Volume of distribution (L/kg)       :1.2
half-life – normal/ESRD (hrs)      :3–4 (8–13 for active metabolite)/Increased (32 for active metabolite)
DOSE IN RENAL IMPAIRMENT
GFR (mL/MIN)
25–50 Dose as in normal renal function, but frequency should not exceed once daily in renal impairment10–25 50% of normal dose, but frequency should not exceed once daily in renal impairment
<10           : 30–50% of normal dose, but frequency should not exceed once daily in renal impairment
DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES
CAPD                :Unknown dialysability. Dose as in GFR <10 mL/min
HD                             :Dialysed. Dose as in GFR <10 mL/min
HDF/high flux   :Dialysed. Dose as in GFR <10 mL/min
CAV/VVHD      :Dialysed. Dose as in GFR=10–25 mL/min
IMPORTANT DRUG INTERACTIONS
Potentially hazardous interactions with other drugs
Anaesthetics: enhanced hypotensive effect
Analgesics: NSAIDs antagonise hypotensive effect
Anti-arrhythmics: increased risk of myocardial depression and bradycardia; increased risk of bradycardia, myocardial depression and AV block with amiodarone
Antidepressants: enhanced hypotensive effect with MAOIs
Antihypertensives: enhanced hypotensive effect; increased risk of withdrawal hypertension with clonidine; increased risk of first dose hypotensive effect with post-synaptic alpha-blockers such as prazosin
Antimalarials: increased risk of bradycardia with mefloquineAntipsychotics enhanced hypotensive effect with phenothiazines
Calcium-channel blockers: increased risk of bradycardia and AV block with diltiazem; hypotension and heart failure possible with nifedipine and nisoldipine; asystole, severe hypotension and heart failure with verapamil
Diuretics: enhanced hypotensive effect
Moxisylyte: possible severe postural hypotensionSympathomimetics: severe hypertension with adrenaline and noradrenaline and possibly with dobutamine
Tropisetron: increased risk of ventricular arrhythmias – use with caution
ADMINISTRATION
Reconstition
–
Route
Oral
Rate of Administration
N/A
Comments
–
OTHER INFORMATION
Administration of high doses in severe renal failure cautioned due to accumulation
Dose frequency should not exceed once daily in renal impairment