Help with transplant immunosuppressant maintenance regimens

Immunosuppressants aim to prevent this from happening:

Screen Shot 2017-01-29 at 3.52.15 PM.png
Organ rejection.

But too much immunosuppression can cause this:

Screen Shot 2017-01-29 at 7.16.22 PM.png
Drug toxicity and dead fish.

That’s why people can’t just be on ONE immunosuppressant after transplant: the doses required would be too toxic, so the effect is spread out over 2-3 medications.

Considering that the historical option was total body irradiation, we’ve come a long way. Azathioprine was the first chemical immunosuppressant, but cyclosporine, which came onto the scene in the 1970s, revolutionized kidney transplant survival rates.

***One of my chiefs last year made an amazing figure on maintenance transplant immunosuppression. It is worth this whole post and I highly encourage you to take a look!***

For us peons, what are the commonly used immunosuppressants? 

Mechanism of Action Starting doses Monitoring required Side effects
Tacrolimus (Prograf) Calcineurin inhibitor (CNI) 0.075-0.2 mg/kg/day Cr, drug trough Neurotoxicity, nephrotoxicity, diabetes, alopecia *many drug interactions
Cyclosporine (Neoral) Calcineurin inhibitor (CNI) 2-6 mg/kg/day Cr, drug level Neurotoxicity, nephrotoxicity, diabetes, hypertrichosis, gingival hypertrophy
Mycophenolate mofetil ## (CellCept, MMF) Purine analogue, prevents T cell proliferation 500-1000 mg daily CBC, drug trough GI/diarrhea, myelosuppression, lymphoid neoplasm *many drug interactions, needs dose adjusted for renal failure
Azathioprine (Imuran) Purine analogue, prevents T cell proliferation 1-3 mg/kg/day (maintenance) CBC, LFTs, Cr, check TPMT Nausea/vomiting, myalgias, leukopenia, transaminitis
Sirolimus (Rapamycin) mTOR inhibitor Weight based; 1-5 mg/day (maintenance) Drug level Pneumonitis, arthralgias, edema, hypertension, bone marrow suppression, hyperlipidemia
Everolimus (Afinitor) mTOR inhibitor 0.75-1 mg twice daily Drug level arthralgias, edema, hypertension, bone marrow suppression, hyperlipidemia
Prednisone The dozens of things steroids do Varies widely, minimum 7.5 mg every other day or 5 mg daily n/a Osteopenia, diabetes, headache, Cushing’s, weight, cataracts, psychosis (and many others)

## Mycophenolate can be either mycophenolate mofetil vs. sodium. The difference is that the sodium formulation (Myfortic) is an enteric capsule that may prevent some GI effects like diarrhea(?) but the jury is still out.

What are the major side effects of immunosuppression?

screen-shot-2017-01-29-at-7-04-46-pm
From the National Kidney Foundation

What is the underlying biology? ***This is a gross oversimplification.

Normally, T cells go scouting and if they encounter an antigen-presenting cell with foreign material on it, a chain reaction of events is started: calcineurin is activated, leading to a surge of IL-2 and its receptor, IL-2R, which upregulates the mTOR pathway, which leads to DNA nucleotide synthesis so that the T cell can multiply and generate an immune response.

Notice that the bolded words are the targets of the 6 immunosuppresants in the chart above.

Transplant pharmacology is REALLY COMPLICATED and you can do an entire fellowship training program for this. This is an excellent, but 100-page document from a Canadian transplant website. Here are two organ-specific guides/reviews regarding immunosuppression:

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