How is it that G-d placed some of the Refua for various sicknesses in non Kosher animals? As a result a person who keeps Kosher has no choice but to take a medication that is produced from a non Kosher animal.
The animals that aren't kosher are forbidden not because of themselves, but because Hashem said so. When one is sick and has to eat a non kosher animal because of Pikuach Nefesh he has the Mitzva of Kashrut on one side and the Mitzva of "Vechai Bahem" (one should perform the Mitzvot and live) on the other. Since Pikuach Nefesh outweighs Kashrut, the situation is not that he is eating non kosher but he has no choice, rather the animal is not at all forbidden anymore, at this time, for this person. That is what Hashem wanted, and the prohibition is no longer valid for this person. Rabbi Ro'i Margalit