DIURETICS MBBS UG

1. Physiology of Urine
Formation
Presented by
Dr Arun K Negi
Senior Resident
IGMC, Shimla (H.P.)
Dated: 11th March 2024
Mail id: dbrahmaand@gmail.com

2. Learning objectives
✓ Brief overview of Renal physiology & urine
formation
✓ Introduction to Diuretics
✓ Classification of Diuretics
✓ Adverse effects
✓ Therapeutic uses
✓ Summary
✓ Bibliography

3. Important terminology
▪Diuretic: Agent that increases urine volume.
✓ Drugs that increase the sodium and water excretion
from body through urine.
▪Natriuretic: It causes an ↑se in renal Na+ excretion.
▪Aquaretic: It ↑ses excretion of solute free water.
▪Urearetics: these agent blocks urea transport, which
results in ↑sed urine output & urea excretion, but not
increased excretion of electrolytes.

4. Physiology of Urine Formation
▪ Three major steps are involved :
1) Glomerular filtration.
2) Tubular Reabsorption &
3) Active tubular secretion.
▪ Nephron can be divided into four sites :
- Proximal tubule
- Henle’s loop
- DCT
- Collecting duct.
▪ Normal GFR is 125ml/min or 180 litres/day, of which
99% gets reabsorbed Only 1.5 litres is excreted as urine.

6. Structure of Nephron

8. Proximal tubule
✓ Freely permeable to water.
✓ Water is reabsorbed passively through both
transcellular pathway & paracellular pathway
✓ Transcellular transport : AQP1
✓ Paracellular pathway : Claudin-2
✓ Active absorption of NaCl, NaHCO3, Glucose, Amino
Acids, Organic Solutes in early proximal tubule
✓ K+ ions are reabsorbed by the paracellular pathway
✓ This is followed by passive absorption of water.

9. •65-80 % filtrate is reabsorbed &
•Most reabsorption is coupled to Na+ ion movement
SUBSTANCE % OF FILTRATE REABSORBED IN PCT
(H2O) WATER 60 %
(Na) SODIUM 66 %
NaHCO3 (Sodium
bicarbonate)
85%
K (POTASSIUM) 65%
ORGANIC SOLUTES :
GLUCOSE & AMINO ACIDS
100 %
UREA 50 %
PHOSPHATE 80%

10. Descending Loop of Henle (LH)
✓ Descending limb- Permeable to water.
✓ Osmolarity increases along the this portion because
of the counter current mechanism, that is responsible
for water reabsorption.
✓ This results in tubular fluid with a three fold increase
in Na+ & Cl- concentration

11. Thick ascending loop of Henle
✓ Impermeable to water but Permeable to Na+ , K + &
Cl-
✓ Active Reabsorption of Na+ , K+ & Cl- is mediated by a
Na+ / K+ /2Cl- co transporter
✓ Both Mg2+ & Ca2+ are reabsorbed by paracellular
pathway.
✓ About 25% -30% of the filtered sodium is absorbed
here.
✓ Loop diuretics act here and blocks the co-transporter.

13. Distal convoluted tubule
✓ In the Early distal tubule 10% of NaCl is reabsorbed
by Na-Cl symport transporter mechanism.
✓ On reaching the DCT almost 90% of sodium is
already reabsorbed.
✓ Calcium reabsorption, under the regulation of
parathyroid hormone, is mediated by
- An apical channel & then transported by Na+ / Ca2+
exchanger into interstitial fluid
✓ Thiazides block Na-Cl symport transporter
system.
✓ Thiazides (moderate efficacy) : block only 10% of Na
reabsorption.

15. Collecting Tubule and Collecting Duct
✓ The principal cells of the CT & duct are responsible
for Na+ , K+ & water transport
✓ Whereas intercalated cells affect H+ secretion.
✓ Aldosterone- On membrane receptor and cause
sodium absorption by Na+/H+/ K+ exchange.
✓ ADH- (vasopressin) binds to V2 receptors to
promote the reabsorption of water through Aquaporin
2 channels.

