Core pharmacology

Class Group

Diuretic – Carbonic Anhydrase Inhibitor

Legacy Cicm Level

Level 3

Introduction

Sulfonamide

Indications Uses

Glaucoma
Miniere’s disease
Altitude sickness
Adjunct in epilepsy

Presentation

250mg white tablets
500mg vials for reconstitution

Mechanism of action

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

Physiological effects

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

Adverse Effects Toxicity

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

Tox: Rashes, renal stones

Absorption

IV/PO
PO BA = 100%

Distribution

Lip sol: crosses BBB

Protein binding

70-90%

Metabolism

Not metabolised

Excretion

Unchanged in urine

Half-life

6-9hrs

Route And Dose

250-1000mg q6hrly
IV/PO