Pharmacology: Thiazide Diuretics

Question 1

what part of the nephron do thiazide diuretics act on

Answer 1

distal convoluted tubule

Question 2

what are the main thiazide and thiazide-like diuretics

Answer 2

bendroflumethiazide(thiazide) and metolazone(thiazide-like)

Question 3

describe the action of thiazide diuretics

Answer 3

inhibit Na/Cl carrier by binding to the Cl site

Question 4

describe the effects of thiazide diuretics

Answer 4

prevent dilution of filtrate at early distal tubule, increase Na load at the collecting duct, increase Ca reabsorption

Question 5

what indirect effect do thiazide diuretics have

Answer 5

vasodilation

Question 6

describe the potency of thiazide diuretics compared to loop

Answer 6

loop more potent, ie more Na excreted and more diuresis

thiazide only modest diuresis

Question 7

describe the pharmacokinetics of thiazide diuretics

Answer 7

well absorbed from GI tract, enter nephron via organic anion transporter mechanism

Question 8

when are thiazide diuretics widely used in clinical situations

Answer 8

mild HF, hypertension

Question 9

what are the contraindications to thiazide diuretics

Answer 9

hypokalaemia

Question 10

when should caution be taken with thiazide diuretics

Answer 10

hyponatraemia, gout

Question 11

what are some of the side effects of thiazide diuretics

Answer 11

hypokalaemia, metabolic alkalosis, hypovolaemia/tension, erectile dysfunction

Question 12

describe how loop and thiazide diuretics result in K loss

Answer 12

increased Na load causes increased reabsorption of Na, and in Na/KATP that means K secretion into lumen, which is then excreted