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This work was aimed at the use of dissolution testing and similarity factor to assess the level of damage taken by active drug microspheres during compression in tablet dosage form. To achieve that, combinations of suitable excipients were used to protect drug microspheres during compression. The excipients were used in the form of powders, granules or placebo pellets prepared by extrusion-spheronization technology. The excipients were evaluated alone, in combinations and post-compression into compacts. Preliminary experiments included assessing density, hardness, friability and disintegration of all the selected excipients. Based on such experiments it was found that the flowability of combination of powders was more acceptable than individual excipients. Two combinations of microcrystalline -starch and microcrystalline cellulose -calcium carbonate granules were selected to be compressed with pellets of the active pharmaceutical ingredient ketoprofen. In all the combinations used there was a significant amount of damage to drug pellets. The kinetics of drug release appears to follow the zero-order rate, which remained unchanged even when a significant degree of damage to pellets occurs. It was found that a high level of excipients is required in order to prepare microspheres as a rapid disintegrating tablet.

IntroductIonThe stability of finished pharmaceutical products depends mostly on environmental factors such as ambient temperature, humidity, atmospheric oxygen, light, and on product-related factors. [1] The objective of stability study is usually to determine the shelf life and also to assure the stability of a drug product within the determined time period. Any physical, chemical, or microbiological change in the product potentially impacts the efficiency and integrity of the final product and may therefore directly or indirectly impact patients' health. Chloramphenicol (CH) is a broad-spectrum antibiotic which is more commonly used in ophthalmic dosage forms. [2] The United States Pharmacopeia (USP) states that "CH eye drop solution should be stored at the low temperature of 2°C-8°C." [3] However, there is a common observation of noncompliance with this specific storage condition among pharmacists. [4] And that CH eye solution is stored similarly to its ophthalmic ointment dosage form at room temperature. Such noncompliance could result in potential reduction in product shelf life. [5][6][7] However, there are some mathematical models which can be used to estimate the "true" shelf life of a dosage form based on its actual storage temperature. [8] Hence, the aims of this work were to predict the true (remaining) shelf life of commercially marketed CH eye drops using the Q 10 method, followed by confirmation of findings by the assay of active ingredient content, sterility testing, and minimum inhibitory concentration (MIC) determination using official methods during 6 month storage at variable temperatures (4, 25°C). Also, to conduct an accelerated stability study to characterize the effect of elevated temperature on the rate of change in the ophthalmic solution. MaterIals and Methods MaterialsPhenicol ® eye drops (API-Jordan), CH reference standard (API-Jordan), Escherichia coli standard ATCC 10536 (Becton-Dickinson, France), culture media used:Aims: The aim of this work is to "predict" the remaining shelf-life of chloramphenicol (CH) eye drops, commercially marketed, using the theoretical "Longland-Rowbotham model,"" followed by confirmation of findings by practical means. Materials and Methods: The methods used for the evaluation of CH-eye drops included the assay of the active ingredient, sterility testing, and minimum inhibitory concentration (MIC) determination using official methods during 6 months stability study at variable temperatures (4, 25°C). Furthermore, a 3-month accelerated stability study was carried out. Statistical analysis tests included Student's t-test and analysis of variance. Results: The prediction model indicated that in pessimistic conditions, the remaining shelf life was reduced to a merely 1 month following production (this is versus the 2 years expiration date given by manufacturer). However, the samples analyzed throughout a 6-month stability study revealed that storing CH solution at 4°C or 25°C does not produce any statistical difference regarding drug content, MIC, or steri...