Valuable information concerning stability of compounds can be obtained by using different media (water, hydrochloric acid or sodium hydroxide) for dissolution of active pharmaceutical substances. Furthermore, additional knowledge is gained by performing experiments at different temperatures. This research paper deals with the stability of amlodipine besylate and bisoprolol fumarate in different media at different temperatures, whereby certain conclusions are drawn. For stability assessment, chemical kinetics approach was used, and constant rate (k), half-time (t1/2) and activation energy (Ea) were used for prediction of compound stability degree. The stability of amlodipine besylate and bisoprolol fumarate were tested, both separately and in mixture, in water and in 0.01M HCl. All the investigated solutions were treated at two temperatures 25° and 70°C at the following time intervals: 0, 1 h, 24 h, 48 h and 72 h. Hydrophilic Interaction Liquid Chromatography – HILIC method, previously developed and validated, was used. On the basis of obtained results it was concluded that amlodipine-besylate was more stable in water than in acid medium, more stable in mixture rather than individually and more stable at lower temperatures. This was confirmed by the obtained values of monitored parameters: amlodipine besylate Ea = 30.68 kJ mol-1, k (25 °C) = 0.000333 mM h-1, k (70 °C) = 0.00169 mM h-1; amlodipine besylate in mixture Ea = 42,414 kJ mol-1, k (25 °C) = 1.27∙10-4 mM h-1, k (70 °C) = 0.0012 mM h-1. Based on the obtained approximate Ea value for bisoprolol fumarate in acid (59 kJ mol-1) and in water (56 kJ mol-1), bisoprolol fumarate showed excellent stability against the media in which it was studied. On the other hand, the temperature had a significant effect on the stability of bisoprolol fumarate. These results provide the relevant information about the stability of the tested active substances, and may be of importance during the development of an appropriate pharmaceutical product. A bigger influence on the stability of bisoprolol fumarate had a temperature effect.

In this paper, presented are the results of quality control of distilled water used for the reconstitution of powders for oral suspension usually intended for pediatric population. By reviewing the legislation, there is no clearly defined shelf life and storage instruction for this type of water. The conducted analyses confirmed that some pharmacies on the territory of Bosnia and Herzegovina use technical distilled water (water for accumulators, iron and antifreeze dilution), but also distilled water that does not meet quality requirements prescribed by European Pharmacopoeia. The tested water samples did not have adequately labeled packaging (production time and shelf life). The results showed that out of a total of 10 samples, 2 had conductivity greater than permissible, 3 had an exceeded limit for heavy metals, and 2 of the samples showed the presence of oxidisable substances. Out of all tested samples, only one sample met microbiological criteria for purified water. Based on the results of these analyses, it can be assumed that in many pharmacies around the country, inadequate distilled water is used which could endanger the stability of the pharmaceutical preparation and the safety of the patient. Bearing in mind that antibiotic oral suspensions are prescribed from the age of the infant, and that a large number of children consume these products for a long period due to frequent infections, the question arises as to whether prepared drugs accomplish their purpose and whether pharmacists are sufficiently aware of the importance of the quality of this type of water?

Lisinopril is an antihypertensive drug from the ACE inhibitor group. It is often used in practice and, in oral administration is characterized by very low percentage of resorption (~25%). Therefore, it is important to ensure the stability of this drug, since any degradation leads to a decrease in the percentage of resorption and an increased risk of sub-dosage of patients. In accordance with modern trends of pharmaceutical analysis, the chemical stability of lisinopril under the influence of various aqueous media was tested: distilled water, 0.1M HCl, 0.1M and 0.01M NaOH and 3% hydrogen peroxide solution. In order to clearly define the effect of elevated temperature on the stability of this drug, tests were carried out at 25 °C and 50 °C. High-pressure liquid chromatography was used as the method for stability testing. The obtained results clearly define that lisinopril is the most sensitive to hydrolysis in the base environment, where at 25 °C, in the first minute, it degrades ~100%. In this paper, kinetic parameters (degradation constant rate, half-life of degradation, order kinetics, and activation energy) were also determined, which enabled clear definition of the stability and identification of degradation products of lisinopril under the influence of various stress agents. In the degradation of lisinopril in neutral and acidic medium, impurity D is identified as the main degradation product.