17. The relative magnitudes of Na+
reabsorption at sites
❖ PT - 65%
❖ Asc LH - 25%
❖ DT - 9%
❖ CD - 1%.

18. SEGMENT FUNCTIONS WATER
PERMEABILI
TY
PRIMARY
TRANSPORTE
RS & DRUG
TARGETS
DIURETIC
S WITH
MAJOR
ACTION
GLOMERUL
US
FORMATION OF
GLOMERULAR
FILTRATE
EXTREMELY
HIGH
NONE NONE
PCT REABSORPTION OF
65% OF FILTERED
Na/K/Ca/ Mg
85 % of HCO3 ; 100
% GLUCOSE, Amino
Acids.
ISOSMOTIC
REABSORPTION OF
WATER
VERY HIGH Na/ H (NHE3),
CARBONIC
ANHYDRASE;
Na/ Glucose
cotransporter
s2
SGLT2
CARBONI
C
ANHYDRA
SE
INHIBITO
RS
PROXIMAL
TUBULE ,
STRAIGHT
SEGMENT
SECRETION &
REABSORPTION OF
ORGANIC ACIDS &
BASES INCLUDING
URIC ACID & MOST
VERY HIGH ACID (URIC
ACID) AND
BASE
TRANSPORTE
RS
NONE

19. SEGMENT FUNCTION WATER
PERMEABILITY
PRIMARY
TRANSPORTERS
AND DRUG
TARGETS
DIURETIC WITH
MAJOR ACTION
THIN
DESCENDING
LIMB OF LOOP OF
HENLE
PASSIVE
REABSORPTION OF
WATER
HIGH AQUAPORINS NONE
THICK
ASCENDING LIMB
OF LOOP OF
HENLE
ACTIVE
REABSORPTION OF
15-25 % OF
FILTERED Na/K/Cl
Secondary
reabsorption of Ca
& Mg
VERY LOW Na/K/2Cl(NKCC2) LOOP DIURETICS
DISTAL
CONVOLUTED
TUBULE
ACTIVE
Reabsorption of 4-8
% of filtered Na &
Cl; Ca 2+
reabsorption under
parathyroid
hormone control
VERY LOW Na/Cl (NCC) THIAZIDES

20. SEGMENT FUNCTIONS WATER
PERMEABI
LITY
PRIMARY
TRANSPORT
ERS AND
DRUG
TARGETS
DIURETIC
WITH
MAJOR
ACTION
CORTICAL
COLLECTING
TUBULE
Na+
REABSORPTIO
N (2-5%)
COUPLED TO
K+ and H+
SECRETION
VARIABLE Na
CHANNELS,
K Channels ,
H+
Transporter
s,
Aquaporins
K + Sparing
Diuretics ;
Adenosine
antagonists
under trial
MEDULLARY
Collecting
Duct
Water
reabsorption
under
VASOPRESSIN
Control
VARIABLE SEGMENT Vasopressin
Antagonists

21. Diuretics
Presented by
Dr Arun K Negi
Senior Resident
IGMC, Shimla (H.P.)
Dated: 11th March 2024

23. Diuretics
❖ Drugs which increase the excretion of Na+ &
water from the body by an action on kidney.
❖ (Except Osmotic diuretics which do not cause
Natriuresis but produce diuresis)
✓ Primary effect is to decrease the reabsorption of Na+
& Cl- from the filtrate
✓ Increase water loss being secondary to the Increased
excretion of salt.

