Water medication can only be effective if the pharmaceutical product completely dissolves in water and remains dissolved for a sufficient period of time. Unfortunately, a product can sometimes dissolve initially but proceed to precipitate shortly after. This depends on several factors:
- The temperature of the water
In general, solubility in cold water is much lower. If water cools down downstream (e.g. if some segments of the pipes are outside), there is a risk of product precipitation and subsequent nipple clogging.
- The pH of the solution
The pH of the water could change if water comes in contact with oxygen from the air, for example in open systems. These changes in pH may cause the active ingredient to precipitate.
- Other elements in the water
Some active ingredients can bind with ions in the water and form complexes. For example, tetracyclines can bind with iron if the iron content in the water is > 5 mg/L. If the system has galvanised pipes, the iron concentration can be higher than in the stock solution, resulting in precipitation.