Block 2 - Diuretic Med Chem Flashcards
Label the corresponding diuretic and how it effects the the nephron pathology
What is the MOA of osmotic diuretics?
Allows water to be retained in the tubules preventing it from being reabsorbed into systemic circulation
What is the predominant osmotic diuretic? When is it used?
Mannitol (Osmitrol) is used is the hospital for trauma (head) patients usually with CNS fluid retention
Example of osmotic diuretics?
Mannitol
Sorbital
Glycerin
Isosorbide
MOA of carbonic anhydrase inhibitors?
Causes diuresis by inhibiting H+ formation -> less Na+ and H2O reabsorption
What are the disadvantages of using carbonic anhydrase?
Being the oldest diuretic class, 99% of the drug must be inhibited to be effective
Therefore, not considered first-line
How much of sodium is filtered by carbonic anhydrase?
2-5%
Example of carbonic anhydrase?
Acetazolamide (Diamox)
What is Acetazolamide’s indication?
Diamox is used to treat glaucoma by reducing the amount of aqueous humor that causes the pressure
How does Diamox’s structure contribute to its bioavailability and excretion?
Sulfonamide has a negative charge, however, lipophilic structure gives it >90% PO F and excreted unchanged
What is the outcome of chronic Acetazolamide use?
Prolonged use causes urine to become alkaline -> acidosis in blood and use is very limited
What functional group became the basis of popular diuretic structures?
Sulfonamide
How does thiazide structures differ from carbonic anyhydrase?
Contain disulfonamide analogues
What increases thiazide activity?
Chloro and amino substitutions causes acetylation of amino groups causing ring closure
What is the MOA of benzothiadiazines?
Inhibits Na+/Cl- transporter in the DCT -> Inhibits Na+ reabsorption (saluretic)
What is the main diurectics indicated for HTN?
Thiazides
Describe the thiazides SAR?
- Benzothiadiazide-1,1-dioxide is essential
- Sulfonamide @C7 is essential for activity
- EWG @C6 greatly enhances activity (EDG reduces)
- 3,4-dihydro derivative enhance activity 10-fold
- Lipophilic group @C3 increases DOA
- Alkyl substitution @N2
Chlorothiazide? F? t1/2? DOA? Metabolism?
- Diuril is least potent and simplest thiazide
- Low F
- 1-2hrs
- 6-12hrs
- Unchanged urinary excretion
Hydrochlorothiazide? F? t1/2? DOA? Metabolism?
- HydroDiuril has medium potency
- High F
- 6-15hrs
- 6-12 hrs
- Unchanged urinary excretion
Most popular diuretic for HTN