Hypertension: 25 mg twice daily initially, increasing to a maximum of 200 mg daily in 2–3 divided dosesBenign prostatic hyperplasia: 20 mg twice daily increasing to a maximum of 100 mg daily in divided doses
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. See ‘Other Information’
DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES
CAPD                :Not dialysed. Dose as in GFR <10 mL/min
HD                     :Not dialysed. Dose as in GFR <10 mL/min
HDF/high flux   :Unknown dialysability. Dose as in GFR <10 mL/min
CAV/VVHD      :Not dialysed. Dose as in normal renal function
IMPORTANT DRUG INTERACTIONS
Potentially hazardous interactions with other drugs
Anaesthetics: enhanced hypotensive effect NSAIDs: antagonism of hypotensive effect
Antidepressants: enhanced hypotensive effect, especially with MAOIs and linezolid – avoid concomitant use
Beta-blockers: enhanced hypotensive effect; increased risk of first dose hypotensive effect
Calcium-channel blockers: enhanced hypotensive effect; increased risk of first dose hypotensive effect
Diuretics: enhanced hypotensive effect; increased risk of first dose hypotensive effect
Moxisylyte: possibly severe postural hypotension when used in combination
Vardenafil, sildenafil and tadalafil: enhanced hypotensive effect – avoid concomitant use
ADMINISTRATION
Reconstition
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Route
Oral
Rate of Administration
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Comments
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OTHER INFORMATION
For BPH, 20 mg at night may be adequate in the elderlyIn the elderly the half-life can be prolonged to 6.6–32.8 hours with a mean of 14.7 hours due to reduced clearanceSeyffart recommends a maximum dose of 50 mg daily for patients with severe renal impairment if not on dialysis. Dialysis patients should receive a maximum of 100 mg daily on dialysis days, but 50 mg on non-dialysis days.