Pharmacology of CKD

Question 1

How does the patient present?

Answer 1

BP - 170/110
HR - 72
The urinary dipstick test was positive for protein
Creatinine (140umol/L) and urea (11mmol/L)
ABPM - 165/110
Renal ultrasound showed unobstructed, slightly small kidneys (10.5cm left kidney and 10cm right kidney)

Question 2

Write a problem list and calculate his eGFR

Answer 2

Proteinuria

Stage 2 Hypertension

Chronic Kidney Disease

eGFR = 48ml/min (58ml/min if he is of black origin)

Question 3

What are the therapeutic objectives?

Answer 3

Reduce BP to reduce Cardiovascular risk

Treat CKD

Question 4

What treatment would the GP initiate at this point?

Answer 4

Amlodipine for HTN

Aim for lower target than normal due to CKD

Tight BP control to slow CKD progression

Conservative measures - Smoking, salt and exercise

Question 5

What treatments should the nephrologist initiate for the proteinuria and what treatment might need to be stopped?

Answer 5

ACEi

Stop Amlodipine as it may lower BP too much

Question 6

His use of trimethoprim invalidates the GFR calculator. Why is this, and do you think his GFR has in fact changed?

Answer 6

Trimethoprim inhibits the active secretion of creatinine so the equation to calculate GFR is no invalid

Breaks the link between GFR and creatinine

Question 7

What drugs are further contributing to his GFR?

Answer 7

Ibuprofen - Inhibits PG synthesis and reduces renal blood flow

ACEi - Reduces perfusion pressure in glomerulus exacerbated by sepsis

Question 8

What are the two things to consider when prescribing for a patient with reduces renal function?

Answer 8

Might the drug damage the kidney

Is the drug eliminated by the kidney?