Acetazolamide
Chemical
A CARBONIC ANHYDRASE inhibitor
Use
- Metabolic alkalosis
- Glaucoma
- Altitude sickness
Presentation
PO 250mg tablets
Dose
250 – 1000mg Q4h
MoA
- Non-competitive inhibition of CA
- CA present in PCT (heaps), Thick Asc. LoH
- Intercalated cells of Collecting Duct
- ↓H+ supply in cell of tubule
- H/Na antiporter can’t work
- Na not reabsorbed
- Na+, HCO3–, H2O lost in urine
PD
Renal: excretion of alkaline urine, modest diuresis
Metabolic: hyperchloraemic metabolic acidosis
Resp: ↑MV due to metabolic acidosis
CNS: ↓CSF & intraocular P by ↓rate of CSF & aqueous humour formation
PK
A
OBA 100%
D
90% PPB, high lipid solubility, crosses BBB
E
Not metabolised
K
Unchanged in urine t ½ 7hrs
Adverse Effects
- ↓Na+, ↓K+
- Paraesthesia
- Fatigue
- Drowsiness
- Depression