Authors:G. Navaneethan, K. Karunakaran, and K. P. Elango
A stability-indicating reversed-phase high-performance liquid chromatography method has been developed and validated for the estimation of nevirapine and its impurity, namely the related compound A and the related compound B in combination drug product. The separation was carried out on SUPELCOSIL ABZ (150 mm × 4.6 mm, 5 µm) column. Tablet was admitted to the stress conditions of acid, base, peroxide, thermal, humidity, and photolytic degradation. The degradation products were well resolved from nevirapine, and its impurities peaks and the peak homogeneity of compound were obtained using photo diode array detector, hence proving the stability-indicating nature of the method. Moreover, to prove the selectivity of the method, individual lamivudine, zidovudine, and their main impurities were injected. The developed method was linear for nevirapine from 120 to 360 µg mL−1, and the linear regression obtained was >0.999. Recovery data were in the range 98.2–101.5%. The limit of quantification for related compound A and related compound B was found to be 0.02%. The proposed method was validated according to the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use guidelines and proved suitable for stability testing and quality control of these drugs in pharmaceutical preparations.
Authors:Danielle Giron, S. Monnier, M. Mutz, P. Piechon, T. Buser, F. Stowasser, K. Schulze, and M. Bellus
Adequate very sensitive quantification methods are needed for the development and are also now required for the monitoring
of undesirable solid form(s) as routine tests. The pre-requisite for quantitation are selectivity, sensitivity and most important
the purity of standards and their proper storage, what is a challenge for metastable forms.
Several analytical techniques are available such as X-ray diffraction, spectroscopy, thermal analysis and microcalorimetry.
The different steps of the validation of the analytical methods and problems to be solved are discussed. Examples illustrate
the different techniques and compare their possible advantages and limits. The relative standard deviation of measurements
should allow for checking the homogenization procedure of mixtures for calibration. The validation should be carried out following
ICH guidelines for validation of analytical methods. Comparison of different techniques in adequate concentration range add
confidence in the analytical results.
Authors:Ming-Chao Huang, Shih-Chieh Fang, and Shao-Chi Chang
The pharmaceutical industry is heavily R&D intensive, with incumbents requiring ten to 15 years on average to develop new drugproducts from initial discovery to final FDA approval. The cost of a new drug
included in this article, our extensive previous experience in drugproduct analysis and exhaustive literature searches through SciFinder® (Chemical Abstracts), ISI Web of Science, and Google Scholar were employed to guide our method development and
The health authorities require that equipment used in the pharmaceutical industry is clean prior to use. The main raison is to prevent any contamination or adulteration of the drugproducts. In the past, a number
Authors:Marco Júnio Peres-Filho, Marilisa Pedroso Nogueira Gaeti, Stela Ramirez de Oliveira, Ricardo Neves Marreto, and Eliana Martins Lima
], since incompatibilities between drug and adjuvants may negatively affect both the stability and the bioavailability of drugproducts [ 1 , 3 – 6 ]. A satisfactory formulation work must include a careful selection of excipients [ 3 ], taking into
Authors:D. Giron, P. Remy, S. Thomas, and E. Vilette
The amorphous state of solids is characterized by a higher chemical and physical reactivity and a hygroscopic behaviour. Furthermore processing of amorphous powders is often difficult, because of the instability. Fast crystallizations, precipitations and milling favour the formation of the amorphous state. Galenical processes like granulation, drying, lyophilization, mixing, may also induce amorphous regions in the drug products.
Several drug substances or excipients are hygroscopic. The uptake or loss of water of such substances is generally difficult
to control during processing or storage of drug products. DSC instruments with sub-ambient temperature equipment allow the
determination of the amount of freezable water by measuring the corresponding melting enthalpy.
The determination of freezable water adds valuable information complementary to TG analysis for understanding the processing
and storage of raw materials and drug products. Several substances were tested as is, without treatment, after storage at
92% r.h. and after equilibration with water. The results of these experiments showed that it was possible to demonstrate defined
hydrate formation, to determine the upper level of binding of water in amorphous substances and to confirm reversible hydrate
formations demonstrated by temperature resolved X-ray diffraction.
Modern thermal analysis, microcalorimetry and new emerging combined techniques which deliver calorimetric, microscopic and
spectroscopic data offer a powerful analytical battery for the study of pharmaceuticals. These techniques are very useful
in all steps of development of new drug products as well as methods for quality control in production. The characterization
of raw materials enables to understand the relationships between polymorphs, solvates and hydrates and to choose the proper
development of new drug products with very small amount of material in a very short time. Information on stability, purity
is valuable for new entities as well as for marketed drug substances from different suppliers. Excipients which vary from
single organic or inorganic entity to complexes matrixes or polymers need to be characterized and properly controlled. The
thermodynamic phase-diagrams are the basis of the studies of drug-excipients interactions. They are very useful for the development
of new delivery systems. A great number of new formulations need proper knowledge of the behaviour of the glass transition
temperature of the components. Semi-liquid systems, interactions in aqueous media are also successfully studied by these techniques.