Question

THE PROBLEM After reading about the risks and benefits of taking vitamin supplements as part of your daily routine. you decide to start taking vitamins C and E to decrease your risk of heart attack and cancer. Some articles recommend taking mega doses more than once a day, while others suggest you take the Recommended Daily Allowance (RDA). The dose of a medication must be high enough to maintain the therapeutic effect but not so high that it causes side effects. When a drug is given, it reaches its peak concentration (C ) in the blood pretty quickly. The concentration then decreases as the drug is broken down or removed from the blood. The lowest concentration, just before the next dose, is referred to as C or the trough level. The half-life of the medication must be long enough to allow for a reasonable dose schedule. Many products are being developed with a half-life long enough for them to be taken only once each day. Figures 2 and 3 show the concentrations of vitamins C and E in the blood as a function of time after the initial dosage. Note the scale difference of the x-axes. You have to use your knowledge of solubility to determine which figure is for vitamin C and which is for vitamin E What dosage and frequency would you suggest, considering the structures and solubility properties of these two different vitamins?

Answer 1

Vitamin X = Vitamin C, and Vitamin Y = Vitamin E. Since, the C_max for vitamin X is much higher than vitamin Y, therefore the solubility of vitamin X must be higher than vitamin Y. Between vitamin C and E, the vitamin contains ascorbic acid which is highly soluble in water, whereas vitamin E is fat soluble. Since blood contains mostly water (ca. 92 %), therefore, vitamin C is highly soluble in blood compared to vitamin E.

Since, the half life of vitamin C is very less (30 minutes) compared to vitamin E (2 days).Therefore, the dosage of vitamin C shoud be more than that of the vitamin E. The C_min for vitamin Cwould be 3 hours whereas for vitamin E it would be ca. one week. Thus, vitamin C dosage should be 4 times a day, and the vitamin E dosage should be once in a week.