3.7: Drugs Acting on the Kidney 2 Flashcards
Major class of drugs that work on the kidneys?
Diuretics
Give an example of Osmotic Diuretics?
How are they adminstered?
Mannitol
Given IV
Osmotic Diuretics:
How do they work pharmacologically?
How do they work physiologically?
What part of the nephron do they work at?
Pharmacologically inert
Physiologically, they produce an osmotic effect to cause inhibit water reabsorption
Work at proximal tubule
Osmotic Diuretics:
- Describe filtration at glomerulus?
- Describe their reabsorption?
Freely filtered at glomerulus
Cannot be reabsorbed
What is the action of osmotic diuretics in the proximal tubule?
Inhibit reabsorption of water
This dilutes the filtrate
Causes inhibition of sodium reabsorption (Secondary)
Give some examples where osmotic diuretics would be used?
- Given IV in acute kidney failure (Eg: After Hypovolaemia where kidneys stop producing urine and the distal tubule is at risk of drying up)
- Raised intracranial and intraocular pressure
-
Can mannitol (osmotic diuretic) enter organs that have tight junctions?
Describe the effect on these organs?
Give two example organs?
No, unable to enter
Instead increases plasma osmolarity to remove water from these organs
Reduces pressure
Eg: Eyes and Brain
Give two examples where osmotic diuresis can occur (accidentally) without the use of diuretics?
- Type 2 Diabetes (Glucose transporters are saturated, causes hyperosmotic filtrate –> Osmotic Diuresis)
- Contrast Dyes
Name a carbonic annhydrase inhibitior?
Acetazolamine
(A-SEAT-O-ZOLAMINE)
How do carbonic annhydrase inhibitors work?
Inhibit the action of carbonic annhydrase in the proximal tubule
This increases excretion of bicarbonate, sodium and water
Produces alkaline urine
Use of carbonic annhydrase inhibitors?
No longer used a diuretics
- Glaucoma and after eye surgery
- Prophylaxis of altitude sickness
- Infantile Epilepsy
What causes alkaline urine?
Why would you want alkaline urine?
Carbonic Annhydrase Inhibitor
Oral Bicarbonate
Citrate Salts
Relief of dysuria
Where is adolsterone secreted from?
Describe its affect on the collecting tubule?
Adolsterone secreted from adrenal cortex
Causes enhanced tubular sodium reabsorption and salt retention
Where is ADH secreted from?
What is its affect on the collecting duct?
Secreted from posterior pituitary
Causes enhanced H20 reabsorption
What is diabetes insipidus?
What are the symptoms?
Rare form of diabetes caused by ADH deficiency
Symptoms:
- Thirst
- Polydipsia
- Polyuria
- Large volume of dilute urine