24. Classifications of Diuretics
❖ Thiazide Diuretics:
a) Thiazides: Hydrochlorothiazide, Benzthiazide
b) Thiazide like: Chlorthalidone, Metolazone, Xipamide,
Indapamide, Clopamide
❖ Loop Diuretics: Frusemide, Bumetanide, Torasemide,
Ethacrynic acid
❖ Potassium Sparing Diuretics:
➢ Aldosterone Antagonist: Spironolactone, Canrenone,
Eplerenone
➢ Directly Acting (Inhibition of Na+ channel):
Triamterene, Amiloride
❖ Carbonic anhydrase inhibitors: Acetazolamide,
Brinzolamide, Dorzolamide
❖ Osmotic Diuretics: Mannitol, Glycerine, Urea,
Isosorbide.

26. Thiazides Diuretics
✓ First discovered in 1957 (chlorothiazide)while trying
to synthesize more potent carbonic anhydrase
inhibitors
✓ Some members of this group retain significant
Carbonic anhydrase inhibitor activity E.g.
Chlorthalidone
✓ Not effective in very low GFR of < 30ml/min, may
reduce GFR further
✓ Metolazone → additional action on PT, effective at
low GFR, can be tried in refractory edema.

27. Thiazide diuretics
✓ The thiazides are the most widely used diuretics
because of their antihypertensive effects
✓ With long term use, these drugs reduce peripheral
vascular resistance.
✓ Thiazides act at early DCT ; called low ceiling becoz
,increasing the dose above normal therapeutic doses
doesn’t produce extra diuretic effect.

28. Thiazide Diuretics - MOA
✓ Thiazide diuretic inhibits NaCl symport in the early
DCT.
✓ Proximal tubule act as secondary site of action
✓ Inhibit Na+ - Cl- symporter and reabsorption
✓ Increase NaCl excretion (5-10% Medium efficacy)
✓ Na+ exchanges with K+ in the DT → K+ loss
→Hypokalaemia.
✓ Mutations in the Na+ - Cl- symporter cause a form of
inherited hypokalemic alkalosis called Gitelman
syndrome.

30. Therapeutic uses of Thiazide Diuretics
❖ Hypertension: clinically thiazides are mainstay of
antihypertensive treatment
✓ Hydrochlorothiazide and Chlorthalidone is considered
becoz of longer half life (50 Hrs)
❖ Congestive Heart failure: Loop diuretics are 1st
choice in reducing extracellular volume in Heart
failure.
✓ In patients resistant to Loop diuretics, thiazides may
be added with careful monitoring for hypokalaemia
e.g. Metolazone is used.

31. Therapeutic uses of Thiazide diuretics
❖ Hypercalciuria: useful in treating idiopathic
hypercalciuria and
✓ calcium oxalate stones in urinary tract, because they
inhibit urinary Ca2+ excretion.
❖ Diabetes Insipidus: as thiazides have unique ability
to produce a hyperosmolar (concentrated) urine
✓ Used in nephrogenic diabetes insipidus
✓ Urine volume may drop from 11L / Day to about
3L/day ,when treated with thiazides.

33. Adverse effects
I. Hypokalemia: because thiazide increase the Na+ in
the filtrate arriving at the distal tubule
• More K+ is also exchanged for Na+ , resulting in a
continual loss of K+ from body.
• Therefore K+ levels should be measured periodically.
• K+ supplementation or combination of K+ sparing
diuretic may be used .
2. Hypomagnesaemia: due to urinary loss of
magnesium (normal level is 1.5-2.5 mEq/ L)

34. 3.Hyponatremia: it develop due to elevation of ADH ;
due to diminished diluting capacity of the kidney
4.Hyperuricemia: increased serum uric acid level by
decreasing the amount of acid
✓ excreted through competition in the organic acid
secretory system.
✓ Being insoluble uric acid deposits in the joints
✓ Therefore to be used with caution in patients with
gout or high levels of serum uric acid.
5. Hypovolemia: It can cause orthostatic hypotension
& light headedness.

