20 to 50     : Dose as in normal renal function
10 to 20     : Dose as in normal renal function
<10           : Dose as in normal renal function
DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES
CAPD                :Not dialysed. Dose as in normal renal function
HD                     :Not dialysed. Dose as in normal renal function
HDF/high flux   :Not dialysed. Dose as in normal renal function
CAV/VVHD      :Not dialysed. Dose as in normal renal function
IMPORTANT DRUG INTERACTIONS
Potentially hazardous interactions with other drugs
Anaesthetics: enhanced hypotensive effect
Antibacterials: metabolism accelerated by rifampicin
Anti-epileptics: effect reduced by carbamazepine, barbiturates, phenytoin and primidone
Antifungals: metabolism possibly inhibited by itraconazole and ketoconazoleAntihypertensives: enhanced hypotensive effect; increased risk of first dose hypotensive effect of post-synaptic alpha-blockers
Antivirals: concentration possibly increased by ritonavir
In elderly patients, or where hepatic or renal function is impaired, initial dose should be 1.25 mg twice daily. Dose should be increased according to the requirements of the individual patient.