diuretics (thiazides)

Question 1

What are thiazide diuretics first line treatment for?

Answer 1

hypertension.

Question 2

What are the names of thiazide diuretics?

Answer 2

Bendroflumethiazide; chlortalidone; cyclopenthiazide; indapamide; metolazine; xipamide.

Question 3

MOA for diuretics?

Answer 3

Diuretics stimulate the production of urine. In the kidney, the blood is filtered in small filtration units called nephrons and after processing, the filtered fluid becomes urine. This means that urine production is increased so more fluid is removed from the blood, therefore blood volume decreases. This in turn reduces preload in the left ventricle and a lower preload means a lower stroke volume and a lower cardiac output. Diuretics work by a common mechanism- altering the osmotic balance in the kidneys and so increasing the amount of urine produced. Diuretics act on the distal tubule to inhibit NaCL reabsorption, leading to excretion of Cl, Na and H20. The increases Na in the distal tubule results in K and H exchange increasing their excretion.

Question 4

How do thiazide diuretics work on the treatment of hypertension?

Answer 4

Thiazide and thiazide like diuretics act on the neohron mainly at the proximal part of the distal tubule. Sodium excretion and urine volume are increased by interference with transfer across the cell membrane. The result is a reduction in blood volume, meaning the heart has less of a workload.

Question 5

contraindications?

Answer 5

addisons disease, hypercalcaemia, hyponatraemia, refractory hypokalaemia, symptomatic hyperuricaemia.

Question 6

common side effects?

Answer 6

altered plasma-lipid concentrations; gout; hypercalcaemia’ hyperglycaemia; metabolic/ electrolyte imbalances; postural hypertension; impaired glucose tolerance.

Question 7

monitoring requirements?

Answer 7

electrolytes should be monitored particularly with high doses and long term use.