35. Adverse effects
6.Hypercalcemia: thiazides inhibit the secretion of
Ca2+ , leading to elevated levels of Ca2+ in blood.
7. Hyperglycaemia: can lead to mild elevation of
serum glucose ; this effect is:
✓ Due to impaired pancreatic release of insulin &
diminished tissue utilization of glucose.
✓ Due to hyperpolarization of beta cells ,thereby
inhibiting insulin release.
✓ Should monitor glucose levels if thiazides initiated

36. Adverse effects
8.Hyperlipidaemia: thiazides causes a 5-15 %
increase in total serum cholesterol & LDL.
✓ These levels may return toward baseline after
prolonged use
9.Allergic reactions (rare ones): photosensitivity,
generalised dermatitis, haemolytic anaemia etc
10.Other toxicities: weakness , fatigability and
✓ impotence(reversible) probably due to volume
depletion.
✓ cases of acute angle closure glaucoma due to
hyponatremia caused by thiazide has been reported.

37. Thiazide drugs
❖ Chlorthalidone: Used only for hypertension, long
acting (t1/2 – approximately 50 hr)
❖ Metolazone: Active even in low GFR. Additive with
furosemide.
✓ Used in CHF patients.
✓ Used mainly for edema, occasionally for hypertension.
❖ Xipamide: More strong diuretic.
✓ Used for edema and hypertension
✓ More incidence of hypokalaemia and ventricular
arrhythmia.
❖ Indapamide: Extensively metabolized ; Very less
amount reach kidney. (Favoured in NICE guidelines
2011)
✓ Used only as antihypertensive.

38. Loop diuretics
✓ Sulphonamide derivative
✓ Most popular powerful diuretic.
✓ Generally cause greater diuresis than thiazides
✓ Can enhance Ca+2 and Mg+2 excretion
✓ Enter tubular lumen via proximal tubular secretion
(unusual secretion segment) because body treats
them as a toxic drug
✓ Drugs that block this secretion reduces efficacy
(e.g. probenecid)

39. Mechanism of action
✓ Loop diuretics blocks the Na+, K+, 2Cl- symporter in
the thick ascending limb of the LH.
✓ It also prevent the reabsorption of Ca+2 & Mg+2
✓ From the loop, they come to DCT where some
sodium & chloride are reabsorbed.
✓ When they come to CD, Na goes out & K
compensates along with H+
✓ This pump is called ROMK; Renal outer medullary
potassium channel & for H+ , it is known as the
ATPase pump.
✓ A Loop diuretic patient will have Hypokalemia &
metabolic alkalosis.

42. High ceiling diuretics (Loop diuretics)
❖ Furosemide–Rapid and short acting, Can be given
IM, IV and oral; plasma T ½ 1-2 hours.
✓ Given Intravenously (10 mg) acts in 2-5 minutes;
✓ Orally (40 mg) it takes 20-40 minutes, Can produce
upto 10 L of urine/day
✓ Effective even in patients with severe renal failure
✓ Cause peripheral venous dilation and relieves LVF
✓ Cause Ca+2 and Mg2+ excretion through urine
✓ Hyperuricemia and Hypokalemia
✓ May cause ototoxicity
✓ Dose: 20 – 80 mg

43. ❖ Edema - 20- 80 mg od
-Hypertension -40mg BD
➢ Acute pulmonary edema – 0.5-1mg/kg iv over
1-2 min. (40-80 mg iv)
➢ Maximum dose in renal insufficiency : 200 mg
6 hrly

44. High ceiling diuretics (Loop diuretics)
❖ Bumetanide – similar to furosemide.
✓ 40 times more potent, Can respond in patients
resistant to furosemide
✓ Can be used in patients allergic to furosemide
✓ Better tolerated because the adverse effects like
hypokalaemia, ototoxicity hyperglycaemia and
hyperuricaemia are milder but may cause
myopathy.
✓ Used in CHF and pulmonary edema
✓ Dose: 1 – 5 mg OD in morning.

