Diuresis
Reversible, non-competitive inhibitor of carbonic anhydrase
PCT: ↓H+ and HCO3- prodn
↓ cytosol H+ → ↓Na+ reabs in PCT→ ↑H2O loss
↓cytosol HCO3→↑luminal HCO3→ H2O diffusion with HCO3 ,Na, K to urine
Eye: ↓Na pump, ↓AH formation

Diuresis
Inhibition of active chloride ion reabsorption in PCT and ascending limb of LoH
↓ reabsorption of NaCl → ↓ tonicity in the renal medulla → ↓water reabsorption and diuresis.
Other effects are mediated by the induction of the COX-2 enzyme which assists in synthesis of prostaglandins.

Metabolic: Acidosis via ↑ excretion of bicarb (and reabsorption of Cl)
Resp: ↑MV → comp resp alk
CNS: anticonvulsant properties, ↓ CSF and IOP by ↓d formation GIT: ↓ Pancreatic and gastric
GU: mild diuresis, Na retention

Pulmonary and systemic vasodilation
Diuresis ↑ RBF and ↑ corticomedullary blood flow
↓O₂ demand in the LoH (ischaemic
protection)

IV/PO
PO BA = 100%

PO/IV/SL/IM. PO BA 50% Onset PO/SL 30-60mins, IV 5 mins .
Dur PO/SL 6-8hrs, IV 2hrs

Lip sol: crosses BBB

70-90%

91-99% (Albumin)

0.1L/kg

Not metabolised

Renal to glucuronide
Minimal hepatic

Unchanged in urine

80% unchanged in urine

6-9hrs

0.5-2hrs. ESRF: 9hrs

metabolic acidosis, urinary alkalinisation, parathesias, fatigue,
hypokalaemia, N+V, abdo pain

Tox: Rashes, renal stones

↓ K+/Na+/Cl-/Ca++, Hyper- urea/glu/chol, Metabolic alkalosis
Tox: Deafness, Pancreatitis
BM depression
Interstitial nephritis (worse with aminoglycoside)

Diuretic – Carbonic Anhydrase Inhibitor

Diuretic - Loop

Glaucoma
Miniere’s disease
Altitude sickness
Adjunct in epilepsy

Oedema of cardiac, renal or hepatic origin, Renal insufficency
Hypertension
Raised ICP
Hypercalcaemia

Sulfonamide

Sulfonamide derivative

Level 3

Level 1

250mg white tablets
500mg vials for reconstitution

Photosensitive solution 10mg/ml
20/40/500mg tabs, Syrup

250-1000mg q6hrly
IV/PO

20-2000mg daily
PO/IV/SL/IM.