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Browsing by Subject "ophthalmics"

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  • Ollinkangas, Joni (2022)
    The problems caused by hypromellose in sterile filtration of ophthalmic products in the pharmaceutical industry were investigated. The research project was performed at NextPharma Oy's ophthalmics manufacturing facility in Tampere during the autumn of 2020. Hypromellose is an excipient commonly used in ophthalmic products as a viscosity enhancer to prolong the contact time of the preparation on the eye surface. In the ophthalmics compounding process, hypromellose is first dispersed by slowly sprinkling it into a hot solution and thoroughly mixing, after which the solution is cooled to room temperature. During cooling, the hypromellose dissolves and gels, increasing the viscosity of the solution. Incomplete dispersion or dissolution of hypromellose during the manufacturing process can slow down the filtration rate or even clog the filter completely due to undissolved hypromellose polymer material. Hypromellose is an industrially produced cellulose derivative that often contains some amounts of unreacted cellulose and other sparingly soluble polymer particles as impurities, which can also cause problems in filtration processes. Sterile filtration is a commonly used sterilization method for ophthalmic products, in which the prepared bulk solution is filtered through a 0.1 to 0.2 µm pore size filter membrane into a sterile receiving vessel. Due to the very small pore size, sterile filters are easily clogged if the solution contains poorly dissolved material. The purpose of this work was to collect additional information on the possible causes of clogging caused by hypromellose and to determine whether the filterability of a solution containing hypromellose can be improved by optimizing the manufacturing process parameters. The design of experiments was prepared, creating a two-level full-factorial test matrix without replicates and with three centre points. Four different process parameters were used (mixing time, mixing speed, dispersion temperature, and cooling temperature). Minimum and maximum levels for the parameters were obtained in the initial tests, after which the test solutions were prepared and filtered in a randomized order according to the test matrix. The aim of the screening was to find out which parameters were affecting the filterability and what would be their optimal combination that would maximize the filtration rate and the yield of filtration. Finally, the optimized parameters were used to test different batches of hypromellose, comparing the results to previous filtration tests. Additionally, an alternative hypromellose dispersion method was tested to minimize the amount of insoluble material remained during the dispersion and cooling steps. Of the parameters tested, mixing speed was the least significant, while cooling temperature had the most effect on the filtration results. The solutions with lower cooling temperature had better filtration results, which may be due to reduced aggregation of hypromellose due to increased hydration of the polymer chains. The temperature behaviour of hypromellose solutions could be an interesting subject for further investigation. Longer mixing times and higher dispersion temperatures produced slightly better filtration results on average, but the differences were not statistically significant. Most challenging in the study was controlling the temperature and mixing of the solutions, and the retention of insoluble hypromellose material at the walls of the compounding vessel. The alternative dispersion method gave promising preliminary results, but the method still requires further testing. It would be important to also find the root cause of the filter clogging mechanism e.g., by further analysing the clogged filter membrane. The study provided additional useful information of the behaviour of hypromellose solutions in solution preparations and during sterile filtration, which has been helpful in solving production problems.