45. Bumetanide
✓ More lipid soluble
✓ Oral bioavailability is 80-100 %
✓ Preferred for oral use in severe CHF
✓ Plasma T ½ is 60 minute but gets prolonged in
renal & hepatic insufficiency
✓ 1-5 mg oral morning dose.
✓ 2-4 mg iv/im dose
✓ Maximum dose in renal failure : 15mg/ day.

46. Torasemide – aka torsemide / dytor
✓ Similar to furosemide – 3 times more potent
✓ Slightly longer acting
❑ Used in edema: dose 5-20 mg/day
❑ Hypertension: 2.5-5 mg/day
❑ Renal failure: 100mg Bid
▪ Oral absorption is more rapid and complete in
Patients with edema of bowels due to CHF
▪ Elimination T ½ is 3.5 hrs & duration of action
is 4-8 hrs

48. Etacrynic acid or ethacrynic acid
➢ It is a loop diuretic used to treat high blood
pressure and the swelling caused by diseases
like Congestive heart failure , liver failure and kidney
failure
➢ Unlike the other loop diuretics, etacrynic acid is not
a sulfonamide and thus, its use is not contraindicated
in those with sulfa allergies.
➢ Ethacrynic acid is a phenoxyacetic acid derivative
containing a ketone group and a methylene group.

49. Ethacrynic acid
❑ T½ - 60-90 min
❑ Off label Use - glaucoma
❑ 50-100mg/day –oral
❑ 50mg iv –single dose
❑ Most ototoxic
❑ Vestibular function may also be affected
❑ Inducing vertigo.

50. Uses - Loop diuretics
✓ Edema
✓ Acute renal failure & in chronic renal failure
large doses are needed.
✓ Acute pulmonary oedema
✓ Cerebral oedema
✓ Forced diuresis: In poisoning due to fluoride,
iodide and bromide respond to furosemide with
saline infusion.
✓ Hypertension: With renal impairment
✓ Thiazides are preferred diuretics in primary
hypertension.

51. Uses - Loop diuretics
❑ Hypercalcemia: loop diuretics along with
hydration
✓ are useful in treating acute hypercalcemia
because they stimulate Ca2+ excretion.
❑ In acute Hyperkalemia also used for
management.

52. Loop diuretics: Adverse effects
❑ Hypokalaemia and metabolic alkalosis
(Hypokalaemia should be particularly prevented in post
MI patients) and in patients who are receiving digitalis.
❑ Hyponatraemia, hypovolemia, hypotension and
dehydration
❑ Hypocalcaemia
❑ Hypomagnesaemia
❑ Hyperuricaemia, Hyperglycaemia.
❑ Ototoxicity.
❑ Allergic reactions like skin rashes can occur.
✓ Remember 6 Hypo, 2 Hyper & 1 O

53. Loop & Thiazide drugs: Interactions
❑ Potentiate antihypertensive drugs
❑ Hypokalaemia by diuretics — cause digitalis
toxicity, arrhythmias.
❑ Furosemide with aminoglycosides – Ototoxicity
and nephrotoxicity.
❑ Cotrimoxazole with diuretics: thrombocytopenia
❑ NSAIDS with furosemide — blunt action of
furosemide

54. ❑ Potassium Sparing Diuretics
❖ Aldosterone Antagonist: Spironolactone, Canrenone,
Eplerenone.
❖ Directly Acting (Epithelial Na+ channel blocker):
Triamterene, Amiloride.
❑ Carbonic anhydrase inhibitors
✓ Acetazolamide
✓ Brinzolamide
✓ Dorzolamide
❑ Osmotic Diuretics: Mannitol, Glycerine, Urea,
Isosorbide.

