Answer to Question 1
The 2 kcals/cc tube feeding is more concentrated than the rest of his body and is being deposited into his stomach. The stomach will hold its contents and dilute it until it is the same concentration as the rest of the body. In this process water is added, some of which will not be reabsorbed. The net results are a loss of water from the body causing his dehydration. The large intestines try to compensate by absorbing more water and cause constipation. A lack of sufficient water intake, fiber, and exercise all contribute.
The new feeding is less concentrated and will not draw water into the stomach to dilute it, thus leaving more water in circulation; nor will it draw water into the intestines. If sufficient water is given with the feeding, the fiber will soften the fecal material and contribute to decreasing constipation.
Answer to Question 2
Drugs are usually tested with animals to determine their usefulness. Articles are published on the results and additional trials are conducted, each trial costing a drug time and money. If the results are favorable, they are usually repeated at other institutions. If still favorable, they are tested in human trials, and if successful, finally tested in large clinical trials. This may take years and millions of dollars. If proven to be effective, the FDA is petitioned to allow the drug to be placed on the market.
Water Loss Through Evaporation
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Anatomy & Physiology
Regulation of Water Reabsorption by ADH