also impurities and degradation products.  Impurities present in the active pharmaceutical ingredient (API) have to be identified to ensure no mutagenic or toxic substances will be administered to patients.  Drug product degradation profiles need to be established to guide stable formulation development and provide suitable drug shelf-life assessment.  Drug regulatory agencies also have requirements for characterization of the impurity profile of a pharmaceutical.

The United States Food and Drug Administration (U.S. FDA) recently released a guidance document for stability testing of Abbreviated New Drug Application (ANDA) products in an effort to spur discussion on what the new guidelines should contain.  The guidance describes the FDA’s current thinking on this topic and are only recommendations at this time.  In this guidance document, FDA suggests that ANDA's submitted and the Drug Master Files (DMF's) that support ANDA's should follow the stability recommendations provided in International Conference on Harmonization (ICH) stability guidances.

As drug candidates, there is currently great interest in oligonucleotides due to the reduced time required to achieve lead molecules and to their potential for treating previously untractable diseases.  Synthetic oligonucleotides are used extensively in the field of molecular biology, clinical diagnosis and the development of new therapeutic agents.

The recent increase in development of protein and peptide therapeutics demands highly informative methodologies.  More than 600 biological drugs are currently approved by FDA.  The interest in analyzing peptides and proteins arises from the need, during preclinical and clinical studies, to quantify levels of the metabolites in protein and peptide drugs.

Developing and verifying a specific, accurate, precise and reproducible quality control method capable of simultaneously separating and quantifying actives, preservatives and impurities, including the separation of possible degradation products and excipients can be a complex and challenging task.

Biodegradable microparticles formulated using biodegradable polymers, such as polylactide (PLA), poly (lactideco- glycolide) (PLGA) (1Y6), gelatin (7Y9) and albumin have been used as carriers for small molecules and biologically active peptides and proteins.  In addition to being biodegradable, other advantages include reduced frequency of administration, enhanced patient compliance, sustained drug release, reduced dosage and less systemic side effects.  PLA and PLGA have been approved for human use by the United States Food and Drug Administration (US FDA) as surgical sutures, implantable devices and other drug delivery systems.

Modification of low density lipoproteins (LDL) by oxidation of their polyunsaturated lipid components has been implicated in the etiology of atherosclerosis.  Oxidation proceeds by interaction of polyunsaturated fatty acids (PUFA) with active oxygen species or with lipid oxidation products.  Moreover, there are indications that lipid oxidation promotes pre-mature coronary atherosclerosis since susceptibility to LDL oxidation has been associated with the severity of coronary heart disease.  Protection against oxidation can come from antioxidants, antioxidant enzymes and co-factors. The use of antioxidants to inhibit LDL oxidation has been reviewed extensively. Under in vivo conditions, there exists a competition between oxidative and protective processes that depend on PUFA composition and on antioxidant levels.  Therefore, it is important to properly assess the oxidation of the fatty acids in marine oils.

The purpose of dermal absorption studies of topical formulations is to obtain quantitative information on the amounts that can enter, under in-use conditions, into the systemic compartment.  These quantities can then be taken into consideration to calculate a safety factor.  Justification for the use of in vitro dermal absorption studies on isolated skin is based on the fact that the epidermis, in particular the stratum corneum, forms the principal in vivo barrier of the skin against the penetration and uptake of xenobiotics in the body.

First introduced over 100 years ago, USP<231> is a colorimetric procedure based on the precipitation of insoluble metal sulfides.  This test for heavy metals is qualitative rather than quantitative.  It is not an element specific method, nor is it equally sensitive to each metal.  The limits specified by the test are based on the ability to observe the precipitate, rather than on the analysis of toxicological data.  The procedure does not necessarily detect all potential forms and/or valences of elements of concern when they are present as the oxo ions or in the organometallic form.  Chromium and nickel are potential contaminants from modern stainless steel processing equipment and are not detected by the USP<231> test method.  Other studies indicate inconsistent recoveries of monitor and standard solutions using USP<231> method II.2, 3

The efficient characterization of antibody drugs is important to both regulatory agencies and pharmaceutical companies to ensure the safety and efficacy of biopharmaceutical products.  Proteins with different sizes may show similar hydrophobicity and are therefore difficult to separate by traditional reversed-phase chromatography (RP).