55. Potassium sparing Diuretics
❖ Aldosterone Antagonist: Spironolactone,
Canrenone, Eplerenone.
❖ Directly Acting (Inhibition of Na+ channel):
Triamterene, Amiloride
✓ Mechanism of action
✓ Individual drugs
✓ Pharmacokinetics
✓ Indications
✓ Dose
✓ Side effects and Precautions

56. K + Sparing Diuretics : MOA
❑ Acts on cortical segment of distal tubules/Collecting
duct
❑ Competitive antagonist of Aldosterone
❑ Inhibit ATP → inhibit Na+ reabsorption.
✓ Mild saluretic (natriuresis) 3% of NaCl
✓ Causes K+ retention (K+ sparing effect)
→ Hyperkalemia
▪ Never used alone as diuretic.
▪ Useful when combined with thiazide or frusemide.

59. Spironolactone
❑ It is a steroid, chemically related to mineralocorticoid
Aldosterone.
❑ Oral bioavailability of spironolactone from microfine
powder tablet is 75%
✓ Completely metabolized in liver to generate
✓ Active metabolite Canrenone ; it is responsible for ½
to 2/3 of its action.
❑ Half life of spironolactone is 1-2 hrs & for
Canrenone is approx 18 hrs.
❑ Dose 25-50 mg BD-QID ; max dose:400mg/day

60. Spironolactone - uses
❑ Oedema: Useful in cirrhotic and nephrotic syndrome.
✓ E.g. hepatic cirrhosis (breaks resistance to thiazides
or frusemide in refractory edema)
❑ To counteract K+ loss due to thiazides, frusemide
❑ Resistant Hypertension: combined with thiazide
❑ CHF: as an adjunctive therapy, it retards disease
progression and reduces mortality.
❑ Primary Hyperaldosteronism (Conn’s syndrome)
❑ In Polycystic ovary syndrome: used as off label

61. Spironolactone: Adverse Effects
❑ Hyperkalemia risk
✓ In CRF patients
✓ Patients taking ACEI (Enalapril) or ATRB (Losartan)
✓ KCl supplement/ K+ supplements.
❑ Related to steroid structure
✓ Gynaecomastia, Impotence in males as ADRs.
✓ (note * this drug is used to treat Hirsutism & PCOD
menstrual irregularities in females-as this drug ↓ses
production of testosterone.)
❑ Misc.: drowsiness, abdominal upset.

62. Drug Interactions
✓ May increase plasma digoxin levels in CHF
✓ NSAIDs (Aspirin) decreases its effect by Inhibiting
tubular secretion of its active metabolite canrenone.

63. Potassium sparing diuretics
❑ Eplerenone
✓ More selective aldosterone antagonist
✓ Less hormonal adverse effects
✓ Hyperkalemia risk similar to spironolactone
❑ Uses:
✓ Moderate to severe CHF
✓ Post MI Left Ventricular dysfunction.
❑ Dose: 25-50 mg BD
✓ Well absorbed orally, inactivated in liver by CYP3A4
✓ T ½ is 4-6 hrs.

64. Potassium sparing diuretics: Preparations
❑ Aldosterone Antagonist Dose (mg) Route
✓ Spironolactone 25-100 mg oral
✓ K canrenoate I.V.
✓ Eplerenone 25-100 mg oral
❑ Directly Acting
✓ Amiloride 5mg Oral, Aerosol
✓ Triamterene 50mg oral
✓ Fixed dose combinations with thiazides and frusemide
available but not advisable.

65. Carbonic anhydrase inhibitors
✓ Acts on Proximal tubule
✓ Acetazolamide & Methazolamide
✓ Less potent than Loop & Thiazide Diuretics
❑ Mechanism of action:
✓ Carbonic anhydrase is an enzyme that catalyses the
formation of carbonic acid which spontaneously
ionises to H+ and HCO3-
❖ By inhibiting the enzyme, carbonic anhydrase
inhibitors block sodium bicarbonate reabsorption
and causes HCO3- diuresis.
✓ They induce metabolic acidosis which reduces their
diuretic effect within 2 to 4 days

