PHARM Flashcards
What are the 4 major processes involved with renal drug elimination?
1) Measuring output of urine
2) Evaluating the quality of the urine (UA)
3) Measuring renal function based on CrCL/GFR
4) Measuring renal function with blood tests
Why will increasing urine pH increase renal elimination of weak acids? When would you do this and what drugs would be involved?
If a patient overdoses on aspirin or phenobarbitol, which are weak acids, you can increase the pH of the tubules ionizing the drugs, and making then less lipid soluble and more water soluble. As a result, the drugs will be less likely to reabsorb and elimination will increase.
NaHCO3 IV is used to alkalinize the urine
What are the differences between the Cockcroft Gault equation and the MDRD, and CKD-EPI
All are estimates of CrCL
The Cockcroft Gault equation is good for drug dosing. It includes variables such as age, gender, and weight. ml/min
MDRD is for diet modification in renal disease. ml/min/1.73m2
CKD-EPI- is used on EMR and is specific for stages of chronic kidney disease. Factors in race as well as the other factors mentioned for eCrCl. ml/min/1.73m2
What are some drugs involved in pre-renal causes of decrease renal function?
Diuretics, NSAIDS, ACEI can decrease renal function
NSAIDS and ACEI decrease GFR by inhibition of prostaglandins and angiotensin II respectively
What drugs are implicated in acute renal injury including acute tubular necrosis?
NSAIDS Radiocontrast agents Aminoglycosides Vancomycin Amphotericin B-Deoxycholate Colistin
Drugs inducing hyperkalemia?
ACEI/ARB
NSAID
K+ sparring diuretics
You patient is sick and being treated with ZAMO a great new drug. She’s a big gal and her CG equation gives you a value for eGFR using IBW. This value is on the border of some dosing guidelines for ZAMO.
Should you round up or down and why?
What are the units for CG equation?
What else should you do?
Round up, because she’s big and the equation used her IBW which is a conservative est.
Units are ml/min
Adjust the value based on the sex of the patient.
Your patient is sick and being treated with SUPER DRUG XY90. He’s a rale thin old man and the lab work gives you an eGFR using the MDRD using IBW. The value you get is on the boarder of the dosing guidelines for the drug.
What are the units for the MDRD?
What else should you know?
Round up or down?
ml/min/1.73m2
using IBW will likely be greater than his actual body weight. Use his actual weight
This adjustment should move you into a definitive drug dosing range. Rounding depends on your findings
Why is serum creatinine alone NOT accurate for the elderly?
They have decreased creatinine with age and this can mask the fact that their actual GFR has decreased.
Your patients GFR is 47 what do you need to do with their renal drug dosage
Adjust when drops below 50-60 ml/min
What’s the MOA of TMP-SMX? What type of drug is it?
Bacterial inhibition of folate metabolism by blocking dihydrofolate reductase thus preventing the formation of Tetrahydrofolate (active form used for DNA and RNA sysnthesis).
Bacteria synthesize folate from Para amino benzoic acid PABA which mimics folic acid.
Sulfa drug- sulfonamide antimicrobial
They have a synergistic effect!!!
Which drugs for UTI should be avoided if you suspect acute pyelonephritis?
Nitrofurantoin and Fosfomycin
When is TMP-SMX indicated in cystitis treatment?
If you have at least 80% sensitivity to the drug on the antibiogram and patient has no sulfa allergy
Nitrofurantoin and Fosfomycin are indicated for UTI under what circumstances?
If E.coli are more than 20% resistant to TMP-SMX or if patient has a sulfa allergy.
TMP-SMX aka what else?
Cotrimoxazole
Trim sulfa
