Unfortunately, I don't know anything about either of those meds.
In Dr. Hodkins' book, "Your Cat: Simple New Secrets to a Longer, Stronger Life" she writes that "Another strategy that works well [to effectively remove substantial amounts of the dietary phosphorus from the food] is the addition of chopped, cooked egg white to the patient's wet diet. Egg white is high in top-quality protein but contains no phosphate, so it effectively "dilutes" the phosphorus in the food. This strategy allows the cat to have the protein building blocks of repair and energy production available in abundance, while reducing the intake of a nutrient that may be harmful to the patient. This is truly the best of both worlds."
I don't know if this will help, but Miss Kitty also had anemia due to her chronic diarrhea. She showed up in my neighborhood one year and a neighbor was feeding her, then I started to feed her, trapped her and brought her home. I don't know her history but suspect she was abused. She did NOT do well at the vet's and needed sedation, and I could not hold her to medicate her. I write all this to explain that giving her medications was a challenge, and neither vet that saw her even suggested doing anything about her anemia.
What I finally did was sprinkle a tiny amount of B-100 complex supplement (for humans) in her food. While it didn't contain iron, it did have 100mg of each B vitamin to at least help her. B vitamins are water soluble, meaning your excrete what you don't use, and they work with iron, if I remember correctly. In fact, I just checked one of my nutritional books and under iron, it mentions "In some cases, a deficiency of vitamin B6 (pyridoxine) or vitamin B12 can be the underlying cause of anemia." [Prescription for Nutritional Healing, 4th Edition, by Phyllis A. Balch, CNC]. So you might want to consider adding a good quality B-100 complex to help your cat. If you're interested, I'm happy to give you the name of the brand I used.
It took about 3 months of adding it to every meal and Kitty had more energy, so I think it did help her. I don't think it would cause any harm. Does the vet know what's causing the anemia? Is it connected to the CKD?