66. Acetazolamide
✓ Sulphonamide derivative
✓ Enhances excretion of sodium , potassium,
bicarbonate and water.
❖ Other Actions:
1. Eye- reduces intra ocular pressure.
2. Brain- reduces the formation of CSF
❑ Pharmacokinetics:
✓ Well absorbed orally
✓ Onset of action within 60-90 min
✓ Duration of action 8-12 hr.
✓ Excreted unchanged by the kidney

67. Acetazolamide: Mountain sickness
• It is DOC for acute mountain sickness or high
altitude sickness
• MOA: when a person ascends to a high altitude
there is hypoxia causing the patient to breathe
faster & to lose Carbon dioxide
• This will lead to respiratory alkalosis
• Hence Acetazolamide compensates for that by
producing Metabolic alkalosis.

68. Adverse effects
✓ Metabolic acidosis: (due to bicarbonate loss)
✓ Anorexia
✓ Haematuria
✓ Photosensitivity
✓ Melena
✓ Hypokalemia
✓ Drowsiness
✓ Paraesthesia
✓ Urticaria
✓ Renal stones : Ca+2 is lost with HCO3 resulting in
hypercalciuria.

69. OSMOTIC DIURETICS
❑ Mannitol is a pharmacologically inert substance.
✓ Mannitol gets filtered by the glomerulus but is
reabsorbed.
✓ It causes water retention in the proximal tubule and
descending limb of Henle’s loop by osmotic effect
resulting in water diuresis.
✓ There is also some loss of sodium.
❑ Adverse effects: are dehydration, ECF volume
expansion, hyponatremia, headache, nausea,
vomiting and allergic reactions.

70. Uses of Osmotic Diuretics
❑ To maintain urine volume and prevent oliguria in
conditions like massive haemolysis, rhabdomyolysis,
shock and severe trauma.
✓ In such situations mannitol prevents renal failure
✓ To reduce intracranial and intraocular pressure
❑ Contraindicated in patients who have already gone
into renal failure, mannitol can be dangerous since
it can cause pulmonary edema and may precipitate
heart failure due to volume expansion.
❑ Glycerol is effective orally: reduces Intraocular and
intracranial pressure
❑ Methylxanthines like theophylline have mild diuretic
effect.

71. Points to Remember – Clinical Practice
❑ Don’t use diuretics overenthusiastically.
(dehydration, hypotension)
❑ Brisk diuresis in cirrhosis may precipitate
hepatic coma.
✓ Hypokalemia, alkalosis and increased NH3 levels
❑ Diuretics not used in Toxaemia of Pregnancy.
✓ Blood volume is low despite edema.
✓ Diuretics will compromise placental circulation

72. Points to Remember
❑ Most of Loop and Thiazide diuretics are
sulphonamide derivatives.
✓ Think of allergic manifestations
❑ Hypokalemia by diuretics precipitates digitalis,
quinidine side effects.
❑ Hypokalemia by diuretics decrease
sulfonylurea action
✓ reduced insulin release due to reduced action of ATP
dependent potassium channel

73. ✓ High ceiling not given with Amino-glycosides
✓ ACE inhibitors with Thiazides reduce the chances of
hypokalaemia (FDC)
✓ Probenecid inhibits tubular secretion of Frusemide
and Thiazides and reduce action.
❖ Potency of producing hypokalaemia
✓ CAsI >Thiazides > Loop
❖ NSAIDS reduce diuretic action due to PG inhibition
and affecting glomerular blood flow

74. ✓ Acetazolamide action is self limiting
✓ Spironolactone breaks the Thiazide resistance
✓ Aspirin blocks Spironolactone action by inhibiting
tubular secretion of canrenone
✓ Spironolactone can produce dangerous hyperkalaemia
when used along with ACEI and ARBs
✓ Spironolactone has antiandrogenic side effects
✓ Eplerenone is new potassium sparing diuretics with
less antiandrogenic effects.
✓ Osmotic diuretics indicated in impending ARF : Don’t
use if ARF has set in

75. THANKS