Friday, July 2, 2010

Turning the Yellow Tide

The week we studied kidneys was the same week that my glandular fever decided to make its final stand to see just how much it could mess up my life. I therefore missed the introduction to the kidneys, and subsequently didn't understand a damn thing for the next few weeks. It is human nature to fear that which we do not understand, fear leads to anger, and anger leads to hate. God I hated the kidneys for the longest time. Then I jumped on this "studying" band wagon. They're like the coolest things ever, you just have to look a little deeper.
The majority of this section is about diuretics, you know, being the kidneys and all. I've divided them up according to which section of the nephron they act upon. There are few drugs that act upon the Proximal Convoluted Tubule, the main one is acetazolamide, causing excretion of bicarbonate and along with it more water.
Loop diuretics act upon the thick ascending limb and are the most powerful diuretics. They inhibit absorbtion of Na+ and Cl- and secretion of Mg2+ and Ca2+ resulting in what can be described as a "torrential flow" of urine which can cause a number of problems if not monitored. The most common loop diuretic is Fureosemide and is commmonly marketed under the name Lasix. They have a degree of vasodilation as well.
Thiazide diuretics act upon the Distal Convoluted tubule in a similar manner to loop diuretics (inhibiting Na+ and Cl- absortion), they are commonly used as anti-hypertensives.
Spironolactone and Eplerenone are potassium sparing diuretics and are often used alongside non-potassium sparing diuretics as they are quite weak in isolation. They act as aldosterone antagonists, inhibiting water and potassium absorbtion.
Amiloride and triamterene act on the collecting duct and are also potassium sparing diuretics.
There is only one common osmotic diuretic and that is mannitol. It is filtered by the glomerulus but is not absorbed, thus is raises the osmotic pressure within the nephron causing more water to be excreted.
Moving on from the diuretics we come to drugs used to alter urine pH. Why? Apparently carbonic anhydrase inhibitors and citrate will raise the pH and this reduces incidence of kidney stones. Ammonium chloride will lower the pH but no-one uses it any more.
Finally there are drugs to alter excretion of uric acid. The two main drugs that do this are probenecid, which stops reabsorbtion and allopurinol, which stops synthesis. These are important in relation to gout.

Leaving for QC tomorrow, and so far I've packed... A jacket. Yep, that's really it. Although I did have to go out and buy a case to pack it in. You'd think that's something I also would have considered earlier. Anyway....