Effect Timings
Effect Timings
Onset of Effect
  • IV: 5-7 minutes
  • PO: 1-2 hours
Duration of Effect
  • IV: 3-7 hours
  • PO: Up to 8 hours
Absorption
Absorption
Oral Bioavailability
70-100%
Comments
  • Absorption is rapid, with peak plasma levels within 1-2 hours
Distribution
Distribution
Protein Binding
20%
Volume of Distribution (Vd)
1.7–2.5 L/kg
Comments
  • Readily crosses the blood-brain and placenta barriers
Metabolism
Metabolism
Site
  • Around 40% metabolised in the liver
  • Remaining is excreted unchanged by the kidneys
Metabolites
  • Produces inactive metabolites
  • Excreted renally (95%) and faecally (4%)
Elimination
Elimination
Distribution Half-Life
20 minutes
Terminal Half-Life
~7 hours
Significantly increased in renal failure (up to 23 hours)
Clearance
1.9–4.3 ml/min/kg