Drugs and the kidney Flashcards
What is excreted more readily by the kidney?
→polar compounds more than non polar compounds
→non polar compounds can be reabsorbed by the kidney
What are the three methods of drug excretion by the kidney?
→ Glomerular filtration
→ Tubular reabsorption
→ Tubular secretion
What size do drugs have to be to be freely filtered?
→Smaller than 20 kDA it is freely filtered
What are drugs bound to that doesn’t allow them to be filtered?
→ when bound to albumin
What is the clinical importance of whether a drug is bound to albumin or not and give an example?
→ Warfarin
→ 98% bound to albumin
→ long half life - stays in the body for long
How are drugs that are not bound removed?
→ removed by secretion
→ non specific cation and anion transporters for charged drugs
How is morphine removed?
→ Cation transporter
How is penicillin removed?
→ Anion transporter
What does the degree of drug ionization depend on?
→ pKa and pH of environment
What do diuretics cause?
→ Increase in urine output (diuresis)
What do diuretics increase?
→ Na+ (natriuresis)
→ K+ excretion (hypokalaemia)
What are diuretics used for?
→hypertension
→acute pulmonary oedema
→ heart failure
What are the two major groups of diuretics?
→ affecting H2O excretion
→ increasing electrolyte excretion
What are the diuretics that affect water excretion?
→ water
→ ethanol (decreases ADH release)
→ osmotic diuretics
What are the diuretics that increase electrolyte excretion?
→ Carbonic anhydrase inhibitors
→ loop diuretics
→ Thiazides
→ K+ sparing diuretics
What is reabsorbed at the PCT and how (site 1 +2) ?
→ 65% of Na+ is reabsorbed
→ by the Na+ and glucose symporter
→ Na+/H+ antiport
What is reabsorbed at the descending looP?
→ Pure water
What is reabsorbed at the ascending loop ( site 3) ?
→ NaCl
→ K+
→ Cl-
What is reabsorbed at the DCT and how (site 4-6) ?
→ NaCl and H2O 4
→ Na+ through the eNAC channels in exchange for K+ - stimulated by aldosterone - 5
→ Na+/H+ exchanger - stimulated by aldosterone -6
How is mannitol usually administered?
→ I.V