Abstract
For the majority of the pharmaceutical dosage forms, the substances that are used maintain solid state under the standard storage conditions, i.e. powders. The interactions of pharmaceutical powders (active ingredient(s) and excipients) with liquids and vapors (particularly aqueous solutions and their vapors) occur almost always during the production process. From the physical point of view, the interactions among individual components may differ from the expected because chemically identical substances obtained from different producers vary very much. These differences influence either the production process and/or the pharmaceutical form properties. In order to overcome these problems it is necessary to establish a control over the physico-chemical properties of the used materials. The aim of this work was to determine physico-chemical properties of three powder clindamycin phosphate samples (labeled as sample S(1), S(2) and S(3)) acquired through different suppliers. All the analysis were made for the purpose of establishing possible differences among the tested samples that showed variable physical stability in the solution: recrystallization of the S(3) sample in the aqueous solution has been established during storage under standard conditions. On the basis of the obtained data it was possible to recognize the differences among the tested clindamycin phosphate samples and to explain the anomalous behavior of one sample. The surface free energy components for the investigated clindamycin phosphate samples were determined using Wu and Good- van Oss method. The investigated clindamycin phosphate samples exhibit certain differences in surface free energy values as well as in surface morphology and thermal behavior. Comparison of alpha + and alpha - values leads to the conclusion that all three clindamycin phosphate samples perform as monopolar, more electron acceptors, i.e. Lewis acids. However, an important difference exists between samples S(1) and S(2) on one and S(3) on the other side. Sample S(3) exhibits stronger acidic behavior, what could be connected with its recrystallization during the storage. The samples S(1), S(2) and S(3) have different melting points e.g. "onset" temperatures. When the melting points move towards 200 (o ) C, the width of the "onset" temperature peak is especially important. In the case of wider peak, the potential for recrystallization seems to be higher. According to the stated, the sample S1 would be the "sample of choice" for the formulation of the stable pharmaceutical dosage form and has not shown any recrystallization tendencies during the storage period.
Highlights
Technological processes of incorporating the active pharmaceutical ingredient(s) in the appropriate pharmaceutical dosage form are often very complex, difficulties may occur in simple processes
From the physical point of view, the interactions among individual components may differ from the expected because chemically identical substances obtained from different producers vary very much
The theory underlying the Young equation includes rigorous assumptions: the solid must be smooth, homogeneous and rigid, the solid must not be perturbed by chemical interaction or by adsorption due to a liquid phase, and there should be a unique contact angle
Summary
Technological processes of incorporating the active pharmaceutical ingredient(s) in the appropriate pharmaceutical dosage form are often very complex, difficulties may occur in simple processes. The interactions of pharmaceutical powders (active ingredient(s) and excipients) with liquids and vapors ( aqueous solutions and their vapors) occur almost always during the production process. They depend on the physico-chemical properties of all the components in the process (1). From the physical point of view, the interactions among individual components often differ from the expected because chemically identical substances obtained from different producers vary very much It influences either the production process and/or pharmaceutical form. These substances may vary in the quantity of the impurities, different polymorphic modifications present, degree of crystallinity, particle size etc This variability may cause more or less serious technological problems during the production process. To overcome these problems it is necessary to explain and control all relevant physico-chemical properties that influence the technological processes and stability of pharmaceutical form
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